Reusable composite filter material and methods for making and using same for removing and destroying molecular contaminants from water - Patents.com

Abstract

A specially functionalized composite filter material with a high specific surface area is used to adsorb PFA from drinking water. In a preferred embodiment, the base filter material is granular activated carbon (GAC), which is sequentially coated with a thin layer of polydopamine, a thin layer of partially oxidized iron, and a thin coating of octadecylamine. After PFA is adsorbed onto the coated GAC particles, it is removed by a rinsing process, but remains in the rinse wastewater. The GAC particles are recovered and, if necessary, recoated to regenerate their adsorption capacity. The PFA-containing wastewater is treated using a photochemical process to destroy the PFA molecules. The PFA-free wastewater at this point can be disposed of as a non-hazardous substance. The composite filter material functions in systems ranging from small passive systems for personal use to large-scale, high-flow, practical water treatment systems.

Description

[Technical field]

[0001] The present invention generally relates to the treatment of water by sorption using composite sorbents. The present invention more particularly relates to the removal of contaminants containing fluorine compounds or fluorine-containing compounds. The present invention also relates to the regeneration of sorbents / filters. In particular, the present invention relates to the removal of molecular contaminants from water with safe decomposition, in particular the removal and destruction of perfluoroalkyl and polyfluoroalkyl molecules such as the long chain (C=8) molecules perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) and related short chain PFAs (C≦7) in general. [Background technology]

[0002] There is now a large body of evidence that there are several anthropogenic substances present in the environment that are persistent and harmful to human (and animal) life. Trace amounts of synthetic molecular substances in drinking water, such as perfluoroalkyls and polyfluoroalkyls, collectively abbreviated as PFAs, are of particular concern. Examples of methods for removing such molecular contaminants include 1) passing the contaminated water through a bed of granular particles, the surface of which contains active sites for chemical absorption and / or physical adsorption (physisorption), or 2) passing the contaminated water through a porous membrane, which is an ultrafine mesh or a network of very dense fibers made of a variety of materials, all of which have active sites on their surface for chemical absorption and / or physical adsorption. The effectiveness of either of these approaches varies with the number of active sites for capturing and retaining the contaminant molecules, which in turn varies with the total surface area in contact with the water. An important characteristic of the base filter material is the ratio of the surface area to the mass of the material, or specific surface area, which is S A and is usually expressed as m 2 The unit is / g.

[0003] The higher the specific surface area of ​​the composite filter material, the less likely the material will need to be replaced or possibly reactivated. There are two ways to obtain high specific surface area for granular particles: by limiting the diameter (or largest dimension) to a few microns or less if they are solid particles, or by creating a large number of nanometer-scale pores (tens of nanometers to hundreds of nanometers) on the surface of each granular particle. An example of the former would be silica spheres of a few microns in diameter, compared to silica spheres of a millimeter or more in diameter (as an example, a 1 mm diameter silica sphere has an area of ​​about 0.1 m2). 2 / g, whereas a 10 micron diameter sphere has a specific surface area of ​​approximately 90 m 2 / g). An example of the latter is a porous base filter material.

[0004] Those skilled in the art of molecular contaminant adsorption know that the distribution of pore sizes in the porous base filter material is important. In general, the stronger the adsorption, the closer the contaminant molecules can reach the surface of the base filter element. In small diameter pores, the molecules will automatically be in close proximity to the pore walls, making the adsorption stronger. Smaller, more strongly adsorbing pores are usually said to have higher energy. A non-limiting example of a porous base filter material is granular activated carbon (GAC). Depending on the activation process, GAC can be made to have a pore size of tens of microns. 2 / g equivalent to as low as 1500m 2The specific surface area of ​​the GAC particles can be greater than 1 / g. The surface active sites are substantially all present on the interior sidewalls of the pores of the GAC particles. In general, the pore sizes are usually classified into three major categories in terms of size: micropores, which are smaller than 2 nanometers and usually measured in this application from a few tenths of a nanometer to a few nanometers; macropores, which are larger than 50 nanometers and usually measured in this application from a few nanometers to tens of nanometers; and mesopores, which are between 2 and 50 nanometers and usually measured in this application from tens of nanometers to hundreds of nanometers. The higher energy pores are the micropores of the GAC particles. Mesopores have been described in the art as a pathway for molecules to reach smaller pores and are therefore expected to contribute less to the adsorption capacity of GAC than micropores and macropores.

