Derivatized polyamine polymers for use in metal scavenging applications

Abstract

Provided herein is a method of preparing a metal ion scavenger comprising adding an effective amount of a piperazine derivative to a polyamine and epihalohydrin condensation reaction. Further provided herein is a method of treating an aqueous stream and a non-aqueous stream, the method comprising adding a metal ion scavenger to the aqueous stream and the non-aqueous stream, the metal ion scavenger prepared by adding an effective amount of a piperazine derivative to a polyamine and epihalohydrin condensation reaction.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 464,231, filed May 5, 2023, which is incorporated by reference herein in its entirety. BACKGROUND

[0003] The disclosed technology provides methods for preparing polyamine prepolymer backbones for use in the production of metal ion scavengers and chelators. More specifically, the disclosed technology provides methods for preparing polyamine prepolymer backbones for use in the production of polydithiocarbamate-based metal ion scavengers and chelators, which methods include introducing an effective amount of a piperazine derivative into a polyamine and an epihalohydrin condensation reaction.

[0004] Heavy metal contamination is a present and growing global problem. For example, wastewater effluent from waste treatment facilities, the chlor-alkali industry, the metal finishing industry, cooling tower blowdown, incinerator scrubbers, municipal drainage, oil refineries, and from certain municipal landfills often presents a metal contamination problem. Similarly, the metal content of water discharged from either or both of active and abandoned mines is a significant environmental problem in geographic areas where mining is practiced. In addition to aqueous process water and wastewater streams, non-aqueous hydrocarbon streams common in petroleum refining processes or petrochemical processes also contain significant levels of heavy metal content that need to be reduced. Heavy metal ions can cause problems to the environment, and their concentration in water is regulated.

[0005] Different treatment technologies have been developed to remove either or both of dissolved and suspended heavy metal ions from industrial liquid streams. In aqueous streams, a common practice is to precipitate a substantial portion of the heavy metal contaminants in the form of their hydroxides. For example, metal ions such as copper and lead readily precipitate in this manner, but the minimum concentration that is achievable is limited by the limited solubility of the hydroxide complex. The resulting wastewater from the hydroxide precipitation can be treated with metal scavengers to remove any trace metal contaminants to meet discharge regulations. These scavengers can be precipitants, adsorbents, or metal-specific ion exchange resins. Metal scavenger precipitants can also be effective when added in the same step as the hydroxide precipitation. Typical compounds used as precipitating scavengers include sulfides, (thio)carbonates, alkyl dithiocarbamates, mercaptans, and polydithiocarbamates.

[0006] Water-soluble polymeric dithiocarbamate-based scavengers are known in the industry for removing heavy metal ions from contaminated water. These polymeric products have advantages over small molecular weight dithiocarbamates or other organosulfide compounds in both their aquatic toxicity profile and their precipitation ability. However, current pre-polymer backbone materials, especially polyethyleneimine (PEI), are expensive and can not be sufficient to remove certain metal ions.

[0007] Accordingly, there is a need in the art for a lower cost backbone alternative that has improved handling properties when converted to dithiocarbamate products. SUMMARY

[0008] The disclosed technology provides a method of making a polyamine pre-polymer backbone for use in the production of metal ion scavengers and chelators, the method comprising introducing an effective amount of a piperazine derivative into a polyamine and an epihalohydrin condensation reaction.

[0009] Various aspects of the disclosed technology relate to a method of making a metal ion scavenger, the method comprising adding an effective amount of a piperazine derivative to a polyamine and an epihalohydrin condensation reaction.

[0010] In various aspects, the piperazine derivative can be aminoethylpiperazine, the polyamine can be a polyethylene polyamine, and the epihalohydrin can be epichlorohydrin.

[0011] In various aspects, the metal ion scavenger can be a transition metal scavenger, such as a dithiocarbamate.

[0012] In various aspects, the metal ion scavenger can be used to treat an aqueous stream or a non-aqueous stream.

[0013] Various aspects of the disclosed technology further relate to a method of making a polyamine pre-polymer backbone, the method comprising adding an effective amount of a piperazine derivative to a polyamine and an epihalohydrin condensation reaction.

