Study On Syntheses, Properties And Application Of Two Heavy Metal Capturing Agents

With the development of industrial technology, such as metallurgy, paper making, electroplating, the industrial wastewater containing various heavy metal ions has been largely discharged into rivers. So removal of heavy metal ions from aqueous solution has been an important issue for treatment of such wastewater.The chelating precipitation could overcome the drawbacks of conventional methods. Because the chelating precipitation not only removes heavy metal ions containing EDTA or citric acid, but also treats large wastewater with little chelating agent. Removal of heavy metal ions has been studied in this paper with chelating precipitation. Firstly, the Chinese Standard GB 7473-87, which is a method of determining copper ion, has been improved. The contents and conclusions of research have been given. Otherwise, two heavy metal capturing agents, which were the CU2# and synthesized DTC(EDA), have both been studied to remove copper ion, lead ion and zinc ion.(1)Ammonium chloride-ammonia was used as buffer solution in Chinese Standard GB 7473-87. But the borax-sodium hydroxide has been instead of ammonium chloride-ammonia to be buffer solution in order to overcome the drawbacks of ammonium chloride-ammonia in this paper. When the copper has been in the range of 0—0.65 mg/L at 440 nm, Beer's law was obeyed.(2)The removal rate of copper ion containing EDTA was 99.8%, when stirring time was 5 min and pH value was in the range of 1-14, CU2# was 5.7g to remove 1g copper ion. The removal rate of lead ion containing EDTA was 93.4%, when stirring time was 2 min and pH value was in the range of 1-7, CU2# was 32g to remove 1g lead ion. The removal rate of complex zinc ion was 82.4%, when stirring time was 5 min and pH value was in the range of 1-14, CU2# was 6.9g to remove 1g zinc ion. In addition, the mechanism of removing copper ion with CU2# has been explored in this paper.(3)The DTC(EDA) has been synthesized and the optimum condition of synthesis has been given. The results have been shown that the productivity has been 64.5%, when ethylenediamine was 7.5mL; carbon bisulfide was 12.06mL; water was 40mL; the temperature was 22℃; the stirring time was 2.5h; and the stewing time was 2h. The solubility and melting point of DTC(EDA) have been researched. The...