[0005] One common approach to treating drinking water containing molecular contaminants such as PFA is a bed of GAC, but the difficulty with this approach is that once the GAC becomes saturated with, for example, PFA molecules, it itself becomes a hazardous material and must be handled accordingly. Currently, there are two general methods of dealing with PFA-saturated granular activated carbon material: 1) disposing of it as a hazardous material so that the contaminants cannot escape from the used GAC and re-enter the environment, or 2) removing the contaminants from the GAC and incinerating them at very high temperatures. Typically, these temperatures are close to 1000°C. Recent evidence now clearly indicates that excessive precautions must be taken to prevent any release of the PFA contaminants generated in the air into the environment during the incineration process. A filtration medium specifically designed to eliminate the need for harsh treatment methods such as 1000°C furnaces would clearly be desirable. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is a reusable composite filter material and a method for producing the reusable composite filter material, which can be produced from various base filter materials using a simple process under mild conditions. Suitable base filter materials include solid granular particles, porous granular particles, porous membranes, meshes, and solid or porous fibers bundled into a network. Generally, high-performance filter materials have a high specific surface area with a large amount of active sites on the surface. Improvements to such filter materials include filter materials that are pretreated in such a way that, upon adsorption of contaminants, the contaminants are released from the filter material into treated wastewater by a post-adsorption gas-based treatment process, a solution-based treatment process, or a combination of these treatment processes. This post-treatment wastewater can be directed to a suitable container where it can be further treated to destroy the contaminants. This allows the wastewater, which is now free of contaminants, to be safely disposed of. [Brief description of the drawings]

[0007] [Figure 1] Figure 1 represents a two-dimensional cross-section of a portion of a three-dimensional particle of granular activated carbon (1), showing the ideal arrangement of pore openings (2) produced by the activation process. The surface of the three-dimensional particle (1) with pores (2) is further coated with polydopamine (PDA) (3), which has been functionalized to improve its metal chelating ability. An iron film (4) is placed on top of the functionalized PDA, followed by a film of octadecylamine (ODA) (5). The smaller tunnels are micropores, and the larger openings are mesopores that reach into the micropores. The drawing is not to scale. [Diagram 2] 1 shows a flow chart of the steps required to remove contaminants from water using a composite filter material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] All embodiments of the present invention capture a range of molecular contaminants from drinking water over a variety of concentrations. As a non-limiting example, the expected concentration range of the PFA molecules ranges from a few nanograms per liter to a few micrograms per liter. Furthermore, without indicating any limitation, the remaining paragraphs of this section are directed to removing PFA molecules from drinking water at the cited concentration ranges. Two prominent examples of the PFA molecules are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Without indicating any limitation on the selection or composition of the base (i.e., pre-treatment) filter material, at least one embodiment of the base filter material is granular activated carbon. The pore width of the pre-treated GAC can range from a few tenths of a nanometer (nm) to more than 100 nm. A first process step deposits a thin coating of an adhesive material on at least a portion of the GAC particles, a second process step enhances the chelating ability of the adhesive material, a third process step deposits a thin coating of an at least partially oxidized metal on at least a portion of the functionalized adhesive material, and a fourth process step deposits a hydrophobic coating on at least a portion of the oxidized metal coating, all of which are deposited in a single room temperature (or near room temperature) process.

[0009] Since the present invention involves applying a coating to the pore surface that may block the smaller micropores, it is important to have at least some macropores that end up as micropores in the worst case after the entire coating process, which causes some mesopores to end up as micropores and some macropores that, if small enough, contribute to the overall adsorption as well. In one embodiment of the invention, the coating of the functionalized adhesive material directly on the GAC surface is composed of a layer of functionalized polydopamine (PDA). The thickness of the functionalized PDA layer ranges from about a few tenths of a nanometer to about 5 nm. The second layer is a thin film of iron deposited on at least a portion of the functionalized PDA layer. The iron film may or may not be continuous across the entire GAC surface and has a thickness ranging from one monolayer thickness to about 5 nm. At least a portion of the iron film is at least partially oxidized. The third layer is composed of the partially oxidized iron film and optionally a hydrophobic material, if present, that covers the entire or a portion of the surface of any of the following: the unoxidized iron film, the functionalized PDA coating, such as the deposited PDA coating, and the uncoated GAC substrate.

[0010] Other transition metals, alkali metals, alkaline earth metals, rare earth metals, and all remaining other metals from Groups 13, 14 and 15 of the Periodic Table of the Elements, and their oxides, if present, may be used in place of or in addition to iron.

