Ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group and applications of chelating heavy metals

Abstract

An ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group and its applications as a heavy metal chelating agent are disclosed, which relates to the field of chemical and environmental protection technology. The hyperbranched polymer has a chemical formula of C[CH.sub.2OCH.sub.2CH.sub.2OCOCH.sub.2CH.sub.2N(CSSM)CH.sub.2CH.sub.2NHCSSM].sub.4, wherein M is Na.sup.+, K.sup.+ or NH.sub.4.sup.+. A preparation method of the hyperbranched polymer is simple, the raw materials are easily available, and it is easy to be industrialized. The hyperbranched polymer is able to be used as a heavy metal chelating agent. Its special three-dimensional space structure is able to alternately chelate with heavy metals to form a large three-dimensional molecular conjugate with low solubility, strong stability, and compactness, which is able to effectively treat wastewater and waste containing heavy metals.

Claims

1. An ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group, which has a chemical formula of C[CH.sub.2OCH.sub.2CH.sub.2OCOCH.sub.2CH.sub.2N(CSSM)CH.sub.2CH.sub.2NHCSSM].sub.4, wherein M is Na.sup.+, K.sup.+ or NH.sub.4.sup.+; and a structural formula of ##STR00004##

2. A preparation method of an ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group, wherein: the ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group has a chemical formula of C[CH.sub.2OCH.sub.2CH.sub.2OCOCH.sub.2CH.sub.2N(CSSM)CH.sub.2CH.sub.2NHCSSM].sub.4, wherein M is Na.sup.+, K.sup.+ or NH.sub.4.sup.+; and a structural formula of ##STR00005## the preparation method comprises steps of: (1) under nitrogen protection, adding ethylenediamine (EDA) and a first amount of low-carbon alcohol to a reaction vessel with a stirrer, a reflux device and a thermometer, evenly stirring, slowly adding a low-carbon alcohol solution containing ethoxylated pentaerythritol tetraacrylate (EO-PETA) drop by drop, performing a first addition reaction; and then removing low-carbon alcohol solvent and excessive ethylenediamine through vacuum distillation, and obtaining a light amber viscous product, which is an intermediate product ethoxylated pentaerythritol tetra((N-(2-aminoethyl))-3-alaninate) hyperbranched polymer; (2) slowly adding water, alkaline solution and carbon disulfide drop by drop to the ethoxylated pentaerythritol tetra((N-(2-aminoethyl))-3-alaninate) hyperbranched polymer obtained by the step of (1), performing a second addition reaction, and obtaining an aqueous solution of the ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group; and (3) adding a second amount of low-carbon alcohol to the aqueous solution of the ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group obtained by the step (3), evenly stirring, precipitating a solid product, filtering and drying the solid product to obtain the ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group.

3. The preparation method according to claim 2, wherein each of the first amount of low-carbon alcohol in the step (1) and the second amount of low-carbon alcohol in the step (2) is one member selected from the group consisting of methanol, ethanol, propanol and ethylene glycol.

4. The preparation method according to claim 2, wherein a molar ratio of ethylenediamine and ethoxylated pentaerythritol tetraacrylate in the step (1) is in a range of (4-10): 1.

5. The preparation method according to claim 2, wherein the first addition reaction in the step (1) has a reaction temperature in a range of 25-35° C., and a reaction time in a range of 24 to 48 h.

6. The preparation method according to claim 2, wherein the vacuum distillation in the step (1) has a temperature in a range of 80 to 100° C., and a time in a range of 3 to 5 h.

7. The preparation method according to claim 2, wherein the alkaline solution in the step (2) is sodium hydroxide solution, potassium hydroxide solution or ammonium hydroxide.

8. The preparation method according to claim 7, wherein in the step (2), a molar ratio of the ethoxylated pentaerythritol tetra((N-(2-aminoethyl))-3-alaninate) hyperbranched polymer, carbon disulfide and alkaline is in a range of 1:(8.0-9.0):(8.0-9.0).

9. The preparation method according to claim 2, wherein the second addition reaction in the step (2) has a reaction temperature in a range of 25-40° C., and a reaction time in a range of 3 to 5 h.

10. A method for treating heavy metal wastewater and heavy metal waste, comprising applying an ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group as a heavy metal chelating agent, wherein: the ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group has a chemical formula of C[CH.sub.2OCH.sub.2CH.sub.2OCOCH.sub.2CH.sub.2N(CSSM)CH.sub.2CH.sub.2NHCSSM].sub.4, wherein M is Na.sup.+, K.sup.+ or NH.sub.4.sup.+; and a structural formula of ##STR00006##

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(1) The ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group and its applications of chelating heavy metal provided by the present invention will be described in detail with reference to embodiments as follows, but these embodiments are unable to be understood as limiting the protective scope of the present invention.

