This application claims the benefit of 62/793,644 filed 17 January 2019, Thompson & Soukri, Atty. Dkt. 121-88-PROV which is hereby incorporated by reference in its entirety.

1. FIELD

[0002] The present disclosure provides novel solid sorbents synthesized by the reaction of polyamines with polyaldehyde phosphorus dendrimer (P-dendrimer) compounds for metal sequestration. The sorbents are highly stable and exhibit desirable thermodynamics and reaction kinetics with a wide variety of metals including heavy metals and rare earth elements. The sorbents can be easily regenerated for repeated use to extract metals from an aqueous solution. The materials are stable to aqueous and organic media, as well as strong acid and bases. The sorbents maintain full capacity over many cycles of use.

2. BACKGROUND

[0003] The“background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

2.1. Introduction: Heavy Metal Removal

[0004] The contamination of water sources by heavy metals (e.g. Pb, Hg, As, etc.) stemming from industrial pollution or natural occurrence can have devastating effects on the environment and poses a significant threat to human health. Industrial waste discharges contain heavy metals, which are highly water-soluble, that enter aquatic streams leading to absorptive build up in cultivated soils, and present technical challenges for removal to preserve drinking water quality. Long-term exposure to heavy metals or ingestion beyond permitted concentrations can lead to serious human health disorders or even death. World-wide regulatory efforts have been established to limit the exposure of humans to dangerous heavy metals and the effective reduction in concentration of the metals to trace levels (< 5 ppb) remains a significant challenge to-date.1

[0005] Three of the most highly toxic water-contaminating elements are lead (Pb), mercury (Hg), and arsenic (As). These metals cause various adverse health effects at low exposure levels, with significant risk for death at high ingestion levels and causing cancer from long term exposure. The current regulatory limits of the U.S. environmental protection agency (EPA) for lead (Pb), mercury (Hg), and arsenic (As) are 15 ppb, 2 ppb, and 10 ppb respectively. Heavy metals commonly enter drinking water supplies from the erosion and dissolution of natural deposits, as well as from agricultural and industrial waste water. Lead specifically poses a challenge for drinking water when pipes that contain lead corrode, which is prevalent in water supplies with high acidity or low mineral content. Due to strict human exposure standards, extremely efficient and cost-effective technologies are required to purify water supplies before mass consumption.

[0006] Various technologies have been developed to remove contaminating heavy metals from water streams, including precipitation, coagulation, reverse osmosis, ion exchange, solvent extraction, flotation, and membrane separation. These processes typically face economic and technical hurdles, such as low capacities and low removal rates which prevent their implementation due to low-energy process requirements and the necessary avoidance of toxic sludge.2 Adsorption technologies have emerged as attractive alternatives due to low cost, simplistic process designs with strong metal binding affinities and high removal rates.3 Solid sorbents that do not mix with waste water but can remove toxic and harmful impurities are greatly sought after. The adsorbent technologies have been based off zeolite, activated carbon, silica, polymers, biomaterials, ion exchange resins, industrial byproducts, biomass, and biological materials.4 Of the class of adsorbent technologies, those that bind heavy metals via the chelation effect offer a cheap and environmentally friendly technique that has minimized technical limitations.5

[0007] In the polymer class of adsorbents, dendritic polymers have gained significant attention in water purification applications. Dendrimers are well-defined, step-wise constructed polymers that have many reactive end groups. These macromolecules have a well-defined structure that can be finely tuned through the precise addition of specific monomers. The ease of diversification and functionalization with a variety of end groups has made dendritic materials promising candidates for heavy metal removal from polluted water sources. Dendrimers are well suited adsorbents due to their three-dimensional structure providing both external and internal binding sites, strong chelation effects from a larger number reactive sites, and tunability to specifically target various contaminants.6 The most widely studied and applied dendritic polymer is the poly(amidoamine) (PAMAM) dendrimer, which consists of ethylenediamine and methylacrylate repeating units. The PAMAM dendrimer is non-toxic, low cost, easily synthesized, and shows high affinities towards

heavy metals.7 The amine-functionalized dendrimers remove heavy metals through strong chelation effects by the various amine units of the polymer.