[0011] All embodiments of the present invention physisorb contaminant molecules in water over a range of concentrations. Physisorption (i.e., non-chemisorption) processes are controlled by hydrophobic, electrostatic or dispersion forces between contaminant molecules and any given filter material. Adsorption of PFA molecules from water by a surface that carries a near-zero but slightly negative surface charge occurs predominantly through hydrophobic forces. Similarly, when a surface carries a near-zero but slightly positive surface charge, adsorption may be a combination of both hydrophobic and weak electrostatic forces. It is generally accepted that hydrophobic forces dominate the physisorption of phobic water molecules onto hydrophobic surfaces.

[0012] In one embodiment of the removal process, once the composite GAC particles are saturated with one or more PFA adsorbates, they can be placed in a solution designed to release the PFA adsorbate molecules from the composite GAC particles. When released into the treatment solution, the PFA adsorbate molecules can be swept away with the wastewater, and the adsorbate substrate particles can be stored for reuse. In one embodiment of the present invention, the rinsed substrate particles can be returned to the original uncoated surface. In another embodiment, the rinsed substrate particles can contain a coating of adhesive catechol-based material on its surface. In yet another embodiment of the present invention, the rinsed substrate particles can include both a coating of adhesive PDA material and a partially oxidized metal coating of the adhesive PDA coating. In yet another embodiment, the rinsed GAC substrate particles can include a coating of adhesive material, a metal coating, a partially oxidized metal coating, and a coating of hydrophobic material. Once rinsed and freed of the hydrophobic coating and contaminant molecules, the GAC substrate particles can be reprocessed as necessary to regenerate the material to its pre-adsorption configuration and reused.

[0013] The contaminated wastewater from the filtration and rinsing processes may be treated using one of several well-known photocatalytic processes. By way of example and not limitation, the wastewater from the rinsing process containing the PFA adsorbate may be mixed with a nanometer-scale volume of photocatalytic particles composed of one or more metal oxides that promote the photocatalytic decomposition of the PFA adsorbate molecules. The catalyst nanoparticles may have a maximum dimension ranging from about 5 nm to about 500 nm. The wavelength of light that promotes the photocatalytic decomposition of the PFA contaminants may range from about 650 nm to about 100 nm, depending on the electronic band gap of the photocatalytic particles. Once the decomposition of the contaminants is complete, the photocatalytic particles are collected by any suitable means (filtration, centrifugation, etc.) and the wastewater is withdrawn off-site for disposal.

[0014] The method for producing a reusable composite filter material that is the subject of the present invention consists of a series of consecutive steps, the details of which are provided below. Without being limited with respect to other substrates, the steps described herein apply to GAC particles. Similar procedures can be used for other composite filter materials, whether they are granules that are naturally occurring or in porous form, or fiber networks such as non-porous membranes, ultra-fine meshes, bundles of quartz wool fibers, etc. Procedure 1 provides process steps for preparing commercially available granular activated carbon particles for the subsequent procedures described below. Procedures 2 and 3 provide two alternative sets of process steps for depositing a coating of adhesive material on GAC. In a preferred embodiment, the adhesive material is polydopamine (PDA). Procedure 4 provides process steps for modifying (i.e. functionalizing) a PDA film to generate dihydroxyindole (DHI) subunits on its surface and increasing its metal chelating ability. Procedure 5 provides process steps for coating the functionalized PDA surface with an at least partially oxidized iron film. Step 6 provides process steps for applying a hydrophobic coating of octadecylamine (ODA) to the at least partially oxidized metal coating as a final layer on the GAC particles. The ODA coating is illustrative and not limiting with respect to other hydrophobic coatings that may be used with other suitable process steps not included herein.

[0015] All procedures are carried out at room temperature unless otherwise stated.

[0016] By way of illustration and not by way of limitation, once the composite functionalized GAC particles have adsorbed a predetermined mass of PFA molecules, the adsorbed PFA molecules can be removed from the GAC by removing the hydrophobic layer as described in step 7. If desired, the iron film can be later removed from the particles according to the process step of step 8. The resulting wastewater can be added to the rinse wastewater from step 7. The PFA molecules contained in the wastewater from the rinse step are subsequently modified or destroyed by being added to the process step provided in step 9.

[0017] The adsorption capacity of the particles and the total amount of PFA molecules adsorbed under a given set of conditions can be measured by following the process steps provided in Procedure 10.

[0018] The particles, procedures for making and using the particles, and contaminants described as targets for adsorption are exemplary and not limiting, and alternatives to the techniques described herein will be known to those skilled in the art of depositing and removing materials from surfaces.

