亚硫酸钠、磷酸钠联合处理铬渣中的六价铬

发布时间：2018-10-14 15:16

【摘要】：铬渣是毒性较强的危险废物,通过实验室模拟化学还原处理技术,以亚硫酸钠为还原剂,将铬渣中毒性强的六价铬(Cr(VI))还原转化为低毒的三价铬(Cr(III)),考察不同的反应时间和亚硫酸钠用量对铬渣中六价铬去除效果的影响.结果表明:亚硫酸钠可以有效去除铬渣中的六价铬,当亚硫酸钠与六价铬的计量比为理论计量比的12倍、修复时间为15d以上时,总铬浸出浓度去除率最高(78%);继续延长反应时间或增加亚硫酸钠用量均不能有效提高去除率.随后加入磷酸钠作为稳定剂稳定解毒后的铬渣,当磷酸钠与三价铬的摩尔比为4∶1时,总铬浸出浓度为6.9mg/L,低于危险废物鉴别标准GB 5085.3—2007中规定的总铬浸出浓度限值15mg/L,并生成稳定的CrPO_4·6H_2O晶体.此外,亚硫酸钠与磷酸钠分步加入(两步法)处理铬渣的效果好于两者同时加入(一步法)的效果.
[Abstract]:Chromium slag is a highly toxic hazardous waste. Sodium sulfite is used as reducing agent through laboratory simulation chemical reduction treatment technology. The reduction of highly toxic hexavalent chromium (Cr (VI) from chromium slag to low toxic trivalent chromium (Cr (III), was studied. The effects of different reaction time and sodium sulfite dosage on the removal efficiency of hexavalent chromium from chromium residue were investigated. The results show that sodium sulfite can effectively remove hexavalent chromium from chromium residue. When the measurement ratio of sodium sulfite to hexavalent chromium is 12 times of the theoretical measurement ratio, the repair time is more than 15 days. The removal rate of total chromium leaching concentration was the highest (78%), and the removal rate could not be improved by prolonging the reaction time or increasing the amount of sodium sulfite. Then sodium phosphate was added as a stabilizer to stabilize the chromium residue after detoxification. When the molar ratio of sodium phosphate to trivalent chromium was 4:1, The total chromium leaching concentration is 6.9 mg / L, which is lower than the limit of 15mg / L in hazardous waste identification standard GB 5085.3-2007, and a stable CrPO_4 6H_2O crystal is formed. In addition, the effect of adding sodium sulfite and sodium phosphate step by step (two-step method) is better than that of adding both of them (one-step method) at the same time.
【作者单位】：北京大学环境科学与工程学院北京市固体废弃物资源化技术与管理重点实验室;北京科技大学土木与环境工程学院;环境保护部宣传教育中心;
【基金】：国家自然科学基金项目(21077002)
【分类号】：X705

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