A method for preparing porous adsorbent material, porous adsorbent material, a flow-through column, use of porous adsorbent material, and a system for treating contaminated water

Abstract

Disclosed is a method for preparing porous adsorbent material (22), the method comprising providing a mixture of metakaolin (10) and calcium titanate (12, CaTiO3), mixing the mixture with alkali solution (14) and reacting to obtain alkali-activated modified material (16), providing oil comprising oleic acid (18) as a foaming agent to the alkali-activated modified material (16), and providing hydrogen peroxide (20) as a foaming agent to the alkali-activated modified material (16), and allowing the alkali-activated modified material to foam in the presence of the hydrogen peroxide to obtain porous adsorbent material (22) comprising alkali-activated titanate-modified metakaolin. Also disclosed is porous adsorbent material comprising alkali-activated titanate-modified metakaolin, a flow- through column (24) comprising the porous adsorbent material and system for treating contaminated water.

Description

[0001] A method for preparing porous adsorbent material, porous adsorbent material, a flow-through column, use of porous adsorbent material, and a system for treating contaminated water

[0002] Field of the application

[0003] The present application relates to a method for preparing porous adsorbent material, and to porous adsorbent material and a flow-through column comprising thereof. The present application also relates to a method and for a system for treating contaminated water to remove one or more contaminating substances from the water.

[0004] Background

[0005] Porous adsorbent materials are used in water treatment methods, wherein contaminated water is passed though the adsorbent material, which can absorb contaminating materials from the water. However, the porous adsorbent materials are prepared by using harmful chemical foaming or air-entraining agents, which are not able to provide homogenous porosity, especially at larger volumes. For example, sodium lauryl sulphate (SDS) widely used in prior art methods is harmful and the air-entraining requires use of an oxidizing agent.

[0006] The prior art methods for water treatment involve precipitation chemicals, active carbon or membrane filtration, especially to purify metal-containing waters. These methods are costly, laborious and produce waste, such as in the precipitation process. In the membrane filtration the problems also include blocking of the membrane, high energy consumption, the need for membrane purification chemicals and the like. Active carbon is prepared from problematic raw materials, such as charcoal or coconut charcoal, which are not available everywhere, and the regeneration of the active carbon is often carried out at a distant location.

[0007] There is a need to provide new adsorbent materials, which can be prepared by simple, safe and environment friendly methods. There is also a need to provide adsorbent materials with enhanced adsorption capacity and other properties. For example, it is desired to obtain adsorbent materials with homogenous porosity, and for example granules with controlled size, shape and structure. There is also a need to provide adsorbent materials, which can be regenerated efficiently, and also to find efficient regeneration methods. There is a need to find improved methods for preparing adsorbent materials, which methods are simple, economical, safe, controllable and do not require harmful agents and / or complex or expensive equipment and / or extreme conditions. There is a need to find improved methods for treating water, which methods are simple, economical, safe, controllable and do not require complex or expensive equipment and / or rare materials.

[0008] Summary

[0009] The present materials and methods can overcome drawbacks of prior art and provide solutions to the needs of prior art. The present methods enable controllably preparing efficient adsorbent materials for treating a flow of variety of solutions or dispersions. The present highly porous adsorbent materials can be provided in a form enabling obtaining and / or maintaining high flow of the solution or dispersion through the adsorbent material, while also maintaining a good adsorption capacity.

[0010] The present adsorbent material is a composite alkali-activated material (AAM), wherein calcium titanate is added to the alkali-activated material during preparation. This provides about 50% higher adsorption capacity compared to pure alkali-activated material. It was noted that the titanate is bound to the network structure of the alkali-activated material thus enhancing waste purification efficiency.

[0011] The present application provides a method for preparing porous adsorbent material, the method comprising

[0012] -providing metakaolin and calcium titanate (CaTiOs), mixing e with alkali solution, and reacting to obtain alkali-activated modified material,

[0013] -providing oil comprising oleic acid as a foaming agent to the alkali-activated modified material, and

[0014] -providing hydrogen peroxide as a foaming agent to the alkali-activated modified material, preferably in mixing, and preferably after the oil comprising oleic acid has reacted with the alkali, and

[0015] -allowing the alkali-activated modified material to foam in the presence of the hydrogen peroxide to obtain porous adsorbent material.

[0016] The present application provides porous adsorbent material comprising alkali- activated titanate-modified metakaolin. The present application provides a flow-through column comprising the porous adsorbent material.

[0017] Disclosed is a method for treating water or aqueous solution, such as contaminated water, to remove one or more substances, such as contaminating substances, from the water or the aqueous solution, the method comprising -providing water or aqueous solution, such as contaminated water, -providing the porous adsorbent material or one or more of the columns, and -contacting the water or the aqueous solution, such as the contaminated water, with the adsorbent material to adsorb one or more substances, such as contaminating substances, to the porous adsorbent material.

[0018] Disclosed is a method for regenerating the porous adsorbent material comprising one or more adsorbed substances and / or recovering the adsorbed substances, the method comprising

[0019] -treating the porous adsorbent material, preferably comprising the adsorbed substances, with an aqueous regeneration solution comprising sodium citrate to desorb one or more of the substances from the porous adsorbent material to the aqueous regeneration solution and to regenerate the porous adsorbent material.

[0020] The present application provides a system for treating water or aqueous solution, such as contaminated water, the system comprising

[0021] -preferably a source of water or aqueous solution, such as contaminated water, -one or more flow-through columns containing the porous adsorbent material, -means for providing flow of aqueous solution through the column, wherein the one or more columns is / are arranged to be run into a first direction of flow to convey the water or the aqueous solution, such as the contaminated water, from the source of water or aqueous solution, such as contaminated water, to the column,

[0022] -a source of washing solution, and preferably

[0023] -means for reversing the flow to a second direction to convey the washing solution to the column in the second direction of flow.

[0024] The present application provides use of the porous adsorbent material, or the flow- through column, for any of the methods disclosed herein, such as for treating water. The preset application provides use of a flow-through column comprising porous adsorbent material comprising alkali-activated titanate-mod ified metakaolin for any of the methods disclosed herein.

[0025] The main embodiments are characterized in the independent claims. Various embodiments are disclosed in the dependent claims. The embodiments and examples disclosed herein are mutually freely combinable unless otherwise explicitly stated. The embodiments and examples not in the scope of the claims are embodiments and examples not part of the invention, but useful for understanding the invention.

[0026] The present adsorbent materials can be used to treat a variety of contaminating agents and / or other agents from a variety of sources, which include for example different waters and aqueous solutions, such as waste waters, industrial waters, washing solutions and liquids containing valuable metals. The present materials and methods are cost-efficient, safe and environmentally friendly. They do not include harmful air-entraining or foaming agents, but instead use safe materials providing homogenic porosity even at large volumes. The present adsorbent materials are especially suitable for treating waste waters from a variety of industrial processes, especially to purify water waters from metals and to recover valuable metals.

[0027] The present adsorbent materials can be formed into different forms, which enable providing tailored materials for different uses. For example, flow-through columns are suitable for uses such as treating waste waters, whereas powdery material may be desired for uses such as treating solutions containing organic substances, for example pharmaceutical compounds. The adsorbent material can be casted directly to the column or the like casing to enhance the porosity and surface area without any support structure.

[0028] The present materials can be regenerated using simple, economical and safe regeneration solution. This could be done at the same time as the adsorbed substances were desorbed from the adsorbent material.

[0029] Brief description of the figures

[0030] Figure 1 shows a flowchart of an example of a method for preparing porous adsorbent material, optionally also final product. Figure 2 shows a flowchart of an example of a method for treating contaminated water.

[0031] Figure 3 shows the raw materials for preparing the adsorbent material.

[0032] Figure 4 shows drying of the mass in an oven.

[0033] Figure 5 shows examples of final products comprising the adsorbent material.

[0034] Figure 6 shows an exemplary setup for desorption of adsorbed copper with regeneration solution from a column comprising the adsorbent material.

[0035] Figure 7 shows samples of crystallized citrate metal complexes including, from left for right, copper, cadmium, cobalt and nickel.

[0036] Figure 8 shows XRD of an example of the adsorbent material. The compounds are: 1 ) calcium titanium oxide, 2) silicon oxide, 3) aluminium oxide silicate, and 4) sodium aluminium silicate hydroxide hydrate.

[0037] Figure 9 shows DRIFT of an example of the adsorbent material. The vibrational modes are: a) TiO2 / SiO2, b) Ti-O-Ti, c) TiO2 / SiO2, d) Ti-O, e) Si-O- Si, g) Ti-0 and h) AI / Si-OH—H2O

[0038] Figure 10 shows XPS analysis results of an example of the adsorbent material: a) survey, b) O1s scan.

[0039] Figure 11 shows a SEM image of an example of the adsorbent material.

[0040] Figure 12 shows a SEM distribution map of the elements.

[0041] Figure 13 shows an EDS of an example of the adsorbent material.

[0042] Figure 14 shows determination of surface charge of the material by acid-base titration method

[0043] Figure 15 shows the effect of concentration and flow rate on adsorption efficacy (a, c) and q-values (b, d). With a) and b), the flow rate was 100 mL / min, pH 4.5 and temperature 25°C. With c) and d), the concentration was 500 mg / L, pH 4.5 and temperature 25°C. All experiments were performed in closed loop configurations.

[0044] Figure 16 shows the effect of the concentration (a) and pH value (b) of citrate to the regeneration for Zn, Mn and Cu. With (a), the pH was 8.6, flow rate 50 mL / min and temperature 25°C. With (b), the citrate concentration was 0.1 M, flow rate 50 mL / min and temperature 25°C.

[0045] Figure 17 shows adsorption efficacy as % (a), regeneration efficacy as % (b), qads as mg / g (c) and qregas mg / g (d) for 31 consecutive adsorption-regeneration cycles of Cu. Adsorption was conducted with pH of 4.5, concentration of 500 mg / L, flowrate of 100 mL / min and temperature 25°C. In regeneration, pH was 6.6, concentration 0.5 M, flowrate 50 mL / min and temperature 25°C.

[0046] Figure 18 shows metal oxide distribution in the column after adsorption by XRF. The concentration of copper solution after 31stadsorption-desorption cycle was 1000 mg / L, pH was 4.5 and temperature 25°C. Fresh adsorbent is labelled as native for comparison.

[0047] Figure 19 shows proposed structure of titanate modified AAM, structure after deprotonation and when pre-regenerated with sodium citrate solution before experiments. ••• illustrates the continuum of the basic AAM framework.

