CHROMIUM AND ARSENIC SEPARATIONS USING POROUS ORGANIC FRAMEWORKS
20260102764 ยท 2026-04-16
Inventors
Cpc classification
C02F2101/22
CHEMISTRY; METALLURGY
B01J41/04
PERFORMING OPERATIONS; TRANSPORTING
C07C215/68
CHEMISTRY; METALLURGY
International classification
B01J41/04
PERFORMING OPERATIONS; TRANSPORTING
Abstract
The disclosure provides for porous organic frameworks functionalized to comprise pendant amino-dial groups and/or amino-polyol groups, and uses thereof, including for use in selectively capturing and/or separating anionic contaminants, such as chromium and arsenic oxyanions, including Cr(O), Cr(ll), Cr (III), Cr (IV), and/or Cr (VI), from other components.
Claims
1. A method for the selective capture or separation of anionic compound(s), and/or anionic species, comprising: contacting the anionic compound(s), and/or the anionic species with a porous adsorbent that has been functionalized to comprise pendant amino-diol groups and/or amino-polyol groups.
2. The method of claim 1, wherein the porous adsorbent is selected from porous an organic polymer, a porous metal particle, a porous metal oxide particle, a metal organic framework (MOF), a zeolitic organic framework (ZIF), a covalent organic framework (COF), and a porous aromatic framework (PAF).
3. (canceled)
4. The method of claim 2, wherein the PAF have tetrahedral carbon nodes connected by a plurality of linkers having the structure of: ##STR00028## wherein, R.sup.1-R.sup.12 are each independently selected from H, D, an optionally substituted functional group (FG), an optionally substituted (C.sub.1-C.sub.9)alkyl, an optionally substituted (C.sub.1-C.sub.9)alkenyl, an optionally substituted (C.sub.1-C.sub.9) alkynyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkyl, an optionally substituted (C.sub.1-C.sub.5) heteroalkenyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkynyl, an optionally substituted aryl, an optionally substituted heterocycle, wherein at least one of R.sup.1-R.sup.12 is an optionally substituted FG that comprises an amino-diol group or an amino-polyol group; and n is an integer selected from 0, 1, or 2.
5. The method of claim 4, wherein the amino-diol group or the amino-polyol group has a structure selected from: ##STR00029##
6. The method of claim 2, wherein the PAF has tetrahedral carbon nodes connected by a plurality of linkers having the structure of: ##STR00030## wherein, R is selected from ##STR00031##
7. The method of claim 6, wherein R is ##STR00032##
8. The method of claim 1, wherein the adsorbent can be used to selectively capture or separate anionic compounds, and/or an anionic species comprising Cr(0), Cr(II), Cr(III), Cr(IV), Cr(VI), As(0), As(III), and/or As(V).
9. The method of claim 8, wherein the anionic compounds, and/or an anionic species are selected from CrO.sub.4.sup.2, HCrO.sub.4.sup., H.sub.2CrO.sub.4, Cr.sub.2O.sub.7.sup.2, HCr.sub.2O.sub.7.sup., and/or H.sub.2Cr.sub.2O.sub.7.
10. (canceled)
11. The method of claim 8, wherein the anionic compounds, and/or an anionic species are selected from AsO.sub.4.sup.3, HAsO.sub.4.sup.2, H.sub.2AsO.sup.4, H.sub.3AsO.sub.4, H.sub.3AsO.sub.3, H.sub.2AsO.sup.3, HAsO.sub.3.sup.2, and/or AsO.sub.3.sup.3.
12. The method of claim 1, wherein the anionic compound(s), and/or anionic species are selectively captured or separated from a fluid stream.
13. The method of claim 12, wherein the fluid stream is gas mixture or a water source.
14. (canceled)
15. The method of claim 1, wherein the anionic compound(s), and/or anionic species are waterborne oxyanions.
16. The method of claim 15, wherein the waterborne oxyanions are selected from vanadate, molybdate, permanganate, tungstate, antimony oxyanions, ferrate, rhenate, perrhenate, tellurate, tellurite, selenate, selenite, perxenate, carbonate, bicarbonate, phosphite, phosphate, hyposulfite, nitrite, nitrate, chlorate, sulfate, thiosulfate, acetate, perchlorate, hypochlorite, iodate, bromite, perbromate, bromate, and hypobromite.
17. A device comprising a porous adsorbent that has been functionalized to comprise pendant amino-diol groups and/or amino-polyol groups.
18. The device of claim 17, wherein the porous adsorbent is selected from porous an organic polymer, a porous metal particle, a porous metal oxide particle, a metal organic framework (MOF), a zeolitic organic framework (ZIF), a covalent organic framework (MOF), and a porous aromatic framework (PAF).
19. (canceled)
20. The device of claim 18, wherein the PAF has tetrahedral carbon nodes connected by a plurality of linkers having the structure of: ##STR00033## wherein, R.sup.1-R.sup.12 are each independently selected from H, D, an optionally substituted functional group (FG), an optionally substituted (C.sub.1-C.sub.9)alkyl, an optionally substituted (C.sub.1-C.sub.9)alkenyl, an optionally substituted (C.sub.1-C.sub.9) alkynyl, an optionally substituted (C.sub.1-C.sub.5) heteroalkyl, an optionally substituted (C.sub.1-C.sub.5) heteroalkenyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkynyl, an optionally substituted aryl, an optionally substituted heterocycle, wherein at least one of R.sup.1-R.sup.12 is an optionally substituted FG that comprises an amino-diol group or an amino-polyol group; and n is an integer selected from 0, 1, or 2.
21. The device of claim 20, wherein the amino-diol group or the amino-polyol group has a structure selected from: ##STR00034##
22. The device of claim 18, wherein the PAF has tetrahedral carbon nodes connected by a plurality of linkers having the structure of: ##STR00035## wherein, R is selected from ##STR00036##
23. The device of claim 22, wherein R is ##STR00037##
24. The device of claim 17, wherein the adsorbent can be used to selectively capture or separate anionic compounds, and/or an anionic species comprising Cr(0), Cr(II), Cr(III), Cr(IV), Cr(VI), As(0), As(III), and/or As(V).
25. The device of claim 24, wherein the anionic compounds, and/or an anionic species are selected from CrO.sub.4.sup.2, HCrO.sub.4.sup., H.sub.2CrO.sub.4, Cr.sub.2O.sub.7.sup.2, HCr.sub.2O.sub.7.sup., and/or H.sub.2Cr.sub.2O.sub.7.
