Sorption material for purifying aquatic environments from microbiological pollutants

Abstract

FIELD: environmental protection.SUBSTANCE: invention relates to sorption materials and can be used in the process of purifying drinking, natural and denatured waters, as well as other aqueous solutions from microbiological contaminants. The sorption material for purifying aquatic environments from microbiological contaminants consists of a mineral-based carrier and active components. Olivine with a particle size of 0.1-0.5 mm is used as a mineral-based carrier. Finely dispersed particles of copper compounds with a particle size of less than 0.1 mm and aluminium oxyhydroxide nanofibers are used as active components, with the following ratio of components, wt.%: olivine 76.5; finely dispersed particles of copper compounds 1.5; aluminium oxyhydroxide nanofibers 22.EFFECT: increase in the capacity of the developed universal material and imparts antibacterial properties to it.1 cl, 1 dwg, 3 tbl, 1 ex

Description

[0001] The invention relates to the field of environmental protection, namely to sorption materials, and can be used in the process of purifying drinking, natural and denatured waters, as well as other aqueous solutions from microbiological contaminants.

[0002] A technical solution is known such as a SORBENT AND A METHOD FOR ITS PRODUCTION (RU 2242276 dated 27.11.2003, published 20.12.2004) consisting of non-spherical particles of aluminum oxide and particles of fibrous material, characterized in that it additionally contains a component with a negative surface charge and a modifier selected from a series of oxide or hydroxide of magnesium, silicon or a mixture thereof, with the following ratio of components, wt. %: Aluminum oxide Not less than 20; Component with a negative surface charge 0.5-5.0; Modifier 0.1-3.0, Fibrous material The rest.

[0003] However, this sorbent cannot be used in various water purification technologies due to its fibrous structure. Furthermore, due to its high density, its layer has reduced aqueous permeability, unlike powdered sorbents. Furthermore, this sorbent lacks antibacterial properties, which leads to the proliferation of microorganisms in the filter layer of the material.

[0004] Patent [US 6274041 B1, 2001] describes an integrated filter material consisting of two components: the first, adapted for the extraction of contaminants by physical sorption, and the second, capable of electrokinetic adsorption. The first element is a porous adsorbent—activated carbon, active alumina, etc.—and the second is a fibrous material with a modified surface charge. The integrated filter is a structure composed of layers of these two materials. The filter is designed for the comprehensive purification of water or air from suspended particles, chlorine compounds, odor, organic compounds, lead, bacteria, and viruses.

[0005] The main drawback of this filter is the use of known adsorbents, which are not always effective enough. For example, the use of a fibrous material with a modified charge to retain bacteria does not ensure complete disinfection of water even at an initial bacterial concentration of 5.5⋅10 6 CFU / ml.

[0006] A FILTERING MATERIAL, A METHOD FOR ITS PRODUCTION AND A METHOD FOR FILTERING are known (RU 2317843 dated 08.08.2005, published 27.02.2008), containing as a base a non-woven polymer fibrous material and particles of aluminum oxide hydrate fixed to the fibers of the base, characterized in that the particles of aluminum oxide hydrate are fixed to the fibers of the non-woven polymer fibrous material obtained by electrospinning.

[0007] However, this filter material is made of fabric and cannot be used in various water purification technologies. Because the fabric is too thin and has low hydrodynamic resistance, the filtered water passes through it quickly, and the degree of purification is not high. This requires the use of 6-8 layers of this material. Furthermore, this material lacks antibacterial properties, which leads to the proliferation of microorganisms in the filter layer.

[0008] A known sorbent is the work of the authors Plotnikov E., Martemianova I., Martemianov D., Zhuravkov S., Kan T., Voronova O. The study of surface parameters and sorption properties of aerated concrete-based sorbents for water purification from E.Coli bacteria / / Journal of Materials and Environmental Science. 7 (11) (2016) P. 3944-3948, based on a synthetic carrier in the form of construction waste, for the removal of microorganisms from aquatic environments. Modified aerated concrete of a certain fraction was used as a carrier. The sorbent was obtained by treating aerated concrete of the desired granulometric composition with hydrochloric acid. As a result of modification, satisfactory properties of the obtained sorbent in water purification from microbiological contaminants were revealed.

