Tio 2-based material (tio 2-NP), and method for the synthesis thereof, having a multifunctional and versatile property for the simultaneous and one-step photo-oxidation and adsorption of different pollutants, such as arsenic, aluminium, barium, boron, iron, lithium, manganese, molybdenum, strontium, antimony, silicon, zinc and calcium, from water and effluents, and the recovery, reuse and regeneration thereof

Abstract

The present invention discloses a multifunctional nanoparticulate TiO2-based material, denoted as TiO2-NP, with the ability to photooxidise arsenic III and adsorb arsenic V and other metals, such as antimony, silicon, zinc, calcium, aluminium, barium, boron, iron, lithium, manganese, molybdenum and strontium from water and effluents that include surface water, groundwater, mining water or effluents and / or industrial effluents. The invention further discloses a method for obtaining the nanoparticulate material; a system and method for removing arsenic and other metals from water and effluents; and a method for the post-use recovery of the nanoparticulate material, its reuse in consecutive cycles and its regeneration.

Description

[0001] A TIO2-BASED MATERIAL (TIO2-NP), AND ITS SYNTHESIS METHOD, WHICH HAS A MULTIFUNCTIONAL AND VERSATILE PROPERTY TO SIMULTANEOUSLY PHOTO-OXIDIZE AND ADSORB IN A SINGLE STEP DIFFERENT CONTAMINANTS SUCH AS ARSENIC, ALUMINUM, BARIUM, BORON, IRON, LITHIUM, MANGANESE, MOLYBDENUM, STRONTIUM, ANTIMONY, SILICON, ZINC AND CALCIUM, FROM WATERS AND EFFLUENTS, THEIR RECOVERY, REUSE AND REGENERATION

[0002] Field of Invention

[0003] The present invention relates to a water treatment system for the removal of arsenic, aluminum, barium, boron, iron, lithium, manganese, molybdenum, strontium, antimony, silicon, zinc and calcium from water and effluents, which include surface water, groundwater, mining water or effluents (tailings dam water) and / or industrial effluents.

[0004] The invention specifically relates to an optimized system whose operating conditions contemplate photo-oxidation and adsorption processes of contaminants, using a prototype photo-reactor at pilot plant scale to remove the aforementioned contaminants simultaneously and in a single stage, validated from real surface, underground and mining waters. The system mainly consists of a multifunctional nanoparticulate material based on TIO2, designed with a specific surface chemistry and that in specific doses allows it to photo-oxidize arsenic III under the assistance of simulated sunlight and simultaneously adsorb and without irradiation arsenic V, aluminum, barium, boron, iron, lithium, manganese, molybdenum, strontium, antimony, silicon, zinc and calcium in a single stage, from real surface, underground and mining waters.This nanoparticulate material has significant reuse potential in up to four consecutive treatment cycles to obtain drinking water standards, without losing its efficiency or requiring pretreatment. It also requires a method for post-use regeneration, giving it a new lifespan in the treatment system. Background of the Invention.

[0005] Arsenic and its compounds are extremely toxic, especially inorganic arsenic. Several geographic regions around the world have been affected by the presence of this chemical in water.

[0006] The ingestion of small amounts of arsenic can cause chronic effects due to its bioaccumulation in the body. The World Health Organization recommends, as a provisional criterion, a permissible level of arsenic in drinking water of 10 ppb (maximum contaminant level). The presence of arsenic has also been attributed to carcinogenic diseases of the skin, lungs, and bladder. Therefore, water contamination by arsenic (As) has become one of the most serious environmental and public health problems due to the biopersistence, toxicity, and carcinogenicity of this toxic element. This metalloid can be found naturally (usually as As(III) and As(V)) in rocks and minerals, and when it comes into contact with groundwater, surface water, and mine water, it can be released into the environment, thus contaminating effluents and soils.Additionally, it can also be present in waters due to anthropogenic pollution, mainly from agricultural activities, the timber industry, mining and smelting activities (for example, copper mining), among others.

[0007] The consumption of water contaminated by As is a global problem that affects more than 200 million people in the world (at least 70 affected countries), mainly: USA, India, China, Chile, Bangladesh, Taiwan, Argentina, Mexico and, this has made its elimination through efficient purification methods an urgent need.

[0008] In this sense, conventional and advanced technologies such as oxidation, coagulation / precipitation, sedimentation, filtration, adsorption, ion exchange, reverse osmosis, and biological treatments have been implemented to remove As from water. These technologies present a series of advantages and disadvantages depending on the As species to be removed. For example, As(lll) is more difficult to remove than As(V), hence its transformation into As(V) through oxidation methods is necessary to achieve its elimination. In these cases, the implementation of several separate technologies is required to efficiently remove As(lll) and As(V). Therefore, it is necessary to combine several of them to ensure the effective elimination of both species.For example, combining oxidation with filtration or adsorption processes, or combining adsorption processes with membranes or ion exchange resins, are part of the existing solutions at the treatment plant level.

[0009] Conventional drinking water treatments are aimed at removing color, turbidity, and microorganisms. This elimination is achieved through a combination of coagulation, flocculation, sedimentation, filtration, and disinfection processes. However, when removing chemical elements from water, such as arsenic, it is sometimes necessary to resort to advanced methods.

[0010] The technologies generally used to remove arsenic, in addition to coagulation and flocculation, are: adsorption-co-precipitation using iron and aluminum salts, adsorption on activated alumina, reverse osmosis, ion exchange, and oxidation followed by filtration. Other developed technologies, instead of using salts, employ an electrochemical process involving brass electrodes (Cu 2+ and Zn 2+ ) and a power source that provides energy, thereby reducing the concentration of diluted arsenic below the detection level of the atomic absorption spectrophotometer.

[0011] It is also known that there are solar prototypes that allow the removal of contaminants in water samples assisted by sunlight and / or simulated sunlight. These devices are capable of recirculating contaminated water in the presence of a semiconductor material under irradiation. When irradiated, this semiconductor acts under the principle of heterogeneous photocatalysis, achieving photo-oxidation or photo-reduction of the contaminant present in the medium. The configuration of these systems mostly consists of compound parabolic trough (CPC) solar collectors, which allows for greater radiation capture.

[0012] It is important to note that these systems mainly use Titanium dioxide (TiC) as a semiconductor and are mostly applied for the removal of organic contaminants. Although some efforts have been made for its application in the removal of arsenic, these have been focused mainly on its use as a photo-oxidant or as an adsorbent, however, in no case has an exclusive TiO2 material with multifunctional properties been achieved that efficiently allows carrying out both processes simultaneously and effectively, being directed only towards the removal of one species of As (III or V), thus restricting the type of water to be treated; unlike the present invention that is related to the removal of two toxic species of a metalloid such as arsenic using a single multifunctional material.

[0013] In view of the above, the present patent application provides a low-cost, low-complexity, and high-performance technology for the removal of both Arsenic species (III and V) in a single step, avoiding the use of various technologies and materials. This technology is based on a multifunctional nanoparticulate material based on TiO2 that is a photo-oxidant of As(III) and an adsorbent of As(V), and of other metals such as Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca, or a mixture thereof. Said nanoparticulate material operates in a photo-reactor system whose hydraulic design allows in an innovative way:

[0014] 1) efficiently exploit the incident (artificial) radiation to activate the photo-oxidative property of the material for the removal of As(lll); and

[0015] 2) Promote the adsorption capacity of the material to adsorb As(V), all in one system.