[0048] Figure 20 shows possible adsorption mechanism of Me2+to titanate modified AAM. The number of adsorption sites are (1 ) direct ion exchange with Na+attached to the aluminium, (2) ion exchange with two Na+of TiC -group, (3) ion exchange with two Na+attached to TiO-SiO groups and (4) ion exchange with two Na+of SiO2 group. ••• illustrates the continuum of the basic AAM framework.

[0049] Figure 21 shows a possible regeneration mechanism of Me2+with di- and trisodium citrate species. The number of proposed different regeneration mechanisms are (1 ) adsorbed Me2+ion exchange with di- and trisodium citrate forming a linkage between these two forms, (2) ion exchange with trisodium citrate, (3) ion exchange with disodium citrate and (4) ion exchange of Me2+AAM’s aluminium. ••• illustrates the continuum of the basic AAM framework. Detailed description

[0050] In this disclosure, percentage values, unless specifically indicated otherwise, are based on weight (w / w, by weight, or wt%). In specific examples the embodiments and examples specified with the open term “comprise” may be further limited with a closed term “consisting of’.

[0051] The diameters disclosed herein, unless specifically indicated otherwise, may refer to the smallest diameter, and may be presented as average or number-average diameter. The diameter may be also presented as equivalent spherical diameter. The diameter may be determined microscopically or by other optical methods, which may comprise using a camera, and / or by sieve analysis. More particularly, the disclosed dimensions or other features may be measured by image analysis of microscope images, such as images from a light microscope, a field emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), such as a cryogenic transmission electron microscope (CRYO-TEM), or an atomic force microscope (AFM). A suitable imaging and / or analysis software may be used to determine the dimensions and / or the other features.

[0052] The term “alkali-activated” in the art of clay minerals has a specific meaning known for a skilled person. In alkali activation a reaction of aluminium / silicon-based precursor and alkali activator is obtained in a solution at alkaline / high pH, wherein the structure of the precursor disintegrates, and the aluminium and silicon species of the precursor begin to solubilise to the activator. In the alkali activation a silicate solution containing sodium and / or potassium may be obtained, depending on the activator. Silicate is used to provide enough silicon for forming a desired structural network by polymerisation. The ratios of AI2O3 and SiO2, SiO2 and Na2O and well as Na2O and H2O are controlled to obtain a desired formation of final adsorbent material.

[0053] Alkali-activation of clay minerals require concentrated alkaline solutions, such as [OH] > 5 M, corresponding to pH > 14. An optimal range is empirically established as 8-12 M, and preferably a pH of 10 or more, more preferably 11 or more of the solution is used. After this a polymerisation reaction occurs by rearrangement of the species at the highly alkaline conditions. At a lower pH no polymerisation reaction occurs, and the material merely solubilizes and disintegrates. In the present case metakaolin and calcium titanate as precursor materials are reacted at the alkaline pH. The present alkali-activated material (AAM), more particularly alkali-activated adsorbent material or porous alkali-activated adsorbent material, is prepared by using metakaolin as a starting material, which is modified in the method. Metakaolin is anhydrous calcined form of clay mineral kaolinite.

[0054] The metakaolin may be prepared by heating calcined kaolin to an activation temperature, for example to 650-750°C, with controlled temperature increment, for example with rate 3-10°C / min, maintaining the temperature for 2-5 hours, such as for about 3 hours, and decreasing the temperature, preferably in controlled manner, for example with rate 3-10°C / min. In one example the metakaolin is prepared by heating calcined kaolin from about RT / 25°C to about 750°C with about 5°C / min increment, maintaining at about 750°C for about 3 hours, and decreasing the temperature from about 750°C to about RT / 25°C with about 5°C / min decrease.

[0055] The method for preparing porous adsorbent material, as shown in the example of Figure 1 , comprises providing metakaolin (10) and calcium titanate (12) (CaTiOs), which may be provided as a mixture or added separately, mixing with alkali solution (14), and reacting to obtain alkali-activated modified material (16). The alkali-activated modified material (16) may comprise modified metakaolin. Preferably the metakaolin (11 ) and the calcium titanate (12) are both provided as dry solid, such as in dry powder form, and may be combined to obtain a mixture (10). The calcium titanate is in practice a part of the metakaolin. They may be provided in a weight percentage ratio of 70-80:30-20 metakaolin to calcium titanate, such as about 75:25. The obtained dry mixture, or the metakaolin and calcium titanate separately, is / are mixed with alkali solution to obtain a mixture, which may be called as a mass.

[0056] It was found out that using calcium titanate (12) in the modification and activation and to replace a part of the metakaolin increased the adsorption capacity of the adsorbent material compared to alkali-activated material obtained from metakaolin without calcium titanate, such as by about 30% when 25% by weight of metakaolin was replaced. The calcium titanate forms a complex with aluminium contained in the metakaolin (10) thus increasing the adsorption capacity.

[0057] The calcium titanate (CaTiOs) may be obtained from perovskite, which is a calcium titanium oxide mineral. Calcium titanate may be also obtained by combining CaO and TiO2 at temperatures above 1300°C. The alkali solution (14) may be an aqueous solution, and it may be prepared and / or provided with a desired alkali ratio and / or aerated before providing and / or mixing, for example by using a homogenizer. In one example the method comprises aerating the alkali solution before mixing with the metakaolin and calcium titanate. This was found to enhance the preparation of the mixture, which may be a viscous mass. The alkali solution may comprise sodium silicate (Na2SiOs • H2O) and sodium hydroxide (NaOH).

[0058] The pH of the alkali activator solution is increased by using alkali, such as NaOH or KOH. The pH is increased to a level wherein the aluminium, titanium and silicon of the precursor material begin to solubilize and wherein the polymerisation reaction occurs. The pH may be increased to 10 or more, 11 or more, or 12 or more. However, the polymerisation is not complete due to relatively low drying temperature, which is below 100°C, wherein hydrated water and Na+and / or K+ions are left in the structure. These facilitate ion exchange, and the applications disclosed herein such as water purification. If higher drying temperatures would be used, the hydrated water and the ions would be lost and the material would become unreactive geopolymer, which would be classified as concrete.

[0059] The method may comprise

[0060] -mechanically aerating / foaming the alkali solution (14),

[0061] -adding the metakaolin (11 ) and the calcium titanate (12) to the aerated / foamed alkali solution (14) in mixing, and

[0062] -reacting to obtain the alkali-activated material (16).

[0063] The aerating and / or foaming may be carried out with a homogenizer or any other suitable aerating and / or foaming device. The homogenizer may be a disperser, and / or it may have a rotor-stator structure.

[0064] The metakaolin and the calcium titanate may be added to the aerated alkali solution in a ratio of 60-80:40-20 by weight, such as 70-80:30-20 by weight, for example about 75:25 by weight of metakaolimcalcium titanate.

[0065] To foam the material, and to form porous material, suitable foaming agents are required. The foaming may be called air-entraining, and the foaming agent(s) may be called air-entraining agents or aids. The formed porous material may be called foamed material or air-entrained material. With the present method it was possible to control the foaming and porosity during the process and in the final product. It is desired to avoid less controllable, less efficient, harmful and / or expensive foaming agents, such as added aluminium powder, used in prior art methods, so the total foaming agents may consist of the first and the second foaming agents disclosed herein.

[0066] It was found out that by using vegetable / natural oil provided double effect of aerating / air-entraining the material by releasing oxygen at alkalic conditions and acting as aid for the further foaming agent peroxide due to change in the viscosity of the mass (mixture). Thus, the oxygen produced by the hydrogen peroxide can act more freely thus enhancing the homogeneity of the forming porosity.

[0067] Further, such oils are environmental-friendly and safe. Preferably the method does not involve other types of oils.

[0068] The method comprises providing oil comprising oleic acid (18) as a first foaming agent, or providing a first foaming agent comprising oil comprising oleic acid 18, to the alkali-activated modified material. The oil comprising oleic acid may refer to natural oil, such as vegetable oil, which contains suitable fatty acids and / or composition thereof, which could provide the discussed effects, and which enabled controlling and forming desired products with desired properties.

[0069] The oil comprising oleic acid may comprise 55% by weight or more oleic acid, preferably 70% by weight or more, of the total fatty acid content of the oil. In one example the oil comprising oleic acid comprises oleic acid in the range of 55-83% by weight of the total fatty acid content of the oil.

[0070] In one embodiment the oil comprising oleic acid comprises mainly or substantially only unsaturated fatty acids, such as 80% by weight or more, 85% by weight or more, or 90% by weight or more, of the total fatty acid content of the oil. Preferably the oil comprising oleic acid comprises mainly monounsaturated fatty acids of the total content of saturated fatty acids. The content of monounsaturated fatty acids of the total fatty acid content of the oil may be 60% by weight or more, such as 65% by weight or more, such as in the range of 65-85% by weight, which is usually the case with extra virgin olive oil. Such fatty acid composition was found to increase the degree of porosity in the final material. In general, natural oils can be used, but if the oil contains saturated and / or polyunsaturated fatty acids in substantial amounts, the degree of porosity remains lower compared to when mainly or substantially only monounsaturated fatty acids were used. In one embodiment the oil comprising oleic acid is olive oil, preferably virgin olive oil, such as extra virgin olive oil. This oil was found to have a suitable fatty acid content for preparing the present materials. Other suitable vegetable oils having high monounsaturated fatty acid content include rapeseed oil, peanut oil and almond oil. However, of these the rapeseed oil is industrially most applicable due to its good availability and low price.

[0071] The method comprises providing hydrogen peroxide (20) as a second foaming agent, or providing a second foaming agent comprising hydrogen peroxide (20), to the alkali-activated modified material. A mixture is obtained. The second foaming agent may be provided at the same time as the first foaming agent, such as the oil comprising oleic acid, but preferably it is provided subsequently, i.e. after the first foaming agent, such as the oil comprising oleic acid, has reacted with the alkali, at least partly.

[0072] This, and / or other method steps, especially ones including combining ingredients, may be carried out in mixing, such as by using a suitable mixer.

[0073] The product may be obtained by using only the ingredients disclosed herein, so preferably the method and / or the product directly obtained from the method does not comprise other ingredients. However, it is possible to further modify the product, for example after the preparation and / or after the product has obtained its final form, and / or other agents not having substantial effect to the formation of the product may be included.

