CONDUCTIVE POLYMER GRAFTED REUSABLE 3D PLATFORM FOR WATER RESTORATION

Abstract

A platform and system for concentration, reduction and regeneration of heavy metals and other contaminants from fluids is provided. The platform has a three-tiered hierarchical porous structure, composed of micropores formed by woven carbon cloth, nanopores formed after carbon nanotube growth on the cloth fibers and mesopores formed by a polymer outer layer. The material of the platform can be incorporated into cells with two electrodes with properly functionalized PDAN grafted 3D carbon as an anode and cathode respectively. Metal ions and toxic anions in water will be captured selectively by primary amine, secondary amine and quaternary amine groups in porous PDAN on the anode. Metals are captured and reduced by the cathode.

Claims

1. A heavy metal ion adsorber material, comprising: (a) a scaffold of multiple interwoven carbon strands, said strands having an outer surface; (b) a plurality of 1D conductive nanostructures mounted to the outer surface of each carbon strand; and (c) a coating of at least one polymer on outer surfaces of said nanostructures and said carbon strands.

2. The adsorber of claim 1, wherein said scaffold comprises a carbon cloth of interwoven carbon strands with a diameter of between 5 μm and 10 μm.

3. The adsorber of claim 1, wherein said 1D nanostructures are selected from the group of nanostructures consisting of multiwalled carbon nanotubes, carbon nanofibers and carbon nanowires.

4. The adsorber of claim 1, wherein said polymer is a polymer selected from the group of polymers consisting of polyaniline, PANI, and polypyrrole.

5. The adsorber of claim 1, wherein said polymer is a polymer selected from the group of polymers consisting of poly(1,5-diaminonaphthalene) and poly(1,8-diaminonaphthalene).

6. The adsorber of claim 1, said polymer coating further comprising functionalized amine groups from exhaustive methylation.

7. The adsorber of claim 1, said scaffold further comprising an electrical contact, said contact configured to connect to an electrical power source.

8. A method for fabricating an adsorber material, the method comprising: (a) fabricating a one, two or three-dimensional carbon scaffold; (b) forming a plurality of 1D nanostructures on the carbon scaffold to form a modified carbon scaffold structure; and (c) applying a thin layer of a N-containing conductive polymer on outer surfaces of the modified carbon scaffold structure.

9. The method of claim 8, wherein said carbon scaffold comprises a carbon cloth of interwoven carbon microfiber strands having a diameter of between of between 5 μm and 10 μm.

10. The method of claim 9, further comprising: activating carbon cloth strands with KOH; and electroplating a seed layer of a catalyst for carbon nanotube growth.

11. The method of claim 8, wherein said carbon scaffold comprises a carbon aerogel.

12. The method of claim 8, wherein said 1D nanostructures are selected from the group of nanostructures consisting of multiwalled carbon nanotubes, carbon nanofibers and carbon nanowires.

13. The method of claim 8, wherein said N-containing polymer is a polymer selected from the group of polymers consisting of polyaniline, PANI, and polypyrrole.

14. The method of claim 8, wherein said N-containing polymer is a polymer selected from the group of polymers consisting of poly-1,5-diaminonaphthalene, poly-1,8-diaminonaphthalene, and combinations thereof.

15. The method of claim 8, further comprising chemically modifying the polymer layer to produce a modified carbon scaffold structure with a functionalized polymer outer surface.

16. The method of claim 15, wherein said chemical modification of said polymer layer comprises thiolation of polymer amines.

17. The method of claim 15, wherein said chemical modification of said polymer layer comprises or exhaustive methylation of polymer amines.

18. The method of claim 8, further comprising: leaching unreacted polymer species; wherein a three-tiered hierarchical porous structure is produced, comprising micropores formed by woven carbon cloth, nanopores formed after carbon nanotube growth and mesopores formed by polymer after leaching unreacted species.

19. A fluid treatment cell apparatus, the apparatus comprising: (a) an anode of a carbon scaffold modified with a plurality of 1 D carbon nanostructures coated with a polymer; (b) a cathode of a carbon scaffold modified with 1 D carbon nanostructures coated with a polymer; and (c) a voltage source electrically coupled with the anode and cathode.