[0009] However, this sorbent does not have a sufficient specific surface area to effectively extract microorganisms from water. Furthermore, when aerated concrete is immersed in water, it makes it alkaline due to the presence of calcium hydroxide. Furthermore, this material does not have antibacterial properties.

[0010] A NANO-SIZED ELECTROPOSITIVE FIBROUS ADSORBENT is known (RU 2304463 dated 21.06.2002, published 20.08.2007), consisting of non-spherical particles of aluminum hydroxide, in the form of fibers with a diameter of less than 50 nm and a length-to-thickness ratio of more than five to one, obtained as a result of the transformation of the original aluminum component in an aqueous solution at a temperature of up to 100°C, and directly applied to the surface of the fibrous structure, characterized by the possibility of adsorbing at least one electronegative particle from a liquid, and the aluminum particles can have nanometer dimensions.

[0011] However, this sorbent has a fibrous structure and cannot be used in various water purification technologies. Furthermore, the compacted fibrous material has a high density, and the permeability of the aqueous medium through its layer is reduced, unlike powdered sorbents. Furthermore, this material lacks antibacterial properties, which leads to the proliferation of microorganisms in the filter layer.

[0012] The closest analogue of the proposed technical solution is the work of the authors (Martemianova I., Tin HL, Duong HH, Martemianov D., Plotnikov E. Effective approach to water purification from microbiological contamination based on novel surface-modified adsorbents / / Resource-Efficient Technologies. 4 (2020) 1-9), which uses synthetic and natural zeolites. The production technology is optimized for coating minerals with aluminum oxyhydroxide using a sol-gel process to obtain the required surface charge. To modify the surface of the sorbent and acquire bacteriostatic properties, additional treatment with finely dispersed particles of zinc compounds obtained by electric spark dispersion was used.

[0013] However, due to the fact that this sorbent contains a lower amount of aluminum oxyhydroxide than the proposed sorption material, insufficient extraction of microorganisms from the aqueous medium occurs. Furthermore, to impart antibacterial properties to the product, the proposed sorption material uses finely dispersed particles of copper compounds, while the prototype sorbent uses finely dispersed particles of zinc compounds. Literature data indicate that copper has superior bactericidal and bacteriostatic properties compared to zinc. Therefore, our proposed material has superior antibacterial properties compared to the prototype sorbent.

[0014] The purpose of the presented invention is to create a new sorption universal antibacterial material for purifying aquatic environments from microbiological contaminants with high capacity.

[0015] The technical result of the claimed invention is to increase the capacity of the developed universal material and impart antibacterial properties to it.

[0016] The technical result is achieved by the fact that the sorption material for purifying aqueous media from microbiological pollutants consists of a mineral-based carrier and active components, and olivine with a particle size of 0.1-0.5 mm is used as a mineral-based carrier, and finely dispersed particles of copper compounds and aluminum oxyhydroxide nanofibers are used as active components, with the following ratio of components by weight%: olivine - 76.5; finely dispersed particles of copper compounds - 1.5; aluminum oxyhydroxide nanofibers - 22.

[0017] The claimed invention enables the achievement of a technical result that increases the efficiency of water purification from microbiological contaminants by increasing the amount of active component in the material and the possibility of using the sorption material in various water treatment equipment with different sorption bed layers. Furthermore, the resulting material will possess good antibacterial properties.

[0018] Using crushed olivine as a carrier, a magnesium-iron silicate with a Mohs hardness of 6.5-7, this sorption material for purifying aquatic environments from microbiological contaminants exhibits good strength and also exhibits chemisorption properties, removing a number of chemical contaminants from water. Due to its sufficient strength, olivine has reduced hydrodynamic resistance compared to similar minerals.

[0019] By using aluminum oxyhydroxide nanofibers as the active component, the resulting sorption material is given enhanced sorption properties for the extraction of microbiological contaminants from aquatic environments. This is achieved because the aluminum oxyhydroxide nanofibers have a positive charge, while microorganisms in the water are typically electronegatively charged. Depending on whether the charge is the same or opposite, there may be attraction or repulsion between the contaminant particle and the surface of the sorption material. If the surface of the material and the particle in the water have opposite charges, and there is no repulsion between their electrical double layers, then the particle, which is smaller than the sorption material, can be removed from the water. This process involves electrokinetic forces, and the mechanism for capturing contaminants from water is called electrokinetic adsorption.Aluminum oxyhydroxide nanofibers alone cannot be used in practical water purification due to their small size. However, when immobilized on the surface of mineral carriers, they greatly increase the active surface area of ​​the minerals and, therefore, their water purification properties.