[0019] Step 1: Sorting and washing of raw coal-based or plant-based granular activated carbon particles

[0020] Materials used:

[0021] -900m 2 Granular activated carbon (GAC) particles with a specific surface area of ​​more than 1000 g / g

[0022] -150mL to 300mL of deionized (DI) water

[0023] -Nitrogen gas

[0024] Process steps:

[0025] -Weigh out 10-20 g of untreated particles.

[0026] - By way of example and for one particular embodiment, sieve and retain only GAC between 2.36 mm (#8 sieve) and 2.8 mm (#7 sieve).

[0027] - Use compressed air to remove dust.

[0028] -Rinse the particles using 150 mL to 300 mL of DI water.

[0029] - Dry using a low pressure stream of nitrogen gas.

[0030] Bake at -125°C overnight.

[0031] Step 2: Basic solution (pH=8.5) deposition of a thin coating of adhesive catechol-based material onto granular activated carbon particles

[0032] Materials used:

[0033] - 2g of GAC was selected and washed according to procedure 1 above.

[0034] -250mL Tris Base (pH 8.5)

[0035] -0.4g dopamine hydrochloride

[0036] Process steps:

[0037] - In a 1000 mL Erlenmeyer flask, combine 2 g of particles with 250 mL of Tris and 0.4 g of dopamine.

[0038] -Aerate and shake at 125 rpm for 2 hours.

[0039] -Rinse with 100mL DI water.

[0040] Dry the samples at -70 °C for 16-24 h.

[0041] -Weigh again.

[0042] Step 3: Deposition of an acid-based adhesive catechol-based material onto granular activated carbon particles

[0043] Materials used:

[0044] -1 g of GAC was selected and washed according to step 1 above.

[0045] -250mL McIlvaine buffer (pH 5)

[0046] -0.4g dopamine hydrochloride

[0047] -0.01g sodium periodate

[0048] Process steps:

[0049] - In a 1000 mL Erlenmeyer flask, combine 1 g of GAC with 250 mL of McIlvaine's buffer and 0.4 g of dopamine.

[0050] -Add sodium periodate, swirl, aerate and shake at 125 rpm for 2 hours.

[0051] - Rinse the particles with approximately 40 mL of DI water.

[0052] - Stir in 150 mL DI water at 250 rpm for 60 minutes.

[0053] -Rinse the particles with 100 mL of DI water.

[0054] Dry the samples at -70 °C for 16-24 h.

[0055] -Weigh again.

[0056] Step 4: Functionalization of the PDA layer on the GAC substrate particles to generate dihydroxyindole (DHI) subunits on the PDA surface

[0057] Materials used:

[0058] -33.29 g CaCl 2

[0059] -6.05 g Tris buffer

[0060] -1L DI H 2 O

[0061] -1g of polydopamine coated particles

[0062] -HCl

[0063] Process steps:

[0064] -1L DI H 2 33.29 g CaCl in 20 2 Mix 6.05g of Tris with CaCl 2 Prepare a solution of Tris with:

[0065] -Adjust the pH to 9.5.

[0066] - Mix 1 g of particles per 100 mL of treatment solution.

[0067] -Air is bubbled through the solution for 4 hours and mixed with a stir bar.

[0068] -Remove particles from solution and add 200 mL of DI H 2 Rinse with O.

[0069] - Incubate the particles in HCl pH 2.5 for 15 minutes.

[0070] -Remove particles from solution and add 200 mL of DI H 2 Rinse with O.

[0071] Step 5: Deposition of an at least partially oxidized iron film onto the functionalized PDA layer of GAC substrate particles - ferrous chloride process

[0072] Materials used:

[0073] -0.01g FeCl 2

[0074] -5g PDA@GAC

[0075] -1 mL NaClO

[0076] -HCl

[0077] -NaOH

[0078] -Shaking table

[0079] -pH meter

[0080] Process steps:

[0081] - In a 50 mL flask, add FeCl with 25 mL of DI water. 2 and up to 5 g of PDA@GAC per 25 mL.

[0082] Shake at less than -160 rpm for 2 hours.

[0083] After -2 hours, insert the pH meter and take a reading.

[0084] -Add 1mL of NaClO.

[0085] -Once stabilized, adjust pH using NaOH solution (or HCl if necessary) to a pH of about 5.0.

[0086] -Restart shaking.

[0087] - Repeat steps 2-6 three more times (using a total of 4 mL NaClO).