20. The apparatus of claim 19, further comprising: (a) a stack of flow-through electrodes with an electrode plane; and (b) a housing configured to direct fluid in a direction normal to the electrode plane allowing advection of the contaminant species to active sites within the electrode stack and reduces the diffusion length to the scale of the boundary layer in the porous scaffold structure.

21. The apparatus of claim 19, wherein said carbon scaffold comprises a carbon cloth of interwoven carbon strands with a diameter of about 10 μm.

22. The apparatus of claim 19, wherein said 1D nanostructures are selected from the group of nanostructures consisting of multiwalled carbon nanotubes, carbon nanofibers and carbon nanowires.

23. The apparatus of claim 19, wherein said polymer is a polymer selected from the group of polymers consisting of polyaniline, PANI, polypyrrole, poly(1,5-diaminonaphthalene) and poly(1,8-diaminonaphthalene).

24. The apparatus of claim 19, said polymer coating further comprising functionalized amine groups functionalized with a thiol group or a methyl group.

25. A method for decontaminating a fluid, the method comprising: (a) exposing a flow of fluid to a treatment cell apparatus, comprising: (1) an anode of a carbon scaffold modified with 1D carbon nanostructures coated with a functionalized polymer; (2) a cathode of a carbon scaffold modified with 1D carbon nanostructures coated with a functionalized polymer; and (3) a voltage source electrically coupled with the anode and cathode; (b) regenerating the electrodes by releasing adsorbed contaminants; and (c) collecting the released contaminants.

26. The method of claim 25, said treatment cell apparatus further comprising: (a) a stack of flow-through electrodes with an electrode plane; and (b) a housing configured to direct fluid in a direction normal to the electrode plane allowing advection of the contaminant species to active sites within the electrode stack and reduces the diffusion length to the scale of the boundary layer in the porous scaffold structure.

27. The method of claim 25, wherein said anode can absorb and regenerate metal cations selected from the group of cations consisting of Hg.sup.+, Hg.sup.2+, Ag.sup.+, Fe.sup.2+, Fe.sup.3+ and Cr.sup.3+.

28. The method of claim 25, wherein said cathode can absorb and denature anions present within the fluid.

29. The method of claim 25, wherein said voltage source can accelerate reactions.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0029] The technology described herein will be more fully understood by reference to the following drawings which are for illustrative purposes only:

[0030] FIG. 1 is a schematic block system diagram of a method for fabricating a 3D hierarchical, conductive carbon-based electrode element according to one embodiment of the technology.

[0031] FIG. 2A is a 1,5 DAN and corresponding polymer chemical structures and in the linear form for Hg incorporation according to one embodiment of the presented technology.

[0032] FIG. 2B is a 1,8 DAN and corresponding polymer chemical structures in the ladder form before and after metal sequestration according to one embodiment of the presented technology.

[0033] FIG. 3 is a cyclic voltammetry analysis graph showing two different structure forms (0.5 MH.sub.2SO.sub.4, 10 mV/sec) of 1,5 DAN and corresponding polymer linear polymer and 1,8 DAN and corresponding ladder polymer.

[0034] FIG. 4 is a schematic cross-sectional view of polymer coated carbon nanotube carbon cloth and a polymer structure after complexation with CH.sub.3Hg.sup.+ ions.

[0035] FIG. 5 is a graph of the effects of equilibration time on the removal of Hg.sup.2+ and CH.sub.3Hg.sup.+ ions by PANI according to one embodiment of the technology.

[0036] FIG. 6 is a schematic diagram of a treatment cell utilizing flow-through bipolar electrode stack for advection accelerated mass transfer.

DETAILED DESCRIPTION

[0037] Referring more specifically to the drawings, for illustrative purposes, embodiments of apparatus, system and methods for heavy metal contaminant removal from fluids are generally shown. Several embodiments of the technology are described generally in FIG. 1 to FIG. 6 to illustrate the characteristics and functionality of the devices, methods and systems. It will be appreciated that the methods may vary as to the specific steps and sequence and the systems and apparatus may vary as to structural details without departing from the basic concepts as disclosed herein. The method steps are merely exemplary of the order that these steps may occur. The steps may occur in any order that is desired, such that it still performs the goals of the claimed technology.