[0020] The use of finely dispersed copper particles as an active component imparts antibacterial properties to the developed sorption material, which prevents the proliferation of microorganisms in the water purification material layer. Copper ions destroy many microorganisms due to the oligodynamic effect - the toxic effect of metal ions on living microorganism cells, even in relatively low concentrations. The antibacterial effect of copper occurs through various mechanisms: 1. Destruction of the bacterial cell membrane - when copper ions mechanically rupture the cell wall; 2. Chemical reaction of copper with oxygen - during copper oxidation, reactive oxygen species are formed, which damage the cellular components of bacteria; 3. Violation of the integrity of microbial membranes - leads to the leakage of specific nutrients necessary for cells, such as potassium and glutamate, which causes drying out and death of cells.

[0021] This combination of the presented components provides the best result for the extraction of microbiological contaminants from the aquatic environment.

[0022] The result is a sorption material containing a sufficient amount of aluminum oxyhydroxide on the carrier surface, significantly increasing the product's effective surface area and allowing for a higher concentration of the active component in the form of nanofibers, unlike similar sorbents. The material also possesses antibacterial properties, preventing the growth of microorganisms within the sorbent layer itself.

[0023] Obtaining a sorption material for purifying aquatic environments from microbiological contaminants is solved as follows. Take a carrier in the form of the mineral olivine and grind it in an agate mortar. Next, sift the crushed carrier to the required granule size on sieves in the range from 0.1 to 0.5 mm. Next, take a sample of crushed olivine (0.1-0.5 mm), weighing 10 g, and carry out the process of immobilization of finely dispersed particles of copper compounds (obtained by electric explosion) on the surface of the mineral carrier, in an amount of 0.2 g. For this, weighed portions of olivine and finely dispersed particles of copper compounds were placed in a laboratory glass beaker (1000 cm 3 ). Poured into a glass with the carrier and the active component 500 cm 3Distilled water was added and placed on a magnetic stirrer, stirring at low speed. The carrier and active component were mixed in distilled water for 10 minutes. After mixing, the solid phase was separated from the aqueous phase by centrifugation. The precipitate was then dried at 120°C for 3 hours until completely dry. The olivine treated with finely dispersed zinc compounds was then placed in a muffle furnace and the temperature was raised to 400°C for 1 minute, followed by cooling.

[0024] Then a weighed portion of the carrier, crushed olivine modified with finely dispersed particles of copper compounds, in the amount of 8 g, is placed in a laboratory glass beaker with a volume of 2 dm3 3 , followed by adding 1 dm3 of distilled water to it 3The bottom of the glass beaker, containing the contents, is wrapped in basalt cloth and placed on an electric hotplate, heating the contents to 60°C. An aqueous NaOH solution with a concentration of 20 grams per liter is then added, bringing the pH to 10. Pre-weighed AD1 food-grade aluminum powder with a particle size of less than 0.1 mm (1.12 grams) is added to the total volume. Under these conditions, the synthesis process is carried out for 50 minutes, with occasional stirring. The process temperature is monitored with a thermometer. After the synthesis is complete, the hotplate is turned off, and the reaction mixture is cooled to room temperature. The beaker contents are then emptied onto a viscose filter, and the product is washed (filtered) using a Buchner funnel and a Bunsen flask. Filtration is carried out with distilled water until the product reaches a neutral pH, using a vacuum pump.After washing, the filtered material is dried in a drying oven at 110°C until all moisture is removed.

[0025] The synthesis, carried out using a sol-gel process, results in the formation and immobilization of aluminum oxyhydroxide nanofibers on the surface of the mineral support, which imparts additional active surface area and thereby enhances sorption properties. Furthermore, the immobilization of finely dispersed copper compound particles obtained by electric explosion on the support surface imparts antibacterial properties to the sorption material. The olivine-based sorption material prepared during the synthesis is being used for further research.

[0026] An example of the practical implementation of obtaining a sorption material and its activity in extracting microorganisms from aqueous media, as well as antibacterial properties, is given below.