[0088] -200mL DI H 2 Rinse twice with O.

[0089] - Dry the finished particles at 80°C for a minimum of 4 hours before use.

[0090] Step 6: AL 2 O 3 or deposition of a thin layer of octadecylamine (ODA) onto an adhesive catechol-based layer of GAC porous particle substrate, followed by a metal oxide layer on top of that, by a chloroform process.

[0091] Materials used:

[0092] -100mL of chloroform

[0093] - 0.4g octadecylamine

[0094] -1.0g composite particles for coating

[0095] Process steps:

[0096] -Add 100mL of chloroform to a suitable beaker.

[0097] -Add 0.4 g of octadecylamine to chloroform.

[0098] -Add 1.0 g of coated composite particles.

[0099] -The mixture is shaken for the desired time frame (5 minutes to 2 hours).

[0100] - Use a stainless steel mesh to filter out particles.

[0101] Dry the particles at no more than -60°C.

[0102] Step 7: Post-adsorption removal of the octadecylamine (ODA) layer containing PFA molecules

[0103] Materials used:

[0104] -100mL DI H 2 O

[0105] - Up to 5g of contaminant particles

[0106] -Hot plate

[0107] Process steps:

[0108] - Add DI H to the beaker 2 Add O and heat to 80°C on a hot plate.

[0109] -Add contaminant particles to the beaker and cover it.

[0110] - Heat for up to 1 day.

[0111] - Filtering particles from waste liquids.

[0112] -Test effluent for PFA content in accordance with US Environmental Protection Agency (EPA) Notice 537.1.

[0113] Step 8: After ODA / PFA removal, dissolve pre-deposited iron from the adsorbate particles

[0114] Materials used:

[0115] - 0.5g of intact GAC particles, kept from step 6

[0116] -50mL of 5% nitric acid

[0117] PROCESS STEPS: IMPORTANT: Perform all work in a fume hood.

[0118] 0.5 g of the previously prepared adsorbate particles are placed in 50 mL of 5% nitric acid preheated to -70°C.

[0119] - Shake on a shaking table at 125-400 rpm for 15 minutes.

[0120] -Remove GAC particles from the solution by filtering through a Nalgene filter.

[0121] -Test the filtrate for iron concentration.

[0122] - Rinse the particles and save the wastewater for analysis.

[0123] -Test effluent for PFA content in accordance with US Environmental Protection Agency (EPA) Notice 537.1.

[0124] - Test the rinse wastewater for iron content using any convenient standard technique such as an atomic adsorption spectrometer.

[0125] Step 9: Photocatalytic degradation of PFOS, PFOA and related PFA compounds using combined metal oxide nanoparticles

[0126] Materials needed:

[0127] - 0.1 g Fe, with approximate average maximum dimensions ranging from 20 nm to 60 nm 2 O 3 @TiO 2 Nanoparticles in Composite Materials

[0128] -An acid-resistant photocatalytic reaction chamber with a total volume capacity of 350 mL

[0129] -Quartz tube coated UV-C light source (6W, 120V)

[0130] - 300 mL of filtrate and rinse wastewater from steps 7 and 8

[0131] -Mini orbital shaker

[0132] Process Step

[0133] - Pour 300 mL of rinsing waste water into the reaction chamber.

[0134] -Add 0.1 g of the composite dry nanoparticles to the chamber.

[0135] -The chamber is sealed and placed on a shaking table at 200-450 rpm.

[0136] -Turn on the UV light and allow the reaction to proceed for at least 24 hours.

[0137] -Remove the solution from the reaction chamber.

[0138] - Allow the solution to settle, then decant as much liquid as possible to test for PFA without pouring off any nanoparticles. If desired, centrifuge the solution for maximum nanoparticle retention.

[0139] Step 10: Photocatalytic degradation of PFOA, PFOS and related PFA compounds using combined simple oxide nanoparticles

[0140] Materials needed:

[0141] - 0.1 g of TiO, with approximate average largest dimensions ranging from 5 nm to 60 nm 2 Nanoparticles

[0142] -An acid-resistant photocatalytic reaction chamber with a total volume capacity of 350 mL

[0143] -Quartz tube coated UV-C light source (6W, 120V)

[0144] - 300 mL of filtrate and rinse wastewater from steps 7 and 8

[0145] -Mini orbital shaker

[0146] Process steps:

[0147] - Pour 300 mL of filtrate and rinsing waste water into the reaction chamber.

[0148] -Add 0.1 g of dry nanoparticles to the chamber.