[0008] Typically, dendrimers, such as PAMAM, must be supported or integrated with other inorganic or organic materials to enhance the mechanical strength, to form a solid material, and to increase the available surface area for heavy metal removal. The most common supports are silica and carbon-based, however titania, magnetic nanoparticles, cellulose, chitin, and membranes have also been demonstrated. The supported dendrimers have shown capabilities to remove a wide range of heavy metals (Pb(II), Cd(II), Cu(II), Mn(II), Ni(II), Hg(II), etc.). The support of the dendrimers inevitably decreases the overall chelator content in the final material, due to the dilution (by weight) of the dendrimer onto the sorbent. Amine-functionalized dendrimers typically operate under narrow pH ranges (4.0-7.0) with nominal adsorption capacities (<50 mg/g), with a few exceptions reaching over >500 mg/g.6 Likewise, the regeneration and stability of dendritic materials has not been thoroughly explored.

2.2. Introduction: Rare Earth Element Recovery

[0009] Rare earth elements (REEs), which consist mainly of the lanthanide (Ln) metals along with scandium (Sc) and yttrium (Y), are chemically similar elements that have unique properties that have made REEs vital for developing technologies. Specifically, the REEs are highly desired based on a steadily increasing demand in the energy, electronics, and defense industries, but also because of instability of the supply market. In 2015, the U.S. Geological Society estimated that global REE reserves totaled 130,000,000 tons, and the main REE reserves are controlled mainly by China (42%) and Brazil (17%), with only 1.3% owned by the U.S. As of 2012, China controlled 95% of the global REE market.22 The lack of a stable U.S. supply chain and concerns not only of environmental and social concerns by which REEs are mined, but of national security due to foreign REE dependence has prompted significant efforts to develop new technologies to recover and recycle REEs.23

[0010] Recovering REEs from water bodies in the U.S. is too large of a challenge. A report from Noack et al. in 2014 found REE concentrations ranging between 5 - 170 pmol/L from ocean, groundwater, river, and lakes.24 REE concentrations were found to be dramatically increased when measured from acidic water sources and acidic soils.24,25 Recently, acid mine drainage (AMD) sludges, which are inherently highly acidic, have been found to contain significant concentrations of REEs. REEs have been detected from coal mining AMD in concentrations of 300 to over 3,000 m/L, which is a remarkably high concentration, allowing for this waste stream to be a potential

source for REE recovery.26-28 The AMD liquid stream is complex, containing a variety of other metal contaminants alongside the REE mixture making extraction of mixed or pure REE components challenging.

[0011] The most common industrial separation technologies use multistage liquid-liquid extraction (LLE) and resin-based chromatography.29 The LLE processes utilize large volumes of organic solvents for repetitive extractions to obtain a partial selective REE concentrated solution while generating a large volume of organic waste. The resin-based chromatographic process can overcome selectivity challenges, however, the costs of the ion-exchange resins is too high due to their inability to be regenerated. Emerging technologies for REE extraction utilize chemical precipitation, membrane separation, and adsorption. Of these approaches, the adsorption process minimizes solvent waste while also improving separation efficiencies between REEs and other co contaminants.30 The absorbents are typically functionalized with Lewis basic compounds so that they have a strong interaction with the highly Lewis acidic REEs. For example, adsorbents such as monmorillonite and bentonite display poor REE adsorption efficiency, however, when modified with chelating agents their adsorption efficiency was greatly enhanced.31-33 The most common Lewis basic chelating agents employed for REE capture are carboxylate and amine moieties.