[0027] Example.

[0028] To obtain the stated sorption material, crushed olivine mineral is taken per load, with the following component ratio, wt. %: aluminum oxyhydroxide - 22; finely dispersed particles of copper compounds - 1.5; olivine - 76.5.

[0029] The olivine mineral is crushed in an agate mortar, then sieved using sieves (mesh size 0.1 mm and 0.5 mm) to obtain the desired granule fraction of 0.1-0.5 mm. Then, a 10 g sample of crushed olivine is taken and the process of immobilization of finely dispersed particles of copper compounds (obtained by electric explosion) is carried out on the surface of the mineral carrier in an amount of 0.2 g. For this, a 10 g sample of olivine was weighed on a laboratory scale and placed in a laboratory glass beaker (1000 cm 3 ). Next, a 0.2 g sample of finely dispersed copper compound particles was weighed and placed in the beaker with the carrier. 500 cm3 of water was poured into the beaker with the carrier and the active component. 3Distilled water was added and placed on a magnetic stirrer, stirring at low speed. The carrier and active component were mixed in distilled water for 10 minutes. After mixing, the solid phase was separated from the aqueous phase by centrifugation. The precipitate was then dried at 120°C for 3 hours until completely dry. The olivine treated with finely dispersed zinc compounds was then placed in a muffle furnace and the temperature was raised to 400°C for 1 minute, followed by cooling.

[0030] Next, take an 8 g sample of olivine treated with finely dispersed particles of copper compounds, and immobilize aluminum oxyhydroxide nanofibers on the surface of the modified mineral. For this, olivine, with 8 g of finely dispersed particles of copper compounds attached to its surface, is placed in a laboratory glass beaker (2 dm3). 3), pour distilled water into it in the amount of 1 dm 3 An aqueous NaOH solution with a concentration of 20 grams per liter is added until the pH reaches 10. The bottom of the beaker is then wrapped in basalt cloth and placed on an electric hotplate, heating the contents. The reaction mixture is heated to 70°C, followed by the addition of 1.12 grams of AD1 food-grade aluminum powder with a particle size of less than 0.1 mm.

[0031] The sorbent is synthesized with periodic stirring for 50 minutes, maintaining a temperature of 60°C. The resulting sorbent is then washed repeatedly with distilled water until the wash water reaches a neutral pH. The precipitate is then filtered on a Buchner funnel using a vacuum pump. The filtered precipitate is dried at a temperature of 110°C until all moisture is removed.

[0032] The specific surface area and specific pore volume of the presented sorption material and its components are determined using the thermal desorption method of nitrogen, using the SORBTOMETER M device. Specific surface area is 42.9 m 2 / g; specific pore volume - 0.019 cm 3 / G.

[0033] To determine the antibacterial properties of the surface of the studied sorption material and its components, a test culture of Escherichia coli ATCC 25922 (Liofilchem, Italy) on a solid nutrient medium was used. The method was as follows: a 24-hour E. coli culture with a concentration of 2.1⋅10 7 CFU / cm 3The samples were inoculated onto a 90 mm diameter Petri dish with meat-peptone agar (ZAO NICF, Russia). The dishes were air-dried for 10 min. The sample application zones were marked on the back surface with a marker. A 0.1 g sample of the test material was then weighed and placed onto the inoculated Petri dish in the corresponding marked zone. After 24 hours, contact inhibition of microorganism growth was determined in the application zone and the surrounding area. The zone of bacterial growth inhibition was measured in mm. Bacterial growth inhibition was assessed visually; the absence of visible colonies in transmitted light was considered absent.

[0034] The obtained sorption material and its analogs were tested for the extraction of Escherichia coli cultures from model solutions using dynamic testing. The experimental setup for dynamically passing solutions, shown in the figure, was used.

[0035] Figure 1 shows a diagram of an experimental setup for determining the degree of extraction of microbiological contaminants from aquatic environments using a sorption material.

[0036] The experimental setup consisted of a tank for a model solution - 1, a peristaltic pump MDP-200 Mini (Aurora Pack Engineering LLC, Russia) - 2, a tube with the studied sorption material - 3, a tank for receiving filtered water - 4, a silicone hose - 5, 6, 7. All the described components of the setup are connected to each other by a silicone hose - 5, 6 and 7. Using a peristaltic pump, a model solution was passed through in an amount of 1000 cm 3 through a tube (filter module) filled with the sorption material being studied. Each passed filtrate sample (100 cm 3), as well as the initial model solution, for the presence of Escherichia coli bacteria. The flow rate of the model solution through the sorption material layer was 100 cm3 / hour.