[0074] The method comprises allowing the alkali-activated modified material to foam in the presence of the second foaming agent to obtain porous adsorbent material (22) comprising alkali-activated titanate-modified metakaolin. This material is foamed material, which is different from porous materials obtained without foaming. The foaming may be controlled, for example by controlling the amount of one or more of the foaming agents, such as the oil comprising oleic acid and / or hydrogen peroxide, and / or carrying out the foaming and / or reacting for a time period and / or at conditions suitable for obtaining a desired foaming, for example desired porosity, desired homogeneity, and / or properties, which may be properties of the final product. With the present process the obtained material is homogenous, for example the material has homogenous porosity, such as even and / or homogenous distribution of pores and / or material. In one embodiment the amount of the hydrogen peroxide is in the range of 0.1- 0.5% by weight, such as in the range of 0.2-0.4% by weight, for example about 0.3% by weight, of the total amount of the mixture of the alkali-activated modified material, the oil comprising oleic acid and the hydrogen peroxide before the foaming.

[0075] The method may comprise washing the dewatered porous adsorbent material, for example with water and / or aqueous solution, preferably at an elevated temperature, such as at about 75°C, for example one or more times. The fatty acids of the oil are digested into glycerol at the alkalic conditions, and the washing may be carried out to wash the glycerol from the material, or at least part thereof. The washing may be continued until the washing water fulfils one or more predetermined criteria, such as has a certain pH, for example about 8.5, has a lowered content of glycerol and / or any other substance considered as impurity, for example unreacted reactant, preferably under certain predetermined level.

[0076] The porous material may be finally formed into a desired form, which may depend on the intended application of the material. The method may comprise forming the porous adsorbent material into form of a product (23) and preferably dewatering the product. The dewatering is carried out at conditions and / or for a time period enabling obtaining a desired dry matter content and / or other properties, such as degree of polymerisation. The dewatering may be carried out at elevated temperature of 50°C or more, such as 60°C or more, but preferably below 100°C, such as 90°C or less, for example 80°C or less. The final dry matter content may be 90% or more by weight, such as 95% or more by weight, preferably 99% by weight or more.

[0077] A product (23) comprising the porous adsorbent material is obtained, such as a dewatered product. The product may have a specific form, which may be characterized by dimensions, porosity, bulk density, surface area, composition, properties measured by for example FTIR, DRIFT, SEM, EDS, and / or XPS and / or the like properties.

[0078] In one embodiment the product (23) comprises or is a granule or granules. The granule(s) may be granulated granule(s), wherein the forming may comprise granulating the mixture of the alkali-activated modified material, the oil comprising oleic acid and the hydrogen peroxide and / or the porous adsorbent material with a granulator / granulating device. The granules may have an average diameter in the range of 1-10 mm, for example in the range of 1-5 mm, such as 1-4 mm, 1-3 mm, 2-4 mm, or 3-5 mm. The average diameter may be also obtained and / or determined with sieves in a mesh scale, for example in the range of 18-7 / 16.

[0079] The granules may be fractionated, such as sieved, to obtain one or more fractions with a desired average or range of particle (granule) size(s), such as an average diameter, which may be number-average diameter, and / or to obtain one or more fractions with a desired granule weight, density, porosity and / or other property, which may have an impact to suitability of the granules to a specific end use. The average particle diameter of the granules may be determined as a volume median particle size or diameter. Particle sizes or diameters of non-spherical granules can be determined or presented as equivalent spherical diameter (ESD). The equivalent spherical diameter of an irregularly shaped object is the diameter of a sphere of equivalent volume.

[0080] In one embodiment the product (23) comprises or is a pellet or pellets, wherein the forming may comprise pelleting / pelletizing the mixture of the alkali-activated modified material, the oil comprising oleic acid and the hydrogen peroxide and / or the porous adsorbent material with a pelleting / pelletizing device, or forming the pellets by compacting and / or crushing the porous adsorbent material. However, if spherical or substantially spherical pellets are desired, a pelletizing device is preferred. The pellets may have an average diameter in the range of 1-20 mm, for example in the range of 5-20 mm, 1-10 mm, or 3-10 mm.

[0081] In one embodiment the product (23) comprises or is powder, wherein the forming may comprise disintegrating, such as grinding, crushing, powdering or pulverizing, the (dry) porous adsorbent material, such as a moulded object of the material, to obtain powder, preferably to obtain powder having an average particle diameter in the range of 125-1000 pm. In one example the powder is prepared by moulding the adsorbent material into a mould, allowing to dry, harden and / or cure, and disintegrating, such as grinding, crushing, powdering or pulverizing the dried material into powder, preferably into powder with a desired particle or grain size. As the calcium titanate form a complex with the aluminium of the metakaolin, the product exhibits photocatalytic properties, which are especially provided when the material is in powder form. Because of the complexing the photocatalytic properties are presented at visible light ranges, and no UV light is required for photocatalytic activity. The external surface area is large in powder form, for example compared to column form, wherein the powdery form is especially suitable for example for removing organic molecules such as pharmaceuticals.

[0082] Preferably majority of the granules, the pellets or the powder particles has / have a diameter in the disclosed range. The majority may refer to at least 50%, to at least 60%, to at least 70%, to at least 80%, to at least 90%, or to at least 95%, which may be determined by volume or by number. Regarding the shape, majority, or preferably all or substantially all of the granules, the pellets or the powder particles have the spherical shape, for example at least 80%, at least 90% or at least 95% have the spherical shape.

[0083] The present granules, pellets or powder particles may be specified as having a very high sphericity and roundness, preferably close to 1 each, such as 0.80 or more, for example 0.90 or more. Sphericity is a measure of how closely the shape of an object resembles that of a perfect sphere. Roundness is the measure of how closely the shape of an object approaches that of a mathematically perfect circle. The very high sphericity and roundness indicate the preparation method, i.e. they may be a result of granulation process, as it is not possible to obtain spherical and round granules by crushing, milling or casting. Crushing may comprise methods including breaking the structure of material to obtain smaller particles or blocks, such as by milling, cutting and / or the like procedures. Such methods yield very small particles, even powder, which may have an average diameter of less than 1000 micrometers, less than 500 micrometers or less than 100 micrometers, and which may have an uneven shape.

[0084] In one embodiment the product (23) comprises or is foam, wherein the forming may comprise foaming the mixture of the alkali-activated modified material, the oil comprising oleic acid and the hydrogen peroxide. Such product may have not been disintegrated, granulated and / or otherwise (mechanically) modified, for example with methods disclosed herein. The foam is a foamed foam, which means that it is obtained in a foaming process. A foam may be present in substantially larger entities, for example having at least one diameter of 5 mm or more, such as 10 mm or more or 15 mm or more, and it may be non-granular, unpelletized and / or unpowderized. The foam may be present as a monolithic form.

[0085] Porosity may be defined as the ratio of the volume of the voids or pore space divided by the total volume, and expressed as a percentage. The porous material may have a porosity in the range of 30-90%, such as in the range of 30-60%, 40- 70%, 40-80%, 50-80%, or 50-90%. Pore size and pore volumes of the samples can be measured using a N2 gas adsorption-desorption isotherms, pycnometer, microscope combined with image analysis, or X-ray microtomography, preferably by using a dedicated instrument such as a porosimeter.

[0086] The granules, pellets, powder and / or other forms of the porous material may be characterized with one or more further properties disclosed herein, or other properties. The properties may be determined by using standard methods, such as by microscopic methods, for example electron microscopy methods such as SEM, EDX, TGA, XRD, XRF, and the like commonly used methods for characterizing inorganic granules and / or inorganic materials. Properties determined by for example SEM, FTIR, DRIFT, EDS, and / or XPS, were determined in the Examples.

[0087] Content of elements in the material, as determined by XRF, for examples as shown in Table 1 , indicate that the product comprises alkali-activated titanate- modified metakaolin. The composition can be characterized for example with XRD, which shows as main peaks one or more of calcium titanium oxide Ca(TiOs) with 20 values of 33.0, 33.2, 33.4, 47.6, 59.5, 69.7, 79.5; silicon oxide SiO2 26.7, 50.2; aluminium oxide silicate A^OsSi 26.7, 27.6, 34.9, 40.7 and / or sodium aluminium silicate hydroxide hydrate AleH Nao.sC^Sis 19.8, 35.0, 62.1 , respectively.

[0088] The composition of the product can be also characterized by DRIFT spectrum identifying one or more bands / wavenumbers at 1650 cm’1and 3400 cm’1corresponding to O-H stretching vibrations and H-O-H bending vibrations of water molecules in AI / Si-OH*«H2O; one or more of the rest of the bands from 450 to 1200 cm’1corresponding to TiC / SiC , Ti-O-Ti, Ti-O, Si-O-Ti, Si-0 and Ti-0 vibrations; one or more of the main bands with wavenumber 768 cm’1and 1200 cm’1corresponding to Ti-0 vibrations from TiO4, followed by Si-0 symmetrical stretching at 1058 cm’1; the band at 768 cm’1also corresponding to Si-O-AI from the metakaolin; one or more of the bands with a wavenumber from 866 to 954 corresponding to Si-O-Si / Si-OH bending and Si-O-Ti from condensed TiO4 vibrations; and / or one or more of the wavenumber bands from 439 cm’1to 461 cm’1corresponding to TiO2 / SiO2 vibrations, Si-O-Si and Ti-O-Ti rocking, respectively.

[0089] XPS survey can be also used for characterizing the product identifying one or more of AI2p oxide with binding energy 74.4 eV; Si2p oxide 102.6 eV; Si2s 153 eV; Ti2p oxide 456.6 eV; Ti2p 1stand 2ndbulk plasmon 500 eV and 01 s 531 .4 eV, as main peaks. One or more other values from Table 2 may be used as well.

[0090] It is confirmed by the experimental data presented in the Examples that the titanate is bound to the network structure of the alkali-activate material. The Ti-O- Ti, Ti-O, and / or Si-O-Ti bonds can be used for characterizing the present product. These indicate titan bound by oxygen bonds to silicon of the alkali-activated material.

[0091] The morphology of the surface and general pore size distribution can be detected by electron microscopy, such as by SEM. SEM can be also used to identify the distribution of elements in the material, wherein can be seen that especially titanium is evenly distributed on the surface.

[0092] SEM with energy dispersive X-ray spectroscopy (SEM-EDS) can be also used for materials characterization and to show the elements present in the material.

[0093] In one embodiment the product (23) comprises or is a mould product, wherein the forming may comprise applying the mixture of the alkali-activated modified material, the oil comprising oleic acid and the hydrogen peroxide into a mould. The mould product may be in a monolithic form, and it may be inside a mould, which may be a column or the like structure and / or a casing, which allows the use of the porous materials for example in methods for treating water and the like. The mould product may be in a flow-through column (24) or the like flow-through structure.