First Embodiment

(2) Under nitrogen protection, add 48.00 g (0.8 mol) of ethylenediamine (EDA) and 48.00 g of methanol to a round-bottomed flask with a stirred, a reflux condenser, a constant pressure dropping funnel and a thermometer, stir and cool to 5° C.; and then slowly add 105.60 g (0.10 mol, 50%) of a methanol solution containing ethoxylated pentaerythritol tetraacrylate (EO-PETA) drop by drop through the constant pressure dropping funnel, react for 24 h at 25° C.; and remove excessive ethylenediamine and methanol through vacuum distillation for 4 h at 90° C., and obtain a light amber viscous product, namely, an intermediate product ethoxylated pentaerythritol tetra((N-(2-aminoethyl))-3-alaninate) hyperbranched polymer (EO-PETA/EDA); and then add 200.00 g of deionized water into the intermediate product, evenly stir, cool to 5° C., slowly add 64.00 g (50%, 0.80 mol) of sodium hydroxide aqueous solution through the constant pressure dropping funnel; and then slowly add 60.80 g (0.80 mol) of carbon disulfide through the constant pressure dropping funnel for obtaining a mixture, wherein a temperature of the mixture is less than 5° C. through controlling an addition speed during an addition process; increases the temperature to 25° C., react for 5 h at 25° C.; and then add methanol, precipitate a product, filter, and dry the product at 80° C. to obtain 145.98 g of a final product, namely, the ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group (EO-PETA/EDA/DTC) with a yield of 94.06%.

(3) Chemical shifts of the characteristic absorption peak of .sup.13C nuclear magnetic resonance spectrum (D.sub.2O) of the final product are respectively: 34.76, 40.12, 41.45, 45.19, 59.32, 65.48, 68.90, 69.52, 175.33, 211.02 and 212.93 ppm, which shows that the final product obtained by the first embodiment is a hyperbranched polymer which takes ethoxylated pentaerythritol as a core, and dithiocarboxylate as side functional group and terminal functional group.

Second Embodiment

(4) Under nitrogen protection, add 60.00 g (1.0 mol) of ethylenediamine (EDA) and 60.00 g of methanol to a round-bottomed flask with a stirred, a reflux condenser, a constant pressure dropping funnel and a thermometer, stir and cool to 5° C.; and then slowly add 105.60 g (0.10 mol, 50%) of a methanol solution containing ethoxylated pentaerythritol tetraacrylate (EO-PETA) drop by drop through the constant pressure dropping funnel, react for 24 h at 25° C.; and remove excessive ethylenediamine and methanol through vacuum distillation for 4 h at 95° C., and obtain a light amber viscous product, namely, an intermediate product ethoxylated pentaerythritol tetra((N-(2-aminoethyl))-3-alaninate) hyperbranched polymer (EO-PETA/EDA); and then add 195.00 g of deionized water into the intermediate product, evenly stir, cool to 5° C., slowly add 68.00 g (50%, 0.85 mol) of sodium hydroxide aqueous solution through the constant pressure dropping funnel; and then slowly add 61.56 g (0.81 mol) of carbon disulfide through the constant pressure dropping funnel for obtaining a mixture, wherein a temperature of the mixture is less than 5° C. through controlling an addition speed during an addition process; and then react for 1 h at 5° C.; and then increase the temperature to 25° C. and react for 5 h at 25° C.; and then add methanol, stand overnight, precipitate a white solid, filter, and dry at 90° C. to obtain 147.22 g of a final product, namely, the ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group (EO-PETA/EDA/DTC) with a yield of 94.86%.

(5) Chemical shifts of the characteristic absorption peak of .sup.13C nuclear magnetic resonance spectrum (D.sub.2O) of the final product are respectively: 34.53, 40.11, 41.34, 45.23, 59.41, 65.49, 68.97, 69.51, 175.35, 211.13 and 212.86 ppm, which shows that the final product obtained by the second embodiment is a hyperbranched polymer which takes ethoxylated pentaerythritol as a core, and dithiocarboxylate as side functional group and terminal functional group.