[0016] Regarding the state of the art, three documents can be highlighted, which include some of the characteristics of the product, the method and / or the system related to the technology. Document CN 102381777 provides a method for the treatment of acidic wastewater with high arsenic content by using nano T¡O2 and arsenic recycling, which comprises the following steps: adjusting the pH value of the wastewater to 5 by using milk of lime and separating the wastewater into solid and liquid; continuously absorbing a solution with high arsenic content three times using a nano T¡O2 adsorbent and adjusting the pH value to 7. The adsorbent can be recycled through the elution and regeneration of sodium hydroxide. Meanwhile, the arsenic in the backwash liquor is recycled by adding calcium oxide.According to the method, trivalent arsenic and heavy metal ions in wastewater can be effectively removed, the adsorbent can be recycled, with almost no waste generated, and the arsenic can be recycled to reduce environmental pollution and obtain economic benefits. In contrast, the multifunctional nanoparticulate material TiC-NP takes advantage of its photo-oxidative and adsorbent properties to simultaneously and efficiently remove both As (III and V) species and other metals in a single system. In addition, the TiC-NP material shows the ability to remove high concentrations of As (up to 30,000 ppb) in a single system, without requiring the use of parallel systems to achieve maximum efficiency.

[0017] US 7,497,952 discloses a method for removing dissolved contaminants from a solution using a surface-activated crystalline titanium oxide product having a high adsorption capacity and adsorption rate for dissolved contaminants, particularly arsenate and arsenite. Preferably, the titanium oxide product includes crystalline anatase having primary crystallite diameters in the range of 1-30 nm. The surface-activated titanium oxide is combined with other filter media to further enhance the removal of dissolved contaminants. As noted above, the multifunctional nanoparticulate material of the present application, T¡O2-NP, exhibits the ability to efficiently remove both As (III and V) species and other metals simultaneously through photo-oxidation and adsorption processes that can be carried out in a single system without combining or requiring other media.Additionally, as indicated, the material shows the ability to remove other metals such as Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca or a mixture of them.

[0018] Document US 10661265, describes composite particles based on semiconductor oxide nanotubes useful for the removal of dyes and their process, has been described in this invention, which refers to an innovative method, involving an ion exchange mechanism operating under dark conditions in an aqueous solution, for the processing of innovative products consisting of semiconductor oxide nanotubes deposited on (or anchored or bonded to) the surface of fly ash particles and metal oxide nanoparticles (magnetic and non-magnetic). The resulting micro- nano and nano-nano integrated composite particles find potential application in the removal of organic synthetic dye from aqueous solution and industrial effluents through surface adsorption process, involving ion exchange and electrostatic attraction mechanisms, operating under dark conditions.The novel composite particles can be recycled for the next dye adsorption cycle by decomposing the previously adsorbed dye on their surfaces through an innovative approach involving the use of photocatalyst deposited on a noble metal or a magnetically separable magnetic photocatalyst and exposure to ultraviolet (UV) or solar radiation. In the present application, the multifunctional nanoparticulate material TiC-NP has the ability to remove As and other metals present in wastewater, which may not include the removal of colorants and / or dyes, so both technologies are intended for different objectives.

[0019] The technologies mentioned above for removing arsenic present certain disadvantages such as: i) the majority of them use composite materials, that is, composite materials from the impregnation of an element on a material or the combination of two elements / materials converted into one, during the synthesis of the same, where the preparation of these composite materials requires more complex methods than those presented in this application;

[0020] (i) The arsenic removal mechanism used in these methods described in the state of the art is removal by adsorption processes or by photooxidation processes. Few cases report both processes simultaneously, which limits their efficiency and applicability, being only for the removal of one species of As (As III or As V), thus restricting the type of water to be treated, since they have not achieved the multifunction of removing other elements (metals) from chemically complex waters (real surface, underground and mining); (iii) arsenic removal by precipitation methods is limited by the inability of material regeneration; (iv) the limits of arsenic concentration and pH of the water to be treated are limited in very specific ranges; (v) low feasibility for the application of technologies in remote areas.

[0021] In view of the above, there is a need to provide methods and systems that effectively remove both As (III and V) species and other metals from water to prevent their negative effects on human health. The present invention satisfies this need and provides other associated benefits, such as the use of a single material with multifunctional properties to carry out photooxidation and adsorption processes on its own, thus expanding the type of water to be treated; it allows the removal of high concentrations of As (up to 30%).000 ppb in a single step; the presence of other coexisting ions does not limit its performance; it can remove other metals such as Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca or mixtures of them; the dose of the multifunctional material to be used is adapted to the concentration of As and initial characteristics of the water to be treated; it presents an efficient performance for the removal of As and other metals in water and effluents from different sources (surface, underground and mining), it can be used without prior treatment in up to four consecutive cycles without losing its effectiveness in removing these elements; and it allows its post-use regeneration to give it a new useful life in the treatment system.

[0022] In view of the above, this patent application solves the technical problem of removing arsenic (species As III and V) and other metals from water and effluents affected by these pollutants, such as surface water, groundwater, mining water or effluents and / or industrial effluents, in a single step and, in addition, allows the removal of other metals such as Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca or a mixture of them.

[0023] Summary of the Invention

[0024] An aspect of the present invention provides a multifunctional nanoparticulate material based on TiO2, denoted as TiC-NP, with the capacity to photo-oxidize arsenic III and adsorb arsenic V and other metals, such as: antimony (Sb), silicon (Si), zinc (Zn) and calcium (Ca), aluminum (Al), barium (Ba), boron (B), iron (Fe), lithium (Li), manganese (Mn), molybdenum (Mo), strontium (Sr) and its post-use recovery, its reuse in consecutive cycles and its regeneration.

[0025] A second aspect of the present invention is to provide a method for producing the multifunctional nanoparticulate material.

[0026] A third aspect of the present invention provides a system comprising a photo-reactor together with a metallic tank with mechanical agitation containing a multifunctional nanoparticulate material comprising TiO2-NP nanoparticles that operates in suspension, a system that allows the double function of photooxidation of As (III) to As (V) and simultaneously, absorb the generated As (V) and the other metals. In a fourth aspect, the invention provides the operating conditions required to simultaneously remove (in a single step) arsenic and Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca or a mixture thereof from waters and effluents comprising surface water, groundwater, mining water or effluents and / or industrial effluents, and an analytical method for the determination of arsenic and other metals in real surface, groundwater and mining waters.

[0027] In a fifth aspect, the invention provides a method for regenerating the recovered post-reuse multifunctional nanoparticulate material after four continuous reuse cycles.

[0028] Brief Description of the Figures

[0029] FIG. 1. Transmission electron microscopy (TEM) image of TÍÜ2-NP nanoparticles

[0030] FIG. 2. Configuration of the photo-reactor scaled to a pilot plant, improved in its agitation type.

[0031] FIG. 3. Nanoparticulate material separation system (schematic diagrams of the separation system are also shown).

[0032] FIG. 4. Comparison of As removal efficiency according to the type of agitation in the prototype: A) peristaltic pump, B) centrifugal pump). Photo-oxidation kinetics of As(lll) and progressive adsorption of As(V). Conditions: Simulated As waters with interferents that simulate the chemical composition of the Loa River with an initial concentration greater than 600ppb, load: 0.4g / L, pH = 3.51 (adjusted with a 0.1M HCl solution), Irradiation source: UV:Visible (15:85).

[0033] FIG. 5. Photo-reactor for batch-scale testing.

[0034] FIG. 6. Shows the ratio of multifunctional material dosage to As concentration to be treated as a function of the desired final water quality. Conditions: Actual water; pH 3.51.

[0035] FIG. 7. Percentage removal of some coexisting ions and heavy metals in all case studies using the multifunctional TiC-NP material at prototype scale. FIG. 8. Comparison of the percentage removal of As according to the reuse of the nanoparticulate material for six applications, after 90 min of reaction in surface waters. Case studies: Salado River and Socaire River.