[0094] In one embodiment the method comprises

[0095] -providing, such as moulding, the alkali-activated modified material (16), the oil comprising oleic acid (18) and the hydrogen peroxide (20) into a casing, such as into a flow-through casing, or into a flow-through column,

[0096] -allowing the alkali-activated modified material to foam in the presence of the oil comprising oleic acid and the hydrogen peroxide to obtain porous adsorbent material (22) mould into the casing or into the flow-through column (24), and -dewatering the foamed adsorbent material mould into the casing or into the flow- through column. The dewatering may be carried out at elevated temperature of 50°C or more. The dewatered adsorbent material may be washed, for example by flowing water or aqueous solution through the flow-through casing or the flow- through column. A product (23) is formed, which may comprise or be a flow- through column (24). The method may be a method for preparing a column, such as a flow-through column (24), comprising porous adsorbent material. This can be done by providing, such as by moulding, and by foaming the adsorbent material into the column, as described herein.

[0097] The present disclosure provides porous adsorbent material comprising alkali- activated titanate-mod ified metakaolin. The porous adsorbent material may be obtained by any of the methods disclosed herein.

[0098] The porous adsorbent material may be in the form of granules. The granules may be granulated granules, which may be obtained by using a granulating device, i.e. a granulator. Crushed granules or the like disintegrated particles may be excluded, i.e. the granules may be uncrushed.

[0099] The porous adsorbent material may be in the form of pellets, which may be pelletized pellets or pellets obtained by disintegrating, such as by cutting, for example by cutting an elongated piece of material or a sheet of material.

[0100] The porous adsorbent material may be in the form of powder. The powder may be obtained by grinding, crushing or the like mechanical disintegration method. Powder with a desired particle size and / or distribution can be obtained by controlling the disintegration / powdering method. The powder may be crushed powder.

[0101] The porous adsorbent material may be in the form of foam. The foam refers to pieces or an entity of the foamed material, which may be present as separate pieces of entity / entities, or which may be mould in a mould, such as a column, a casing or the like, such as a flow-through column or casing. Also granules, pellets and other forms of the material include foam form.

[0102] The porous adsorbent material may be in the form of a mould product. The mould product may be provided in the mould, such as wherein the mould is a column, a casing or the like structure which is included in the final product. For example, the mould product may comprise adsorbent material mould into a column or a casing, which may have a flow-through structure.

[0103] The present disclosure provides a flow-through column (14) comprising the porous adsorbent material (12), preferably in a casing. The flow-through column may be obtained by the method disclosed herein, which comprises providing the alkali- activated modified material, the oil comprising oleic acid and the hydrogen peroxide into a flow-through casing or a flow-through column.

[0104] In general level the present disclosure provides a method for treating aqueous solution comprising one or more substances of interest, as shown in the example of Figure 2, to remove and preferably recover one or more substances of interest from the aqueous solution, the method comprising

[0105] -providing aqueous solution comprising one or more substances of interest (20), -providing the porous adsorbent material (22) comprising alkali-activated titanate- modified metakaolin or one or more columns, such as one or more flow-through columns (24), comprising the porous adsorbent material (22) comprising alkali- activated titanate-modified metakaolin,

[0106] -contacting the aqueous solution comprising one or more substances of interest with the adsorbent material (22) to adsorb one or more substances of interest. The adsorbed one or more substances of interest may comprise substantially the one or more substances of interest in the aqueous solution, or the adsorbed one or more substances of interest may comprise less than all, such as less than all the types of, substances of interest in the aqueous solution. As a result, treated and / or purified water is obtained. The method may be a method for purifying water, contaminated water, wastewater, metal-containing water, or any other aqueous solution, such as disclosed herein. The term “substance” as used herein refers to the substances of interest in general, which cover contaminating substances, reaction products and other applicable substances.

[0107] The aqueous solution comprising one or more substances of interest may be considered as contaminated water (20). The contaminated water (20) may be any applicable water or aqueous solution or dispersion, which contains one or more substances, which may be considered as a contaminant, and / or as a substance of interest, wherein it may be desired to remove and preferably recover the substance(s) from the contaminated water. If necessary, the contaminated water, especially when present as a dispersion comprising particles, may be filtered or otherwise pretreated to prevent clogging of the adsorbent material. A “solution” was used herein may refer to the water or the aqueous solution or a dispersion comprising the contaminants and / or substances of interests. The term “solution” in this context thus may refer to the “contaminated water” or to the “aqueous solution comprising one or more substances of interest”. The present disclosure provides a method for treating contaminated water to remove one or more contaminating substances from the water, the method comprising

[0108] -providing contaminated water (20),

[0109] -providing the porous adsorbent material (22) comprising alkali-activated titanate- modified metakaolin or one or more columns, such as one or more flow-through columns (24), comprising the porous adsorbent material (22) comprising alkali- activated titanate-modified metakaolin,

[0110] -contacting the contaminated water with the adsorbent material (22) to adsorb one or more contaminating substances. The porous adsorbent material (22) may be obtained by any of the methods disclosed herein.

[0111] The present disclosure also provides use of the porous adsorbent material (22) comprising alkali-activated titanate-modified metakaolin for treating contaminated water to remove one or more contaminating substances from the water with the method.

[0112] The method may comprise providing visible light to the adsorbent material to obtain photocatalytic activity. Light outside visible range, such as UV light, is not necessary and may be excluded. A suitable light source may be provided and operated.

[0113] The adsorbent material may be treated to release the adsorbed substances with a method, which also results in regeneration of the adsorbent material. When the adsorption capacity of the material is used / reached, which may be detected, the material may be washed with eluent, such as with sodium citrate solution, which result in desorption / elution of the adsorbed substances, such as metals, into the solution. The desorption process can be optimized to each substance, such as each metal, by adjusting the pH value of the solution. Part of the adsorption mechanism of the present AAM is based on ion exchange, so by using a solution of sodium citrate the sodium in the solution can replace the most common regeneration agent sodium chloride. Therefore, the sodium citrate provides dual action thus providing both desorption and regeneration with a single agent. The substances, such as metals, desorbed into the citrate solution can be reused either as such, for example as fertilizers (such as in the form of zinc and / or copper citrate), or they can be recovered by breaking the metal-citrate complex with strong sulphuric acid and increasing the pH to the hydroxide range of each metal thus resulting in precipitation of the metal. The metals can be recovered also by crystallizing to obtain solid end product.

[0114] With the present regeneration method there is no need to use other acids, such as strong acids, for regeneration of the material, for example HCI or acetic acid used in prior art methods. Such acids would cause problems for example in respect of the durability of the adsorbent material. For example, these acids may even cause disintegration thereof.

[0115] The method may comprise treating the porous adsorbent material comprising the adsorbed substances with an aqueous regeneration solution (26) of sodium citrate, which may be a solution comprising sodium citrate, to desorb one or more of the substances from the porous adsorbent material to the aqueous regeneration solution to obtain regeneration solution (28) comprising desorbed substances, and preferably to regenerate the adsorbent material (22). The adsorbent material may be regenerated to the initial form. The method may comprise preparing and / or providing the aqueous regeneration solution.

[0116] The method may comprise detecting a decrease in the adsorption capacity, which indicates a need for regeneration and / or need for recovering the adsorbed substances. This may result in a decision to carry out regeneration method, so the method may comprise, as a result, carrying out the regeneration method disclosed herein. This may be carried out by the control unit. The detection may be carried out by monitoring the flowthrough, for example by using methods such as spectrophotometry, measuring conductivity and / or the like, wherein the decrease in adsorption capacity can be detected by a change in the monitored parameter.

[0117] The present disclosure provides a method for regenerating adsorbent material and / or recovering the adsorbed substances, the method comprising providing porous alkali-activated adsorbent material in need for regeneration. Such material may be considered as exhausted adsorbent material, and / or adsorbent material with lowered adsorption capacity. The regeneration may be needed after an adsorption run, i.e. after water has been treated with adsorbent material and the adsorption capacity of the adsorbent material may have been substantially used or lowered. The regenerating may refer to activating the adsorbent material, and / or to enhancing and / or restoring of the properties of the adsorbent material. The method comprises treating the porous adsorbent material (22) comprising the adsorbed substances with an aqueous regeneration solution (26) comprising sodium citrate to desorb one or more of the substances from the porous adsorbent material to the aqueous regeneration solution to obtain regeneration solution (28) comprising desorbed substances and preferably to regenerate the porous adsorbent material. The desorbed substances are substances released and / or eluted from the adsorbent material, they may be bound to the citrate, and they may be soluble.

[0118] The porous adsorbent material (22) comprising the adsorbed substances may be also treated with a different desorbing or elution solution, such as one comprising one or more salts, and the regeneration with the present regeneration solution may be carried out separately and / or when needed.

[0119] The porous adsorbent material, which is to be regenerated, may comprise one or more adsorbed substances. In such case the method may further be a method for recovering the adsorbed substances, the method comprising desorbing one or more of the substances from the porous adsorbent material to the aqueous regeneration solution, or to the other elution solution, to obtain a solution, such as a regeneration solution, comprising desorbed substances (28).

[0120] The adsorbent material to be regenerated may be alkali-activated adsorbent material, and / or porous material. The adsorbent material may comprise and / or be derived from metakaolin. The adsorbent material may be the porous adsorbent material disclosed herein, such as porous adsorbent material comprising alkali- activated titanate-modified metakaolin, which may be prepared with the methods disclosed herein.

[0121] Because sodium citrate is an anionic form of citric acid, it works best at substantially neutral or alkalic conditions. When sodium citrate is used, the pH range for metal desorption and use of the washing agent is broad thus ranging from 4 to 9. If a specific desorption of a metal is desired the pH of the citric acid solution can be adjusted to an optimal value for a target metal. In such case the loss of the present material, according to laboratory tests, was found to be 0%, and when using the citrate as washing agent almost 100% desorption efficiency of adsorber metals was achieved. The present material also provides a prolonged lifespan compared to prior art materials, and according to experimental results it was estimated that it can be used at least for 600 cycles. The aqueous regeneration solution (26) may comprise 0.3-1 .0 M sodium citrate and / or have a pH in the range of 4-9, preferably in the range of 5-7. Aqueous regeneration solution may be prepared by providing a water solution of (only) citric acid and increasing the pH of the solution to a desired value by adding sodium hydroxide, thus resulting in the formation of sodium citrate. The aqueous regeneration solution 26 preferably does not contain one or more of (added) acid(s), and / or KNOs, K2SO4, NaCI, NaNOs, NaSC , CH3COOH, other salt(s) and / or a solution containing NaCI and NaOH, such as about 0.2 M NaCI and about 0.1 M NaOH, which are commonly used washing / regeneration chemicals often causing material loss and even destroying the AAM adsorbent. In one embodiment the aqueous regeneration solution does not contain acid and / or other regeneration agents. The aqueous regeneration solution may consist of the pH-adjusted citrate solution, more particularly it may consist of a water solution of 0.3-1 .0 M sodium citrate, the solution having a pH in the range of 4-9, preferably the pH being adjusted with NaOH. Regeneration with pH-adjusted citrate did not affect the mechanical durability or adsorption efficacy of the adsorbent material.