26. (canceled)
27. The device of claim 24, wherein the anionic compounds, and/or an anionic species are selected from AsO.sub.4.sup.3, HAsO.sub.4.sup.2, H.sub.2AsO.sup.4, H.sub.3AsO.sub.4, H.sub.3AsO.sub.3, H.sub.2AsO.sup.3, HAsO.sub.3.sup.2, and/or AsO.sub.3.sup.3.
28. The device of claim 17, wherein the device is a storage device that stores the captured anionic compounds and/or anionic species.
29. The device of claim 17, wherein the device is a separation or a sensor device that selectively separates, or indicates the capture, of anionic compounds and/or anionic species.
30. The device of claim 29, wherein the adsorbent is integrated into membranes, films, electrodes, coatings, pellets, co-polymers, porous substrates, or indicators.
31. A functionalized porous organic framework (PAF) having tetrahedral carbon nodes connected by linkers having the general structure of: ##STR00038## wherein, R.sup.1-R.sup.12 are each independently selected from H, D, an optionally substituted functional group (FG), an optionally substituted (C.sub.1-C.sub.9)alkyl, an optionally substituted (C.sub.1-C.sub.9)alkenyl, an optionally substituted (C.sub.1-C.sub.9)alkynyl, an optionally substituted (C.sub.1-C.sub.5) heteroalkyl, an optionally substituted (C.sub.1-C.sub.5) heteroalkenyl, an optionally substituted (C.sub.1-C.sub.5) heteroalkynyl, an optionally substituted cycloalkyl, an optionally substituted aryl, an optionally substituted heterocycle, wherein at least one of R.sup.1-R.sup.12 is an FG comprising a secondary or tertiary amine; and n is an integer selected from 0, 1, 2, or 3; wherein, the optionally substituted FG comprising a secondary and/or a tertiary amine does not have the structure of ##STR00039##
32. The functionalized PAF of claim 31, wherein at least one of R.sup.1-R.sup.12 is an optionally substituted FG having the structure of ##STR00040## and n is an integer selected from 0, 1, 2, or 3.
33. The functionalized PAF of claim 31, wherein linkers have the structure of: ##STR00041## wherein, R is selected from ##STR00042##
Description
DESCRIPTION OF DRAWINGS
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DETAILED DESCRIPTION
[0054] As used herein and in the appended claims, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a functional group includes a plurality of such functional groups and reference to the pore includes reference to one or more pores and equivalents thereof and so forth.
[0055] Also, the use of or means and/or unless stated otherwise. Similarly, comprise, comprises, comprising include, includes, and including are interchangeable and not intended to be limiting.
[0056] It is to be further understood that where descriptions of various embodiments use the term comprising, those skilled in the art would understand that in some specific instances, an embodiment can be alternatively described using language consisting essentially of or consisting of.
[0057] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although many methods and reagents are similar or equivalent to those described herein, the exemplary methods and materials are disclosed herein.
[0058] All publications mentioned herein are incorporated herein by reference in full for the purpose of describing and disclosing the methodologies, which might be used in connection with the description herein. Moreover, with respect to any term that is presented in one or more publications that is similar to, or identical with, a term that has been expressly defined in this disclosure, the definition of the term as expressly provided in this disclosure will control in all respects.
[0059] It should be understood that this disclosure is not limited to the particular methodology, protocols, and reagents, etc., described herein and as such may vary. The terminology used herein is for the purpose of describing particular embodiments or aspects only and is not intended to limit the scope of the present disclosure.
[0060] Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein should be understood as modified in all instances by the term about. The term about when used to described the present disclosure, in connection with percentages means+13. The term about, as used herein can mean within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which can depend in part on how the value is measured or determined, e.g., the limitations of the measurement system. Alternatively, about can mean a range of plus or minus 20%, plus or minus 10%, plus or minus 58, or plus or minus 1% of a given value. Alternatively, particularly with respect to biological systems or processes, the term can mean within an order of magnitude, within 5-fold, or within 2-fold, of a value. Where particular values are described in the application and claims, unless otherwise stated the term about meaning within an acceptable error range for the particular value can be assumed. Also, where ranges and/or subranges of values are provided, the ranges and/or subranges can include the endpoints of the ranges and/or subranges. In some cases, variations can include an amount or concentration of 20%, 10%, 5%, 1%, 0.5%, or even 0.1% of the specified amount.
[0061] For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is explicitly contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the number 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are explicitly contemplated.
[0062] As used herein an adsorbent refers to a molecular entity that can effectively bind and separate from a mixture of components an anionic contaminant and/or anionic species. In another embodiment an adsorbent comprises porous organic polymers, porous metal particles, porous metal oxide particles, metal organic frameworks (MOF), a zeolitic organic frameworks (ZIFs), covalent organic frameworks (COFs), or porous aromatic frameworks (PAFs). In certain embodiments, the adsorbent comprises PAFs. In certain embodiments, an adsorbent is functionalized to be selective for a particular molecular entity. In certain embodiments, the adsorbent is functionalized with a functional group disclosed herein (e.g., secondary or tertiary amine containing group). In certain embodiments, the pore of a MOF, ZIF, COF, PAF is functionalized to contain the functional group.
[0063] The term functional group or FG refers to specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. While the same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of, its relative reactivity can be modified by nearby functional groups. The atoms of functional groups are linked to each other and to the rest of the molecule by covalent bonds. Examples of FG that can be used in this disclosure, include, but are not limited to, substituted or unsubstituted alkyls, substituted or unsubstituted alkenyls, substituted or unsubstituted alkynyls, substituted or unsubstituted aryls, substituted or unsubstituted hetero-alkyls, substituted or unsubstituted hetero-alkenyls, substituted or unsubstituted hetero-alkynyls, substituted or unsubstituted cycloalkyls, substituted or unsubstituted cycloalkenyls, substituted or unsubstituted hetero-aryls, substituted or unsubstituted heterocycles, halos, hydroxyls, anhydrides, carbonyls, carboxyls, carbonates, carboxylates, aldehydes, haloformyls, esters, hydroperoxy, peroxy, ethers, orthoesters, carboxamides, amines, imines, imides, azides, azos, cyanates, isocyanates, nitrates, nitriles, isonitriles, nitrosos, nitros, nitrosooxy, pyridyls, sulfhydryls, sulfides, disulfides, sulfinyls, sulfos, thiocyanates, isothiocyanates, carbonothioyls, phosphinos, phosphonos, and phosphates. In a particular embodiment, the functional group or FG may be optionally substituted with additional functional groups. For example, an FG that is an amine may be optionally substituted with one or more hydroxyls. In a certain embodiment, the FG comprises a secondary and/or a tertiary amine.