[0014] Various aspects of the disclosed technology further relate to a method of making a polyamine pre-polymer backbone, the method comprising: reacting a piperazine derivative with a first portion of an epihalohydrin to form a first reaction mixture; adding a polyamine to the first reaction mixture to form a second reaction mixture; and adding a second portion of the epihalohydrin to the second reaction mixture. BRIEF DESCRIPTION OF DRAWINGS

[0015] Those skilled in the art will understand that the figures described below are for purposes of illustration only. The figures are not intended to limit the scope of the present teachings in any way.

[0016] Figure 1 Co concentration in supernatant of synthetic water sample treated with an embodiment of the metal ion scavenger of the present disclosure is shown.

[0017] Figure 2 Nickel concentration in supernatant of synthetic water samples treated with embodiments of metal ion scavengers of the present disclosure is shown.

[0018] Figure 3 Zinc concentration in supernatant of synthetic water samples treated with embodiments of metal ion scavengers of the present disclosure is shown.

[0019] Figure 4 Cobalt concentration in supernatant of synthetic water samples treated with embodiments of metal ion scavengers of the present disclosure is shown.

[0020] Figure 5 Nickel concentration in supernatant of synthetic water samples treated with embodiments of metal ion scavengers of the present disclosure is shown.

[0021] Figure 6 Zinc concentration in supernatant of synthetic water samples treated with embodiments of metal ion scavengers of the present disclosure is shown. DETAILED DESCRIPTION

[0022] The disclosed technology provides a method for preparing a polyamine prepolymer backbone for use in the production of metal ion scavengers and chelators. More specifically, the disclosed technology provides a method for preparing a polyamine prepolymer backbone for use in the production of metal ion scavengers and chelators, the method comprising the step of introducing an effective amount of a piperazine derivative into a polyamine and a epihalohydrin condensation reaction.

[0023] The disclosed technology provides a method of design and synthesis of a polyamine prepolymer backbone for the production of polyvalent metal ion chelators and / or scavengers. The polyamine prepolymer backbone can be designed and synthesized by introducing an effective amount of a piperazine derivative into a polyamine and a epihalohydrin condensation reaction. Without being bound by theory, the piperazine content in the polyamine prepolymer backbone can contribute to controlling the structural, branched, conformational, and solubility characteristics of the final metal ion chelator and / or scavenger product.

[0024] The disclosed technology further provides a method of synthesis of a polyamine polymer backbone that is easily controlled and cost effective. It has been surprisingly discovered that the order of addition of reactants, wherein the piperazine derivative is reacted with the epihalohydrin prior to the addition of the polyamine to the reaction vessel, affects the effectiveness of the prepolymer backbone synthesis process. If this order of addition is not followed, or the effective amount of the piperazine derivative and its ratio to the epihalohydrin are changed, then the desired prepolymer backbone synthesis will not be optimal. In some aspects, when the polyamine polymer backbone prepared using the synthesis method of the present disclosure is converted to the corresponding metal ion scavenger and / or chelator, i) improved sensitivity and affinity to certain metal ions, ii) a wider effective dosage range, and iii) a desired floc formation characteristic can be observed.

[0025] As used herein, the term “metal ion scavenger” or “metal ion chelator” can be understood to mean an organic compound or polymeric material capable of binding a metal ion to form a chelate structure. Examples of metal ion scavengers or chelators can include dithiocarbamates, polydithiocarbamates, or other organosulfide compounds.

[0026] As used herein, the term “effective amount” can be understood to mean any amount of a piperazine derivative that will be effective to impart a desired property to the final metal ion chelator and / or scavenger product.

[0027] As used herein, the term “aqueous stream” can be understood to mean process water used in industry, manufacturing processes, power generation, and the like.

[0028] As used herein, the term “wastewater” can be understood to mean used water, surface runoff / rainfall, and any sewer inflow or sewer infiltration from any combination of domestic, industrial, commercial, or agricultural activities.

