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采集某电镀厂污泥,以膨润土和改性膨润土为稳定剂,采用TCLP毒性浸出试验分析膨润土和改性膨润土对污泥中重金属Cr、Cd、Zn和Pb的稳定化效果。未加入稳定化剂前,电镀污泥中重金属Cr、Cd、Zn和Pb的浸出毒性分别为154 mg/L、13.5 mg/L、658 mg/L和76 mg/L。稳定化试验结果表明,在膨润土和改性膨润土的投加量与干污泥的质量比分别为1∶5和3∶10,振荡时间为12 h时,浸出液中重金属质量浓度最低,稳定化效果最好。形态分析结果表明,加入膨润土和改性膨润土稳定后重金属以有机结合态和残渣态为主,与未稳定前相比污泥中重金属不稳定态的含量变少。扫描电镜和红外分析结果表明,膨润土和改性膨润土可能通过吸附和离子交换来稳定污泥中的重金属。研究表明,改性膨润土对电镀污泥中高含量重金属的稳定化效果要优于未改性膨润土的稳定化效果。
The sludge of an electroplating plant was collected. Bentonite and modified bentonite were used as stabilizers. The effects of bentonite and modified bentonite on the stability of heavy metals Cr, Cd, Zn and Pb in sludge were analyzed by TCLP toxicity leaching test. Before the addition of stabilizer, the leaching toxicity of Cr, Cd, Zn and Pb in electroplating sludge were 154 mg / L, 13.5 mg / L, 658 mg / L and 76 mg / L, respectively. The results of the stabilization test showed that when the mass ratio of bentonite to modified bentonite to dry sludge is 1: 5 and 3:10, respectively, and the shaking time is 12 h, the concentration of heavy metals in the leachate is the lowest, and the stabilization effect the best. The results of morphological analysis showed that the content of heavy metals in the sludge was less than that in the unsteadified state after adding bentonite and modified bentonite. Scanning electron microscopy and infrared analysis showed that bentonite and modified bentonite could stabilize heavy metals in sludge by adsorption and ion exchange. The results show that the modified bentonite stabilizes the high content of heavy metals in electroplating sludge better than that of unmodified bentonite.