[0064] As used herein a fluid refers to a liquid or gas. The fluid can be a multicomponent fluid containing a plurality of molecular entities.
[0065] The term porous aromatic framework or PAF, refers to a framework characterized by a rigid aromatic open-framework structure constructed by covalent bonds (Ben et al., 2009, Angew. Chem., Intl Ed. 48:9457; Ren et al., 2010, Chem. Commun. 46:291; Peng et al., 2011, Dalton Trans. 40:2720; Ben et al., 2011, Energy Environ. Sci. 4:3991; Ben et al., J. Mater. Chem. 21:18208; Ren et al., J. Mater. Chem. 21:10348; Yuan et al., 2011, J. Mater. Chem. 21:13498; Zhao et al., 2011, Chem. Commun. 47:6389; Ben & Qiu, 2012, Cryst Eng Comm, DOI: 10. 1039/c2ce25409c). PAFs show high surface areas and excellent physicochemical stability, generally with long range orders and, to a certain extent, an amorphous nature. Porous aromatic frameworks lack the extended conjugation found in conjugated microporous polymers. A porous aromatic framework can have a surface area from about 50 m.sup.2/g to about 7,000 m.sup.2/g, about 80 m.sup.2/g to about 1,000 m.sup.2/g, 1,000 m.sup.2/g to about 6,000 m.sup.2/g, or about 1,500 m.sup.2/g to about 5,000 m.sup.2/g. A PAF can have a pore width of about 7 angstroms to about 30 angstroms (e.g., 10, 15, 20, 25 angstroms of any value between any of the foregoing). PAFs can have a differential pore volume of 0.02 to 0.30 cm.sup.3 g.sup.1 .sup.1 (e.g., 0.02, 0.05, 0.10, 0.15, 0.20, 0.25 cm.sup.3 g.sup.1 .sup.1 of any value between any of the foregoing values).
[0066] Various separation methods have been proposed to achieve selective chromium and arsenic removal from water, including ion-exchange, adsorption, membrane separations, electrocoagulation, and photocatalytic degradation. Of these methods, adsorption and ion exchange are often considered as the most promising due to their low operating and capital costs, high sorption capacities, and ease of use. Adsorbents and ion-exchange resins consist of an inorganic material (e.g., zeolites, layered double hydroxides, metal oxides) or organic polymer. These materials are cost-effective but typically exhibit poor sorption kinetics, chemical and thermal stabilities, and/or recycling capabilities. Moreover, these methods typically rely on leveraging electrostatic interactions (e.g., ion-exchange) that exhibit relatively low selectivity for chromium and arsenic oxyanions over other common waterborne anions. These drawbacks necessitate the development of robust materials and methods that can more effectively achieve chromium and arsenic oxyanion separations.
[0067] The disclosure provides a technical solution to address the limitations of existing adsorption and ion-exchange methods by developing methods based on the use of functionalized porous aromatic frameworks (PAFs). These framework materials feature targeted molecular interactions with chromium and arsenic oxyanions, leading to their high-performance removal from water. PAFs are a class of recently emerging porous polymers and porous organic frameworks that feature a high-porosity, diamondoid-like structure composed of organic nodes covalently and irreversibly coupled to aromatic linkages (see
[0068] While aminopolyols and diols in macroporous polymeric materials achieve chromium and arsenic capture, these materials exhibit limited capacities, uptake rates, and stabilities, owing to their low porosities and synthetic tunabilities. Other material classes with higher porosities and tunabilities (e.g., metal-organic frameworks) have been reported as alternative adsorbents for chromium and arsenic oxyanion capture. However, these reported materials have typically relied on electrostatic ion-exchange interactions between the oxyanions and cationic groups on the material, leading to relatively low selectivity over other waterborne anions.
[0069] In a particular embodiment, the disclosure provides for a functionalized porous organic framework (PAF) having tetrahedral carbon nodes connected by linkers having the general structure of:
##STR00016##
wherein, [0070] R.sup.1-R.sup.12 are each independently selected from H, D, an optionally substituted functional group (FG), an optionally substituted (C.sub.1-C.sub.9)alkyl, an optionally substituted (C.sub.1-C.sub.9)alkenyl, an optionally substituted (C.sub.1-C.sub.9) alkynyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkenyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkynyl, an optionally substituted cycloalkyl, an optionally substituted aryl, an optionally substituted heterocycle, wherein at least one of R.sup.1-R.sup.12 is an FG comprising a secondary or tertiary amine; and [0071] n is an integer selected from 0, 1, 2, or 3. In a further embodiment, the optionally substituted FG comprising a secondary and/or a tertiary amine does not have the structure of
##STR00017##
[0072] In another embodiment, the disclosure provides for a functionalized PAF having tetrahedral carbon nodes connected by linkers having the structure of:
##STR00018##
wherein, [0073] R.sup.1-R.sup.12 are each independently selected from H, D, an optionally substituted functional group (FG), an optionally substituted (C.sub.1-C.sub.9) alkyl, an optionally substituted (C.sub.1-C.sub.9)alkenyl, an optionally substituted (C.sub.1-C.sub.9) alkynyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkenyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkynyl, an optionally substituted cycloalkyl, an optionally substituted aryl, an optionally substituted heterocycle, wherein at least one of R.sup.1-R.sup.12 is an optionally substituted FG having the structure of
##STR00019##
and [0074] n is an integer selected from 0, 1, 2, or 3.
