Dendritic polymer heavy metal precipitant with double functions of chelation and self-flocculation and its application

Abstract

Dendritic polymer heavy metal precipitant with double functions of chelation and self-flocculation and its application is provided. The heavy metal precipitant is dithiocarbamates end group polyamidoamine dendritic polymer prepared by reaction of carbon bisulfide and polyamidoamine dendritic polymer with a generation at a range of 1-3 (denoted as PAMAM-(NH2).sub.8G, wherein G is generation number). Due to the special three dimensional spatial structure, appropriate molecular weight, high density of the end chelating group dithiocarbamates, the dithiocarbamates end group polyamidoamine dendritic polymer of the present invention not only has strong chelating performance with the heavy metal iron, the sediment floc formed has a large volume, a fast sedimentation velocity and easy separation. The present invention has high efficiency performance in chelating and flocculating heavy metals.

Claims

1. A dendrimer heavy metal precipitant with double functions of chelation and self-flocculation and its application, wherein the heavy metal precipitant is a terminal dithiocarbamate polyamidoamine dendrimer with the terminal chelating group dithiocarbamates, the number of the dithiocarbamates is 8 times that of the G (G is generation, G0, G=1-3), wherein a structural formula thereof is as shown in formula I: wherein A represents a core which is specified as [N(CH.sub.2).sub.212N]; represents a branched chain which is specified as [CH.sub.2CH.sub.2CONHCH.sub.2CH.sub.2]; N represents an internal branched atom which is specified as a nitrogen atom; G represents generations which is specified as a positive number between 1-3.

2. The dendritic-polymer heavy metal precipitant according to claim 1, wherein the dendrimer heavy metal collector with double functions of chelation and self-flocculation is prepared by a reaction of a raw material of polyamidoamine has terminal amine groups with an amount of 8 times that of the G (G0, G=1-3) and carbon bisulfide; wherein the amount of the terminal amine groups is 8 times that of the G (G0, G=1-3); a structural formula is as shown in formula II: wherein A represents a core which is specified as [N(CH.sub.2).sub.212N]; represents a branched chain which is specified as [CH.sub.2CH.sub.2CONHCH.sub.2CH.sub.2]; N represents an internal branched atom which is specified as a nitrogen atom; G represents generations which is specified as a positive number between 1-3.

3. A method for removing heavy metals in heavy metal wastewater or complexing form heavy metal wastewater comprising introducing the dendritic-polymer heavy metal precipitant with double functions of chelation and self-flocculation as recited in claim 1.

4. A method for stably treating on heavy metals in municipal solid waste incineration fly ash and stably restoring heavy metals in contaminated soil.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0034] Further description of the present invention is illustrated combining with the preferred embodiments. One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

[0035] Comparative example Preparation of 0-generation dithiocarbamates end group polyamidoamine dendritic polymer

[0036] 129.17 g (20%, 0.05 mol) methanol solution of (Ethylenediamine core, 0 generation, PAMAM dendrimer, M516.68), denoted as PAMAM-(NH.sub.2).sub.4 for short, was slowly added to a four-neck flask which is equipped with a stirrer, a condenser, a thermometer and a dropping funnel. Temperature was dropped to 5 C. 60.91 g (50%, 0.40 mol methanol solution of carbon bisulfide (M76.14) was slowly added drop by drop. Control the dropping rate to make a temperature of a reaction mixture below 10 C. After the dropping is finished, the temperature was increased to 25 C. to react for 4 hours, white precipitate was separated out, filtered and dried at 60 C. to obtain 40.87 g intermediate formyloxy dithiocarbamates end group polyamidoamine, (denoted as PAMAM-(NHCSSH).sub.4), M821.24), all of the intermediate dithiocarbamates end group polyamidoamine, (PAMAM-(NHCSSH).sub.4) was sent to the four-necked flask, 33.50 g water and 20.00 g (40%, 0.20 mol) sodium hydroxide solution was added to react for 2 hours at 50 C., so as to obtain dithiocarbamates end group polyamidoamine with a solid content of 50%, denoted as PAMAM-(DTC).sub.4, wherein a structural formula is as follows:

##STR00001##

Example 1

Preparation of 1-Generation Dithiocarbamates End Group Polyamidoamine Dendritic Polymer