[0036] FIG. 9. Calibration curve obtained for the determination of A) As(V) and B) total As by the optimized colohmmetic method in the present invention considering coexisting elements / ions in waters and effluents comprising surface waters, groundwaters, mining waters or effluents and / or industrial effluents.

[0037] Detailed Description of the Invention

[0038] The components of the water and effluent treatment system are described below. Each methodological step developed for each of the system components is described, primarily with reference to the group's specific background:

[0039] Method for the production of multifunctional nanoparticulate material (photocatalyst / adsorbent) based on titanium dioxide (TIO2-NP)

[0040] The multifunctional nanoparticulate material for removing arsenic and metals from water and effluents comprising surface water, groundwater, mining water or effluents and / or industrial effluents of the present invention is based on titanium dioxide (TiC) with 100% anatase crystalline phase, surface area of ​​at least 186 m 2 / g and a band gap energy (Eg) of maximum 3.09 eV. These specific characteristics allow it to photo-oxidize As(lll) and simultaneously adsorb As(V), Al, B, Ba, Ca, Fe, Li, Mo, Mn, Sb, Si, Sr and Zn. Furthermore, the nanoparticles have a particle size between 5 and 10 nm and can be reused up to 4 times without losing their post-use efficiency.

[0041] To obtain titanium dioxide (TiC ) that allows the efficient photo-oxidation of As(lll) under simulated sunlight irradiation and the simultaneous adsorption of As(V), Al, B, Ba, Ca, Fe, Li, Mo, Mn, Sb, Si, Sr and Zn without irradiation, a synthesis method was implemented where each step is described:

[0042] A white gel is prepared by adding 4 to 5 mL of concentrated sulfuric acid with a purity of at least 97% and 9 to 10 mL of titanium isopropoxide with a purity of at least 97% under vigorous magnetic stirring, using a stir plate, to generate a millimolar ratio S:T¡ of 80:30.

[0043] Under magnetic stirring, a solution A with a pH between 1 and 3 is prepared, adding between 70 and 80 mL of distilled water to the gel obtained.

[0044] To solution A, between 50 and 70 mL of an aqueous solution between 2 and 3M of KOH is added dropwise under magnetic stirring at a speed between 1 and 3 mL / min followed by between 5 and 30 mL of distilled water until a pH between 3 and 4 is obtained. The mixture obtained has a final concentration between 0.8 and 1 M of KOH, and is kept under continuous stirring for between 40 and 50 min.

[0045] The obtained mixture is transferred to a 200mL Teflon vessel contained within a stainless steel autoclave reactor and maintained at a temperature between 160°C and 180°C for 24-48 h.

[0046] After hydrothermal treatment, it is allowed to cool and the material is centrifuged and washed 3 times with distilled water and once with acetone.

[0047] The material is dried at room temperature for at least 12 hours.

[0048] The most important material properties obtained with this synthesis are described below: TiC-NP presents as a single crystalline phase anatase determined by X-ray diffraction (XRD). The crystalline phase presented by this nanoparticulate material is the active phase to achieve efficient photocatalytic activities for the oxidation of As(lll) to As(V) under UV-Visible light irradiation. Using a Diffuse Reflectance Ultraviolet-Visible Spectroscopy (UV-Vis DRS) analysis, the band gap energy (Ebg) of the synthesized TiC-NP was estimated. An Ebg value of 3.09 eV was obtained, which is equivalent to an absorption range that covers the Visible spectrum, allowing the nanoparticulate material to be used under sunlight irradiation. In addition, a high surface area of ​​186 m 2 / g was measured by BET area through N2 adsorption-desorption isotherms. This high surface area increases the active sites in the nanoparticulate material, which influences both the increase in photocatalytic and adsorptive performance. TEM analysis shows a material composed of spherical nanoparticles with an average size between 5-10 nm (FIG. 1). Table 1. Summary of the properties of the nanoparticulate material TÍÜ2-NP

[0049] The methodological differences for obtaining the multifunctional nanoparticulate material TÍÜ2-NP to photo-oxidize As(lll) and simultaneously adsorb As(V), Al, B, Ba, Ca, Fe, L¡, Mo, Mn, Sb, Si, Sr and Zn used in the present invention with respect to what has been reported in the state of the art lie in the optimization / increase / adjustment of the molar ratio S:T¡, the type of mineralizer (base used (KOH)), the concentration of the mineralizer, the speed of incorporation of the mineralizer, the stirring times and the heat treatment times.

[0050] The modified synthesis method, optimized and adjusted with respect to that described in the state of the art, allows obtaining a nanoparticulate material that presents a lower energy band of 3.09 eV, consequently, the nanoparticulate material requires less energy to be activated, that is, it has a greater capacity to absorb energy in the visible range (sunlight). Furthermore, its surface properties such as the surface area were drastically improved (186 m 2 / g) as well as the particle size, whose size range was noticeably homogenized and decreased, that is, nanoparticles with a size between 5-10 nm were obtained. The improvement of both properties promotes an increase in the active sites of the material, allowing it to increase its photocatalytic and absorbent efficiency. Furthermore, the presence of anatase as a crystalline phase, optimal for photocatalytic processes, was not altered. The synthesis not only achieves an improvement in some of the material's properties, but also entails shorter synthesis times and a higher yield in the quantity of final product obtained. This would also be reflected in a significant reduction in the production costs of the material by reducing heat treatment times and increasing the final yield obtained from the product.

[0051] Scaling up to a pilot plant and configuration of the improved photo-reactor in its agitation type

[0052] The scaling, design, construction and configuration at pilot plant scale of the improved stirred type photoreactor is compactly presented in FIG. 2. The configuration of the improved and scaled photoreactor in the present invention includes specific features, such as: a.- A metal tank, preferably aluminum, with a capacity of between 150 and 250 L: the multifunctional nanoparticulate material is placed in this tank to carry out the adsorption process of As, Al, B, Ba, Ca, Fe, Li, Mo, Mn, Sb, Si, Sr and Zn. b.- The photoreactor includes a light emission module with an annular configuration, where the photooxidation process of As(lll) to As(V) is carried out by means of UV-Visible radiation: it consists of an annular system constructed of anodized aluminum reflector material, a borosilicate tube 1 m long and 6 cm in diameter, and a simulated sunlight illumination system.The annular configuration design of the irradiation system (lighting system) comprises at least 14 lamps. The percentage of visible light versus near ultraviolet (UVA) light is between 80 and 90% and 10 and 20%, respectively. Based on this consideration, there are at least two UVA lamps (top and bottom), 122 cm long and 3.81 cm in diameter, and at least 12 visible lamps, 120 cm long and 2.8 cm in diameter. This configuration allows for an increase in the irradiation area and power by between 50 and 55 W / m. 2 ' more preferably 53.98 W / m 2. c.- Centrifugal pump, responsible for carrying out the water propulsion process throughout the system, including the adsorption tank and the photoreactor. This centrifugal pump of at least 1 HP of power is responsible for carrying out the process of agitating the water with the nanoparticulate material within the system. d.- Dosing and pH controller system that has a resolution of 0.01 and a control flow of 0.5 to 3.4 L / h e.- Post-use nanoparticulate material separation and recovery system: to recover post-use nanoparticulate material, which consists of a glass decanter and membrane filtration, for this, commercial membranes are used, preferably PVDF with a pore size of at least 0.2 pm and 90 mm in diameter.The filtration system has 2 membrane modules connected to a centrifugal pump of at least 1 HP of power, which propels the post-treatment solution (treated water + nanoparticles) through the membranes, to obtain filtered water free of particles after its passage through the membrane (FIG. 3). f.- a power system to provide energy to the system to remove arsenic and metals from water and effluents comprising surface water, groundwater, mining water or effluents and / or industrial effluents. This system provides 100% electrical autonomy by being electrically powered by solar panels. The system comprises between 2 and 4 solar panels with a power between 300 and 545 W each, at least two lithium batteries with a capacity of at least 50 V, an inverter and an inverter connector system.