[0029] As used herein, the term “non-aqueous stream” can be understood to mean a non-aqueous hydrocarbon stream used in petroleum refining processes, petrochemical processes, and the like.

[0030] In various aspects, the disclosed technology provides methods of making a polyamine prepolymer backbone, the methods comprising adding an effective amount of a piperazine derivative to a polyamine and a haloalkyl alcohol condensation reaction. The disclosed technology further provides metal ion scavengers comprising a polyamine polymer backbone made by the methods of the present disclosure.

[0031] In some aspects, the method can comprise making a polyamine prepolymer backbone by: reacting a piperazine derivative with a first portion of a haloalkyl alcohol to form a first reaction mixture; adding a polyamine to the first reaction mixture to form a second reaction mixture; and adding a second portion of the haloalkyl alcohol to the second reaction mixture.

[0032] Suitable piperazine derivatives can include any piperazine derivative capable of forming a prepolymer backbone with a polyamine and a haloalkyl alcohol. In various aspects, suitable piperazine derivatives can include soluble piperazine derivatives. In some aspects, suitable piperazine derivatives can include aminoethylpiperazine (AEP).

[0033] Suitable polyamines can include any polyamine compound capable of forming a prepolymer backbone with a piperazine derivative and an epihalohydrin. In some aspects, suitable polyamine compounds can include polyethylene polyamines such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), hexaethyleneheptamine (HEHA), other higher amines, and mixtures thereof.

[0034] Suitable epihalohydrins can include any epihalohydrin compound capable of forming a prepolymer backbone with a piperazine derivative and a polyamine. In certain aspects, suitable epihalohydrin compounds can include epichlorohydrin, epibromohydrin, epifluorohydrin, or epioiodohydrin.

[0035] In various aspects, the methods of the present disclosure can include adding the piperazine derivative and the polyamine in a molar ratio of about 1 : 1 to about 1 :5 or about 1 : 1, 1 :2, 1 :3, 1 :4, or 1 :5 or any value between any of these ratios or about 1 :2.

[0036] In various aspects, the methods of the present disclosure can include adding the polyamine and the epihalohydrin in a total amine to epihalohydrin molar ratio of between 1 : 1 to about 1 : 1.35 or any value between any of these ratios.

[0037] In various aspects, the disclosed technology provides metal ion scavengers and / or chelators prepared using the methods of the present disclosure. In some aspects, the metal ion scavengers and / or chelators can be transition metal ion scavengers and / or chelators, such as polydithiocarbamates. In some aspects, the metal ion scavengers and / or chelators can be used to treat aqueous streams and non-aqueous streams. In some aspects, the aqueous streams that can be treated with the metal ion scavengers and / or chelators of the present disclosure can include process waters, such as wastewater. In some aspects, the non-aqueous streams that can be treated with the metal ion scavengers and / or chelators of the present disclosure can include non-aqueous hydrocarbon streams, such as non-aqueous hydrocarbon streams used in petroleum refining processes, petrochemical processes, and the like.

[0038] In various aspects, the disclosed technology further provides a method of making a metal ion scavenger and / or chelator, the method comprising adding an effective amount of a piperazine derivative to a polyamine and epihalohydrin condensation reaction. In some aspects, the disclosed technology provides a method of making a polydithiocarbamate, the method comprising the steps of: preparing a polyamine prepolymer backbone by adding an effective amount of a piperazine derivative to a polyamine and epihalohydrin condensation reaction and reacting the prepolymer backbone with carbon disulfide.

[0039] In various aspects, the disclosed technology further provides a method of removing metal ions from an aqueous stream and a non-aqueous stream, the method comprising adding a metal ion scavenger and / or chelator prepared according to the methods of the present disclosure to the aqueous stream and the non-aqueous stream. In various aspects, the metal ion scavenger and / or chelator can be added to the aqueous stream and the non-aqueous stream in any amount effective to remove metal ions from the aqueous stream and the non-aqueous stream. In some aspects, the metal ion scavenger and / or chelator can be added to the aqueous stream and the non-aqueous stream in an amount of about 0.1 ppm to about 10000 ppm, or about 0.1 ppm, 1 ppm, 10 ppm, 50 ppm, 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm, 6000 ppm, 6500 ppm, 7000 ppm, 7500 ppm, 8000 ppm, 8500 ppm, 9000 ppm, 9500 ppm, or 10000 ppm, or about 0.1 ppm to about 1000 ppm, or about 0.1 ppm to about 500 ppm, or any amount between any of these values.