[0012] The two main types of solid-phase adsorbents are based on Lewis basic functionalities anchored to solid support materials (e.g. silica) covalently or in the chemical composition of polymeric materials. The first example of using amine-functionalized silica supports was reported by Florek et al. in 2014, in which they prepared a diglycolamide- modified KIT-6 silica to extract and separate lanthanides.34 In 2015, Zheng et al. prepared maleic anhydride functionalized mesoporous silicas for REE capture, with specifically high activity for Eu3+ and Gd3+.35 Recognizing the role of the Lewis base’s geometry for REE capture, Hu et al. prepared phthaloyl diamide functionalized KIT-6 silicas for targeted REE adsorption with a maximum capacity of 8.47 mg/g adsorption capacity.29 Hybrid silica-amine-polymer matrix materials was prepared by Wilfong et al. in 2017, which displayed high ppm and ppb REE adsorption efficiencies.36,37 Although silica materials are highly effective, the grafting materials tend to be costly and scaling the grafting process is technically challenging.

[0013] Polymeric REE adsorptive materials were first prepared by Gao et al. in 2015 using immobilized gel particles derived from poly-y-glutamic acid (PGA) crosslinked with polyvinyl alcohol (PVA) to remove lanthanides and Ce3+.38 The PGA-PVA polymers were capable of adsorbing all the lanthanides from a mixture at 10 mg/L dosages with 0.2 g/L sorbent loadings. A variety of other cross-linked polymer materials have been prepared for REE adsorption.39-44 One of the most promising polymer sorbents adsorbed 384 mg/g La3+ within 30 minutes of exposure.42 The benefits of polymeric materials is derived from the high loading of chelating agents that can be incorporated into the polymer material. This allows for the material to adsorb higher concentrations of REEs from solution.

3. SUMMARY OF THE DISCLOSURE

[0014] The present disclosure provides a method of removing a metal from an aqueous fluid stream which comprises contacting an aqueous fluid stream with a polyamine phosphorus dendrimer (P-dendrimer) having the formula I

I

wherein W is a phosphorus based dendrimer core; X is a polyfunctional aromatic linker; Y may be present or absent and if present is a polyfunctional amino phosphoryl group linked to a polyfunctional aromatic linker; Z is an diamino alkyl group, a polyalkyl amino group, a polyethyleneimine having a Mw ranging from 400 to about 1,000,000, or a polypropyleneimine; j and k are numerical values corresponding to the branch point multiplicity and whose values independently range from 1 to 10; and 1 is a numerical value corresponding to the branch point multiplicity and whose values ranges from 2 to 10.

[0015] The disclosure also provides a method of adsorbing, separating, storing or sequestering a metal from an aqueous fluid stream, comprising contacting the aqueous fluid stream with a polyamine phosphorus dendrimer (P-dendrimer) having the formula I

I

wherein W is a phosphorus based dendrimer core; X is a polyfunctional aromatic linker; Y may be present or absent and if present is a polyfunctional amino phosphoryl group linked to a

polyfunctional aromatic linker; Z is an diamino alkyl group, a polyalkyl amino group, a polyethyleneimine, or a polypropyleneimine; j and k are numerical values corresponding to the branch point multiplicity and whose values independently range from 1 to 10; and 1 is a numerical value corresponding to the branch point multiplicity and whose values ranges from 2 to 10; so as to adsorb, separate, store or sequester the metal from the aqueous fluid stream.

[0016] The disclosure also provides a process for the capture and removal of metals from an aqueous metal-containing stream the process comprising: (a) providing a housing having dispersed therein a sorbent comprising a polyamine phosphorus dendrimer (P-dendrimer) having the formula I

I

wherein W is a phosphorus based dendrimer core; X is a polyfunctional aromatic linker; Y may be present or absent and if present is a polyfunctional amino phosphoryl group linked to a polyfunctional aromatic linker; Z is an diamino alkyl group, a polyalkyl amino group, a polyethyleneimine having a Mw ranging from 400 to about 1,000,000, or a polypropyleneimine; j and k are numerical values corresponding to the branch point multiplicity and whose values independently range from 1 to 10; and 1 is a numerical value corresponding to the branch point multiplicity and whose values ranges from 2 to 10; (b) passing a metal-containing stream through the housing such that the metal-containing stream contacts the sorbent; (c) flushing the housing with a concentrated acidic stream to cause the sorbent to desorb a metal-retained therein and form a desorbed metal solution; and (d) flushing the housing to remove the desorbed metal from the housing.