[0038] Turning now to FIG. 1, one embodiment of a method 10 for fabricating porous electrode collection elements for use in water treatment cells is shown schematically and is used to illustrate the technology.

[0039] At block 12 of FIG. 1, a base of a cloth of woven of strands of carbon fibers or microfibers is provided. The weave of the carbon cloth base can be of carbon strands of selected diameters that will permit a controllable porosity between the fibers. Preferred strands forming the carbon cloth are preferably microfibers with a diameter of between about 5 microns and about 10 microns. While 10 μm microfiber strands are preferred, larger or smaller diameter strands of equal or mixed diameters can be used to weave the carbon cloth at block 12.

[0040] In other embodiments, a weave of carbon coated strands of conductive materials such as silicon nanowires are used in the base for settings where an increase in strength over that of carbon only strands is desired. Weaves of carbon coated microfibers may be able to handle increased fluid loads/pressures over carbon only strands forming the cloth base structure.

[0041] In the embodiment of FIG. 1, the surfaces of the strands forming the carbon cloth base are activated with KOH and a seed layer of Ni or Cu or other growth catalyst is applied to the strands at block 14 in preparation for the growth of carbon nanotubes, carbon nanofibers or carbon nanowires at block 16. Alternatively, conductive carbon aerogels can be used as a scaffold for carbon nanotube production from the surface of the carbon cloth.

[0042] Multi-walled carbon nanotubes (CNTs) or other 1D structures are then grown conformally on the surfaces of the cloth base at block 16. This creates a well-defined and mechanically robust 3D structure with unobstructed microchannels and nanochannels. It is possible to grow carbon nanotubes at high densities CNTs for high-loading of absorbent through adjusting growth conditions and catalyst composition.

[0043] The seed-mediated growth approach can be used to grow carbon nanotubes, carbon nanofibers and other 1D nanostructures with uniform diameter and tunable density and morphologies on a variety of surfaces at block 16. Scanning electron micrograph (SEM) images can confirm that multi-walled CNTs emanate from the surfaces of individual carbon microfibers that are interwoven into carbon cloth.

[0044] Electrochemical analysis has shown a 20-fold increase in electrochemical surface area after carbon nanotube formation. Multi-walled CNTs are chosen due to the combination of large synthesis latitude and excellent mechanical properties with superb electrical conductivity.

[0045] The entire 3D real estate of the platform is then uniformly grafted with a thin layer of poly(diaminonaphthalene) (PDAN) or another suitable polymer in the step of block 18 of FIG. 1. Although PDAN is preferred, other N-containing polymers such as polyaniline, PANI and polypyrrole can be used to effectively collect both inorganic and organic Hg species and other heavy metals via complexation.

[0046] Electrografting of PDAN, for example, can form a conformably grafted thin layer on the carbon nanotubes and carbon cloth. Both the thickness and morphology of the applied layer can be rationally controlled. Surfactants may also be employed as a template to create an enhanced porous structure.

[0047] Accordingly, in one embodiment, a three-tiered hierarchical porous structure, composed of micropores formed by woven carbon cloth, nanopores formed after MWCNT growth and mesopores formed by the polymer after leaching unreacted species is generated to insure sufficient permeability. Unlike carbon aerogels, the system based on carbon cloth will be mechanically robust, more conductive and less prone to clogging.

[0048] Electrochemical analysis indicates that both diarylamine in linear and ladder forms can be observed as illustrated in FIG. 3 and FIG. 2A and FIG. 2B. To capture Cl.sup.− and NO.sup.3−, in one embodiment, 1,5 DAN is electropolymerized in an acid media to graft 1,5 PDAN onto MWCNTs as shown in FIG. 2A and FIG. 4.