[0122] Disclosed is use of a water solution of 0.3-1 .0 M sodium citrate having a pH in the range of 4-9 for regenerating porous alkali-activated adsorbent material and / or for desorbing / eluting one or more of adsorbed substances from the porous adsorbent material to the aqueous regeneration solution.

[0123] The methods may comprise recovering the one or more substances from the aqueous regeneration solution. This can be carried out by any suitable methods, such as by precipitating, by crystallizing and / or by electrolysis.

[0124] The present adsorbent material may be used to adsorb a variety of substances from solutions or dispersions, such as from aqueous solutions. The substances may be contaminating substances and / or they may be substances which are to be recovered from the contaminated water, in general substance(s) of interest. In one embodiment the contaminating substances comprises one or more metals, which may be considered as metals(s) of interest.

[0125] The present application provides a method for treating metal-containing water or aqueous solution to remove and to recover one or more metals from the water, the method comprising

[0126] -providing metal-containing water (20), -treating the metal-containing water with the method for treating contaminated water to obtain metal-containing regeneration solution (28), and

[0127] -recovering one or more metals from the metal-containing regeneration solution 28.

[0128] In this case the contaminated water is the metal-containing water, which may be also a metal-containing dispersion. The contaminating substances comprises one or more metals.

[0129] One example provides a method for treating metal-containing water or aqueous solution to remove and to recover one or more metals from the water, the method comprising

[0130] -providing metal-containing water or aqueous solution (20),

[0131] -providing one or more flow-through columns (24) comprising the porous adsorbent material (22) comprising alkali-activated titanate-mod ified metakaolin, -contacting the metal-containing water or aqueous solution (20) with the porous adsorbent material (22) in the flow-through column (24) to adsorb the one or more metals to the porous adsorbent material (22),

[0132] -treating the porous adsorbent material (22) comprising the adsorbed metals with an aqueous regeneration solution (26) comprising sodium citrate and to desorb one or more of the substances from the porous adsorbent material to the aqueous regeneration solution to obtain metal-containing regeneration solution (28), preferably also to regenerate the adsorbent material (22),

[0133] -recovering (30) one or more metals from the metal-containing regeneration solution (28). The flow-through column (24) may comprise the porous adsorbent material (22) mould into the column.

[0134] Examples of the metals of interest include any applicable metals, such as heavy metals and / or metals considered as harmful and / or valuable. Specific examples include cadmium, cobalt, copper, iron, lead, zinc, and nickel. Each of the metals of interest have a specific pH, where the metal precipitates as a metal hydroxide.

[0135] The methods may comprise providing the aqueous solution comprising sodium citrate at a pH specific for a metal of interest, preferably wherein the pH is above the hydroxide precipitation pH of the metal of interest, to recover the metal of interest. In one embodiment the contaminating substances comprises one or more organic compounds. The organic compounds may be pharmaceutical compounds, organic compounds from industrial process, or organic compounds in wastewater.

[0136] In one embodiment the contaminated water is industrial water, such as water from steel industry, water from mining industry, water from pharmaceutical industry, or water from pulp and / or paper industry. The industrial water may refer to wastewater or effluent, or to aqueous liquid of an industrial process, which in not waste water / effluent, but which may be for example process water, a reaction solution, a reagent solution, a solution of final product, a fraction of process water and / or the like.

[0137] In a water purification process the present adsorbent material is provided in a suitable form, such as in a flow-through column, or alternatively in another form enabling the same process steps. The column may be run as pressurized with a low pressure, for example by using a circulation pump and / or according to membrane filtration principle. The column may be installed in vertical direction, and the flow direction may be upwards. When the adsorption capacity of the adsorbent material in reached, or it is desired to elute the adsorbed substances, a backwash is started, i.e. the flow direction is reversed. As a first washing solution the filtrate from the process can be used, and / or other washing solution may be added, either instead or subsequently, such as water. After a first washing with the first washing solution is carried out, a second washing solution is applied, which may be the regeneration solution based on sodium citrate. The second wash with the second washing solution may be carried out by using flow-stop-flow method, wherein the washing solution is flowed through the column for a period of time, such as for 3-5 minutes, then the flow is stopped for a period of time, such as for 1-2 minutes, whereafter the washing solution is flowed through the column for another period of time, such as for 3-5 minutes. These cycles can be repeated until a desired result has been obtained, such as when all the metals and / or other substances have been eluted (desorbed) from the column. This can be detected for example by monitoring the properties of the outcoming washing solution, for example by monitoring absorbance and / or conductivity by using a suitable adsorption meter and / or conductivity meter. When a change in absorbance and / or conductivity is detected, it indicates that the adsorbed substances have been desorbed from the column. With this method the column can be washed. In one embodiment the porous adsorbent material is in a flow-through column, which has been run with a flow in a first direction, the method comprising -reversing the direction of flow in the column and washing the column with a flow of filtrate and / or water and / or aqueous solution in a second direction, -subsequently washing the column with the aqueous solution comprising sodium citrate in the same (reverse and / or second) direction of flow to desorb one or more of the substances from the porous adsorbent material to aqueous solution and to regenerate the porous adsorbent material.

[0138] The porous adsorbent material or the one or more columns, or other forms of casings, which are preferably flow-through columns or casings, can be provided in a system, which may be a system for treating water. The system may comprise other parts such as pipes, tubes, containers, pumps, valves, actuators, sensors, cameras and / or the like. The system may be electronically controllable system, and it may comprise one or more (electronic) controlling means, such as control units, for controlling the operation of the system and / or one or more of the parts of the system.

[0139] The controlling means, such as the control unit, may be for example arranged to provide and maintain desired temperature, desired pH, desired flow of liquids, desired addition of substances, such as liquids, desired level of mixing, and the like operations, by controlling mixing means, aerating means, pumps, actuators connected to pumps, valves or other means, heating means such as heating elements, and the like. For example, the flow of liquids may be controlled by providing a valve operatively connected to the control unit and operatively controllable by the controlling means. A valve may be operatively controllable or it may be connected to an actuator, which is operatively controllable. Operatively controllable refers to a device which is electronically operatively connected or connectable to the controlling means and can be controlled, such as monitored and / or operated, by the controlling means. Operatively connected may be operatively controlled, when applicable. The controlling means, as well as the system, may be manual, automatic or semi-automatic.

[0140] The controlling means may comprise one or more processors and memory, and optionally a user interface, a display, a keyboard, touch screen and / or other inputting means, power connection, a network connection, which may be wired and / or wireless, and / or connections to each of the controllable means of the apparatus as disclosed herein. The controlling means may comprise one or more computers and / or embedded systems. The controlling means may comprise software, which is arranged, when run with the processor, to carry out one or more controlling actions to carry out the present method or part thereof, and optionally one or more other methods, in general the operation of the system. As the means of the system, including any actuators, valves, relays, motors, such as electric motors, pumps, heating means, sensors, cameras and the like parts, which may be required to monitor and carry out operations, are electronically connected to the controlling means, the controlling means can be arranged, including programmed, to operate these means. By controlling said means it is possible to obtain and / or maintain the desired operation of the system. A desired operation may comprise for example obtaining and / or maintaining a certain (predetermined) value, such as keeping a variable at a defined range by providing controlling actions having effect to the variable, such as temperature, flow speed, level of liquid or suspension, pH, concentration of a substance, and the like, and / or inputting and / or outputting a substance, such as liquid, solids and / or gas. The control unit may be connected to one or more sensors to monitor inflow and / or flowthrough, for example to detect decrease in the adsorption capacity of the adsorbent material.

[0141] The sensors may comprise one or more conductivity sensors, one or more light sources and sensors for spectrophotometric measurements, and / or the like sensors and related devices, which may be needed to monitor the flowthrough from the column and / or inflow to the column.

[0142] For example, one or more pumps may be operatively connected to the control unit, and the control unit may be arranged to control the operation of the pumps, for example to reverse the direction of a pump, start and / or stop a pump, adjust the operating speed of the pump to adjust flow rate and / or to obtain other necessary functionalities and / or operations.

[0143] The disclosures presented herein referring to columns may be applied to other types of casings as well. The columns, systems and / or other device applications of the present materials can be used in the methods disclosed herein. The methods may be continuous methods or batch methods, of a combination thereof.

[0144] The present disclosure provides a system for treating contaminated water, the system comprising

[0145] -preferably a source of contaminated water, -one or more flow-through columns containing the porous adsorbent material, -means for providing flow of aqueous solution through the column, wherein the one or more columns is / are arranged to be run into a first direction of flow to convey the contaminated water from the source of contaminated water to the column,

[0146] -a source of washing solution,

[0147] -preferably means for reversing the flow to a second direction to convey the washing solution to the column in the second direction of flow, such as with the means for providing flow of aqueous solution through the column.

[0148] In one embodiment the method for treating contaminated water to remove one or more contaminating substances from the water, and / or the method for regenerating porous alkali-activated adsorbent material comprises providing a system comprising

[0149] -preferably a source of contaminated water,

[0150] -one or more flow-through columns containing the porous alkali-activated adsorbent material, such as porous adsorbent material comprising alkali-activated titanate-modified metakaolin,

[0151] -means for providing flow of aqueous solution through the column, such as a pump, wherein the one or more columns is / are arranged to be run into a first direction of flow to convey the contaminated water from the source of contaminated water to the column, preferably with the means for providing flow of aqueous solution through the column, and

[0152] -a source of washing solution,

[0153] -preferably means for reversing the flow to a second direction to convey the washing solution to the column in the second direction of flow, such as with the means for providing flow of aqueous solution through the column.