[0053] The optimization and scaling of some of the photoreactor components with respect to those described in the state of the art, allow an increase in treatment capacity of up to 200 L / h and improve lighting efficiency (due to the annular configuration). Additionally, the change in the type of agitation significantly improved the efficiency of As removal from the centrifugal pump drive. A comparison was made between the agitation from the centrifugal pump drive and that of a peristaltic pump to maintain the water + nanoparticulate material mixture in close contact, as can be seen in FIG. 4, a greater efficiency was obtained in As removal (managing to remove both As species (III and V) from oxidation and adsorption, along with shorter treatment times). This would also be reflected in a significant reduction in system costs by eliminating the use of pumping by using a peristaltic pump.The incorporation of a post-use nanoparticulate separation and recovery system achieved a recovery efficiency of between 90 and 96% of the initial dose added. This allows the material to be recovered after use in the system to remove As and reused in up to three additional cycles, which improves the system from a circular economy perspective. Finally, the incorporation of a power supply system gives the system electrical autonomy, allowing it to be used and installed in remote areas.

[0054] Analytical method for determining arsenic speciation and its concentration in water and effluents with up to 30,000 ppb of arsenic in the presence of other coexisting ions / elements

[0055] A method for removing arsenic and metals from water and effluents, characterized in that it comprises the following steps: i. contacting the system comprising the photo-reactor that includes the metallic tank with mechanical agitation containing a multifunctional nanoparticulate material, comprising TiO2 nanoparticles in 100% anatase crystalline phase, a surface area of ​​at least 186 m 2 / gy, a band gap energy (Eg) of maximum 3.09 eV in suspension;

[0056] i. exposing the obtained mixture to UV-Visible irradiation for complete photooxidation of arsenic III by means of an agitation system using a centrifugal pump and simultaneously adsorbing the photo-produced arsenic V; ill. adsorbing arsenic (V) and, Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca or a mixture thereof, contacting the multifunctional material with the water to be treated by means of an agitation system using a centrifugal pump in the absence of light; wherein the method further comprises: determining and quantifying the concentration of As(lll) and As(V) in the water to be treated in the presence of other coexisting elements / ions such as As, Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca or a mixture thereof.

[0057] The multifunctional nanoparticulate material in the removal system has a concentration between 0.1 and 4.0 g / l and a pH adjusted between 3 and 4.5.

[0058] The method allows the removal of elements selected from As, Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca, a mixture of them or all of them simultaneously and can be reused consecutively up to 4 times.

[0059] In order to determine and quantify the concentration of As(lll) and As(V) in the water to be treated, a molybdenum blue (MO) colohmmetric method is used, which comprises the following steps: a. preparing standard aqueous solutions with fixed concentrations for each of the elements / ions Al, Ba, B, Fe, L¡, Mg, Mo, Sr, Sb, Si, Zn and Ca; b. preparing standard solutions of arsenic (III and V) with different concentrations between 5 and 10,000 ppb to which a fixed volume of each of the standard solutions of the coexisting elements / ions prepared in the previous step is added; c. preparing a MO color reagent from the mixture of four solutions A:B:C:D in proportions 2:2:1:5, where A - ascorbic acid, B - ammonium heptamolybdate, C - antimony potassium tartrate and D - sulfuric acid; d. Add HCl until a concentration between 0.005 and 0.015% is reached in the sample; e. Add phosphate until a concentration between 5 and 10 uM is reached in the sample; f.divide the sample into two parts, to one of the parts add KMnCU until reaching a concentration between 0.05 and 0.15 mM in the sample and stir between 5 and 10 minutes; g. add the MO color reagent in a 10:1 sample: MO ratio to the parts obtained in the previous step and stir between 5 and 10 minutes and measure absorbance at between 880 and 920 nm; and h. determine the absorbance vs. concentration relationship using a calibration curve. where the method also comprises: determining and quantifying the concentration of As(lll) and As(V) in the water to be treated in the presence of other coexisting elements / ions such as Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca or a mixture thereof.

[0060] The analytical method modified and optimized with respect to that described in the state of the art, allows to quantify up to 30,000 ppb of As, and to use waters and effluents that include surface water, groundwater, mining waters or effluents and / or industrial effluents, unlike the reported methodologies which used underground waters and effluents, high salinity waters, or distilled water enriched with arsenic and quantify up to 1,000 ppb of As. Furthermore, the other metals Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca or mixtures of them are not considered, which makes its implementation difficult in real waters of high chemical complexity.

[0061] Procedure for the regeneration of TIO2-NP material:

[0062] The TÍÜ2-NP regeneration protocol is based on i) an arsenic desorption process in batch scale systems in a basic medium, i) regeneration of the material in an acidic medium, in order to maintain its initial properties.

[0063] Each step is described below: a. In a beaker, add between 90 and 110 mL of a solution of

[0064] 0.5 M NaOH to which between 1 and 3 g of the recovered T¡O2-NP nanoparticulate material are added after four continuous reuse cycles, maintaining a dose or concentration of T¡O2-NP material of 20 g / L. The dispersion is maintained under continuous magnetic stirring at between 300 and 400 RPM for at least 4 hours at room temperature. b. After the stirring time has elapsed, the solid is separated by centrifugation at between 5,000 and 7,000 RPM for at least 10 min. c. A sample of the supernatant (NaOH + As solution and other elements) is used to quantify the desorbed arsenic concentration. After the As quantification analysis, it is shown that the desorption procedure described in the present invention allows a desorption of 67% of the arsenic adsorbed on the material. d. The solid recovered from desorption is then regenerated.For this purpose, between 90 and 110 mL of a 0.5 M H2SO4 solution are added to a beaker to which between 1 and 3 g of the TIO2-NP nanoparticulate material treated with NaOH are added, maintaining a dose or concentration of TIO2-NP material of 20 g / L. The dispersion is maintained under continuous magnetic stirring at between 300 and 400 RPM for at least 1 hour at room temperature. e. After the stirring time has elapsed, the solid is separated by centrifugation at between 5,000 and 7,000 RPM for at least 10 min. f. Finally, between 300 and 500 mL of distilled water are added to a beaker to which between 1 and 3 g of the TiC - NP nanoparticulate material treated with H2SO4 are added, maintaining a dose or concentration of TiC-NP material of 5 g / L. The dispersion is kept under continuous magnetic stirring at between 300 and 400 RPM for at least 15 min at room temperature. After the stirring time has elapsed, the solid is separated by centrifugation at between 5,000 and 7.000 RPM for at least 10 min. g. The previous step is repeated three times. h. The recovered solid is dried for 24 h at room temperature.

[0065] The post-use material regeneration protocol used in the process of removing As and other metals after four consecutive use cycles, compared to that described in the prior art, allows for maximizing the use of the material without affecting its properties or diminishing its efficiency, restoring its initial characteristics and making active sites available for reuse in the system. Furthermore, it increases the added value of the treatment system by reducing environmental impacts, by reducing the amount of waste and promoting the circular economy of both the material and the system. The regeneration method reported in the present invention shows evident differences with respect to what has been reported.The regenerated material is a single multifunctional material composed of TÍÜ2-NP that was reused in four consecutive cycles before its regeneration process (number of use cycles in which the nanoparticulate material maintained its efficiency in removing As up to drinking water standards). This protocol includes a treatment in an acidic medium that allows the material to return to its original properties, unlike what has been reported, which only desorbs the captured As after a single use in the system. This method reduces treatment times and improves the type of agitation. Finally, the regenerated material can be used again in the system. All of this significantly reduces system costs by allowing continuous reuse of the same material, while simultaneously reducing waste generation and disposal.