[0049] As seen in FIG. 2A, the 1,5 DAN polymer 22 is grafted in a linear form 24 that can be further modified. Both primary and secondary amine groups of the structure 26, can be further functionalized to —N.sup.+(CH.sub.3).sub.3 groups via exhaustive methylation or thiolation as indicated in FIG. 2A to enable absorption of nitrate as well as chlorine ions. Unfunctionalized diarylamine can also capture metal ions.

[0050] To increase absorption of metal ions such as Hg.sup.2+, in one embodiment; 1,8 PDAN polymers 28 is grafted in latter form 30 as shown in FIG. 2B. The ladder diarylamine group is known to “trap” metal ions including Hg.sup.2+ as illustrated in the structure 32 of FIG. 2B.

[0051] The final coated porous electrode structure 38 is shown schematically in cross-section in FIG. 4, with nanotubes on only one side of the strand to illustrate the structure. The carbon microfiber strand 40 with nanotubes 42 or other carbon structures are coated with a thin layer of polymer 44 such as PDAN. Additionally, as shown in FIG. 4, the diarylamine groups 46 of the polymer coating 44 of the porous electrode element 38 can complex with CH.sub.3Hg.sup.+ as well as Hg.sup.2+ ions.

[0052] The effect of equilibration time on the removal of Hg.sup.2+ and CH.sub.3Hg.sup.+ by PANI is shown in FIG. 5. One lone pair of electrons on a nitrogen of the polymer can coordinate with Hg and other heavy metal compounds. PANI, which contains arylimine groups, can be used to adsorb Hg.sup.2+ from an aqueous solution. It can be also used for pre-concentration of CH.sub.3Hg.sup.+ species. At pH>6, >95% uptake of CH.sub.3Hg.sup.+ has been achieved within 5 min as demonstrated by the data in FIG. 5. Diaminonaphthalene, DAN, can be viewed as two fused anilines as seen in FIG. 2A and FIG. 2B. It should more effectively capture both organic and inorganic Hg species as it can form a more stable complex between one Hg species and two N ligands. 97% uptake and about 394 mg/g absorbing capacity for an initial concentration of Hg.sup.2+ of 4 mM after 24 hours at 30° C. was reported for PDAN that was not optimized for Hg capture.

[0053] The chemical structure of the polymer can be tuned by pH (protonation) as well as the applied oxidation potential during the polymerization. In addition to diverse chemical structures, tunable morphology and high affinity for absorbing Hg and other heavy metal species, the preferred polymer offers excellent thermal stability and thus allows use in harsh thermal and chemical processes.

[0054] Since PANI can be thiolated by soaking in mercaptan, it is also possible to substitute sulfur groups on aromatic rings in PDAN using this approach. If needed, the film can be exposed to hydrogen sulfide to generate —SH functional groups. This newly functionalized surface is capable of forming strong Hg—S bonds, for example. Although this will help to capture Hg species, the Hg—S bonds might be too strong for reduction in some settings.

[0055] The sheets of porous, 3D conductive carbon-based porous electrode that are produced can be incorporated into treatment cell designs that are capable of concentrating and reducing heavy metal ion species from fluids.

[0056] One embodiment of a treatment cell 48 utilizing a flow-through electrode stack for advection accelerated mass transfer is shown schematically in FIG. 6. In this embodiment, the cell 48 is formed from a stack of flow through porous bipolar electrodes 60. The inner electrodes 60 in this stack are bipolar. Cation and anion capturing electrode layers may be mated together, reducing resistance associated with electronic conduction and simplifying cell construction. The outer anode 52 and cathode 54 electrodes are monopolar, converting ionic to electronic current and interfacing to the power supply 56. Potential fouling of the cell is minimized by a filter 50 prefiltering the incoming water 58 to remove suspended micro sized particles. The stack geometry in this embodiment allows operation at higher voltages and lower currents than with single electrode pairs, which minimizes electrical subsystem costs, and facilitates a compact cell design with low superficial flow velocity and high removal capacity.

[0057] As a result, anions such as NO.sup.3−, Cl.sup.− and cations such as Hg.sup.2+ and Pb.sup.2+ can be captured and removed from underground water. The anode 52 can be —N.sup.+(CH.sub.3).sup.3 functionalized PDAN which is capable of sequestering oxyanions such as nitrate (NO.sub.3.sup.−) while the cathode can also be PDAN that is replete with diarylamine groups, which can complex with Hg.sup.2+ and CH.sub.3Hg.sup.+as depicted in the detail of FIG. 6. The system will also be resistant to Cl.sup.− attack.