[0075] In yet another embodiment, the disclosure provides for a functionalized PAF having tetrahedral carbon nodes connected by linkers having the structure of:
##STR00020##
wherein, [0076] R is selected from
##STR00021##
[0077] In a particular embodiment, the disclosure provides methods for the selective capture of an anionic compound, and/or an anionic species, comprising: [0078] contacting the anionic compounds, and/or anionic species with a functionalized porous aromatic framework (PAF) having tetrahedral carbon nodes connected by a plurality of linkers having the structure of:
##STR00022##
wherein, [0079] R.sup.1-R.sup.12 are each independently selected from H, D, an optionally substituted functional group (FG), an optionally substituted (C.sub.1-C.sub.9) alkyl, an optionally substituted (C.sub.1-C.sub.9)alkenyl, an optionally substituted (C.sub.1-C.sub.9) alkynyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkenyl, an optionally substituted (C.sub.1-C.sub.8) heteroalkynyl, an optionally substituted aryl, an optionally substituted heterocycle, wherein at least one of R.sup.1-R.sup.12 is an optionally substituted FG that comprises a secondary and/or a tertiary amine; and n is an integer selected from 0, 1, or 2. In a further embodiment, the FG comprising a secondary and/or tertiary amine comprises 1, 2, 3, 4, 5, 6, 7, 8 (or a range thereof) hydroxyl group(s). In another embodiment, at least one of R.sup.1-R.sup.12 is an optionally substituted FG having the structure of
##STR00023##
In a particular embodiment, when n is 0, then one of R.sup.1-R.sup.4 is an optionally FG selected from
##STR00024##
and R.sup.9-R.sup.10 are H. In another embodiment, when n is 1, then one of R.sup.5-R.sup.8 is optionally substituted FG selected from
##STR00025##
R.sup.1-R.sup.4 are H, and R.sup.9-R.sup.12 are H.
[0080] In a particular embodiment, the disclosure provides methods for the selective capture of an anionic compound, and/or an anionic species, comprising: [0081] contacting the anionic compound, and/or the anionic species with a functionalized porous aromatic framework (PAF) having tetrahedral carbon nodes connected by a plurality of linkers having the structure of:
##STR00026##
wherein, [0082] R is selected from
##STR00027##
[0083] The methods of the disclosure can separate or selectively capture anionic contaminants (e.g., chromium and/or arsenic oxyanions) even in the presence of other ions and/or metals. In contrast, most ion exchangers and adsorbents developed for selective ion separations are developed for selective cation separations, rather than anion separations. In addition, current anion exchangers typically rely on functional groups that adsorb anions using ion exchange interactions only, rather than other selective interactions such as chelation and hydrogen bonding. Further, the separation mechanisms disclosed herein for isolating chromium and arsenic metals are different than the mechanisms used in previous reports for the metalloid boron. For example, the boron capture mechanism previously published did not involve ion exchange or hydrogen bonding interactions, and instead involved the filling of an originally empty p-orbital (absent in chromium and arsenic) in B(OH).sub.3 to bind boron.
[0084] The methods and functionalized PAFs disclosed herein, can be applied generally to various separation processes, as well as to applications that involve chromium and arsenic. Examples of potential applications and variations of the methods disclosed herein, include, but are not limited to, the following: [0085] (1) Water remediation. The methods and functionalized PAFs of the disclosure can be used to remove chromium and/or arsenic from various types of water sources (e.g., groundwater, surface water, freshwater, seawater, wastewater, well water, mining water, brackish water). [0086] (2) Soil and other environmental remediation. The methods and functionalized PAFs of the disclosure can be used to remove chromium and/or arsenic from solid-, liquid-, or gas-state sources. [0087] (3) Applications and separations that involve chromium and arsenic of any oxidation state or speciation. For example, The methods and functionalized PAFs of the disclosure can be used to bind or separate Cr(0), Cr(II), Cr(III), Cr(IV), or Cr(VI)as well as As(0), As(III), or As(V)from mixtures. Examples of different Cr(VI) dissolved waterborne species that can be targeted include, but are not limited to, CrO.sub.4.sup.2, HCrO.sub.4.sup., H.sub.2CrO.sub.4, Cr.sub.2O.sub.7.sup.2, HCr.sub.2O.sub.7.sup., and H.sub.2Cr.sub.2O.sub.7. Examples of different As(III) and As(V) waterborne species that can be targeted include, but are not limited to, AsO.sub.4.sup.3, HAsO.sub.4.sup.2, H.sub.2AsO.sup.4, H.sub.3AsO.sub.4, H.sub.3AsO.sub.3, H.sub.2AsO.sup.3, HAsO.sub.3.sup.2, and AsO.sub.3.sup.3. [0088] (4) Separating chromium, arsenic, and boron from one another. For example, the methods and functionalized PAFs disclosed herein display chromium and boron selectivity over arsenic at neutral pH, chromium selectivity over arsenic and boron at acidic pH, and boron selectivity over chromium and arsenic at alkaline pH conditions. These selectivity differences can be leveraged to achieve chromium/arsenic/boron separations. Furthermore, charge differences to achieve selectivity using the methods and functionalized PAFs of the disclosure can be leveraged using pH swingsfor example, boron and As(III) are present as neutral B(OH).sub.3 and H.sub.3AsO.sub.3, respectively, at neutral pH, while Cr(VI) and As(V) are anionic oxyanions at this pH condition. [0089] (5) Separating chromium, arsenic, and/or boron from gaseous mixtures. [0090] (6) Adsorption column applications. The functionalized PAFs described in this disclosure can be integrated into adsorption, chromatography, and/or separation columns. [0091] (7) Adsorptive coating applications. Porous polymer adsorbents functionalized with aminopolyols can be coated onto surfaces (either directly or after dispersion into a polymer matrix) that can be used to capture chromium and/or arsenic. [0092] (8) As a similar material application, other porous materials (BET surface area 20 m.sup.2/g), such as other porous polymers or metal-organic frameworks, that are functionalized with the NMDG functional group may also be similarly used for selective chromium and arsenic separations. [0093] (9) In-situ reduction of chromium (VI) using the