[0037] 143.00 g (20%, 0.02 mol) methanol solution of (Ethylenediamine core, 1 generation, PAMAM dendrimer, M1429.85), denoted as PAMAM-(NH.sub.2).sub.8 for short, was slowly added to a four-neck flask which is equipped with a stirrer, a condenser, a thermometer and a dropping funnel. Temperature was dropped to 5 C. 60.91 g (50%, 0.40 mol) methanol solution of carbon bisulfide (M76.14) was slowly added drop by drop. Control the dropping rate to make a temperature of a reaction mixture below 10 C. After the dropping is finished, the temperature was increased to 25 C. to react for 2 hours, white precipitate was separated out, filtered and dried at 60 C. to obtain 40.76 g formyloxy dithiocarbamates end group polyamidoamine, (denoted as PAMAM-(NHCSSH).sub.8), M2018.97), wherein a yield is 99.95%, which indicates that a molar ratio of amino end group (calculated as -NH.sub.2) and carbon bisulfide which is reacted is (NH.sub.2):(CS2)=1:1. Mother liquid is a mixture of methanol and unreacted carbon bisulfide and can be recycled.

[0038] All of the intermediate dithiocarbamates end group polyamidoamine, PAMAM-(NHCSSH).sub.8 obtained was sent to the four-necked flask, 35.00 g water and 16.00 g (40%, 0.16 mol) sodium hydroxide solution was added to react for 2 hours at 50 C., so as to obtain dithiocarbamates end group polyamidoamine with a solid content of 50%, denoted as PAMAM-(DTC).sub.8.

[0039] Nuclear magnetic resonance spectroscopy (.sup.13C NMR) of the PAMAM-(DTC).sub.8 obtained: 33.23, 33.45, 37.33, 39.68, 42.28, 52.98, 53.22, 55.98, 56.02, 174.56, 175.92, 212.25 ppm, wherein structural formula is as follows:

##STR00002##

Example 2

Preparation of 1-Generation Dithiocarbamates End Group Polyamidoamine Dendritic Polymer

[0040] 162.81 g (20%, 0.01 mol) methanol solution of (Ethylenediamine core, 2 generation, PAMAM dendrimer, M3256.18), denoted as PAMAM-(NH.sub.2)16 for short, was slowly added to a four-neck flask which is equipped with a stirrer, a condenser, a thermometer and a dropping funnel. Temperature was dropped to 5 C. 73.09 g (50%, 0.48 mol methanol solution of carbon bisulfide (M76.14) was slowly added drop by drop. Control the dropping rate to make a temperature of a reaction mixture below 10 C. After the dropping is finished, the temperature was increased to 25 C. to react for 2 hours, white precipitate was separated out, filtered and dried at 60 C. to obtain 44.71 g formyloxy dithiocarbamates end group polyamidoamine, (denoted as PAMAM-(NHCSSH).sub.16), M4474.42), wherein a yield is 99.93%. Mother liquid is a mixture of methanol and unreacted carbon bisulfide and can be recycled.

[0041] All of the intermediate dithiocarbamates end group polyamidoamine, PAMAM-(NHCSSH).sub.16 obtained was sent to the four-necked flask, 42.00 g water and 16.00 g (40%, 0.16 mol) sodium hydroxide solution was added to react for 2 hours at 50 C., so as to obtain dithiocarbamates end group polyamidoamine with a solid content of 50%, denoted as PAMAM-(DTC).sub.16.

[0042] Nuclear magnetic resonance spectroscopy (.sup.13C NMR) of the PAMAM-(DTC).sub.16 obtained: 33.36, 33.56, 33.84, 37.38, 39.61, 39.78, 42.42, 51.98, 52.93, 52.96, 55.32, 55.76, 56.63, 175.46, 175.89, 176.22, 212.75 ppm, wherein structural formula is as follows:

##STR00003##

Example 3

Treatment of Circuit-Board (PCB) Heavy Metal Wastewater

[0043] Wastewater of a circuit board: pH.sub.2.6, Cu.sup.2+165.282 mg/19 L.sup.1Ni.sup.2+101.395 mg.Math.L.sup.1, heavy metal precipitant in the example 1 and 2 is added, stir for 5 minutes, deposit for 5 minutes, filter to measure metal concentration and the result is as shown in Table. 1.