[0058] Cell designs that optimize advective and diffusive mass transport to maximize throughput and minimize parasitic resistance for fast charge transfer and low energy loss are preferred as shown in FIG. 6.

[0059] Adsorbents provide an effective means to attack heavy metal contamination in aqueous solutions, and electrochemical methods can convert the metals into more benign forms for disposal or recycling. However, both approaches pose transport limitations. These limitations arise from the requirements that contaminant ions diffuse to the adsorbent surface and charges be transported to the active site. Diffusion of the contaminant ions to the active surface is generally the rate controlling step in the treatment process.

[0060] Conduction of charge further imposes penalties in terms of energy consumption and parasitic electrochemical processes that may reduce the effectiveness of metal reduction. Both transport limitations suggest the need to minimize transport distances for chemical species and charge, which translates to a preference for minimum electrode thicknesses and separations in electrochemical cells in general. However, these parameter choices also limit electrode capacity and feed flow resistance, respectively. Therefore, the use the tailored 3D meso- and micro-structure of the electrode design takes advantage of convective flow that is an additional transport mechanism within the electrode structure. Utilizing the open structure of the carbon cloth substrate, it is possible to direct feedwater flow 58 normal to the electrode plane as shown in FIG. 6. This results in advection of the contaminant species to the active sites within the electrode and reduces the diffusion length to the scale of the boundary layer in the porous structure (e.g. <1 μm). The reduction in diffusion length dramatically increases the rate of adsorption and throughput of the cell.

[0061] Accordingly, the 3D hierarchical conductive carbon-based electrode is capable of concentrating and reducing Hg species and other metal ions. Absorbent moieties offered by PDAN that are covalently coated on the surface of a 3D carbon scaffold, for example, can form complexes with both CH.sub.3Hg.sup.+ and Hg.sup.2+. The local concentration of the Hg species and the consequent adsorption rate at the electrode will increase by applying a negative potential bias. Using an electrochemical step, both species can be reduced into Hg(0) droplets that can be extracted from the electrode for store or recycling. After the removal of Hg, the electrode can be then regenerated. No chemicals are needed during either the sequestration process or the regeneration process.

[0062] The technology described herein may be better understood with reference to the accompanying examples, which are intended for purposes of illustration only and should not be construed as in any sense limiting the scope of the technology described herein as defined in the claims appended hereto.

Example 1

[0063] To demonstrate the functionality of the system and methods, 1,5 PDAN and 1,8 PDAN polymer grafted carbon nanotubes on carbon cloth electrode element structures and treatment cells were fabricated according to the scheme of FIG. 1 and then tested. Multiwalled carbon nanotubes (MWCNTs) were grown on the carbon cloth and observed by scanning electron microscope (SEM) imaging. For comparison, a carbon aerogel and electro-polymerization of conductive polymer nanowires on carbon cloth followed by pyrolysis were used to produce carbon nanostructures on the carbon cloth strands as conductive scaffolds with high surface area.

[0064] The seed-mediated growth methods were also used to grow carbon nanofibers, nanowires, nanorods and other 1D nanostructures with uniform diameter and tunable density and morphologies on a variety of surfaces.

[0065] A thin layer of various types of polymers with engineered functional groups for effective sequestration of Hg.sup.2+ and CH.sub.3Hg.sup.+ was uniformly grafted on the entire 3D surface of the test nanotube encased carbon cloth for evaluation of Hg capture.

[0066] The scanning electron micrograph (SEM) images displayed multi-walled CNTs emanating from the surfaces of individual carbon microfibers that were interwoven into carbon cloth. Electrochemical analysis showed a 20 fold increase in electrochemical surface area after CNT formation. Multi-walled CNTs were chosen due to the combination of large synthesis latitude and excellent mechanical properties with superb electrical conductivity. The as-synthesized 3D structure could be preserved during the subsequent polymerization process to conformably coat the polymer absorbing layer. The density of CNTs could also be controlled by adjusting growth conditions and catalyst composition for producing high-loading of absorbents.