materials described in this technology. Preliminary evidence suggests that the porous organic frameworks functionalized with N-methyl-D-glucamine detailed in this disclosure may selectivity reduce aqueous chromium (VI) compounds at acidic conditions. [0094] (10) Colorimetric detection of chromium (VI) in solution. Given that the porous organic frameworks described in this disclosure turn from a light beige to a green color upon chromium adsorption, this color change may be used to detect and/or quantify chromium (VI) in solution. [0095] (11) Selective capture of other oxygen-rich compounds, such as silicon (e.g., Si(OH).sub.4 or silicate species) or other waterborne oxyanions (e.g., vanadate, molybdate, permanganate, tungstate, antimony oxyanions, ferrate, rhenate, perrhenate, tellurate, tellurite, selenate, selenite, perxenate, carbonate, bicarbonate, phosphite, phosphate, hyposulfite, nitrite, nitrate, chlorate, sulfate, thiosulfate, acetate, perchlorate, hypochlorite, iodate, bromite, perbromate, bromate, hypobromite, etc.). For example, the chelation, hydrogen-bonding, redox, and ion-exchange mechanisms used in the disclosure to achieve chromium and arsenic separation can also be leveraged to selectively remove these additional oxyanions from water or selectively bind to these oxyanions in other applications. [0096] (12) Chromium, arsenic, and oxyanion storage. By leveraging selective chemical interactions for chromium and/or arsenic, the methods and functionalized PAFs of the disclosure can be used in devices that require the storage or immobilization of chromium and arsenic. For example, the functionalized porous organic frameworks or N-methyl-D-glucamine functional group described in the disclosure can be integrated into such devices. [0097] (13) The porous organic frameworks described in this disclosure can be integrated into other separation and sensor devices, such as into membranes, films, electrodes, coatings, pellets, co-polymers, porous substrates, and indicators. For example, such composites can be used to achieve the chromium and arsenic separations described in detail in this disclosure. For example, membranes containing the porous organic frameworks can be used to achieve chromium and arsenic separations via facilitated transport or irreversible capture, facilitated using separation schematics such as electrodialysis, ion-capture electrodialysis, diffusion dialysis, ultrafiltration, electrofiltration, fuel cells, microfiltration, ultrafiltration, nanofiltration, reverse osmosis, capacitive deionization, and membrane capacitive deionization. [0098] (14) The PAF-1-MAPD, PAF-1-serinol, and PAF-1-N(CH.sub.3).sub.2 materials described herein (see
EXAMPLES
[0100] Syntheses of functionalized PAFs. The parent PAF-1 framework, which consists of tetrahedral carbon nodes connected by biphenyl linkers (see
[0101] Elemental Analysis and Fourier transform infrared spectroscopy (FTIR) of the Functionalized PAFs. The successful syntheses of these materials were verified by elemental analysis, and Fourier transform infrared spectroscopy (FTIR). For each aminopolyol- or amine-functionalized material, elemental analyses revealed an increase in nitrogen content close to the values expected for a loading of one functional group per biphenyl linker. Based on nitrogen elemental analyses, the functional group loadings were calculated to be 2.50, 3.29, 3.27, and 3.51 mmol/g for PAF-1-NMDG, PAF-1-MAPD, PAF-1-serinol, and PAF-1-N(CH.sub.3).sub.2, respectively (see
TABLE-US-00001 TABLE 1 Functional group loadings on the functionalized PAFs, calculated from elemental analysis results. Loadings are provided in units of millimoles of functional group per dry gram of overall functionalized PAF material. # of functional groups Functional group loading Functionalized PAF per biphenyl linker (mmol/g) PAF-1-CH.sub.2Cl.sup.a 1.16 5.60 PAF-1-NMDG.sup.b 0.91 2.50 P2-NMDG.sup.b 1.04 2.36 PAF-1-MAPD.sup.b 0.91 3.29 PAF-1-serinol.sup.b 0.86 3.27 PAF-1-N(CH.sub.3).sub.2.sup.b 0.76 3.51 .sup.aLoadings for PAF-1-CH.sub.2Cl were calculated based on carbon elemental analysis. .sup.bLoadings for PAF-1-NMDG, P2-NMDG, PAF-1-MAPD, PAF-1-serinol, and PAF-1-N(CH.sub.3).sub.2 were calculated based on nitrogen elemental analyses.
[0102] Surface area measurements of the functionalized PAFs. Nitrogen adsorption isotherms were collected at 77 K for the functionalized PAFs to determine their Brunauer-Emmett-Teller (BET) surface areas (see
[0103] Stability measurements of the functionalized PAFs. Thermogravimetric analysis (TGA) decomposition results indicate high thermal stability of the materials (no decomposition below 200 C.), along with expected drops in mass around 200-500 C. that are consistent with the mass of the functional groups (see
[0104] Assessing the Cr(VI) adsorption properties of the functionalized PAFs. The Cr(VI) adsorption properties of the four synthesized PAF materials was examined. Importantly, the amine on each functional group is predicted to have a pka near or above 9, causing these functional groups to be protonated at neutral pH conditions. Simulations performed using HySS software also indicate that Cr(VI) exists completely in the oxyanion state at neutral pH conditions in the measurements, with the predominant species being CrO.sub.4.sup.2 (see
[0105] Interestingly, further inspection in the low-concentration region of these isotherms reveals that PAF-1-NMDG captures Cr(VI) much more effectively than the other frameworks at dilute Cr(VI) concentrations, indicated by the markedly steeper isotherm profile in this region (see
TABLE-US-00002 TABLE 2 Single-site Langmuir model fitting parameters and saturation capacities per functional group (FG) for the obtained Cr(VI) equilibrium adsorption isotherms. Qm is the saturation Cr(VI) adsorption capacity, KL is the Langmuir constant, and Cr:FG is the saturation Cr adsorption capacity per functional group loading in the adsorbent. Q.sub.m K.sub.L Material (mmol/g) (L/mmol) Cr:FG.sup.a PAF-1-NMDG 2.50 14.4 1.00 P2-NMDG 2.39 17.7 1.01 PAF-1-MAPD 3.63 0.8 1.10 PAF-1-serinol 3.70 0.9 1.13 PAF-1-N(CH.sub.3).sub.2 2.87 0.9 0.82 IRA743 1.62 1.2 .sup.aElemental analysis for IRA743 was not conducted in this report. However, a previous study found that this material possesses an NMDG loading of 2.18 mmol/g, based on nitrogen elemental analysis. According to this loading, the Cr:FG value for IRA743 would be 0.74.