[0040] In various aspects, the aqueous stream and the non-aqueous stream treated with the metal ion scavenger and / or chelator of the present disclosure can comprise a metal ion content within regulatory limits as understood by one of skill in the art. In various aspects, the metal ions that can be removed from the aqueous stream and the non-aqueous stream using the metal ion scavenger and / or chelator of the present disclosure can include cadmium, cobalt, copper, nickel, zinc, mercury, and the like.

[0041] Examples

[0042] The present technology will be further described in the following examples, which should be considered illustrative and not construed as narrowing the scope of the disclosed technology or limiting the scope to any particular embodiment.

[0043] Example 1

[0044] AEP-EPI-TEPA Prepolymer Synthesis (1A)

[0045] A reaction kettle equipped with a stirrer, thermometer, and reflux condenser was charged with 62 grams of deionized (DI) water. 42 grams of aminoethylpiperazine (AEP) was added to the kettle and the temperature was adjusted to 25°C or lower. 60 grams of epichlorohydrin (EPI) was pumped into the stirred solution at a constant flow rate over 30 minutes and the reaction temperature was not allowed to exceed 30°C. After the EPI feed was complete, a solution of tetraethylenepentamine (TEPA) (123 grams of TEPA + 103 grams of DI water) was added to the reaction kettle in portions over 5 minutes while maintaining the temperature between 35°C and 40°C. When the temperature stabilized below 40°C, 39 grams of EPI (2nd portion) was fed to the reaction kettle over 20 minutes (AEP:EPI:TEPA molar ratio of 1 :3.15:2). After the EPI feed was complete, the batch was heated to 88°C over 30 minutes and held at 88°C for 3 hours. The heat was then turned off and 99 grams of DI water was added to the product (solid content was adjusted to approximately 50%). The product was allowed to cool to room temperature. The obtained viscous (dark) yellow product was used in the next reaction without any purification.

[0046] 13 C NMR: 70ppm to 35ppm (aliphatic C nuclei in the main chain -N-CH2CH2-N-CH2-CH(OH)-CH2-) 13 C nuclei)

[0047] Dithiocarbamate functionalization of AEP-EPI-TEPA pre-polymer (AEP-EPI-TEPA-CS2) (1B)

[0048] In a reactor equipped with a stirrer, thermometer, and reflux condenser, 93 grams of AEP-EPI-TEPA pre-polymer (50%) solution was diluted with 204 grams of DI water and kept under N2blanketing. To this solution, 52 grams of NaOH (50%) was added over 20 minutes. The light yellow solution was cooled to 38°C before starting the carbon disulfide (CS2) feed. 43.55 grams of CS2 (34.4 mL) was continuously fed to the reactor at a constant rate over 90 minutes while the temperature was gradually increased up to 43°C during the addition. After the CS2 feed was complete, the reaction temperature was held at 44°C for 90 minutes and at 47 to 50°C for another 30 minutes until a bright orange to red product was obtained (29.57% solid content). The product was packaged under N2.

[0049] 13 C NMR: 211ppm (N-CS2); 70ppm to 40ppm (aliphatic C nuclei in the main chain) 13 C nuclei)

[0050] Example 2

[0051] AEP-EPI-E100 prepolymer synthesis (2A)