[0017] The disclosure also provides a sorbent comprising a sorbent comprising (a) iron II or iron III and (b) a polyamine phosphorus dendrimer (P-dendrimer) having the formula I

I

[0018] wherein W is a phosphorus based dendrimer core; X is a polyfunctional aromatic linker; Y may be present or absent and if present is a polyfunctional amino phosphoryl group linked to a polyfunctional aromatic linker; Z is an diamino alkyl group, a polyalkyl amino group, a polyethyleneimine having a Mw ranging from 400 to about 1,000,000, or a polypropyleneimine; j and k are numerical values corresponding to the branch point multiplicity and whose values independently range from 1 to 10; and 1 is a numerical value corresponding to the branch point multiplicity and whose values ranges from 2 to 10.

4. BRIEF DESCRIPTION OF THE FIGURES

[0019] Figure 1. General scheme of two step one-pot reaction involving an aldehyde component and amine component to form the solid sorbent through reductive amination conditions.

[0020] Figure 2. Preparation of PEI- functionalized solid sorbent with various polyaldehyde P-dendrimers.

[0021] Figure 3. Polyaldehyde P-dendrimer examples.

[0022] Figure 4. Poly amine examples.

[0023] Figure 5. Solid State 13C CP/MAS spectrum of I-G0/6OOPEI.

[0024] Figure 6. Infrared spectra comparison of solid sorbent I-G0/6OOPEI with the starting materials (the phosphorus-based dendrimer core and 600PEI).

[0025] Figure 7. Thermogravimetric analysis (TGA) curves displaying the temperature effect on 1-Go-TEPA sorbent capacity.

[0026] Figure 8. Z-polarized confocal microscope image of I-G0/6OOPEI.

[0027] Figure 9A-9C. SEM images showing clusters of I-G0/6OOPEI. Figure 9A I-G0/6OOPEI (10 pm), Figure 9B I-G0/6OOPEI (20 pm), and Figure 9C I-G0/6OOPEI (2.0 pm).

[0028] Figure 10. N2 adsorption-desorption isotherms for I-G0/6OOPEI.

[0029] Figures 11A and 11B. Sorbent treatment of Hg and Pb at 11A) 50 ppm and 11B) 500 ppm concentrations.

[0030] Figures 12A-12B. Sorbent treatment of various heavy metals at 12A) 50 ppm and 12B) 500 ppm concentrations.

[0031] Figure 13. Adsorption kinetics of sorbent removal of Hg and Pb at 50 ppm concentration with 1 g/L or 5 g/L sorbent loading.

[0032] Figure 14. Effect of pH on 50 ppm Hg and Pb removal from 5 g/L sorbent treatment.

[0033] Figure 15. Treatment of mixed metal ion solution with solid sorbent.

[0034] Figure 16. Flow-through adsorption and regeneration of the solid sorbent.

[0035] Figure 17. Visual sorbent color change from adsorption to regeneration with Cu.

[0036] Figure 18. Chromatographic separation of Hg(II) by solid sorbent.

[0037] Figure 19. Characterization of Fe(III) supported P-dendrimer solid sorbent for As removal panel A FT-IR and panel B SEM.

[0038] Figure 20. Removal of As(II) and As(IV) from modeled ground water solution with the solid sorbent and Fe(III) oxide functionalized solid sorbent.

[0039] Figure 21. Sorbent loading effect on As removal.