[0067] Accordingly, a three-tiered hierarchical porous structure, composed of micropores formed by woven carbon cloth, nanopores formed after MWCNT growth and mesopores formed by polymer after leaching unreacted species, was generated to illustrate the fabrication methods.

Example 2

[0068] To further demonstrate the operational principles of the apparatus and methods, different polymer layers and different polymer surface functionalization's were evaluated. To generate ample imine and amine groups, a ladder structure was formed by using 1,5 DAN instead of 1,8 DAN. The grafted polymer thickness and resulting amount of absorbing species was adjusted and consequently the electrochemical surface area was tuned to demonstrate the adaptability of the system. For facile collection of reduced Hg(0), adjustments in the polymerization conditions produced an increase polymer surface roughness or porosity which was illustrated by SEM imaging.

[0069] Tuning of the polymer chemical structure was also demonstrated by incremental adjustments to pH (protonation) as well as by an applied oxidation potential during the polymerization.

[0070] Likewise, substitution of sulfur groups on the aromatic rings in PDAN was demonstrated with exposure to mercaptan. Sulfur functional groups were also generated by exposure to hydrogen sulfide.

[0071] The functionalized materials were also evaluated for their ability to complex and effectively capture both organic and inorganic Hg species. It was demonstrated that there was a 97% uptake and about 394 mg/g absorbing capacity for an initial concentration of Hg.sup.2+of 4 mM after 24 hours at 30° C. for PDAN for Hg capture and 95% uptake of CH.sup.3Hg.sup.+ has been achieved within 5 minutes at pH>6.

Example 3

[0072] An important aspect of the electrochemical platform is the capability of regeneration and release of the sequestered heavy metals. As shown above, the energy efficient electrochemical platform can concentrate mercury contaminants via complexation of one Hg species with two N ligands and then convert the ionic Hg species into elemental liquid Hg(0) micro-droplets which can be readily aggregated and collected. At the same time, oxoanions could be collected and converted into non-toxic waste as needed. As a result, the entire system can be regenerated and used for continuous cleanup. The integrated approach to collect, monitor, reduce, and recycle/store mercury from solution addresses key challenges in wastewater treatment.

[0073] For example, PANI can have the reduction propensity to reduce Ag.sup.+ (0.8 V vs. H.sub.2/H.sup.+) to Ag(0) galvanostatically. Analogously, Hg.sup.2+ (0.85 V vs. H.sub.2/H.sup.+) can be reduced after incorporation in PDAN. However, CH.sub.3Hg.sup.+ is more challenging but it can be reduced electrochemically with the use of a gold (Au) coated planar carbon electrode.

[0074] To reduce concentrated Hg and regenerate the 3D electrodes, an electrochemical method was used with a non-catalytic approach. The high interfacial intension of water/mercury (0.4 N/m) facilitates extraction from the electrode. There is a strong capillary force driving expulsion of the elemental Hg from the porous structure. In-situ capillary pumping generated by nanoscale channels in the new 3D structure facilitated continuous elemental Hg collection. Separation of Hg(0) micro-droplets from water was straightforward by agitation or sonication to agglomerate and followed by decanting since Hg(0) is immiscible and 13 times denser than water.

[0075] In one embodiment, an optional electrocatalytic species was incorporated into the polymer layer to mitigate H.sub.2 evolution. For example, incorporation of electrocatalytically active Au nanoparticles into PDAN will further catalyze the reduction of CH.sub.3Hg.sup.+.

[0076] The very low reduction potential of Hg.sup.2+ and relatively high reduction potential of CH.sub.3Hg.sup.+ allows the selective removal of inorganic and organic Hg species. The active “absorbing” sites of the electrode may also accumulate other cationic species. Due to different affinities of metal ions with ligands, after removal of Hg.sup.2+, polarity reversal allows expulsion of most of interfering cations (back to water). After that, a relatively large negative reduction potential was used to reduce CH.sub.3Hg.sup.+ into Hg(0). An electrochemical means (e.g., EIS) might allow monitoring the accumulation of Hg to determine when regeneration should be performed.