[0037] A model solution for dynamic testing of the studied samples was prepared using tap water, which was left to settle for 24 hours to remove chlorine from it, and then seeded with Escherichia Coli ATCC 25922 culture (Liofilchem, Italy), with a concentration of 1.4*10 7 CFU / cm 3 .

[0038] To determine the content of Escherichia coli bacteria in the model solution and filtrates, the membrane filtration method was used. This method involves passing a certain volume of water through filter materials, followed by growing cultures on a differential nutrient medium and counting the colonies. The studied filtrates and the original model solution are passed through bacterial concentration filters (OOO Elema-N, Russia). Next, the filters are placed on Endo medium in Petri dishes (OOO Petroplast, Russia) and placed them upside down in a B6 Thermo Fisher Scientific thermostat (Thermo Scientific, Germany) and incubated at a temperature of (37 ± 1) ° C for 24 hours. After 24 hours, a visual count of the number of colonies is performed, measured in CFU / cm 3 .

[0039] Table 1 shows the values ​​of the specific surface area and specific pore volume of the developed sorption material, its individual components and analog materials.

[0040] Table 1.

[0041] Name of material Particle size, mm Specific surface area, m2 / g Specific pore volume, cm3 / g Olivine 0,1-0,5 0,51 0 Aluminum oxyhydroxide Less than 0.1 197,4 0,084 Finely dispersed particles of copper compounds Less than 0.1 14,63 0,006 Modified sorption material 0,1-0,5 42,9 0,019 Analogue 1 0,1-0,5 45,71 0,02 Analogue 2 0,1-0,5 10,27 0,004

[0042] As can be seen from the tabular data, the olivine mineral carrier sample has the lowest values. The active component, aluminum oxyhydroxide, has the highest values. The final modified sorbent, due to the treatment of olivine with the active components, has a significantly higher specific surface area and specific pore volume than the original carrier, and its determined values ​​are approximately the same as those of the prototype material (Analog 1).

[0043] This patent involved studying the antibacterial properties of a sample of the obtained sorption material, its carrier and active components, as well as analogous materials. Bacterial growth was assessed according to the method described in the patent. The ability of the studied samples to suppress Escherichia coli culture at a concentration of 2.1⋅10 7 CFU / cm 3 presented in Table 2.

[0044] Table 2.

[0045] Name of material Particle size, mm Suppression zone, mm Olivine 0,1-0,5 Solid growth Aluminum oxyhydroxide Less than 0.1 Solid growth Finely dispersed particles of copper compounds Less than 0.1 10 Modified sorption material 0,1-0,5 3 Analogue 1 0,1-0,5 1 Analogue 2 0,1-0,5 Solid growth

[0046] As can be seen from Table 2, the olivine and aluminum oxyhydroxide carrier exhibits no antibacterial properties, and continuous bacterial growth is visible around and beneath the sample, with no inhibition zone. Finely dispersed copper compound particles exhibit very high antibacterial properties. After immobilization of the active components on the carrier, the modified sorption material exhibits good antibacterial properties, with an inhibition zone of 3 mm.

[0047] Table 3 presents comparative characteristics of the claimed sorption material with analogs, when they extract Escherichia coli bacteria from a model solution.

[0048]

[0049] As can be seen from the results of the table data, the developed sorption material for purifying aquatic environments from microbiological contaminants has characteristics for extracting Escherichia coli bacteria from a model solution that are significantly higher than those of similar materials.

Claims

A sorption material for purifying aquatic environments from microbiological contaminants, consisting of a mineral-based carrier and active components, characterized in that olivine with a particle size of 0.1-0.5 mm is used as the mineral-based carrier, and finely dispersed particles of copper compounds with a particle size of less than 0.1 mm and aluminum oxyhydroxide nanofibers are used as the active components, with the following ratio of components, wt.%: olivine - 76.5; finely dispersed particles of copper compounds - 1.5; aluminum oxyhydroxide nanofibers - 22.

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