[0052] A reaction kettle equipped with a stirrer, thermometer, and reflux condenser was charged with 62 grams of deionized (DI) water. 42 grams of AEP was added to the kettle and the temperature was adjusted to 25°C or lower. 60 grams of EPI was pumped into the stirred solution at a constant flow rate over 30 minutes and the reaction temperature was not allowed to exceed 30°C. After the EPI feed was complete, a solution of E100 (a mixture of TEPA, PEHA, and HEHA) (179 grams of E100 + 160 grams of DI water) was added to the reaction kettle in portions over 5 minutes while maintaining the temperature between 35°C to 40°C. When the temperature stabilized below 40°C, 39 grams of EPI (2nd portion) was fed to the reaction kettle over 20 minutes (AEP:EPI:E100 molar ratio of 1:3.15:2). After the EPI feed was complete, the batch was heated to 88°C over 30 minutes and held at 88°C for 3 hours. The heat was then turned off and 98 grams of DI water was added to the product (solid content was adjusted to approximately 50%) and allowed to cool to room temperature. The obtained viscous (dark) yellow product was used in the next reaction without any purification.

[0053] Dithiocarbamate functionalization of AEP-EPI-E100 prepolymer (AEP-EPI-E100-CS2) (2B)

[0054] A reaction vessel equipped with a stirrer, thermometer, reflux condenser was charged with AEP-EPI-E100 prepolymer (50%) solution (86 grams) diluted with 190 grams of DI water and kept under N2 coverage. To this solution was added 63 grams of NaOH (50%) over 20 minutes. The light yellow solution was cooled to 38°C (prepolymer:CS2 molar ratio of 1:6.5 to 8.1) before starting the carbon disulfide (CS2) feed. 48 grams of CS2 (38 mL) was continuously fed to the reactor at a constant rate over 90 minutes while the temperature was gradually increased up to 43°C during the addition. After the CS2 feed was complete, the reaction temperature was held at 44°C for 90 minutes and at 47 to 50°C for another 30 minutes until a slightly hazy red product was obtained (31.7% solid content). The product was packaged under N2 and turned into a more clear red solution upon storage.

[0055] 13 C NMR: 210 ppm (N-CS2); 75 ppm to 40 ppm (aliphatic 13 C nuclei in the main chain)

[0056] Example 3

[0057] TEPA-EPI prepolymer synthesis (3A)

[0058] A reaction kettle equipped with a stirrer, thermometer, and reflux condenser was charged with 300 grams of deionized (DI) water. 300 grams of TEPA was slowly added to the kettle and the temperature was maintained below 40°C. 191 grams of EPI was pumped into the stirred solution at a constant flow rate (TEPA:EPI molar ratio of 1 : 1.2 to 1.35) over 90 minutes. The reaction temperature was not allowed to exceed 43°C and was maintained between 37°C to 43°C during the EPI feed. After the EPI feed was complete, the batch was heated to 88°C over 30 minutes and held at 88°C for 3 hours. The heat was then turned off and 191 grams of DI water was added to the product (solid content was adjusted to approximately 50%) and allowed to cool to room temperature. The obtained viscous (dark) yellow product was used in the next reaction without any purification.

[0059] 13 C NMR: 70 ppm to 35 ppm (aliphatic C nuclei in the main chain -N-CH2CH2-N-CH2-CH(OH)-CH2-) 13 C nuclei)

[0060] Dithiocarbamate functionalization of TEPA-EPI prepolymer (TEPA-EPI-CS2) (3B)

[0061] A reactor equipped with a stirrer, thermometer, reflux condenser was charged with 87.3 grams of TEPA-EPI prepolymer (50%) solution diluted with 307.5 grams of DI water and kept under N2blanketing. To this solution was added 56.4 grams of NaOH (50%) over 20 minutes. The light yellow solution was cooled to 38°C (copolymer:CS2 molar ratio of 1 : 4.5 to 5.1) before starting the carbon disulfide (CS2) feed. 48.8 grams of CS2 (83.3 mL) was continuously fed to the reactor at a constant rate over 90 minutes while the temperature was gradually increased up to 43°C during the addition. After the CS2 feed was complete, the reaction temperature was maintained at 44°C for 90 minutes and at 47 to 50°C for another 30 minutes until a slightly hazy orange to red product was obtained (solid content of 24.16%). The product was packaged under N2and became a more clear orange-red solution upon storage.