[0066] Specific operating conditions required to remove As, Al, B, Ba, Ca, Fe, Li, Mo, Mn, Sb, Si, Sr and Zn on a case-by-case basis

[0067] To establish the operating conditions required by the material in the system for the present invention, its operating efficiency was validated using water and effluents for two operating conditions: a) at laboratory level (Batch system) and b) at pilot plant level.

[0068] For validation under real groundwater conditions, the following were used:

[0069] - well water in the Antofagasta Region with As (III and V) concentrations of up to 100 pg / L,

[0070] - for the validation in surface waters and effluents contaminated with As (III and / or V) up to 3,000 pg / L, the Loa River basin (Loa Alto Lasana, Loa Medio Después de Junta, Loa Medio Chunchuri), Salado River and Socaire River in the Antofagasta region were taken as a case study, which shows a significant physicochemical variability of the water according to its spatial (length of the basin) and seasonal (time of year) variation, and

[0071] - For mining water and effluents, samples were taken from two tailings dams: Talabre Dam (Codelco Norte) and Ovejería Dam (Codelco Andina), with As(V) concentrations reaching up to 30,000 pg / L.

[0072] In all cases, As concentrations are above the quality standard for drinking water (NCh 409). Furthermore, these waters and effluents contain multiple coexisting ions such as Mn, Mo, Fe, Al, Ba, B, Sr, Sb, Li, Si, Mg, Ca, Na, Zn, Cl, and sulfates at different concentrations.

[0073] Tables 2 and 3 present a summary of the physicochemical variability of the waters and effluents to be treated according to their source, as well as the different coexisting ions present in these waters and effluents.

[0074] Table 2. Physicochemical variability of water and effluents for the different sampling points.

[0075] Table 2 shows a notable difference in the physicochemistry of the different water sources to be treated. These differences include a wide range of As concentrations to be treated, from 64 to 31,000 pg / L, with the presence of As(lll) in groundwater and surface water (case studies of the Loa Lasana and Socaire rivers), while the other water sources only present the As(V) species. These values ​​indicate that the concentration of As present and even its speciation depend strongly on the water source to be treated. Changes in the initial pH were also observed.

[0076] Regarding the presence of other coexisting elements / ions, the results of the ICP-MS analysis are shown in Table 3. According to the results shown, the collected waters and effluents present significant differences in the concentration of other elements present, which provides a relevant physicochemical variability depending on the type of water to be treated. In accordance with the drinking water standard established by the QMS, some of these ions present in these waters and effluents show high concentrations with respect to said standard, being the standardized values ​​for B (0.05 mg / L), Ba (0.07 mg / L), Sb (0.02 mg / L), Na (200 mg / L), although Na does not cause health risks, except in people who require low-sodium diets), and Cl' (400 mg / L according to NCh 409). On the other hand, although Mo is not standardized for drinking water, Mo is standardized for irrigation water (0.01 mg / L NCh 1333).Another ion that shows considerable concentrations, despite not being regulated, is Ca, whose high concentration is associated with water hardness, but which does not cause health problems.

[0077] Table 3. Presence and concentration of ions / elements in groundwater, surface water and mining water for the different sampling points.

[0078] The efficiency of the system, which primarily comprises the nanoparticulate material TÍÜ2-NP, was evaluated using As photooxidation / adsorption tests using the three types of water mentioned above at a pilot plant scale. This efficiency was determined based on the final As concentration below the drinking water standard (<10 pg / L) achieved in the shortest contaminant removal time. To achieve this, the material dosage and pH of the medium were adjusted in batch tests to achieve the desired drinking water standard for each case and scale it up to a pilot plant. These performance tests were conducted using the established operating conditions and methodology as reference, as follows:

[0079] A. Laboratory scale, batch system. Operating methodology

[0080] To establish the operating conditions and parameters of the multifunctional material TiC-NP, tests were carried out in batch systems using a Luz-Chem brand photoreactor with a set of 14 lamps (2-UVA and 12-visible, see FIG. 5). This lamp configuration is related to a UV-Vis distribution (15-85) that corresponds to the same configuration used in a pilot plant scale photoreactor. Inside this photoreactor, a beaker is located with 200 mL of water from each of the described sources, to which the multifunctional nanoparticulate material T¡O2-NP is added in suspension with magnetic stirring. The efficiency was studied over the wide range of initial concentrations of As (III and / or V) shown in Table 1 and for different water pH (3.5 and basic (typical of the water to be treated)), which were adjusted by adding HCl and / or NaOH.Tests were carried out for TiC-NP at different doses until the optimal dose was found for each case study.

[0081] The removal process involved two stages: In the first stage of As adsorption in darkness, the contaminant and the suspended nanoparticulate material are brought into contact under stirring (450 rpm) and in the absence of light, so that the nanoparticulate material reaches its maximum adsorption capacity against As. Once the nanoparticulate material reaches the As adsorption equilibrium, a time which was approximately 60 min for all cases evaluated, the second stage begins: irradiation stage. In this stage, the solution with the nanoparticulate material in suspension is exposed to irradiation until complete photo-oxidation of the As(lll) present and maximum adsorption of the photo-produced As(V) is achieved.To monitor the kinetic disappearance of the arsenic species described in both stages, aliquots of the water were taken for different times of the process and the concentration of As(lll) and / or As(V) was analyzed as appropriate, using the colorimetric method optimized for use with real waters, which was validated by measuring the concentration of As by a direct analytical method such as ICP-MS.

[0082] Table 4 presents a summary of the results obtained for As removal in all case studies (real surface, groundwater, and mining waters) at the batch scale. From this study, the results were obtained that served as a basis for a preliminary analysis to obtain the optimal operational conditions at the pilot plant prototype scale. Samples of groundwater and surface water presenting both As species (III and V) demonstrate that the combination of As(III) photooxidation to As(V) under irradiation and simultaneous adsorption of the generated As(V) manages to remove both species, while in samples presenting only As(V), the adsorption process without irradiation allows achieving the desired standards. Both functionalities were obtained in a single step and with a single TiC-NP material.In summary, to achieve the highest As removal efficiency in the shortest times it is essential to adjust the pH to acidic conditions (pH 3.51), since according to the results obtained this adjustment allows obtaining complete removal in shorter times, and with higher efficiencies. This demonstrates the influence of water pH on the As removal capacity, given by the variation of the arsenic species present under each pH condition, and the influence of the other coexisting species in the waters that can compete for the active sites of the material, and an adjustment of the material dose that fluctuates between 0.2 and 3.0 g / L according to the case study, considering the shortest adsorption / photo-oxidation time achieved, the maximum As removal capacity and the minimum material consumption, in order to achieve As removal up to the desired water quality standards (Drinking water standard NCh 409 and Irrigation standard NCh 1333).The optimal loadings were selected based on the initial As concentration (Table 4), and these loadings were used as a reference for subsequent studies. Finally, the maximum percentage of As (III and / or V) removal in darkness or under irradiation was determined and reported, depending on the initial species present, material dosage, and optimal treatment time.

[0083] Table 4. Effect of the dose of multifunctional nanoparticulate material T¡O2-NP and pH change of real surface, groundwater, and mining waters at batch scale. Conditions: Real water, V = 200 mL, pH = basic (water's own) and 3.51 (adjusted with a 0.1 M HCI solution), Irradiation source: UV:Visible (15:85).