[0154] The source of contaminated water may refer to a reservoir containing contaminated water, such as one or more of tanks, containers or the like. The contaminated water may have been transported to the location of the present system, and / or the present system may be at the location of the source of the contaminated water. The source of contaminated water may be also an outlet or the like of the contaminated water, such as contaminated water obtained directly from a process, for example in a plant, a system or the like. The source of contaminated water may comprise one or more conveying means, such as tubes, pipes, of the like connected to an inlet of the present system. The source of contaminated water may be controllable, so that the flow of the water to the system can be controlled, for example by using one or more of pumps, valves and / or the like. The present system may be at a processing plant or the like industrial location, which produces the contaminated water, wherein the system may be directly connected to the source of contaminated water at the industrial location, for example at an industrial processing plant, such as a processing plant, processing site or the like from steel industry, mining industry, pharmaceutical industry, or pulp and / or paper industry. The same applies to other sources of water or aqueous solution.

[0155] The means for providing flow of aqueous solution through the column may comprise one or more pumps, tubes, pipes, valves, and / or the like connected to the column, preferably from a first end of the column. The aqueous solution may be the contaminated water. Treated water, i.e. the flowthrough from the flow- through column, may exit from a second end of the column, wherein the flow is in a first direction.

[0156] The flow in the first direction and the flow in the second direction may be obtained by using the same means for providing flow of aqueous solution through the column, or by using separate means for providing flow of aqueous solution through the column. These means may be similar, or they may be different, for example a different type of pumps and / or pump arrangements and / or other device(s) may be used for the first flow and for the second flow.

[0157] If two or more columns are provided, the columns may be arranged in parallel and / or in series. Providing two or more columns will enhance the capacity of the system and method. When the columns are arranged in parallel, the flow rate can be enhanced. When the columns are arranged in series, the treatment efficiency can be enhanced, and it is possible to optimize the process to desorb / elute a single type of metal. This may require adjusting the pH of the washing solution for a metal of interest, and after eluting with an elution and / or regeneration solution the metal of interest can be recovered from the concentrated washing solution by crystallizing.

[0158] In one embodiment the system comprises two or more columns, which are arranged to be run continuously and / or simultaneously in different phases, one column being run into a first direction of flow and a second column being run into a second direction of flow, preferably the first column being run to treat the contaminated water and the second column being simultaneously run to recover the adsorbent material with the washing solution.

[0159] In one embodiment the system comprises two or more columns arranged in series. They may be arranged to be run continuously or in batch mode.

[0160] In one embodiment the system comprises a control unit, wherein the control unit is configured to carry out the method, or to carry out controlling the method, for regenerating porous adsorbent material comprising alkali-activated titanate- modified metakaolin. Especially the control unit may be configured to carry out the method, wherein the porous adsorbent material is in a flow-through column, which has been run with a flow in first direction, the method comprising

[0161] -reversing the direction of flow in the flow-through column (24) and washing the flow-through column with a flow of filtrate and / or water or aqueous solution in a second direction,

[0162] -subsequently washing the flow-through column (24) with the aqueous regeneration solution (26), such as with aqueous solution comprising sodium citrate, in the same direction of flow to desorb one or more of the substances from the porous adsorbent material (22) to the aqueous regeneration solution to obtain regeneration solution (28) comprising desorbed substances and to regenerate the porous adsorbent material.

[0163] The control unit may be operatively connected to one or more means for providing flow of aqueous solution through the column and to the means for reversing the flow to a second direction. The control unit may be configured, such as programmed, to carry out one or more of or all the method steps, such as controlling the flow direction, operation of the means, such as controlling flow rate, and / or conveying liquid from a desired source to the column and / or from the column to a desired location. This may involve operating one or more valves, actuators, pumps and the like devices necessary for the operation of the system.

[0164] The system may be used with the methods disclosed herein, such as with the method for treating contaminated water to remove one or more contaminating substances from the water and / or with the method for regenerating porous adsorbent material comprising alkali-activated titanate-mod ified metakaolin. The present method may comprise providing the system, and / or providing the porous adsorbent material comprising alkali-activated titanate-mod ified metakaolin with the system. Examples of adsorbent material in a column

[0165] Percentage values, unless specifically indicated otherwise, are based on weight, while the total mass is 100%.

[0166] Figure 3 shows the raw materials for preparing the adsorbent material.

[0167] An alkali solution was prepared by mixing for 2 hours with a magnetic stirrer at 300 rpm a solution of sodium silicate (45.05%) comprising 27.0% SiO2, 8.0% Na2O and 65% H2O, and granular sodium hydroxide (6.88%) covered by a watch glass to prevent water evaporation. The solution was aerated with a homogenizer for 30 seconds with a speed of 20000 rpm. A mixture of metakaolin (27.57%) and calcium titanate (CaTiOs, 9.19%) was added by mixing with a mixer to the aerated alkali solution in 5 minutes with mixing speed of 1200 rpm to solubilize the metals of the metakaolin and calcium titanate to the alkali solution. A mass was obtained from the mixing. The metakaolin was prepared by heating calcined kaolin from 25°C to 750°C with 5°C / min increment, maintaining at 750°C for 3 hours, and decreasing the temperature from 750°C to 25°C with 5°C / min decrease.

[0168] Extra virgin olive oil (5.52%) comprising mainly unsaturated fatty acids was added to the mass by mixing at 1200 rpm for 10 minutes. This maximizes the released oxygen as the fatty acids are digested into glycerol at alkalic conditions. To the obtained mass finally 5.79% dilute hydrogen peroxide (1.38% 30% H2O2 + 4.41 % H2O) is added by mixing at 500 rpm for 5 minutes to obtain optimal porosity while maintaining a correct water content allowing the metals to migrate during polymerization. The obtained mass was poured into a column or other mould (about 40% of the column volume), and these were applied in an air-tight container to a low temperature drying oven (Type TS 8056, Termaks, Bergen, Norway) at 65°C or 67°C, for example for two to four days depending on the mass volume (Figure 4). Thus, it was noted that the process is well upscalable. The airtight container maintained the moisture inside the mould / column and was released after 24 hours to speed up the drying. During the drying the volume of the mass was expanded by about 250% and the mass was cured by a polymerization reaction, which cross-links the materials into a metal network by oxygen bridging. After drying, in case of the column, the excess material was removed. In case of a different mould, the material was removed from the mould. Excess glycerol was washed from the materials with 75°C water with flow-through until the pH of the washing water was 8.5. After washing the AAM adsorption column was ready for use. When mould into a column the adsorption area increases, as the sample to be treated flows through the whole column material, which is opposite to powdery or granular adsorbent, wherein the adsorption occurs only at the surface of the object.

[0169] With the mould it was possible to obtain different shapes, such as pellets, foam pieces, buttons and spheres. A column, pellets and a foam cylinder are shown in Figure 5. Figure 6 shows an exemplary setup for desorption of adsorbed copper with regeneration solution from a column comprising the adsorbent material. Figure 7 shows samples of crystallized citrate metal complexes including, from left for right, copper, cadmium, cobalt and nickel.

[0170] In other experiments other vegetable oils were used, such as sunflower oil and raffinated olive oil. With these oils however a lower porosity was obtained, which was probably due to the relatively high content of polyunsaturated fatty acids.

[0171] The composition of metal oxides in the prepared AAM was determined by an XRF spectrometer (PANanlytical Axios mAX XRF, Almelo, The Netherlands). The measurements were performed using loose powders run through transparent Mylar films under He atmosphere.

[0172] To obtain the metal oxide ratios, the pure metakaolin based AAM and Ca-Ti modified AAM adsorbents were analysed by XRF. XRF results are presented in Table 1. Comparison between AAMs revealed that aluminium content remained nearly constant but approximately 12% decrease in SiO2 content was observed with Ca-Ti modified AAM, which TiO2 content was 14.11 %. This suggests that part of the Si in AAM’s main framework was replaced by Ti indicating the structure of the titanate modified AAM. Table 1 . Content of elements as mass% from a final product

[0173] The crystalline phase of AAM sample was determined via the XRD method (PANalytical X’Pert Pro, Almelo, The Netherlands) using monochromatic Cu Ka1 radiation (A=1 .5406 A) at 45 kV and 40 mA with a scan step size of 0.017° and 20 of 8°-85°. The diffractogram were analysed using X’Pert Highscore (PANalytical B.V., The Netherlands) and compared with the Powder Diffraction File standards from the International Centre for Diffraction Data (ICDD, PDF-4+ 2024).

[0174] DRIFTS was used to investigate the degree of polymerization in the prepared sample. The DRIFTS spectra were recorded on a Bruker PMA 50 Vertex 80 V (Bruker, Billerica, MA, USA) equipped with a Harrick Praying MantisTM diffuse reflection accessory for baseline measurement using KBr. Measurements were conducted at 400-4000 cm-1with a resolution of 4 cm-1and 500 scans / min.

[0175] The microstructure and morphology of the samples were investigated using a Zeiss Sigma FESEM (Carl Zeiss Microscopy GmbH, Jena, Germany). The FESEM images were taken at 5 kV at magnifications ranging from 150 to 100K.

[0176] The XPS analysis was performed by ESCALAB 250Xi XPS System (Thermo Fisher Scientific, Waltham, MA, USA). The sample was placed into a gold sample holder and a high-resolution scan was conducted with pass energy of 20 eV. Pass energy for a survey scan was 150 eV. The monochromatic AIKa radiation (1486.7 eV) was operated at 20 mA and 15 kV with an X-ray spot size of 900 pm. The oxygen, calcium, silica, magnesium, and carbon were measured, and the data was analysed using the Avantage V5 program. Charge compensation was performed by applying the C1s peak at 284.8 eV as a reference. XRD, XRF, FESEM, and XPS facilities were used at the Centre for Material Analysis, University of Oulu, Finland. Liquid samples from adsorption and regeneration experiments were analysed by AAS (Flame Atomic Absorption Spectroscopy, Varian AA240FS; Varian Inc. Palo Alto, CA, USA) and ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometry, Agilent 5110 VDV, Agilent Technologies, USA).

[0177] The XRD and DRIFT results are presented in the graphs of Figures 8 and 9, respectively. The main peaks in Figure 8 are: 1 ) calcium titanium oxide Ca(TiOs) (ICDD 01 -081 -8560) with 20 values of 33.0, 33.2, 33.4, 47.6, 59.5, 69.7, 79.5; 2) silicon oxide SiO2 (ICDD 01 -085-0865) 26.7, 50.2; 3) aluminium oxide silicate A^OsSi (ICDD 04-014-9725) 26.7, 27.6, 34.9, 40.7 and 4) sodium aluminium silicate hydroxide hydrate Al6Hi8Nao.s034Si8 (ICDD 00-022-0956) 19.8, 35.0, 62.1 , respectively. The titanate peaks (1 ) can be used for characterizing the present product.