[0077] From the description herein, it will be appreciated that that the present disclosure encompasses multiple embodiments which include, but are not limited to, the following:

[0078] 1. A heavy metal ion adsorber material, comprising: (a) a scaffold of multiple interwoven carbon strands, the strands having an outer surface; (b) a plurality of 1D conductive nanostructures mounted to the outer surface of each carbon strand; and (c) a coating of at least one polymer on outer surfaces of the nanostructures and the carbon strands.

[0079] 2. The adsorber of any preceding or following embodiment, wherein the scaffold comprises a carbon cloth of interwoven carbon strands with a diameter of between 5 μm and 10 μm.

[0080] 3. The adsorber of any preceding or following embodiment, wherein the 1D nanostructures are selected from the group of nanostructures consisting of multiwalled carbon nanotubes, carbon nanofibers and carbon nanowires.

[0081] 4. The adsorber of any preceding or following embodiment, wherein the polymer is a polymer selected from the group of polymers consisting of polyaniline, PANI, and polypyrrole.

[0082] 5. The adsorber of any preceding or following embodiment, wherein the polymer is a polymer selected from the group of polymers consisting of poly(1,5-diaminonaphthalene) and poly(1,8-diaminonaphthalene).

[0083] 6. The adsorber of any preceding or following embodiment, the polymer coating further comprising functionalized amine groups from exhaustive methylation.

[0084] 7. The adsorber of any preceding or following embodiment, the scaffold further comprising an electrical contact, the contact configured to connect to an electrical power source.

[0085] 8. A method for fabricating an adsorber material, the method comprising: (a) fabricating a one, two or three-dimensional carbon scaffold; (b) forming a plurality of 1D nanostructures on the carbon scaffold to form a modified carbon scaffold structure; and (c) applying a thin layer of a N-containing conductive polymer on outer surfaces of the modified carbon scaffold structure.

[0086] 9. The method of any preceding or following embodiment, wherein the carbon scaffold comprises a carbon cloth of interwoven carbon microfiber strands having a diameter of between of between 5 μm and 10 μm.

[0087] 10. The method of any preceding or following embodiment, further comprising: activating the carbon cloth strands with KOH; and electroplating a seed layer of a catalyst for carbon nanotube growth.

[0088] 11. The method of any preceding or following embodiment, wherein the carbon scaffold comprises a carbon aerogel.

[0089] 12. The method of any preceding or following embodiment, wherein the 1D nanostructures are selected from the group of nanostructures consisting of multiwalled carbon nanotubes, carbon nanofibers and carbon nanowires.

[0090] 13. The method of any preceding or following embodiment, wherein the N-containing polymer is a polymer selected from the group of polymers consisting of polyaniline, PANI, and polypyrrole.

[0091] 14. The method of any preceding or following embodiment, wherein the N-containing polymer is a polymer selected from the group of polymers consisting of poly-1,5-diaminonaphthalene, poly-1,8-diaminonaphthalene, and combinations thereof.

[0092] 15. The method of any preceding or following embodiment, further comprising chemically modifying the polymer layer to produce a modified carbon scaffold structure with a functionalized polymer outer surface.

[0093] 16. The method of any preceding or following embodiment, wherein the chemical modification of the polymer layer comprises thiolation of polymer amines.

[0094] 17. The method of any preceding or following embodiment, wherein the chemical modification of the polymer layer comprises or exhaustive methylation of polymer amines.

[0095] 18. The method of any preceding or following embodiment, further comprising: leaching unreacted polymer species; wherein a three-tiered hierarchical porous structure is produced, comprising micropores formed by woven carbon cloth, nanopores formed after carbon nanotube growth and mesopores formed by polymer after leaching unreacted species.

[0096] 19. A fluid treatment cell apparatus, the apparatus comprising: (a) an anode of a carbon scaffold modified with a plurality of 1D carbon nanostructures coated with a polymer; (b) a cathode of a carbon scaffold modified with 1D carbon nanostructures coated with a polymer; and (c) a voltage source electrically coupled with the anode and cathode.