[0040] Figure 22. Kinetics for As removal with the solid sorbent.

[0041] Figure 23. pH Effect on As removal with the solid sorbent.

[0042] Figure 24. Batch Removal of selenite, Se(IV), and selenate, Se(VI), with the iron-functionalized solid sorbent.

[0043] Figure 25. Batch REE removal by solid sorbent at different loadings.

5. DETAILED DESCRIPTION OF THE DISCLOSURE

[0044] This disclosure describes the preparation of an adsorbent directly from the reaction between a polyamine compound with a phosphorous dendrimer to provide a solid, water-stable material with a high degree of amine functionality. The dendrimers were recently disclosed in two publications from the inventors describing their preparation, their physical properties, and their uses for CO2 capture.8,9

[0045] The synthetic pathway involves a cross-linking reaction between polyamines with poly aldehyde phosphorous dendrimers, which provides easy access to a solid compound that can be scaled. Phosphorous dendrimers (P-dendrimers) are polymer star-like materials, and can be employed as a cross-linking agent to form solid sorbents. P-dendrimers can be synthesized by straightforward means and commonly are functionalized at terminal positions by reactive end groups, such as aldehydes.10 In general, P-dendrimers are thermally stable robust compounds that can be advantageously employed for materials applications. P-dendrimers can range in size based on the number of branches emanating from the central core, with each branch being called a “generation.” The use of a dense compound layered with aldehydes provides an excellent anchor to react with many amine functionalities to rigidify and ultimately solidify poly amine compounds.

[0046] Importantly, the sorbent preparation is modular allowing for the preparation of materials with various amine content and core structures to fine tune the sorbent’s reactivity. The P-dendrimer core and generation growth unit of the sorbent synthesis can be altered to modify the morphology

of the sorbent. P-dendrimers of generation 0 to 12 can be employed. Any polyamine (>2 amine functionalities) can be employed to prepare a chelating solid sorbent.

[0047] The P-dendrimer solid sorbent materials were found to be excellent candidates for heavy metal and REE removal from liquid sources, for both batch and column flow-through removal applications. The disclosed solid sorbents have high capacities, removing the metals to trace levels (ppb concentrations). Importantly, the sorbents described show excellent stability to acid and bases, showing no decomposition and allow them to operate under harsh conditions for metal removal. Various parameters for metal removal were examined (pH, kinetics, co-contaminant effect, flow through rates) with the sorbent excelling under all conditions.

5.1. Sorbent Preparation

[0048] The solid sorbent is prepared in a one-pot two, step procedure involving 1) a condensation reaction between amine functionality of a polyamine compound and aldehyde moieties of a poly aldehyde compound to form imine intermediates; followed by 2) a reduction of the imine intermediates with sodium borohydride to form alkyl amines; otherwise known as a reductive animation process (Figure 1). This twostep sequence covalently locks polyamine compounds, such as PEI, together through aldehyde units to form a solid sorbent. Between steps, the imine-containing compound is washed with tetrahydrofuran and crushed using a mortar pestle to remove unreactive amine starting materials. The target compound is isolated by filtration and is washed with water, methanol, and diethyl ether to remove sodium borohydride remnants and any soluble organic species. Both reactions take place at room temperature under stirring conditions with no precaution taken to exclude air or moisture. The aldehyde compound employed may be commercially available or synthesized through standard laboratory methods. These compounds may also be formed through direct alkylation conditions. The final sorbent can be sieved or crushed to desired particle sizes.