[0106] The Langmuir constant (KL) obtained from the Langmuir model serves as a measure of equilibrium binding affinity. The KL value for Cr(VI) obtained for PAF-1-NMDG (14.4 L/mmol) was over an order of magnitude higher than those for PAF-1-MAPD (0.8 L/mmol), PAF-1-serinol (0.9 L/mmol), and PAF-1-N(CH.sub.3).sub.2 (0.9 L/mmol) (see Table 2). These differences confirm the higher Cr(VI) binding strength toward the NMDG functional groups than to the MAPD, serinol, and dimethylamine groups. The nearly identical KL values among PAF-1-MAPD, PAF-1-serinol, and PAF-1-N(CH.sub.3).sub.2 also suggest that Cr(VI) binding in each of these three frameworks occurs through a similar mechanism. Given that PAF-1-N(CH.sub.3).sub.2 can only capture Cr(VI) oxyanions through anion-exchange interactions, these results suggest that PAF-1-MAPD and PAF-1-serinol also capture Cr(VI) via anion-exchange. Indeed, images of these three frameworks after Cr(VI) loading show that the frameworks gain a yellow-brown color upon adsorption (see
[0107] Assessing the As(V) Adsorption Properties of the Functionalized PAFs. The high Cr(VI) loadings of these frameworks encouraged studies looking at their arsenic removal capabilities. Like Cr(VI), toxic As(V) generally exists fully in the oxyanion state at neutral pH conditions, predominantly as a mixture of H.sub.2AsO.sub.4.sup. and HAsO.sub.4.sup.2 (pKa7.0). Collected As(V) adsorption isotherms and their single-site Langmuir model fits revealed saturation capacities of 1.14, 0.93, and 1.86 mmol/g for PAF-1-NMDG, PAF-1-MAPD, and PAF-1-N(CH.sub.3).sub.2, respectively (see
TABLE-US-00003 TABLE 3 Single-site Langmuir model fitting parameters and saturation capacities per functional group (FG) for the obtained As(V) equilibrium adsorption isotherms at pH = 7 conditions. Qm is the saturation As(V) adsorption capacity, KL is the Langmuir constant, and As:FG is the saturation As adsorption capacity per functional group loading in the adsorbent. Q.sub.m K.sub.L Material (mmol/g) (L/mmol) As:FG.sup.a PAF-1-NMDG 1.14 2.2 0.46 P2-NMDG 1.04 1.9 0.44 PAF-1-MAPD 0.93 1.0 0.28 PAF-1-N(CH.sub.3).sub.2 1.86 1.2 0.53 IRA743 0.62 1.7 .sup.aElemental analysis for IRA743 was not conducted in this report. However, a previous study found that this material possesses an NMDG loading of 2.18 mmol/g, based on nitrogen elemental analysis. According to this loading, the As:FG value for IRA743 would be 0.28.
[0108] Isotherms collected at pH=4 conditions showed steeper adsorption profiles for each framework but otherwise similar saturation capacities and KL differences among the frameworks (see
TABLE-US-00004 TABLE 4 Single-site Langmuir model fitting parameters and saturation capacities per functional group (FG) for the obtained As(V) equilibrium adsorption isotherms at pH = 4 conditions. Qm is the saturation As(V) adsorption capacity, KL is the Langmuir constant, and As:FG is the saturation As adsorption capacity per functional group loading in the adsorbent. Q.sub.m K.sub.L Material (mmol/g) (L/mmol) As:FG PAF-1-NMDG 1.26 8.5 0.50 PAF-1-MAPD 1.43 3.5 0.44 PAF-1-N(CH.sub.3).sub.2 1.80 5.9 0.51
[0109] Elucidating the binding mechanisms of PAF-1-NMDG for Cr(VI) and As(V). To better elucidate the unique Cr(VI) and As(V) binding mechanisms of PAF-1-NMDG, Cr and As K-edge X-ray absorption spectroscopy (XAS) was utilized. The X-ray absorption near edge structure (XANES) spectrum for Cr-loaded PAF-1-NMDG exhibited a pre-edge feature at 5993 eV, indicative of the +6 Cr oxidation state (see
[0110] The extended X-ray absorption fine structure (EXAFS) spectra were additionally obtained and modeled for both samples (see
TABLE-US-00005 TABLE 5 EXAFS fitting results of the Cr- (unshaded) and As-loaded (shaded in gray) PAF-1-NMDG and PAF-1-N(CH.sub.3).sub.2 materials. R .sup.2 E.sub.0 R-factor Material Path N () (.sup.2) (eV) (%) PAF-1-NMDG-Cr CrO 2 1.63 0.02 0.005 3.99 7.94 1.8 CrO 4 1.93 0.04 0.005 3.99 7.94 1.8 PAF-1-N(CH.sub.3).sub.2Cr CrO 4 1.59 0.01 0.005 3.94 1.95 0.8 PAF-1-NMDG-As AsO 4 1.82 0.02 0.005 5.57 2.43 0.3 PAF-1-N(CH.sub.3).sub.2As AsO 4 1.70 0.01 0.001 6.21 2.06 0.5
[0111] Fits for the As K-edge EXAFS spectrum showed that As(V) maintains four AsO bonds upon adsorption to PAF-1-NMDG, with bond distances (1.82 ) elongated compared to those reported in the Cambridge Crystallographic Data Centre for K.sub.3AsO.sub.4 (1.69 ). Two potential As(V)-NMDG complex structures were investigated to account for the bond elongation. In the first proposed structure (see
[0112] For comparison, XANES spectra was collected for Cr- and As-loaded PAF-1-N(CH.sub.3).sub.2. The data likewise reveal that these adsorbates maintain their+6 and +5 oxidation states upon adsorption, respectively, as expected for anion-exchange interactions (insets of
[0113] Investigating why shorter aminopolyols, MAPD and serinol, cannot achieve the high-affinity Cr(VI) oxyanion binding structures obtained by PAF-1-NMDG. The B(OH) 3 adsorption properties of the three frameworks were investigated. Notably, unlike for chromium or arsenic separations, the NMDG functional group is used on an industrial scale to remove boric acid from water, primarily through proposed monochelate, tetradentate, and bischelate adsorption mechanisms. The MAPD and serinol groups have not been adopted for such separations, though their lighter molecular weights could lead to higher adsorption capacities than NMDG, should they be capable of participating in the same types of chelation interactions.
[0114] Previous studies of the NMDG-B(OH).sub.3 adsorption mechanism revealed that B(OH).sub.3 adsorption is dominated by tetradentate and bischelate binding (see
[0115] The collected B(OH).sub.3 isotherms show that PAF-1-NMDG achieves boron saturation capacities (2.01 mmol/g) that are roughly six times that of PAF-1-MAPD (0.33 mmol/g) and PAF-1-serinol (0.36 mmol/g) (see
TABLE-US-00006 TABLE 6 Langmuir model fitting parameters and saturation capacities per functional group (FG) for the obtained B(OH).sub.3 equilibrium adsorption isotherms. Qm, 1 and Qm, 2 are the saturation B(OH).sub.3 adsorption capacities of two adsorption sites, KL, 1 and KL, 2 are the Langmuir constants of the two adsorption sites, and B:FG is the saturation B adsorption capacity per functional group loading in the adsorbent. Q.sub.m, 1 K.sub.L, 1 Q.sub.m, 2 K.sub.L, 2 Material (mmol/g) (L/mmol) (mmol/g) (L/mmol) B:FG PAF-1-NMDG 1.20 5.4 0.81 0.08 0.80 PAF-1-MAPD.sup.a 0.33 0.4 0.10 PAF-1-serinol.sup.a 0.36 0.5 0.11 .sup.aA single-site Langmuir model was used to fit the adsorption isotherms of the PAF-1-MAPD and PAF-1-serinol materials.