[0044] The result indicates that when adding amount of the heavy metal precipitant is 200 mg.Math.L.sup.1, the PAMAM-(DTC).sub.8 and PAMAM-(DTC).sub.16 in the example 1 and the example 2 is capable of reaching Discharge Standard of Industrial Sources of Copper, Cobalt and Nickel (GB25467-2010) and Town Integrated Wastewater Discharge Standard (GB18918-2002), but the PAMAM-(DTC)4 obtained in the comparative example is not capable of achieving. When adding amount of the PAMAM-(DTC)4 obtained in the comparative example is 250 mg.Math.L.sup.1, the wastewater is capable of reaching Discharge Standard of Industrial Sources of Copper, Cobalt and Nickel (GB25467-2010), but fails to reach the Town Integrated Wastewater Discharge Standard (GB18918-2002).

[0045] Seen from appearances, the deposition formed by the heavy metals and the PAMAM-(DTC).sub.8 and PAMAM-(DTC).sub.16 in the preferred embodiment 1 and 2 of the present invention has large and dense particles and high sedimentation velocity. However, the deposition formed by the heavy metals and the PAMAM-(DTC)4 by the comparative example has large and loose particles and low sedimentation velocity.

TABLE-US-00001 TABLE 1 Content of Gu and Ni before and after treatment Agentia concentration/ Cu.sup.2+/ Ni.sup.2+/ Precipitant mg .Math. L.sup.1 mg .Math. L.sup.1 mg .Math. L.sup.1 Before treatment 0 165.282 101.395 Example 1 150 9.193 16.154 PAMAM-(DTC).sub.8 200 0.024 0.032 Example 2 150 10.565 13.914 PAMAM-(DTC).sub.16 200 0.011 0.025 Comparative example 150 35.284 43.264 PAMAM-(DTC).sub.4 200 9.683 12.393 250 0.094 0.492 Discharge Standard of Industrial 0.2 0.5 Sources of Copper, Cobalt and Nickel (GB25467-2010) Town Integrated Wastewater 0.5 0.05 Discharge Standard (GB18918-2002)

Example 4

Complexed Lead-Containing Wastewater

[0046] The heavy metal precipitant in the example 1 and the comparative example was added to EDTA complexed lead-containing wastewater: pH.sub.2.26, Pb.sup.2+50.02 mg.Math.L.sup.1, stir for 5 min, precipitate 5 min and filter. Concentration of heavy metals is measured and the result is as shown in Table. 2.

[0047] The result shows that when adding amount of PAMAM-(DTC).sub.8 in the example 1 is 150 mg.Math.L.sup.1, discharge standard of GB25467-2010 and GB18918-2002 was reached; when adding amount of PAMAM-(DTC)4 is 200 mg.Math.L.sup.1, discharge standard of GB25467-2010 could be reached, GB18918-2002 could not be reached.

[0048] Meanwhile, it can be seen that the deposition formed by PAMAM-(DTC).sub.8 in the example 1 and lead is large in volume, dense and has a large sedimentation velocity. The deposition formed by PAMAM-(DTC).sub.4 in the comparative example is large in volume, loose and flaky, and the sedimentation velocity is relatively slow.

[0049] Ends of over 1.0 generation PAMAM-(DTC).sub.8 has 8 end group, the PAMAM-(DTC).sub.8 is a dendrimer with three-dimensional structure in space, thus the PAMAM-(DTC).sub.8 is capable of forming large chelate deposition in a net structure with heavy metals, wherein the sedimentation velocity is fast. Ends of the 0 generation PAMAM-(DTC).sub.4 has four end group, and the PAMAM-(DTC).sub.4 is a planar hyperbranched star with two-dimensional structure, although the volume thereof is large, the sedimentation velocity is relatively slow.

TABLE-US-00002 TABLE 2 Content of Gu and Ni before and after treatment Agentia concentration/ Pb.sup.2+/ Precipitant mg .Math. L.sup.1 mg .Math. L.sup.1 Before treatment 0 50.02 Example 1 100 6.615 PAMAM-(DTC).sub.8 150 0.018 Comparative example 100 22.326 PAMAM-(DTC).sub.4 150 10.399 200 0.137 Discharge Standard of Industrial Sources of Copper, 0.2 Cobalt and Nickel (GB25467-2010) Town Integrated Wastewater Discharge Standard 0.1 (GB18918-2002)

[0050] It will thus be seen that the objects of the present invention have been fully and effectively accomplished. Its embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.