[0084] B. Prototype / pilot plant scale. Operating methodology

[0085] From the operating conditions defined above, the arsenic removal tests were scaled up using the photoreactor with a new light configuration (annular configuration), higher capacity and changing the type of agitation (FIG. 3). As in the batch scale, the scale-up in this photoreactor consists of two stages: adsorption in the dark in the presence of the suspended nanoparticulate material with its dose previously optimized according to the initial concentration of As present and that occurs in the metallic tank, preferably aluminum, and photo-oxidation under irradiation with agitation carried out in constant recirculation of water and the nanoparticulate material, driven by the centrifugal pump.The volume to be treated was 100 L, and as in the laboratory batch, the wide spectrum of initial As concentrations was analyzed according to the type of actual water to be treated (groundwater, surface water, mine water) and for the optimized pH conditions (3.51 and basic (natural for each of the waters and effluents to be treated)), which was adjusted by adding a 0.1 M aqueous solution of HCl and / or NaOH. As in the laboratory batch system, kinetic monitoring of the disappearance of arsenic species over time was carried out, for which aliquots of the water were taken for different times of the process and the concentration of As (III) and / or As (V) was analyzed as appropriate, carrying out kinetic monitoring (concentration vs. treatment time), using for this purpose an optimized colohmmetric analytical method for use with real waters, which was validated by measuring the As concentration by a direct analytical method such as ICP.The maximum percentage removal capacity of As (III and / or V) in darkness or under irradiation was determined and reported according to the initial species present, optimal treatment time according to the type of water to be treated and material dose according to the initial As concentration, as shown in Table 5. It is important to highlight that these results suggest that the pH of the medium has a great influence on the oxidation / adsorption capacity of this multifunctional material, making it a key parameter to consider in the technology. In this way, the efficient performance of the system under different cases of real groundwater, surface and mining waters is demonstrated. Table 5. As removal efficiency obtained for different real surface, groundwater, and mining waters at prototype / pilot plant scale. With the dose of multifunctional nanoparticulate material TiC-NP and medium pH optimized as appropriate. Conditions: Real water, V = 7 L, 100 L**; pH = 3.51 (adjusted with 0.1 M HCl solution); *Irradiation source: UV:Visible (15:85).

[0086] Based on the results obtained, optimal operating conditions were selected at the pilot plant scale to achieve As removal up to drinking water and / or irrigation quality standards (NCh 409, NCh 1333). From here, the system operating conditions were defined for adaptation to the pilot plant level, in terms of optimal material dosage and initial pH adjustment, within a wide operating range based on the initial As concentration to be treated, as shown in FIG. 6.

[0087] C. Removal of Al, B, Ba, Ca, Fe, Li, Mo, Mn, Sb, Si, Sr and Zn for water and effluent cases using the treatment system with its multifunctional and nanoparticulate material (TÍO2-NP) Considering that these real waters contain a high variability of coexisting ions in different concentrations as shown in Table 3, which makes them waters and effluents of high chemical complexity, being a great challenge to remove both As and the other elements of interest.

[0088] The results demonstrate that the nanoparticulate material of the present invention is not only multifunctional but versatile in removing other ions contained in water, including cations of interest such as Ca. Optimizing the pH of the medium gives the nanoparticulate material selectivity towards the elements to be removed, in addition to promoting greater efficiency that varies according to this adjustment. Below, the maximum removal percentage of As, Al, B, Ba, Ca, Fe, Li, Mo, Mn, Sb, Si, Sr and Zn is represented in the graphs in FIG. 7, which were obtained through ICP-MS analysis after irradiation-free treatment of these waters and effluents (groundwater, surface water and mining) with the multifunctional material T¡02-NP in the system.Thus, the system of the present invention demonstrates a high capacity to remove a series of elements without the efficiency of the nanoparticulate material being impaired by the entrapment of these coexisting ions in a single system and in a single step. With the appropriate adjustment of the pH of the medium, a removal of 13 elements of great interest is achieved, of which the removal of As, Mo, Mn and Sb is greater than 98%, other valuable and interesting elements such as Ba and Fe are removed by more than 80%, while in the other elements a significant reduction in their initial concentration is observed, fluctuating between 22-62%. This fact gives the material novelty and valuable interest both in the area of ​​​​removal of contaminants in water, as well as their possible recovery.

[0089] D. Recovery, reuse and recycling of materials

[0090] Considering that the reuse of a photocatalytic / adsorbent material is of great importance to reduce the costs associated with this process, reuse and recycling tests were carried out on the material used in the treatment of real surface waters, from the Salado and Socaire rivers, to evaluate the reuse and durability of the nanoparticulate material, validating its maximum capacity to remove As after repeated uses and without any type of prior treatment.

[0091] Once the first removal reaction of As and the other metals of interest was completed, the post-use nanoparticulate material was recovered using the separation system described in the section and shown in FIG. 3. This system achieved a recovery efficiency of the nanoparticulate material between 90 and 96% with respect to the initial dose added. The recovered material was placed back into the reaction system (without any type of treatment or washing) with the water to be treated under the aforementioned conditions, taking care to maintain the correct dose according to the initial water concentration. After the reaction was completed (maximum 90 min according to data shown in Table 5), the material was separated and recovered again.This procedure was repeated in 5 cycles, reaching for the first 3 reuse cycles in the treatment system, final concentrations of As <10 ppb complying with drinking water quality regulations (NCh 409), and in the fourth reuse cycle it was possible to obtain concentrations of As <100 ppb, complying with irrigation water quality regulations (NCh 1333), while in the fifth reuse both water samples were above the irrigation water standard. This is in good agreement with the efficiency loss of only 5-17% in the fifth use recycle, with respect to the nanoparticulate material T¡O2-NP after 90 min of treatment, indicating that the removal capacity of the material decreases slightly after four uses and therefore this nanoparticulate material has adequate reuse without any type of regeneration.Thus, the nanoparticulate material demonstrated that its efficiency in the system is not compromised after being reused up to four consecutive cycles without any prior treatment, maintaining efficiencies above 97% in the removal of As with drinking water quality, and can be reused in an additional consecutive cycle to remove As under irrigation water regulations, as can be seen in the graph presented in FIG. 8.

[0092] E. Material regeneration method

[0093] In order to maximize the use of the material without negatively affecting its properties or decreasing its efficiency, as well as increasing the added value of the treatment system and reducing environmental impacts, a protocol has been established to regenerate the material used in the removal process after six consecutive cycles of use. The regeneration protocol established in the present invention allows the desorption of the elements captured in the material after the reaction and returns its initial characteristics and active sites available for reuse in the system. The regeneration method reported in the present invention shows evident differences with respect to that reported in the prior art.The material to be regenerated is a unique multifunctional material composed of TiC -NP, the material was reused in four consecutive cycles before its regeneration process (number of use cycles in which the nanoparticulate material maintained its efficiency in removing As up to drinking water standard), the As desorption process varies both in the concentration of the basic medium, in the times and type of agitation, also includes the regeneration of the material in an acidic medium to return its surface chemical properties. In addition, an As removal test using the post-regeneration material is included to validate the efficiency in As desorption, regeneration of the material and efficiency in its removal capabilities.

[0094] The methodological differences for the multifunctional titanium dioxide regeneration method to photo-oxidize As(lll) and simultaneously adsorb As(V), Al, B, Ba, Ca, Fe, Li, Mo, Mn, Sb, Si, Sr and Zn used in the present invention with respect to that reported in the state of the art.