5.2. Example Sorbent Procedure

[0049] A polyaldehyde P-dendrimer (1 equivalence) was dissolved in tetrahydrofuran (0.005-0.1 M concentration) and stirred open to air in a round bottomed flask. The polyamine compound (0.1-1.0 equivalence) was dissolved in tetrahydrofuran (0.2-0.5 M) and added rapidly to the above mixture, producing a white solid that begins forming anywhere from 5 seconds to 1 hour. The reaction was left to stir for 2 hours. The imine intermediate was filtered and washed several times with tetrahydrofuran, then crushed with a mortar and pestle to a powder. The powder was transferred to a new round bottomed flask, dispersed in tetrahydrofuran/methanol (2:1 ratio, 0.001-0.1 M) and stirred. To this mixture was added excess sodium borohydride (>5 equivalence) and let stir for 5-24 hours. After completion, the mixture was filtered, washed with water, with methanol, and with diethyl ether and dried (Figure 2). The resulting compound was shelf stable and no precautions were taken for storage.

5.3. Polyaldehyde Component

[0050] The aldehyde component of the sorbent synthesis must possess 2 or greater aldehyde functional groups. Aldehydes can react with amine functional groups of either singular or separate polyamine compounds to produce an insoluble imine compound. The imine compound is composed of a network of bonds, like that of a cross-linked polymer, whereas the aldehyde unit is randomly dispersed in the material through multiple linkages. Sorbents were prepared from a variety of polyaldehyde compounds, and their reactions with polyamine compounds. Changing either component can affect the morphology and the capacity of the sorbent.

[0051] The P-dendrimers used in this study are easily prepared by literature known procedures, or slight modifications therein, through the addition of nucleophiles to an electrophilic phosphorous-containing species. Two examples of P-dendrimer building blocks used in this study are thiophosphoryl chloride and hexachlorophosphazene. An example of a common nucleophile that can be added to these phosphorous chloride compounds is 4-hydroxybenzaldehyde. The P-dendrimers may be synthesized from other nucleophiles to yield compounds with aldehyde functionality for use in making solid sorbents. The preparative method for forming solid sorbents is not limited to P-dendrimer compounds, but may be synthesized from other molecules with 2 or greater aldehydes upon reaction with polyamine compounds.

[0052] Non-limiting examples of the phosphorus based dendrimer core are shown in Figure 3.

[0053] Non-limiting examples of the starting materials for the polyfunctional aromatic linker are:

R-i = H, Me, Et, Halogen

R2 = H, Me, Et, Halogen

5.4. Polyamine Component

[0054] The polyamine component of the solid sorbent may possess 2 or greater amine functionalities for the reaction with the aldehyde component. The amines may be commercially available and are cost-effective for synthesizing solid sorbents. Amines used to make solid sorbents through this method, but not limited to, are ethylenediamine, diethylenetriamine, tetraethylenepentamine, and linear and branched polyethyleneimines. Other amine compounds bearing additional functionalities may be employed to synthesize solid sorbents through the described method.

[0055] Non-limiting examples of polyamines are shown in Figure 4.

[0056] Various polyamine (>2 primary amines) may be reacted with polyaldehyde P-dendrimer compounds to form solid sorbents.

[0057] The sorbents described herein may be incorporated into composite materials. Non limiting examples of composite materials are described below.

[0058] Surface: Composite materials were made using different carbon sheets with or without micro-porous layers. For each of these surfaces, the Hexakis(4-formylphenoxy)cyclo(triphosphazene)-PEI Complex and Kynar UltraFlex®B Resin were used. Commercially available carbon sheets comprising micro-porous layers used in this study are: Sigracet lOBC, 24BC, 25BC, 34BC, 10BA, and 24BA. Glass and metal surfaces (stainless steel) could also be coated.

[0059] Dendrimer: Using the Sigracet 24BC surface layer and Kynar UltraFlex®B Resin, the Hexakis(4-formylphenoxy)cyclo(triphosphazene)-Tetraethylenediamine Complex was used.

[0060] Resin: Using the Sigracet 24BC surface layer and Hexakis(4-formylphenoxy)cyclo(triphosphazene)-PEI Complex, various resins were analyzed. The resins tested were: Methocel and Kynar Flex® 2801.