[0062] 13 C NMR: 210 ppm (N-CS2); 75 ppm to 40 ppm (aliphatic C nuclei in the main chain) 13 C nuclei)

[0063] Example 4

[0064] Premix (AEP + TEPA) - EPI prepolymer synthesis (4A)

[0065] A reaction kettle equipped with a stirrer, thermometer, and reflux condenser was charged with 165 grams of deionized (DI) water. 42 grams of AEP and 123 grams of TEPA were added slowly to the kettle and the temperature was kept below 40°C. 99 grams of epichlorohydrin (EPI) was pumped into the stirred solution at a constant flow rate (AEP:TEPA:EPI molar ratio of 1:2:3.15) over 90 minutes. The reaction temperature was not allowed to exceed 43°C and was kept between 37°C and 43°C during the EPI feed. After the EPI feed was complete, the batch was heated to 88°C over 30 minutes and held at 88°C for 3 hours. The heat was then turned off and 99 grams of DI water was added to the product (solid content was adjusted to approximately 50%) and allowed to cool to room temperature. The obtained viscous (dark) yellow product was used in the next reaction without any purification.

[0066] 13 C NMR: 70ppm to 35ppm (aliphatic C nuclei in the main chain -N-CH2CH2-N-CH2-CH(OH)-CH2-) 13 C nuclei)

[0067] (AEP+TEPA)-EPI prepolymer (AEP+TEPA)-EPI-CS2 dithiocarbamate salt (4B)

[0068] A reactor equipped with a stirrer, thermometer, reflux condenser was charged with 76.5 grams of AEP-TEPA-EPI prepolymer (50%) solution diluted with 118.6 grams of DI water and kept under N2blanketing. To this solution was added 40.5 grams of NaOH (50%) over 20 minutes. The light yellow solution was cooled to 38°C before starting the carbon disulfide (CS2) feed. 35.8 grams of CS2 (28.3 mL) was continuously fed to the reactor at a constant rate over 90 minutes while the temperature was gradually increased up to 43°C during the addition. After the CS2 feed was complete, the reaction temperature was kept at 44°C for 90 minutes and at 47 to 50°C for another 30 minutes until a bright orange to red product was obtained (solid content of 34.75%). The product was packaged under N2.

[0069] 13 C NMR: 211ppm (N-CS2); 70ppm to 40ppm (aliphatic C nuclei in the main chain) 13 C nuclei)

[0070] Example 5

[0071] E100-EPI prepolymer synthesis (5A)

[0072] A reaction kettle equipped with a stirrer, thermometer, and reflux condenser was charged with 300 grams of deionized (DI) water. 300 grams of E100 (a mixture of TEPA, PEHA, and HEHA) was slowly added to the kettle and the temperature was maintained below 40 °C. 137 grams of EPI was pumped into the stirred solution at a constant flow rate (E100:EPI molar ratio of 1 : 1.2 to 1.35) over 90 minutes. The reaction temperature was not allowed to exceed 43 °C and was maintained between 37 °C to 43 °C during the EPI feed. After the EPI feed was complete, the batch was heated to 88 °C over 30 minutes and held at 88 °C for 3 hours. The heat was then turned off and 137 grams of DI water was added to the product (solid content was adjusted to approximately 50%) and allowed to cool to room temperature. The obtained viscous (dark) yellow product was used in the next reaction without any purification.

[0073] 13 C NMR: 70 ppm to 35 ppm (aliphatic C nuclei in the main chain -N-CH2CH2-N-CH2-CH(OH)-CH2- 13 C nuclei)

[0074] Dithiocarbamate functionalization of E100-EPI prepolymer (E100-EPI-CS2) (5B)

[0075] In a reactor equipped with a stirrer, thermometer, reflux condenser, a 50% solution of E100-EPI prepolymer (77 grams) was diluted with 134.3 grams of DI water and maintained under N2blanketing. To this solution was added 55.7 grams of NaOH (50%) over 20 minutes. The light yellow solution was cooled to 38 °C (prepolymer:CS2 molar ratio of 1 : 6.5 to 8.1) before starting the carbon disulfide (CS2) feed. 49 grams of CS2 (38.7 mL) was continuously fed to the reactor at a constant rate over 90 minutes while the temperature was gradually increased up to 43 °C during the addition. After the CS2 feed was complete, the reaction temperature was maintained at 44 °C for 90 minutes and at 47 to 50 °C for another 30 minutes until a slightly hazy red product was obtained (36.5% solid content). The product was packaged under N2and turned into a clear red solution upon storage.