[0116] Assessing the Si(OH).sub.4 adsorption performance of PAF-1-NMDG as a function of pH. Silicon-based compounds pose significant industrial water treatment issues, arising from their propensity to cause scaling and the relative lack of available techniques that can selectively remove these compounds. Given the oxygen-rich speciation of waterborne silicon, it was postulated that the NMDG functional groups could potentially adsorb silicon via analogous chelating mechanisms as those observed for B(OH).sub.3 and Cr(VI) and As(V) oxyanions. Unfortunately, minimal Si uptake was observed at all tested pH values (pH range: 1-12). The highest Si uptake occurred at pH conditions of 9.5 and 12.0, likely because Si is largely anionic (as Si(OH).sub.3O.sup. and/or Si(OH).sub.2O.sub.2.sup.2) at these conditions, enabling some anion-exchange to the NMDG amine. It was hypothesized that the ability of B(OH).sub.3, Cr(VI), and As(V) to increase in coordination number (e.g., to the four-coordinate tetrahedral borate anion upon adsorption, or the six-coordinate Cr(VI) complex) plays an important role in allowing these constituents to accommodate additional coordination to the NMDG alcohol groups. This ability is lacking in Si(OH).sub.4.
[0117] Characterizing the Cr(VI) and As(V) removal performances of PAF-1-NMDG by measuring adsorption kinetics. Informed by the isotherm and mechanistic data provided in the previous two sections, PAF-1-NMDG was identified to be the most promising material for Cr(VI) and As(V) removal out of the four PAF-1-derived frameworks. Accordingly, the systematic characterization of the Cr(VI) and As(V) removal performances of PAF-1-NMDG was carried out, starting with adsorption kinetics measurements.
[0118] Adsorption kinetics are one of the most important properties of adsorbents, influencing factors such as throughput and required adsorbent bed sizes. The adsorption kinetics of PAF-1-NMDG was measured using separate solutions containing 250 mg/L Cr(VI) (in the form of CrO.sub.4.sup.2) or As(V) (in the form of H.sub.2AsO.sup.4/HAsO.sub.4.sup.2). In both cases, PAF-1-NMDG exhibited exceptionally fast kinetics: the equilibrium saturation capacities for Cr(VI) and As(V) were reached by the time of the first data point (<10 s) (see
[0119] Examining the selectivity of PAF-1NMDG for Cr(VI) and As(V) two-component adsorption selectivity experiments. To understand how the unique Cr(VI) and As(V) oxyanion binding mechanisms of PAF-1-NMDG translate into selectivity over competing solutes, two-component adsorption selectivity experiments were conducted. Aqueous testing solutions were prepared by combining 2 mM of either Cr(VI) or As(V) with 2, 20, or 200 mM (i.e., 1, 10, or 100 higher concentrations) of one of the following common competing waterborne species: Cl.sup., NO.sub.3.sup., SO.sub.4.sup.2, or B(OH).sub.3. Adsorption experiments were then conducted by mixing these solutions with PAF-1-NMDG. As displayed in
[0120] However, these selectivity tests also reveal that Cr(VI) and As(V) adsorption is most negatively affected by competing solutes in the following order: B(OH).sub.3>SO.sub.4.sup.2>NO.sub.3.sup.>Cl.sup.. The measurements also demonstrated that selectivity for Cr(VI) over other competing solutes is significantly higher than the As(V) selectivities, consistent with the unique polyol chelation properties confirmed only for Cr(VI), along with the steeper adsorption isotherm profile observed for Cr(VI) (see
[0121] Further examining the selectivity of PAF-1NMDG for Cr(VI) and As(V) three-component adsorption selectivity experiments. Since PAF-1-NMDG can selectively capture Cr(VI), As(V), and B(OH).sub.3, three-component selectivity tests were performed to better understand the PAF-1-NMDG adsorption selectivities between each solute. Aqueous solutions containing equimolar concentrations of these three solutes were tested. The concentration of each solute was varied as 0.2, 2, or 5 mM to also probe concentration effects. Adsorption capacities in these experiments are provided in
[0122] Additionally, the total combined solute adsorption capacity by PAF-1-NMDG plateaus to a 1:1 solute-to-NMDG ratio in these three-component experiments (see
[0123] Assessing pH dependency of PAF-1-NMDG for Cr(VI) and As(V) binding. The aforementioned three-component selectivity tests were performed for PAF-1-NMDG under pH=4 conditions. Selectivities from these experiments are given in
[0124] The improved Cr(VI) and As(V) selectivities observed under mildly acidic conditions also agree with other pH dependency tests that were performed. For example, two-component selectivity measurements also exhibited improved As(V) selectivity by PAF-1-NMDG over other competing solutes (Cl.sup., NO.sub.3.sup., SO.sub.4.sup.2, B(OH).sub.3) at pH=4 conditions compared to at pH=7 conditions (see
[0125] Notably, minimal capacities were achieved under pH=12 conditions. At these basic conditions, the NMDG groups (pKa9.6) are not expected to readily facilitate proton transfer in aqueous solution, and repulsive interactions between the oxyanions and deprotonated NMDG hydroxyl groups may additionally occur. These effects were similarly observed for B(OH).sub.3 capture under basic conditions.