5.5. Definitions

CLAIMS

What is claimed is:

1. A method of removing a metal from an aqueous fluid stream which comprises contacting an aqueous fluid stream with a polyamine phosphorus dendrimer (P-dendrimer) having the formula I

I

wherein W is a phosphorus based dendrimer core; X is a polyfunctional aromatic linker; Y may be present or absent and if present is a polyfunctional amino phosphoryl group linked to a polyfunctional aromatic linker; Z is an diamino alkyl group, a polyalkyl amino group, a polyethyleneimine having a Mw ranging from 400 to about 1,000,000, or a polypropyleneimine; j and k are numerical values corresponding to the branch point multiplicity and whose values independently range from 1 to 10; and 1 is a numerical value corresponding to the branch point multiplicity and whose values ranges from 2 to 10.

2. A method of adsorbing, separating, storing or sequestering a metal from an aqueous fluid stream, comprising contacting the aqueous fluid stream with a polyamine phosphorus dendrimer (P-dendrimer) having the formula I

I

wherein W is a phosphorus based dendrimer core; X is a polyfunctional aromatic linker; Y may be present or absent and if present is a polyfunctional amino phosphoryl group linked to a polyfunctional aromatic linker; Z is an diamino alkyl group, a polyalkyl amino group, a polyethyleneimine, or a polypropyleneimine; j and k are numerical values corresponding to the branch point multiplicity and whose values independently range from 1 to 10; and 1 is a numerical value corresponding to the branch point multiplicity and whose values ranges from 2 to 10;

so as to adsorb, separate, store or sequester the metal from the aqueous fluid stream.

3. The method of claim 1, wherein the aqueous fluid stream has a pH between about 2.0 and about 12.0.

4. The method of claim 2, wherein the aqueous fluid stream has a pH between about 2.0 and about 12.0.

5. The method of claim 1, wherein the aqueous fluid stream is a municipal waste water fluid stream.

6. The method of claim 1, wherein the aqueous fluid stream is an industrial waste water fluid stream.

7. The method of claim 1, wherein the aqueous fluid stream is a drinking water fluid stream.

8. The method of claim 1, wherein the aqueous fluid stream comprises a leachate from a municipal waste landfill, hydraulic fracturing, an acid mine drainage, an acid mine sludge, or a coal-fired power plant.

9. The method of any of claims 1-8, wherein the metal is a heavy metal.

10. The method of claim 9, wherein the heavy metal is arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg), selenium (Se), copper (Cu), zinc (Zn), iron (Fe), aluminum (Al), manganese (Mn), nickel (Ni) or magnesium (Mg).

11. The method of any of claims 1-8, wherein the metal is a rare earth metal.

12. The method of claim 11, wherein the rare earth metal is one or more of the following elements cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), and yttrium (Y).

13. The method of any of claims 1-8, further comprising regenerating the polyamine P-dendrimer of formula I by contacting the P-dendrimer with a concentrated acidic solution.

14. The method of claim 13, wherein the concentrated acidic solution is about 0.1 to about 5.0 M acetic acid or about 0.1 to about 5.0 M HC1.

15. The method of any of claims 1-8, further comprising regenerating the polyamine P-dendrimer of formula I by contacting the P-dendrimer with a concentrated basic solution.

16. The method of claim 15, wherein the concentrated basic solution is about 0.05 to about 2.0 M NaOH or about 0.05 to about 2.0 M ammonium citrate.

17. The method of any of claims 1-8, further comprising contacting the polyamine P-dendrimer of formula I with an iron salt so as to form an iron supported polyamine P-dendrimer solid sorbent.

18. The method of claim 17, wherein the iron supported polyamine P-dendrimer solid sorbent is used to remove adsorb, separate, store or sequester arsenic (As) or selenium (Se) from the aqueous fluid stream.