[0095] To demonstrate the regeneration efficiency of the T¡O2-NP material and to demonstrate that the material's properties were not altered in terms of its As removal capacity, a batch-scale test was conducted using surface water from the Salado River. The results obtained from this test are shown in Table 6.

[0096] Table 6. As removal capacity of the regenerated T¡O2-NP nanoparticulate material after 6 continuous reuse cycles and its comparison with the unregenerated T¡O2-NP nanoparticulate material.

[0097] Conditions: Real surface waters of the Salado River, V = 200 m; pH = 3.51 (adjusted with a 0.1 M HCl solution); Thus, the developed regeneration protocol demonstrates both the possibility of desorbing 67% of the As adsorbed on the T¡O2-NP material after four continuous reuse cycles, and its ability to continue being used after regeneration. This allows the system to be more efficient in operational terms by not requiring immediate replacement of the material after use, reducing technology costs due to the possibility of using the same material in multiple consecutive cycles without losing its efficiency in removing As, reaching concentrations below the drinking water standard, and in environmental terms by reducing the environmental impacts produced by the eventual replacement and disposal of the material.

[0098] F. Analytical method to determine the speciation of arsenic and its concentration in waters and effluents with up to 30,000 ppb of arsenic in the presence of other coexisting ions / elements

[0099] In order to determine the speciation of As present in waters and effluents, and to quantify the concentration of both As(lll) and As(V) present in real surface, underground and mining water samples with up to 30,000 ppb, the present invention reports the implementation of a modified and optimized molybdenum blue colorimetric method, which contemplates the coexisting major ions in real surface waters such as B, Fe, Al, Mn, Cu, Zn, Ca, Mg, SC. 2and Cl; simulating the chemical composition of a case in northern Chile, the Chiu Chiu Well, Loa River Basin, Antofagasta. The concentrations of these ions recorded by the General Water Division (DGA, http: / / snia.dqa.cl / BNAConsultas) were considered. Table 7 shows the concentrations of each of the interferents taken into consideration for the development of the optimized colorimeter method for determining As, specifically for use in real water and effluent samples with high chemical complexity.

[0100] Table 7. Concentration of ions present in the Chiu Chiu Well, Loa River Basin, Antofagasta and considered for the optimization of the colorimetric method Thus, the method involves three main steps: i) the direct determination of As(V) present in water and effluents, by the formation of the blue-colored arsene-molybdate complex that absorbs around 900 nm, i) the direct determination of total As as As(V) species present in the water, by the oxidation of As(lll) with permanganate and subsequent formation of the blue-colored arsene-molybdate complex that absorbs around 900 nm, and iii) the indirect determination of As(lll) present in the water, by the difference between the concentrations of total As and As(V) obtained in the previous steps.

[0101] The steps associated with the methodology are described below, indicating their relationship with the State of the Art: a.- Preparation of the molybdenum blue (MO) reagent

[0102] The color reagent used in the present invention to measure arsenic in real water samples describes the mixture of four solutions A:B:C:D in proportions of 2:2:1:5, in the order indicated. The specifications of the solutions used are given below:

[0103] Solution A - Ascorbic acid (CeHsOe; 10.8% w / v).

[0104] Solution B - Ammonium heptamolybdate ((NH4)6Mo?024. 4H2O; 3% w / v).

[0105] Solution C - Antimony potassium tartrate (CsH4K20i2Sb2. 3H2O; 0.56% w / v).

[0106] Solution D - Sulfuric acid (H2SO4; 13.98% w / v).

[0107] The MO color reagent must be prepared at the time of measurements and is stable for 30 min at room temperature (< 30°C). b.- Type of sample used for arsenic quantification

[0108] The samples used in the present invention to determine As(V) and total As directly and As(lll) indirectly are specific and are adapted to the inlet / outlet waters of the system, which consist of waters that simulate the chemical composition of a case in Northern Chile, Pozo Chiu Chiu, Loa River Basin, Antofagasta, considering the coexisting ions shown in Table 7 and waters and effluents from eight different case studies: green water (groundwater), Loa Alto Lasana, Loa Medio. After Junta, Loa Medio Chunchuñ, ño Salado Ayquina, Socaire River, and mining tailings dams in the Talabre and Ovejería cases, with different physical-chemical variability as shown in Tables 2 and 3, at different pH (natural pH of the water to be treated (basic) and acidic at pH 3.5), therefore, in the presence of hydrochloric acid. c.- Preparation of samples for measuring arsenic in water and effluents, and presence of coexisting ions.Formation of molybdenum blue and quantification of arsenic.

[0109] The reagents and steps used as a basis for the preparation of the sample proposed by the present invention to measure As(V) and As-total directly and As(lll) indirectly are carried out as indicated in the detailed description of the invention. Standard solutions with different concentrations of As(V) and As(lll) and fixed concentrations of each of the elements shown in Table 6 were prepared, in order to optimize the analytical method for the direct determination of As(V) and As-total in real waters with high chemical complexity and different pH.

[0110] The modification in the present invention compared to the state of the art includes the addition to the sample containing As of each of the coexisting elements / ions present in real waters with their respective concentrations presented in Table 6 and the variation in the phosphate concentration in the sample, which led to a shift of the absorption maximum to 900 nm. In general, the presence of coexisting ions / elements in real waters and lower phosphate concentration are reported in the method of the present invention.

[0111] Finally, the samples were treated with the MO color reagent in the proportions and times indicated and detailed in the detailed description of the invention. The optimization of the analytical method for the direct quantification of As(V) and indirect As(lll) by applying the standardized colorimetric method, in the presence of the aforementioned ions allowed obtaining two calibration curves with a linear correlation coefficient R2 > 0.99 for standard solutions of As (III and V) prepared from NaHAsC.7H2O and NaAsC respectively, in a range of concentrations from 10 ppb to 10,000 ppb (FIG. 9).

Claims

CLAIMS 1. A multifunctional nanoparticulate material for removing arsenic and metals from water and effluents, CHARACTERIZED in that it comprises: TiO2 nanoparticles with 100% anatase crystalline phase, a surface area of ​​at least 186 m2 / gy, a band separation energy (Eg) of maximum 3.09 eV; wherein said nanoparticles are multifunctional because they photo-oxidize arsenic III and adsorb arsenic V and other metals simultaneously in a single step.

2. The nanoparticulate material according to claim 1, CHARACTERIZED in that the waters and effluents comprise surface waters, groundwater, mining waters or effluents and / or industrial effluents.

3. The nanoparticulate material according to claim 1, CHARACTERIZED in that the nanoparticles have a particle size between 5 and 10 nm.

4. The nanoparticulate material according to claim 1, CHARACTERIZED in that it allows photo-oxidation of As (III) and simultaneously adsorbs As (V) and metals such as aluminum (Al), bath (Ba), boron (B), iron (Fe), lithium (Li), magnesium (Mg), molybdenum (Mo), strontium (Sr), antimony (Sb), silicon (Si), zinc (Zn), calcium (Ca) or a mixture thereof.

5. The nanoparticulate material according to claims 1 and 4, CHARACTERIZED in that it does not lose its post-use efficiency and can be reused up to 4 times.