[0097] 20. The apparatus of any preceding or following embodiment, further comprising: (a) a stack of flow-through electrodes with an electrode plane; and (b) a housing configured to direct fluid in a direction normal to the electrode plane allowing advection of the contaminant species to active sites within the electrode stack and reduces the diffusion length to the scale of the boundary layer in the porous scaffold structure.

[0098] 21. The apparatus of any preceding or following embodiment, wherein the carbon scaffold comprises a carbon cloth of interwoven carbon strands with a diameter of about 10 μm.

[0099] 22. The apparatus of any preceding or following embodiment, wherein the 1D nanostructures are selected from the group of nanostructures consisting of multiwalled carbon nanotubes, carbon nanofibers and carbon nanowires.

[0100] 23. The apparatus of any preceding or following embodiment, wherein the polymer is a polymer selected from the group of polymers consisting of polyaniline, PANI, polypyrrole, poly(1,5-diaminonaphthalene) and poly(1,8-diaminonaphthalene).

[0101] 24. The apparatus of any preceding or following embodiment, the polymer coating further comprising functionalized amine groups functionalized with a thiol group or a methyl group.

[0102] 25. A method for decontaminating a fluid, the method comprising:

[0103] (a) exposing a flow of fluid to a treatment cell apparatus, comprising: (1) an anode of a carbon scaffold modified with 1 D carbon nanostructures coated with a functionalized polymer; (2) a cathode of a carbon scaffold modified with 1 D carbon nanostructures coated with a functionalized polymer; and (3) a voltage source electrically coupled with the anode and cathode; (b) regenerating the electrodes by releasing adsorbed contaminants; and (c) collecting the released contaminants.

[0104] 26. The method of any preceding or following embodiment, the treatment cell apparatus further comprising: (a) a stack of flow-through electrodes with an electrode plane; and (b) a housing configured to direct fluid in a direction normal to the electrode plane allowing advection of the contaminant species to active sites within the electrode stack and reduces the diffusion length to the scale of the boundary layer in the porous scaffold structure.

[0105] 27. The method of any preceding or following embodiment, wherein the anode can absorb and regenerate metal cations selected from the group of cations consisting of Hg.sup.+, Hg.sup.2+, Ag.sup.+, Fe.sup.2+, Fe.sup.3+ and Cr.sup.3+.

[0106] 28. The method of any preceding or following embodiment, wherein the cathode can absorb and denature anions present within the fluid.

[0107] 29. The method of any preceding or following embodiment, wherein the voltage source can accelerate reactions.

[0108] As used herein, the singular terms “a,” “an,” and “the” may include plural referents unless the context clearly dictates otherwise. Reference to an object in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.”

[0109] As used herein, the term “set” refers to a collection of one or more objects. Thus, for example, a set of objects can include a single object or multiple objects.

[0110] As used herein, the terms “substantially” and “about” are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. When used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ±10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, “substantially” aligned can refer to a range of angular variation of less than or equal to ±10°, such as less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°.

[0111] Additionally, amounts, ratios, and other numerical values may sometimes be presented herein in a range format. It is to be understood that such range format is used for convenience and brevity and should be understood flexibly to include numerical values explicitly specified as limits of a range, but also to include all individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly specified. For example, a ratio in the range of about 1 to about 200 should be understood to include the explicitly recited limits of about 1 and about 200, but also to include individual ratios such as about 2, about 3, and about 4, and sub-ranges such as about 10 to about 50, about 20 to about 100, and so forth.

[0112] Although the description herein contains many details, these should not be construed as limiting the scope of the disclosure but as merely providing illustrations of some of the presently preferred embodiments. Therefore, it will be appreciated that the scope of the disclosure fully encompasses other embodiments which may become obvious to those skilled in the art.

[0113] All structural and functional equivalents to the elements of the disclosed embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed as a “means plus function” element unless the element is expressly recited using the phrase “means for”. No claim element herein is to be construed as a “step plus function” element unless the element is expressly recited using the phrase “step for”.