19. A process for the capture and removal of metals from an aqueous metal-containing stream the process comprising:

(a) providing a housing having dispersed therein a sorbent comprising a polyamine phosphorus dendrimer (P-dendrimer) having the formula I

I

wherein W is a phosphorus based dendrimer core; X is a polyfunctional aromatic linker; Y may be present or absent and if present is a polyfunctional amino phosphoryl group linked to a polyfunctional aromatic linker; Z is an diamino alkyl group, a polyalkyl amino group, a polyethyleneimine having a Mw ranging from 400 to about 1,000,000, or a polypropyleneimine; j and k are numerical values corresponding to the branch point multiplicity and whose values independently range from 1 to 10; and 1 is a numerical value corresponding to the branch point multiplicity and whose values ranges from 2 to 10;

(b) passing a metal-containing stream through the housing such that the metal- containing stream contacts the sorbent;

(c) flushing the housing with a concentrated acidic stream to cause the sorbent to desorb a metal-retained therein and form a desorbed metal solution; and

(d) flushing the housing to remove the desorbed metal from the housing.

20. The process of claim 19, wherein the aqueous metal-containing fluid stream has a pH between about 2.0 and about 12.0.

21. The process of claim 19, wherein the aqueous fluid stream is a municipal waste water fluid stream.

22. The process of claim 19, wherein the aqueous fluid stream is an industrial waste water fluid stream.

23. The process of claims 19, wherein the aqueous fluid stream is a drinking water fluid stream.

24. The process of claims 19, wherein the aqueous fluid stream comprises a leachate from a municipal waste landfill, hydraulic fracturing, an acid mine drainage, an acid mine sludge, or a coal-fired power plant.

25. The process of any of claims 19-24, wherein the metal is a heavy metal.

26. The process of claim 25, wherein the heavy metal is arsenic (As), cadmium, lead (Pb), mercury (Hg), selenium (Se), copper (Cu), zinc (Zn), iron (Fe), aluminum (Al), manganese (Mn), nickel (Ni) or magnesium (Mg).

27. The process of any of claims 19-24, wherein the metal is a rare earth metal.

28. The process of claim 27, wherein the rare earth metal is one or more of the following elements cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), and yttrium (Y).

29. The process of any of claims 19-24, further comprising regenerating the polyamine P-dendrimer of formula I by contacting the P-dendrimer with a concentrated acidic solution.

30. The process of claim 29, wherein the concentrated acidic solution is about 0.1 to about 5.0 M acetic acid or about 0.1 to about 5.0 M HC1.

31. The process of any of claims 19-24, further comprising regenerating the polyamine P-dendrimer of formula I by contacting the P-dendrimer with a concentrated basic solution.

32. The process of claim 31, wherein the concentrated acidic solution is about 0.05 to about 2.0 M NaOH or about 0.05 to about 2.0 M ammonium citrate.

33. The process of any of claims 19-24, further comprising contacting the polyamine P-dendrimer of formula I with an iron salt so as to form an iron supported polyamine P-dendrimer solid sorbent.

34. The process of claim 33, wherein the iron supported polyamine P-dendrimer solid sorbent is used to remove adsorb, separate, store or sequester arsenic (As) or selenium (Se) from the aqueous fluid stream.

35. A sorbent comprising a sorbent comprising (a) iron II or iron III and (b) a polyamine phosphorus dendrimer (P-dendrimer) having the formula I

I

wherein W is a phosphorus based dendrimer core; X is a polyfunctional aromatic linker; Y may be present or absent and if present is a polyfunctional amino phosphoryl group linked to a polyfunctional aromatic linker; Z is an diamino alkyl group, a polyalkyl amino group, a polyethyleneimine having a Mw ranging from 400 to about 1,000,000, or a

polypropyleneimine; j and k are numerical values corresponding to the branch point multiplicity and whose values independently range from 1 to 10; and 1 is a numerical value corresponding to the branch point multiplicity and whose values ranges from 2 to 10.

36. The sorbent of claim 35, wherein Z is polyethyleneimine.