6. A method for producing a multifunctional nanoparticulate material, CHARACTERIZED in that it comprises the following steps: a. preparing a white gel by adding between 4 and 5 mL of concentrated sulfuric acid with a purity of at least 97% and between 9 and 10 mL of titanium isopropoxide with a purity of at least 97% under vigorous magnetic stirring, to generate a millimolar S:T ratio of 80:30; b. prepare a solution A with a pH between 1 and 3, adding between 70 and 80 mL of distilled water to the gel obtained under magnetic stirring; c. add to solution A dropwise between 50 and 70 mL of an aqueous KOH solution with a concentration between 2 and 3M, under magnetic stirring at a rate between 1 and 3 mL / min followed by between 5 and 30 mL of distilled water until a pH between 3 and 4 is obtained, and a final KOH concentration between 0.8 and 1 M; d. magnetically stir the resulting mixture continuously for between 40 and 50 min; e. transfer the resulting mixture to a 200mL Teflon beaker contained within a stainless steel autoclave reactor and maintain at a temperature between 160°C and 180°C for 24-48 h; f. allow to cool and centrifuge the material, then wash at least 3 times with distilled water and one wash with acetone; and g.Dry the material at room temperature for at least 12 hours.

7. A system for removing arsenic and metals from water and effluents, CHARACTERIZED in that it comprises a photoreactor with a capacity of between 100 and 200 L / h that includes: a metal tank with a volume of between 150 and 250 L with mechanical agitation containing a multifunctional nanoparticulate material comprising TiO2 nanoparticles in crystalline phase 100% anatase, a surface area of ​​at least 186 m2 / g, a band separation energy (Eg) of a maximum of 3.09 eV in suspension, where the water to be treated is placed; a light emission module with an annular configuration; an agitation system by means of a centrifugal pump; a dosing system and pH adjustment controller; a system for separating and recovering post-use nanoparticulate material; and a power system to provide energy to the system for removing arsenic and metals from water and effluents.

8. The system according to claim 7, CHARACTERIZED in that the metal tank is made of aluminum.

9. The system according to claim 7, CHARACTERIZED in that the mixing agitation system is carried out by means of a centrifugal pump of at least 1 HP power.

10. The system according to claim 7, CHARACTERIZED in that the post-use nanoparticulate material separation and recovery system comprises a glass decanter and a membrane filter with a pore size of at least 0.2 pm.

1. The system according to claim 10, CHARACTERIZED in that the membrane filter is made of PVDF.

12. The system according to claim 7, CHARACTERIZED in that the pH dosing and control system has a resolution of 0.01 pH and a control flow of 0.5 to 3.5 L / h.

13. The system according to claim 7, CHARACTERIZED in that the light emission module comprises an irradiation system that includes at least 14 lamps.

14. The system according to claim 7, CHARACTERIZED in that the light emission module comprises at least two UVA lamps and at least 12 visible lamps with a total radiation power between 50 and 55 W / m2.

15. The system according to claims 13 and 14, CHARACTERIZED in that the percentage of visible light versus near ultraviolet UVA is between 80 and 90% and between 10 and 20%, respectively.

16. The system according to claim 7, CHARACTERIZED in that the power system is a system that has 100% electrical autonomy.

17. The system according to claim 16, CHARACTERIZED in that the system having 100% electrical autonomy comprises between 2 and 4 solar panels with a power between 300 and 545 W each, at least two lithium batteries with a capacity of at least 50V, an inverter and a connector system to the inverter.

18. A method for removing arsenic and metals from water and effluents, CHARACTERIZED in that it comprises the following steps: i. contacting a system comprising a photoreactor including the mechanically agitated metal tank containing a multifunctional nanoparticulate material, comprising 100% anatase crystalline phase TiO2 nanoparticles, a surface area of ​​at least 186 m2 / gy, a band separation energy (Eg) of maximum 3.09 eV in suspension; i. Exposing the resulting mixture to UV-Visible irradiation for complete photo-oxidation of arsenic(III) using an agitation system with a centrifugal pump and simultaneously adsorbing the photo-produced arsenic(V); ii. Adsorbing arsenic(V) and Al, Ba, B, Fe, L1, Mg, Mo, Sr, Sb, Si, Zn, Ca or a mixture thereof, by contacting the multifunctional material with the water to be treated using an agitation system with a centrifugal pump in the absence of light; wherein the method further comprises: determining and quantifying the concentration of As(III) and As(V) in the water to be treated in the presence of other coexisting elements / ions such as As, Al, Ba, B, Fe, L1, Mg, Mo, Sr, Sb, Si, Zn, Ca or a mixture thereof and the reuse of the multifunctional nanomaterial.

19. The method according to claim 18, CHARACTERIZED in that the multifunctional nanomaterial in the system has a concentration between 0.1 and 4.0 g / L.

20. The method according to claim 18, CHARACTERIZED in that the pH is adjusted to a value between 3 and 4.

5.

21. The method according to claim 18, CHARACTERIZED in that the elements to be removed can be selected from As, Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca, a mixture of them or all of them simultaneously.

22. The method according to claim 18, CHARACTERIZED in that it allows the multifunctional nanoparticulate material to be reused consecutively up to 4 times.

23. The method according to claim 18, CHARACTERIZED in that, to determine and quantify the concentration of As(III) and As(V) in the water to be treated, it is carried out by means of a colohmethic molybdenum blue MO method comprising the following steps: a. preparing standard aqueous solutions with fixed concentrations for each of the elements / ions Al, Ba, B, Fe, I, Mg, Mo, Sr, Sb, Si, Zn and Ca; b. preparing standard solutions of arsenic (III and V) with different concentrations between 5 and 10000 ppb to which a fixed volume of each of the standard solutions of the coexisting elements / ions prepared in the previous step is added; c. Prepare a MO color reagent from the mixture of four solutions A:B:C:D in proportions 2:2:1:5, where A is ascorbic acid, B is ammonium heptamolybdate, C is potassium antimony tartrate, and D is sulfuric acid; d. Add HCl until a concentration between 0.005 and 0.015% is reached in the sample; e.Add phosphate until a concentration between 5 and 10 mM is reached in the sample; f. Divide the sample into two parts; to one of the parts add KMnO4 until a concentration between 0.05 and 0.15 mM is reached in the sample and stir for 5 to 10 minutes; g. Add the MO color reagent to the parts obtained in the previous step in a 10:1 sample:MO ratio and stir for 5 to 10 minutes and measure absorbance at between 880 and 920 nm; and h. Determine the absorbance vs. concentration relationship using a calibration curve. The method also includes: determining and quantifying the concentration of As(III) and As(V) in the water to be treated in the presence of other coexisting elements / ions such as Al, Ba, B, Fe, Li, Mg, Mo, Sr, Sb, Si, Zn, Ca, or a mixture thereof.

24. A method for regenerating a post-reuse multifunctional nanoparticulate material, CHARACTERIZED in that it comprises the following steps: adding between 1 and 3 g of the nanomaterial T102 recovered after four continuous reuse cycles to a volume of between 90 and 110 mL of a 0.5 M NaOH solution; maintaining continuous magnetic stirring at between 300 and 400 RPM for at least 4 hours at room temperature; after the stirring time, separating the solid by centrifugation at between 5000 and 7000 RPM for at least 10 min; taking a sample of the supernatant (NaOH solution + As and other elements) and using it to quantify the concentration of desorbed arsenic; regenerating the recovered solid from the desorption of As and other elements.To do this, in a beaker, add between 90 and 110 mL of a 0.5 M H2SO4 solution to which add between 1 and 3 g of the nanomaterial T1O2 treated with NaOH; maintain continuous magnetic stirring at between 300 and 400 RPM for at least 1 hour at room temperature; After the stirring time has elapsed, separate the solid by centrifugation at between 5000 and 7000 RPM for at least 10 min; add between 300 and 500 mL of distilled water to the solid separated by centrifugation and add between 1 and 3 g of the nanomaterial TiO2 treated with H2SO4; maintain continuous magnetic stirring at between 300 and 400 RPM for at least 15 min at room temperature; separate the solid by centrifugation at between 5000 and 7000 RPM for at least 10 min; repeat the previous step three times; dry the recovered solid for at least 24h at room temperature.

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