[0178] The DRIFT of the end product is presented in Figure 9. Bands in 1650 cm’1and 3400 cm’1correspond to O-H stretching vibrations and H-O-H bending vibrations of water molecules in AI / Si-OH*«H2O. The rest of the bands from 450 to 1200 cm’1correspond to TiO2 / SiO2, Ti-O-Ti, Ti-O, Si-O-Ti, Si-0 and Ti-0 vibrations. Main bands with wavenumber 768 cm’1and 1200 cm’1are Ti-0 vibrations from TiO4, followed by Si-0 symmetrical stretching at 1058 cm’1. Band at 768 cm’1could also correspond to Si-O-AI from the metakaolin. Bands with wavenumber from 866 to 954 are Si-O-Si / Si-OH bending and Si-O-Ti from condensed TiO4 vibrations. Smaller wavenumber bands from 439 cm’1to 461 cm’1are identified to TiO2 / SiO2 vibrations, Si-O-Si and Ti-O-Ti rocking, respectively. Corresponding letter to vibrational mode is: a) TiO2 / SiO2, b) Ti-O-Ti, c) TiO2 / SiO2, d) Ti-O / Si-O-AI, e) Si-O- Si / Si-O-Ti / Si-OH, f) Si-O, g) Ti-0 and h) AI / Si-OH»«H2O.

[0179] The XPS Survey of the final product is shown on Fig. 10 a) and Table 2. According to the “XPS knowledge View” of the Avantage software, the main peaks are: AI2p oxide with binding energy 74.4 eV; Si2p oxide 102.6 eV; Ca2p 3 / 2 oxide 348.1 eV; Ti2p oxide 456.6eV; and O1 s 531 eV, respectively. There are also some traces of K2p 3 / 2 oxide and C1s observed from XPS Survey. Na1 s peak 1072-1075eV has split into two separate ones indicating possible occurrence of Na-Si and Na-AI according to Avantage software. From O1 s scan (Fig 10 b) and Table 2, it can be concluded that aluminium oxide and silicon oxide are the main compounds, few condensed water and no metal oxide on the surface. Table 2 XPS results, binding energy (eV) and atom content (%)

[0180] Figures 11-13 present a SEM image, SEM distribution map, and an EDS of the end product. Figure 11 shows the morphology of the surface and general pore size distribution. Figure 12 demonstrates, how evenly elements are distributed to the surface, especially titanium. Figure 13 represents wt% of the elements by energy dispersive x-ray spectroscopy. A table of elements is presented in Table 3.

[0181] The analysis showed that there was a large variety of different pore sizes on the surface which was due to the preparation method. In curing process, excess water was removed in the oven which affected the materials porosity and pore size distribution. It was also noted that the main elements on the surface were silica, oxygen, aluminium, calcium, sodium and titanium. Modification with calcium titanate was done successfully and titanium content was over 5 w-% on the surface.

[0182] Table 3 EDS analysis of Ca-Ti-modified AAM.

[0183] The Point of Zero Charge (PZC) of the material was also determined to find optimum pH range for adsorption by acid-base potentiometric method. 0.2 g of adsorbent in value of 1 pH difference (11 samples pH range 2-12) was placed in 0.1 M KCI solution and after 24 hours pH difference between initial after 24 h was measured. Results are shown in Figure 14. It is clearly seen that the material optimum negative surface charge is approximately at the pH value of 4.5. Also from the results, the deprotonation stage between the pH values of 2 to 4.5 is noticeable. PZC is approximately at pH 10.5. waters with the adsorbent material

[0184] The column prepared in Example 1 was used for treating metal-containing waters to adsorb the metals from the water. The regeneration solution of Example 2 was used for washing and regeneration of the column.

[0185] The column was installed in a vertical orientation. Water purification process was run with a low pressure providing the water to be purified with a flow direction from the bottom of the column to the top of the column by using a circulation pump using principles of membrane filtration. In the tests it was found that optimal flow rate for a 2.2 dl column volume was 100-125 ml / min.

[0186] Waters with different metals were applied to the column, and purified water was obtained. The purification runs were carried until the water to be treated was completely run through the column, or when the adsorption capacity of the columns was reached.

[0187] Example 3: Desorption of metals and regeneration of the adsorbent material

[0188] 0.5 M citric acid solution was prepared by dissolving 96.06 g citric acid to water in a 0.75 I measuring bottle. pH of the solution was adjusted with NaOH granules or strong NaOH solution to optimal value according to a metal of interest, such as pH 6.5 for copper, pH 5.5 for iron, or using pH value 6.5, which is an optimal complexing average pH for most multi metal solutions. Water was added finally to obtain the 0.75 I volume. The obtained aqueous solution is a regeneration solution.

[0189] When powder, granular or pellet form of the present adsorbent material was used, the fully adsorbed material was applied to the regeneration solution and mixed with a magnetic stirrer. When adsorbent material in a column was used, such as moulded in the column, or granules or pellets in the column, the regeneration solution was flowed through the column by backwashing using flow-stop-flow method to maximize metal desorption. Optimized cycling time with said method was found to be, with 50 ml / min flow for 2.2 dl column, 4 minutes flow - 1 minute stop - 4 minutes flow, which could be continued if necessary. The flow could be carried out until the whole column volume was exchanged to a fresh solution when a new stop phase was started. The cycling was continued until the desired metal desorption was achieved, such as substantially 100% desorption. Simultaneously with the desorption, the adsorbent material is regenerated with the sodium present in the solution for a new adsorption cycle. The system setup used for these steps, comprising the adsorbent material in a column and using 0.5 M regeneration solution having a pH of 6.5, is shown in Figure 6.

[0190] After the metals are desorbed and are present as metal citrate complexes in the solution, the metals were recovered. The metal citrate complexes were disintegrated by adding strong sulphuric acid until the pH reached 2 or less. At the same time for example lead can be precipitated as lead sulphate.

[0191] The separation of metals was carried out either with crystallizing, including evaporation or cooling, or by precipitating metals as hydroxides. Figure 7 shows samples of crystallized citrate metal complexes including, from left for right, copper, cadmium, cobalt and nickel.

[0192] The optimum conditions for adsorbent were optimized by both process flow and metal concentrations. After each test, the column was washed downstream with deionized water followed by the regeneration cycle with sodium citrate solution (0.5 M, pH 6.5). The effect of metal ion concentration and process flow was studied with closed loop configuration with column a). Single metal tests were performed with direct flow configuration with 8 different metal ions and both q- values and adsorption efficacy were determinate.

[0193] Multimetal ion ; Concentration and flow rate

[0194] The effect of metal ion concentration of multimetal solution was performed with closed loop configuration with column a. Concentrations tested were 100, 250, 500, 1000 and 5000 mg / L as metal ion concentration, respectively. The sample volume was 1000 mL with constant flow of 100 mL / min. The process run time was 45 min giving the total flow through volume of 4500 mL. Samples were taken at 5, 10 and 15 minutes intervals from permeate line and finally from the sample vessel and the metal concentration were measured by AAS to determinate the q-values and adsorption efficiency. Result of the test is presented in Figures 15 a) and 15 b). From the results it can be observed clearly the competition effect of different metal ions in multimetal solution. Copper tends to adsorb with higher adsorption rate than manganese and zinc. Up to 1000 mg / L the calculated q-value rate is linear after which the rate is levelled. As for adsorption efficacy, the percentage is over 90% with all metals up to 250 mg / L decreasing to 59.5% for zinc and 49.7% for manganese with the concentration of 500 mg / L and 33.5% for zinc and 27.3% for manganese with concentration of 1000 mg / L. For copper the percentages were 89.1 % and 70.6%, respectively. Therefore, it can be concluded that the maximum metal concentration for effective removal is approximately 500 mg / L.

[0195] For process flow rate experiments, the Me2+concentration of 500 mg / L for each metal was selected from previous results and the samples were taken and analysed as previously mentioned. The flow rates tested were 50, 75, 100, 125 and 250 mL / min and the total sample volume flow through the column was kept constant 4500 mL to keep the proportionality between tests. Result is presented in Figures 15 c) and d). From the result it can be concluded that flow rate remained nearly constant with calculated q-values with all flow rates. However, with calculated adsorption efficacy it can be observed that in case of copper, the efficacy percentage decreases 17% from 88.0% to 71.0% when the flow rate increases from 125 ml / min to 250 ml / L.

[0196] To gain comparison of adsorbent’s efficacy to the other adsorbents studied from literature, the direct flow single metal solution experiments were carried out with column b). Eight different metal ions were selected: zinc, copper, manganese, nickel, cobalt, lead, cadmium and lithium. Metal concentration was kept constant 2000 mg / L for each metal with total sample volume of 4500 ml and flow rate was selected to 100 ml / min from previous tests. Samples were analysed by AAS and ICP-OES. The order of calculated q-values and adsorption efficacy % was Li < Ni < Co < Zn < Mn < Cu < Cd < Pb with values from 13.4 to 66.6 mg / g for q-values and 21 .0 to 99.6% for adsorption efficacy, respectively. The lower value for lithium is explained by valency of 1 while others are multivalent.

[0197] Regeneration conditions were optimized in relation to pH, concentration and contact time. AAMs high regeneration performance for copper was proved by conducting several adsorption-regeneration cycles, 31 in total. Cycles were conducted without any sign of material breakdown or significant decrease in adsorption capacity, which have been usually reported in the literature with other materials.

[0198] Concentration and pH

[0199] The effect of the citrate concentration to the regeneration efficacy was studied in the range of 0.1-1 M. Range was selected by the criterion that regeneration must be efficient but still economically sustainable solution to reduce costs and to minimize the environmental impact. It was shown that with all the elements, Cu, Zn and Mn, highest efficacy was achieved with citric acid concentration of 0.5 M. Regeneration efficacy decreased to all metals, while the strength of the regeneration solution increased. This is caused most probably because the viscosity of the regeneration solution increases and for that reason the regeneration solutions ability to permeate through the AAM is decreased. Results are presented in Fig 16 a).

[0200] The effect of the regeneration solutions pH to the regeneration efficacy was studied in the range of 6.6-10.6. By varying the pH of the regeneration solution, it was shown that citric acid can be used in alkalic conditions (citrate form) because it does not alter the AAM structure. Study showed that by changing the pH of the regeneration solution, it was possible to alter the ratio of removed heavy metals. For instance, it was shown with copper that the highest value was achieved at the pH level of 9.6. With manganese and zinc, the optimal pH value was a bit lower, 6.6 and 7.6, respectively. For the multi metal regeneration, it was noted that the optimal pH level was 6.6. This might be because zinc and manganese tend to bind in more acidic conditions than copper which affect more competition between these heavy metal cations and eventually affect also to the increased copper removal. Results are presented in Fig 16 b).