[0076] 13 C NMR: 210 ppm (N-CS2); 75 ppm to 40 ppm (aliphatic C nuclei in the main chain) 13 C nuclei)

[0077] Various properties of the dithiocarbamate polymers of Examples 1 to 5 are shown in Table 1 below.

[0078] Table 1

[0079]

[0080] Example 6

[0081] Removal of metals from synthetic water

[0082] The soft and hard (Lewis) acid-base classification divides compounds into hard or soft acids and hard or soft bases. Unbound ionic metals are Lewis acids because they can accept electron pairs from donors (Lewis bases). Depending on the electron orbital structure, charge, and size, they can be hard, soft, or intermediate acids. Alkali and alkaline earth metal ions are considered hard acids, while transition metal ions are usually soft or intermediate acids. Since transition metals can cause problems for the environment and public health, their concentration in water is regulated. Due to homologous reactions, soft bases such as sulfur-containing compounds and / or ligands (dithiocarbamates and trithiocarbonates) are usually used to remove these metals by physical-chemical separation. Highly functionalized polyamine-based polymers containing dithiocarbamate functional groups are preferred over small molecules due to their lower toxicity.

[0083] However, these products still have deficiencies in removing intermediate acid metals such as cobalt, nickel, and zinc.

[0084] In this example, synthetic water containing approximately 1.2 ppm of Cd+2, Co+2, Cu+2, Ni+2, Zn+2 was prepared. To prepare the synthetic water, a HEPES buffer was dissolved in deionized water such that the final solution was 0.01 N HEPES. A stock solution of chloride salts was then added to the buffered water to achieve the desired amount of metals. The water was then slowly adjusted to pH 8 with 1 N NaOH.

[0085] A 250 mL aliquot of the synthetic water was tested using a standard jar test apparatus. The metal removal product (i.e., the metal removal product in Examples 1-5) was dosed into the jar while mixing at 100 rpm. After two minutes, the mixing speed was reduced to 35 rpm. Mixing was stopped after 5 minutes and the jar was allowed to stand for an additional 5 minutes. A sample of the supernatant was taken for ICP analysis of the residual metals. The metal concentration of the supernatant was measured for both the unfiltered sample (total) and the 0.45 micron filtered sample (soluble).

[0086] The percent removal and the percent soluble metal removal from the supernatant after the addition of the metal removal products of Examples 1-5 are shown in Tables 2 and 3 below.

[0087] Table 2: Polymers containing TEPA

[0088]

[0089] Table 3: Polymers containing E100

[0090]

[0091] As shown in Tables 2 and 3 and Figures 1 to 6 by varying the polyamine-based polymer backbone and controlling the structure, the ability of the polymers of the present disclosure to remove metals such as cobalt, nickel, and zinc can be improved in both removal percentage and operating window.

[0092] More specifically, as shown in Figures 1 to 3 when compared to the control polymer of Example 3B and the comparative polymer of Example 4B, as well as industry standards. Similarly, the dithiocarbamate polymer of Example 2B showed improved removal of cobalt, nickel, and zinc when compared to the control polymer of Example 5B, as well as industry standards.

[0093] In addition, as shown in Tables 2 and 3, the dithiocarbamate polymer of Example 1B showed improved and / or comparable removal of cadmium and copper when compared to the control polymer of Example 3B, the comparative polymer of Example 4B, as well as industry standards. The dithiocarbamate polymer of Example 2B also showed improved and / or comparable removal of cadmium and copper when compared to the control polymer of Example 5B, as well as industry standards.

