煤矸石螯合改性后对选矿废水中重金属离子吸附研究

Study on adsorption of heavy metal ions in mineral processing wastewater by chelating modified coal gangue

选取贵州省某6个矿区煤矸石进行均匀混合,通过700℃煅烧后获得热活化的样品。采用螯合剂次氮基三乙酸(NTA)与羧甲基淀粉(CMS)对热活化的样品进行改性,制备低成本的改性煤矸石吸附剂。通过单因素静态吸附实验分别研究了pH、CMS与NTA固液比、吸附剂投加量、吸附时间等对改性煤矸石吸附废水中Cu^(2+)和Pb^(2+)的影响。结果表明,在焙烧温度为700℃、CMS与NTA最佳固液质量比(简称固液比)为1∶15、溶液pH=9、吸附时间为2 h、投放量为0.8 g/L条件下,改性煤矸石能够吸附选矿废水中大量Cu^(2+)和Pb^(2+),最佳去除率分别为69.34%和79.98%。结合吸附等温模型拟合分析,吸附剂对Pb^(2+)的吸附过程以单层的化学吸附为主。

The coal gangue from 6 mining areas in Guizhou province was mixed evenly and the thermal activated samples were obtained after calcination at 700℃.The coal gangue was modified by chelating agent NTA and carboxymethyl starch(CMS)and the low cost modified coal gangue adsorbent was prepared.The effects of pH value,solid-liquid ratio of CMS and NTA,adsorbent dosage and adsorption time on the adsorption of Cu^(2+) and Pb^(2+) from wastewater by modified coal gangue were studied by single factor static adsorption experiment.The results showed that the modified coal gangue could adsorb a large amount of Cu^(2+) and Pb^(2+) from mineral processing wastewater under the roasting temperature of 700℃,the optimal solid⁃liquid ratio of CMS and NTA of 1∶15,the solution pH of 9,the adsorption time of 2 h,and the dosage of 0.8 g/L.The optimal removal rates were 69.34%and 79.98%,respectively.Combined with the isothermal model fitting analysis,the ad⁃sorption process of Pb^(2+) was dominated by monolayer chemisorption.