Third Embodiment

(6) Under nitrogen protection, add 30.00 g (0.50 mol) of ethylenediamine (EDA) and 32.40 g of ethanol to a round-bottomed flask with a stirred, a reflux condenser, a constant pressure dropping funnel and a thermometer, stir and cool to 5° C.; and then slowly add 52.80 g (0.05 mol, 50%) of an ethanol solution containing ethoxylated pentaerythritol tetraacrylate (EO-PETA) drop by drop through the constant pressure dropping funnel, react for 24 h at 25° C.; and remove excessive ethylenediamine and ethanol through vacuum distillation for 4 h at 95° C., and obtain a light amber viscous product, namely, an intermediate product ethoxylated pentaerythritol tetra((N-(2-aminoethyl))-3-alaninate) hyperbranched polymer (EO-PETA/EDA); and then add 125.00 g of deionized water into the intermediate product, evenly stir, cool to 5° C., slowly add 32.80 g (50%, 0.41 mol) of sodium hydroxide aqueous solution through the constant pressure dropping funnel; and then slowly add 31.92 g (0.42 mol) of carbon disulfide through the constant pressure dropping funnel for obtaining a mixture, wherein a temperature of the mixture is less than 5° C. through controlling an addition speed during an addition process; and then react for 1 h at 5° C.; and then increase the temperature to 25° C. and react for 5 h at 25° C.; and then add 400 g of methanol, stand overnight, precipitate a white solid, filter, and dry at low temperature to obtain 72.17 g of a final product, namely, the ethoxylated pentaerythritol core hyperbranched polymer with dithiocarboxylate as side group and terminal group (EO-PETA/EDA/DTC) with a yield of 94.86%.

(7) Chemical shifts of the characteristic absorption peak of .sup.13C nuclear magnetic resonance spectrum (D.sub.2O) of the final product are respectively: 34.52, 40.25, 41.25, 45.16, 59.29, 65.41, 68.39, 69.44, 175.54, 211.26 and 212.27 ppm, which shows that the final product obtained by the third embodiment is a hyperbranched polymer which takes ethoxylated pentaerythritol as a core, and dithiocarboxylate as side functional group and terminal functional group.

First Control Example

(8) Commercially available sodium diethyldithiocarbamate solid

Second Control Example

(9) Commercially available disodium N,N′-bis-(dithiocarboxy) ethylenediamine

(10) A preparation method of the disodium N,N′-bis-(dithiocarboxy) ethylenediamine comprises steps of dissolving 30.00 g of ethylenediamine into 152 g of pure water, adding 76.00 g of carbon disulfide and 80 g of sodium hydroxide aqueous solution with a mass concentration of 50% drop by drop at less than 20° C., reacting at 30° C. for 3 h, adding 300 g of ethanol, standing for 1 h, filtering and drying at 80° C. to obtain the disodium N,N′-bis-(dithiocarboxy) ethylenediamine.

Fourth Embodiment

(11) Treatment of Copper-Containing Electroplating Wastewater

(12) The final product obtained by the first embodiment, and the chelating agents provided by the first control example and the second control example are used to treat copper-containing electroplating wastewater (pH 2.6, Cu.sup.2+ 36.28 mg.Math.L.sup.−1 and Ni.sup.2+ 3.91 mg.Math.L.sup.−1) from an electroplating factory in Shanghai, China respectively.

(13) A treatment method comprises steps of: (1) adjusting a pH value of the electroplating wastewater to 8.0 with NaOH; (2) taking 500 mL of the electroplating wastewater, stirring at 150 rpm for 10 min with a stirrer, simultaneously adding a chelating agent on a base of dry basis; (3) performing a next step for the chelating agent provided by the first embodiment, or respectively adding a polyacrylamide (PAM) aqueous solution with a mass concentration of 0.1% and a density of 50 mg.Math.L.sup.−1 to the chelating agents provided by the first control example and the second control example, stirring at 50 rpm for 5 min; and (4) standing for 30 min, filtering and determining a heavy metal content with ICP-MS (7700, Agilent). Determination results are shown in Table 1.

(14) TABLE-US-00001 TABLE 1 Result comparison of treatment on electroplating wastewater (Cu.sup.2+ 36.28 mg .Math. L.sup.−1 and Ni.sup.2+ 3.91 mg .Math. L.sup.−1) Content of residual heavy Chelating agent Whether metals Concentration PAM is (mg .Math. L.sup.−1) No. (mg .Math. L.sup.−1) added Cu.sup.2+ Ni.sup.2+ Precipitation First 240 No 0.278 1.036 Large particles, Embodiment 250 No 0.113 0.014 dense, fast settling, 260 No 0.024 0.003 easy separation, less sludge First 240 Yes 2.293 3.588 Fine particles, slow Control 260 Yes 1.113 2.006 settling, need PAM Example 280 Yes 1.026 1.057 for coagulation, and large amount of sludge Second 240 Yes 0.293 1.588 Small particles, slow Control 260 Yes 0.275 1.006 settling, need PAM Example 280 Yes 0.226 0.257 to help coagulation, and large amount of sludge Special heavy metal emission limit 0.3 0.1 — standards in Table 3 of “Emission Standards of Electroplating Pollutant (GB21900- 2008)”