[0094] While embodiments of the disclosed technology have been described, it is understood that the present disclosure is not limited thereto and can be modified without departing from the disclosed technology. The scope of the disclosed technology is defined by the appended claims, and is intended to encompass all devices, processes and methods within the meaning of the claims (literally or by equivalence).

Claims

1. A method of making a polyamine prepolymer backbone, the method comprising adding an effective amount of a piperazine derivative to a polyamine and an epihalohydrin condensation reaction.

2. The method of claim 1, wherein the piperazine derivative is aminoethyl piperazine.

3. The method of claim 1, wherein the polyamine is a polyethylene polyamine.

4. The method of claim 1, wherein the epihalohydrin is epichlorohydrin.

5. The method of claim 1, wherein the piperazine derivative and polyamine are added in a molar ratio of about 1 : 1 to about 1 :

5.

6. The method of claim 5, wherein the piperazine derivative and polyamine are added in a molar ratio of about 1 :

2.

7. A metal ion scavenger comprising the polyamine prepolymer backbone made according to the method of claim 1.

8. The metal ion scavenger of claim 7, wherein the metal ion scavenger is a transition metal ion scavenger.

9. The metal ion scavenger of claim 8, wherein the transition metal ion scavenger is a dithiocarbamate.

10. A method of removing metal ions from an aqueous stream or a non-aqueous stream, the method comprising adding a metal ion scavenger made according to the method of claim 1.

11. The method of claim 10, wherein the aqueous stream comprises wastewater.

12. The method of claim 10, wherein the metal ion is selected from the group consisting of cobalt, nickel, zinc, mercury, and mixtures thereof.

13. The method of claim 10, wherein the metal ion scavenger is added in an amount of about 0.1 ppm to about 1000 ppm.

14. The method of claim 13, wherein the metal ion scavenger is added in an amount of about 0.1 ppm to about 500 ppm.

15. A method of making a metal ion scavenger, the method comprising adding an effective amount of a piperazine derivative to a polyamine and an epihalohydrin condensation reaction.

16. The method of claim 15, wherein the piperazine derivative is aminoethyl piperazine.

17. The method of claim 15, wherein the polyamine is a polyethylene polyamine.

18. The method of claim 15, wherein the epihalohydrin is epichlorohydrin.

19. The method of claim 15, wherein the metal ion scavenger is a transition metal ion scavenger.

20. The method of claim 19, wherein the transition metal ion scavenger is a dithiocarbamate.

21. A method of making a polyamine prepolymer backbone, the method comprising: reacting a piperazine derivative with a first portion of an epihalohydrin to form a first reaction mixture; adding a polyamine to the first reaction mixture to form a second reaction mixture; and adding a second portion of the epihalohydrin to the second reaction mixture.

22. The method of claim 21, wherein the piperazine derivative is aminoethyl piperazine.

23. The method of claim 21, wherein the polyamine is a polyethylene polyamine.

24. The method of claim 21, wherein the epihalohydrin is epichlorohydrin.

25. The method of claim 21, wherein the piperazine derivative and the polyamine are added in a molar ratio of about 1 : 1 to about 1 :

5.

26. The method of claim 25, wherein the piperazine derivative and the polyamine are added in a molar ratio of about 1 :

2.

27. A metal ion scavenger comprising the polyamine prepolymer backbone prepared according to the method of claim 21.

28. The metal ion scavenger of claim 27, wherein the metal ion scavenger is a transition metal ion scavenger.

29. The metal ion scavenger of claim 28, wherein the transition metal ion scavenger is a dithiocarbamate salt.

30. A method of removing metal ions from an aqueous stream or a non-aqueous stream, the method comprising adding a metal ion scavenger prepared according to the method of claim 21.

31. The method of claim 30, wherein the aqueous stream comprises wastewater.

32. The method of claim 30, wherein the metal ion is selected from the group consisting of cobalt, nickel, zinc, mercury, and mixtures thereof.

33. The method of claim 30, wherein the metal ion scavenger is added in an amount of about 0.1 ppm to about 1000 ppm.

34. The method of claim 33, wherein the metal ion scavenger is added in an amount of about 0.1 ppm to about 500 ppm.

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