[0126] Testing the regeneration and recyclability of PAF-1-NMDG for Cr(VI) and AS (V). To maximize their lifetime and reduce capital costs, adsorbents must be capable of achieving regeneration over numerous cycles without facing significant performance loss or degradation. To this point, Cr(VI) and As(V) adsorption-desorption performances of PAF-1-NMDG were tested over 10 cycles (see
[0127] Determining whether the binding strategies utilized by PAF-1-NMDG for Cr(VI) and As(V) can be replicated in analogous materials. To see if the Cr(VI) and As(V) binding strategies utilized by PAF-1-NMDG could be applied more generally to other PAF materials, an analogous material (P2-NMDG, see
[0128] Characterization data obtained for this material were similar to those of PAF-1-NMDG. For example, consistent with previous reports, elemental analyses demonstrated that P2-NMDG possesses an NMDG loading of 2.36 mmol/g (see Table 2) and a similar TGA decomposition profile (see
[0129] Assessing the adsorption performances of PAF-1-NMDG in comparison with Amberlite IRA743. To provide context for the adsorption performances of PAF-1-NMDG, the adsorption performances of Amberlite IRA743 was investigated for comparison. This material is a commercial resin made up of NMDG-functionalized poly(styrene-divinylbenzene). Adsorption isotherms of IRA743 for Cr(VI) and As(V) exhibited saturation capacities that were only 64.6% and 54.6% that of the Cr(VI) and As(V) saturation capacities, respectively, for PAF-1-NMDG (see
[0130] Assessing the adsorption kinetics of PAF-1-NMDG in comparison with Amberlite IRA743. The Cr(VI) and As(V) adsorption kinetics of Amberlite IRA743, was tested using the same kinetics testing protocols as used for PAF-1-NMDG. The resin was first ball-milled to afford smaller particle sizes similar to those of PAF-1-NMDG, to diminish kinetic effects from particle size differences. For both oxyanions, the ball-milled IRA743 resin displayed markedly slower adsorption kinetics compared to PAF-1-NMDG (see
[0131] PAF-1-NMDG adsorption performance in comparison to leading adsorbents. Tables 7 and 8 compare the Cr(VI) and As(V) adsorption performances, respectively, of PAF-1-NMDG more generally to the performances of other leading sorbents. As previously mentioned, PAF-1-NMDG exhibits the fastest Cr(VI) and As(V) adsorption kinetics of any reported material to date, while maintaining high capacities on par with some of the highest capacity materials. For example, other materials that achieve even higher capacities often take hourseven daysto reach their high equilibrium capacities. Unlike nearly all other materials, PAF-1-NMDG can additionally be recycled numerous times without any measurable loss in performance. It is worth noting that the majority of the other reports did not provide recyclability data, making further comparisons challenging. Importantly, with the exception of metal oxide materials used for As(V) removal, the vast majority of reported Cr(VI) and As(V) adsorbents also rely on simple ion-exchange mechanisms, which often face low selectivities not described in Tables 7 and 8. In contrast, PAF-1-NMDG features unique chelating capabilities.
TABLE-US-00007 TABLE 7 Comparison of the binding mechanism, percentage of adsorption capacity maintained upon adsorption-desorption regeneration cycles, saturation adsorption capacity, and kinetic uptake rates for Cr(VI) among PAF-1-NMDG and reported state-of- the-art adsorbents. The pH condition implemented for each reported value is also included. The vast majority of reported adsorbents rely on ion-exchange interactions, which can also lead to adsorption of undesired competing anions and thus selectivity issues not shown in this table. Time to Reach Saturation (% of Primary Cr(VI) equilibrium Binding Regenerability Capacity capacity reached Material Mechanism (cycles) (mg/g) at time) pH PAF-1-NMDG Chelation 100% (10) 130 <10 s (100) 7 IRA743 Resin Chelation 84 4 h (100) 7 Crosslinked Chitosan Ion-exchange 100% (5) 325 24 h (100) 2 Chitosan Grafted Ion-exchange 85% (10) 104 7 h (100) 2 Graphene Oxide Ionic Liquid Ion-exchange 196 1.5 Impregnated Amberlite XAD-4 Amine-Functionalized Ion-exchange, 159 3 Corn Stalk reduction Chitosan-Cyclodextrin Ion-exchange, 95% (5) 68 3 Grafted Graphene reduction Oxide Tulsion A-27 (MP) Ion-exchange 57 5.5 Cereal By-Product Ion-exchange 132 6 Carbon Bacterial Cellulose- Ion-exchange 92% (5) 230 6 Attapulgite MOR-1-HA Ion-exchange 117 3 min (97.5) 3 MOF-808 Ion-exchange, 95% (1) 50 4.6 hydrogen bonding ABT2ClO.sub.4 Ion-exchange 51 6 h (90) ZJU-101 Ion-exchange 118 10 min (96) FJI-C11 Ion-exchange 93% (3) 155 3 min (95) MOF-1-Cl Ion-exchange 31 30 min (100) UiO-66-NH.sub.2 @ Silica Ion-exchange 100% (8) 134 1 iMOF-2C Ion-exchange 214 25 min (100)
TABLE-US-00008 TABLE 8 Comparison of the binding mechanism, percentage of adsorption capacity maintained upon adsorption-desorption regeneration cycles, saturation adsorption capacity, and kinetic uptake rates for As(V) among PAF- 1-NMDG and reported state-of-the-art adsorbents. The pH condition implemented for each reported value is also included. Time to Reach Saturation (% of As(V) equilibrium Binding Regenerability Capacity capacity reached Material Mechanism (Cycles) (mg/g) at time) pH PAF-1-NMDG Ion exchange, 100% (10) 94.2 4 chelation PAF-1-NMDG Ion-exchange, 100% (10) 85.5 <10 s (100) 7 chelation IRA743 Resin Ion-exchange, 46.7 4 h (100) 7 chelation Fe.sub.2O.sub.3 and MnO Ion-exchange 65.5% (4) 1.5 12 h (97) 7 on Honeycomb Briquette Cinders MOF-808 Ion-exchange 82.1% (5) 24.8 50 min (100) 4 UiO-66 Ion-exchange 147.7 48 h (100) 7 Fe-BTC Fe 12.3 10 min (100) 4 complexation MIL-53 (Al) Ion-exchange 106.5 50 h (100) 8 hydrogen- bonding Crosslinked Polyol 16.4 24 h (90) 6 NMDG and complexation Poly(vinylbenzene chloride) Fe-treated Fe 80% (4) 33.2 10 h (100) 7 Cellulose complexation Fe-modified Fe 51.3 24 h (100) 6 Activated complexation Charcoal Fe(0) Fe 92% (5) 119 3 h (100) 7 Nanoparticles on complexation Chitosan Molybdate Mo 230 24 h (100) 2-3 Chitosan complexation Derivatives H-MFI-90 Ion-exchange 97% (1) 34.8 100 min (100) 6.5 Synthetic Zeolite H-MFI-24 Ion-exchange 35.8 100 min (100) 6.5 Synthetic Zeolite Ultrafine Fe.sub.2O.sub.3 Fe 47 2 h (95) 7 Nanoparticles complexation Poly(glycidyl Ion-exchange, 45.9 3 methacrylate-N- polyol methyl-D- complexation glucamine)
[0132] It will be understood that various modifications may be made without departing from the spirit and scope of this disclosure. Accordingly, other embodiments are within the scope of the following claims.