(15) It is able to be seen from Table 1 that the final product according to the first embodiment of the present invention has a good removal effect on Cu.sup.2+ and Ni.sup.2+, and in the case of adding the chelating agent with a concentration of 250 mg.Math.L.sup.−1 and above, the concentration of residual ions is lower than special heavy metal emission limit standards in Table 3 of “Emission Standards of Electroplating Pollutant (GB21900-2008)”. Judging from the morphology of the deposit formed by the chelating agents with heavy metals, the floc deposits, formed by the chelating agent according to the first embodiment of the present invention with the heavy metals, are large and dense in particles, and have a fast settling speed, do not need PAM to help coagulation, so the sludge is less. However, the floc deposits, formed by sodium diethyldithiocarbamate of the first control example with heavy metals, are small in particles, have a slow settling speed, need PAM to help coagulation, so the sludge is much, which is unable to meet special heavy metal emission limit standards in Table 3 of “Emission Standards of Electroplating Pollutant (GB21900-2008)”. The floc deposits, formed by disodium N,N′-bis-(dithiocarboxy) ethylenediamine of the second control example with heavy metals, are small in particles, have a slow settling speed, need PAM to help coagulation, so the sludge is much, which is also unable to meet special heavy metal emission limit standards in Table 3 of “Emission Standards of Electroplating Pollutant (GB21900-2008)”.

Fifth Embodiment

(16) Treatment of Complex State Nickel-Containing Wastewater

(17) The final products obtained by the first embodiment and the second embodiment, and the chelating agents provided by the first control example and the second control example are used to treat EDTA complex state nickel-containing wastewater (pH 12.6, Ni.sup.2+ 10.59 mg.Math.L.sup.−1) from an electroplating factory in Shanghai, China respectively.

(18) A treatment method comprises steps of: (1) adjusting a pH value of the electroplating wastewater to 5.0 with HCl; (2) taking 500 mL of the electroplating wastewater, stirring at 150 rpm for 10 min with a stirrer, simultaneously adding a chelating agent on a base of dry basis; (3) stirring at 50 rpm for 30 min; (4) performing a next step for the chelating agents provided by the second embodiment and the third embodiment, or respectively adding a polyacrylamide (PAM) aqueous solution with a mass concentration of 0.1% and a density of 50 mg.Math.L.sup.−1 to the chelating agents provided by the first control example and the second control example, stirring at 50 rpm for 5 min; and (4) standing for 30 min, filtering and determining a heavy metal content with ICP-MS (7700, Agilent). Determination results are shown in Table 2.

(19) TABLE-US-00002 TABLE 2 Result comparison of treatment on EDTA complex state nickel-containing wastewater (Ni.sup.2+ 10.59 mg .Math. L.sup.−1) Chelating agent Whether Content of Concentration PAM is residual Ni.sup.2+ No. (mg .Math. L.sup.−1) added (mg .Math. L.sup.−1) Precipitation Second 70 No 1.036 Large particles, dense, Embodiment 80 No 0.319 fast settling, easy 90 No 0.025 separation, does not need PAM Third 70 No 1.012 Large particles, dense, Embodiment 80 No 0.331 fast settling, easy 90 No 0.015 separation, does not need PAM First 70 Yes 3.104 Fine particles, cloudy Control 80 Yes 2.952 solution, does not settle Example 90 Yes 2.927 and needs PAM for 120 Yes 2.893 coagulation Second 70 Yes 2.029 Small particles, slow Control 80 Yes 1.832 settling, needs PAM to Example 90 Yes 1.257 help coagulation, and 120 Yes 0.923 large amount of sludge 150 Yes 0.087 Special heavy metal emission limit 0.1 — standards in Table 3 of “Emission Standards of Electroplating Pollutant (GB21900- 2008)”

(20) It is able to be seen from Table 2 that the final products according to the second embodiment and the third embodiment of the present invention have a good removal effect on Ni.sup.2+, and in the case of adding the chelating agent with a concentration of 90 mg.Math.L.sup.−1, complex nickel is able to be directly settled without breaking the complex, the concentration of residual ions is lower than special heavy metal emission limit standards in Table 3 of “Emission Standards of Electroplating Pollutant (GB21900-2008)”. Moreover, no need for PAM to help coagulation, so the sludge is less. However, the floc deposits, formed by sodium diethyldithiocarbamate of the first control example with heavy metals, are unable to meet special heavy metal emission limit standards in Table 3 of “Emission Standards of Electroplating Pollutant (GB21900-2008)”. For disodium N,N′-bis-(dithiocarboxy) ethylenediamine of the second control example, when the concentration is 150 mg.Math.L.sup.−1, special heavy metal emission limit standards in Table 3 of “Emission Standards of Electroplating Pollutant (GB21900-2008)” is able to be met. And settlement separation requires PAM, so the sludge is much.

(21) It is able to be seen from the above embodiments that the hyperbranched polymer as the heavy metal chelating agent provided by the present invention has a wide application range while processing heavy metals, does not need to add coagulant, has a good processing effect, and has both chelation and flocculation functions.

(22) The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications are able to be made. These improvements and modifications should also be regarded as the protective scope of the present invention.