[0149] -The chamber is sealed and placed on a shaking table at 200-450 rpm.

[0150] -Turn on the UV light and allow the reaction to proceed for at least 24 hours.

[0151] -Remove the solution from the reaction chamber.

[0152] - Decant as much liquid as possible to test for PFA without pouring off any nanoparticles. If desired, centrifuge the solution for maximum nanoparticle retention.

[0153] The now rinsed and separated contaminant-free adsorbate particles obtained from steps 7 and 8 can be re-functionalized by applying the appropriate process or combination of processes described in steps 1-6.

[0154] Once any of the embodiments of the present invention have been produced, they can be tested for their adsorption capacity using Procedure 11 below.

[0155] Procedure 11: Testing Composite Filter Materials for PFOS and PFOA Adsorption

[0156] Materials needed:

[0157] - A few grams of prepared composite filter material

[0158] - A prepared amount of DI water containing specific concentrations of PFOS and PFOA ranging from about 1 ppb each to about 100 ppb each.

[0159] Process steps:

[0160] -Add an amount of composite filter material ranging from 1 g to 10 g to each of multiple Erlenmeyer flasks containing at least 100 mL of prepared contaminated DI water.

[0161] -Place the flask on an orbital shaker table for 24 hours at a speed sufficient to promote mixing of the composite filter material with the contaminant.

[0162] - Decant the liquid and analyze for PFA according to EPA Circular 537.1 test procedure.

[0163] All of the embodiments of the present invention formed using the above procedure or a similar procedure are suitable for adsorbing contaminant PFA molecules from water. Adsorption can be achieved by 1) placing the composite filter material in a fixed bed for filtration and allowing the contaminated water to flow through the bed, or 2) directly mixing the composite filter material with the contaminated water for a period of time, and then separating the composite filter material from the water, for example by centrifugation, simple screening, or another suitable process.

[0164] By way of example, but not by way of limitation, at least one sample of one or more composite GAC particles disclosed in the present invention has the following test results for adsorption capacity: PFOA: 2.99 mg / g adsorption capacity; PFOS: 2.43 mg / g adsorption capacity. For comparison, untreated GAC from the same lot of material after procedure 1 has the following test results: PFOA: 2.86 mg / g; PFOS: 2.30 mg / g. This result shows that particles embodying the present invention are as effective as untreated particles in adsorbing PFA. The main difference is that the PFA molecules adsorbed by untreated GAC particles can only be removed using harsh conditions, whereas the present invention allows for such removal by a simple process under mild conditions.

[0165] In one embodiment of the present invention, PFA molecules are removed from composite GAC particles by applying the process described in Procedure 7 to the composite GAC particles used in the exemplary adsorption test described above. Using Procedure 11, the amount of PFOA adsorbed from 50 mL of contaminated water by 0.5 g of composite GAC particles was determined to be 14±1.5 micrograms. Using Procedure 7, the amount of PFOA initially recovered in 50 mL of clean water was determined to be 12±0.8 micrograms in accordance with EPA Circular 537.1, which is consistent with the amount initially adsorbed within the stated test error range.

Claims

1. 1. A composite filter material for removing contaminants from water, the composite filter material comprising a base filter material having a surface area; the base filter material comprises granular activated carbon (GAC); the surface area of ​​the base filter material is at least partially coated with a layer of adhesive material; the layer of adhesive material comprises polydopamine (PDA); the layer of adhesive material is at least partially coated with a layer of metal; the metal layer comprises iron; the metal layer is at least partially oxidized; the metal layer comprises at least partially oxidized iron; said layer of partially oxidized metal being at least partially coated with a layer of hydrophobic material; 1. A composite filter material for removing contaminants from water, wherein the layer of hydrophobic material comprises octadecylamine (ODA).

2. 1. A method for removing contaminants from water and disposing of the same, comprising the steps of: disposing an amount of the composite filter material of claim 1 in contaminated water and allowing the composite filter material to stand in the mixture of the contaminated water and the composite filter material; removing the composite filter material from the mixture; and forming a second mixture by placing the composite filter material in clean water, heating the second mixture, and maintaining the second mixture at an elevated temperature for one day; removing the composite filter material from the mixture to leave a wastewater; and sealing the wastewater from the second mixture in a photocatalytic reaction chamber equipped with a UV light source and either titanium dioxide and iron oxide composite nanoparticles or titanium dioxide nanoparticles; turning on the UV light and shaking the photocatalytic reaction chamber at 250-400 rpm for at least 24 hours; A method comprising:

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