[0201] Adsorption-desorption cycles were performed in the same way during all cycles. A 500 mg / L copper solution was used as adsorbate and a total of 31 cycles were performed. Regeneration with pH-adjusted citrate therefore did not affect the mechanical durability of AAM, which is a groundbreaking advantage compared to other regeneration chemicals, such as acetic acid. During the cycles, it was noticed that the adsorption capacity showed only a negligible change. The removal-% was over 95% during all cycles. This means that adsorption efficacy was affected only 4% during 31 adsorption-regeneration cycles, which is unseen. In literature, this percentage is substantially higher and for that reason only limited number of cycles are generally conducted. As a regeneration agent, citrate performed excellently even though some variability was seen in couple cycles. More importantly, adsorption efficacy was not affected much because of that, and it can be seen from calculated adsorption and regeneration efficiencies, which are presented in Fig 17.

[0202] Column characterization after adsorption-regeneration cycles

[0203] After adsorption-regeneration cycles experiment, the column was treated after 31stadsorption-desorption cycle with 1000 mg / L copper solution to investigate the vertical distribution of adsorbate inside the column without regeneration cycle. Following the adsorption cycle the column was backwashed only with deionized water to remove excess sample water, dismantled as a whole, dried 48 hours at 105°C and sliced into five 2 cm section. The sections were labelled as one to five from the bottom of the column and analysed by XRF, FESEM-EDS and DRIFTS.

[0204] The FESEM images illustrated minor decomposition of the AAM structure in sections 1 and 2 (not shown). The DRIFTS spectrum of bottom and the top sections showed additional bands with the wavenumbers 1460, 1722, 2888 and 2956 cm’1compared to the native column, which can be identified as CHs, C=O, - C-H aldehydic and -C-H stretch from the residual regeneration chemical used in previous cycle or from virgin olive oil which was used as a surfactant. However, the intensity of the vibration’s bands is greater in the top section than in the bottom one, which refers to the sodium citrate regeneration solution.

[0205] XRF data was gathered from all sections and are presented in Fig. 18. For comparison, the native adsorbent data from Table 1 is included. Si, SiO2 and O content remained constant with all samples with mass-% of 45, 21 and 45%, respectively. This indicates that the basic polymeric structure of silicon based AAM is intact. Although, the AI2O3 content has decreased 3.5% in section 1 from the native 19.01 to 15.60% and further gradually decreasing from section one to five which is 9.96%. The same trend was observed with Na2O from 6.1 to 3.16 and finally to 1.09. The decrease in Na2O mass-% might be interpreted of using water in backwashing stage in which hydrolysis of Na from the AAM structure occur (section 3.6). The opposite trend was found with TiO2 and CaO content. With TiO2, the relative mass-% increased from native 14.11 % to the value of 15.49% of section 1 increasing steadily to the value of 22.50% in section 5. With CaO the values were 11 .86, 9.85 and 13.71 % respectively. This could be explained by TiO2 and CaO leaching from the bottom parts of the columns during adsorption stage which are then adsorbed to the upper part of the column. Preferrable explanation could be that during column manufacturing, when curing is performed in vertical orientation, the elemental distribution inside the column is changed. The CuO adsorbate was adsorbed highest to the second section with the mass-% of 8.18 then decreasing linearly to the value of 4.46% in section 5. As with this AAM material and process, this would give a possibility to determine the optimum column dimensions with the certain flow to maximize the adsorption efficacy. For example, with this test, 16 cm column height with diameter of 4 cm should give an optimum column dimension.

[0206] Adsorption and regeneration mechanisms

[0207] During manufacturing phase calcium titanate is added to the extremely alkaline sodium silicate activator solution. It is assumed that the reaction generates partly calcium hydroxide and TiOs2’ species, which can react with OH’ to form TiO2, sodium titanate (Na2TiOs) with reaction with Na+or bond straight to AAM’s silicon framework during polymerization process. DRIFTS data suggest the latest option of these three, however the XRD proposes also unreacted calcium titanium oxide. Proposed structure of the adsorbent is illustrated in Fig 19.

[0208] Adsorption mechanism of metal cations is usually a two-stage process. Partial hydrolysis takes place in water solutions and the surface of the adsorbent becomes negatively charged and after pre-regeneration of AAM with sodium citrate solution, the excess of sodium is attached to the negatively charged AAM. In adsorption phase Na+is replaced by adsorbate solution metal cations, depending on the charge of the cation as presented in Fig. 20.

[0209] Regeneration was performed by sodium citrate solution instead of using common utilized acetic acid and sodium chloride solutions. Regeneration with acetic acid, with copper for example, can form undesirable copper acetate and due to acidity of solution it may deconstruct the AAM framework. Sodium citrate is considered as triprotic acid and can be in different form according to pH due to number of negatively charged carboxylic groups, such as mono-, di- and trisodium citrate with pKavalues of 3.13, 4.76 and 6.40, respectively. However, a fourth dissociation constant at pKa value of 13.0 may be presented, which is related to deprotonation of -OH group attached to the central carbon. Regeneration mechanism with di- and trisodium citrate species is suggested in Fig 21. In this case, the pH range of regeneration test was 6 to 11 , in which di- and trisodium citrate species are present, trisodium citrate becoming dominant after pH value of 6.4.

Claims

Claims1. A method for preparing porous adsorbent material (22), the method comprising-providing metakaolin (10) and calcium titanate (12, CaTiOs), mixing with alkali solution (14), and reacting to obtain alkali-activated modified material (16), -providing oil comprising oleic acid (18) as a foaming agent to the alkali-activated modified material (16), and-providing hydrogen peroxide (20) as a foaming agent to the alkali-activated modified material (16), preferably in mixing, and preferably after the oil comprising oleic acid (18) has reacted with the alkali,-allowing the alkali-activated modified material to foam in the presence of the hydrogen peroxide to obtain porous adsorbent material (22) comprising alkali- activated titanate-modified metakaolin.

2. The method of claim 1 , wherein the oil comprising oleic acid (18) comprises mainly unsaturated fatty acids, such as 80% by weight or more unsaturated fatty acids, of the total fatty acid content of the oil.

3. The method of claim 1 or 2, wherein the oil comprising oleic acid (18) is olive oil, such as extra virgin olive oil.

4. The method of any preceding claims, comprising forming the porous adsorbent material (22) into form of a product (23) and dewatering, such as by dewatering at elevated temperature of 50°C or more, such as 60°C or more, preferably washing the dewatered porous adsorbent material.

5. The method of claim 4, wherein the product is selected from -granules, such as granulated granules, wherein the forming may comprise granulating the mixture of the alkali-activated modified material, the oil comprising oleic acid and the hydrogen peroxide and / or the porous adsorbent material with a granulator device,-pellets, wherein the forming may comprise pelleting the mixture of the alkali- activated modified material, the oil comprising oleic acid and the hydrogen peroxide and / or the porous adsorbent material with a pelletizing device, or forming the pellets by compacting and / or crushing the porous adsorbent material,-powder, wherein the forming may comprise disintegrating, such as grinding, crushing and / or pulverizing the porous adsorbent material to obtain powder,preferably to obtain powder having an average particle diameter in the range of 125-1000 pm.-foam, wherein the forming may comprise foaming the mixture of the alkali- activated modified material, the oil comprising oleic acid and the hydrogen peroxide, and-a mould product, wherein the forming may comprise applying the mixture of the alkali-activated modified material, the oil comprising oleic acid and the hydrogen peroxide into a mould.

6. The method of any preceding claims, wherein-the amount of the hydrogen peroxide is in the range of 0.1 -0.5% by weight of the total amount of the mixture of the alkali-activated modified material, the oil comprising oleic acid and the hydrogen peroxide before the foaming.

7. The method of any preceding claims, wherein-the calcium titanate (CaTiOs) is obtained from perovskite, and / or-the alkali solution comprises sodium silicate (Na2SiOs • H2O) and sodium hydroxide, preferably the method comprising-mechanically aerating / foaming the alkali solution, such as with a homogenizer, -adding the metakaolin and the calcium titanate to the aerated / foamed alkali solution in mixing, preferably in a ratio of 70-80:30-20 by weight, and -reacting to obtain the alkali-activated material.

8. The method of any preceding claims, comprising-providing the alkali-activated modified material (16), the oil comprising oleic acid (18) and the hydrogen peroxide (20) into a casing, such as into a flow-through casing, or into a flow-through column,-allowing the alkali-activated modified material to foam in the presence of the oil comprising oleic acid and the hydrogen peroxide to obtain porous adsorbent material mould into the casing or into the flow-through column, and-dewatering the foamed adsorbent material mould into the casing or into the flow- through column, such as by dewatering at elevated temperature of 50°C or more, preferably washing the dewatered adsorbent material.

9. Porous adsorbent material (22) comprising alkali-activated titanate- mod ified metakaolin.

10. The porous adsorbent material of claim 9 in the form of granules, such as granulated granules, pellets, powder, such as crushed powder, foam, or a mould product.

11. The porous adsorbent material of claim 9 or 10, wherein the mould product comprises adsorbent material mould into a column (24).

12. The porous adsorbent material of any of claims 9-11 obtained by the method of any of claims 1-8.

13. A flow-through column (24) comprising the porous adsorbent material (22) of any of claims 9-12.

14. The flow-through column (24) of claim 13 obtained by the method of claim 8.

15. Use of porous adsorbent material (22) of any of claims 1-12 for treating water.

16. Use of the flow-through column (24) of claim 13 or 14 for treating water.

17. A system for treating water or aqueous solution, such as contaminated water, the system comprising-preferably a source of water or aqueous solution, such as contaminated water (20),-one or more flow-through columns (24) of claim 13 or 14,-means for providing flow of aqueous solution (20) through the column, such as a pump, wherein the one or more flow-through columns (24) is / are arranged to be run into a first direction of flow to convey the water or the aqueous solution, such as the contaminated water, from the source of water or aqueous solution, such as contaminated water, to the column, preferably with the means for providing flow of aqueous solution through the flow-through column, and-a source of washing solution and / or aqueous regeneration solution (26), -preferably means for reversing the flow to a second direction to convey the washing solution to the flow-through column (24) in the second direction of flow, such as with the means for providing flow of aqueous solution through the flow- through column.

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