铬污染建筑废物清洗剂的筛选

以原海北化工厂的铬污染建筑废物为研究对象，用微波消解、碱消解-共沉淀和改良BCR顺序提取法，研究了不同粒径样品总Cr和Cr(Ⅵ)以及各形态Cr的含量，探讨了6种清洗剂对样品总Cr和Cr(Ⅵ)的清洗效果，最终筛选出合适的清洗剂. 结果表明:粒径对样品总Cr和Cr(Ⅵ)以及各形态Cr含量的影响不显著，对样品总Cr和Cr(Ⅵ)的解吸无影响. 水洗1次后，总Cr和Cr(Ⅵ)的去除率分别为75.24%和77.59%；用6种清洗剂第2次清洗后，柠檬酸、高浓度盐酸和高浓度醋酸对总Cr和Cr(Ⅵ)的去除率最高，均达到94%以上，说明这3种酸可将Cr(Ⅵ)还原为Cr(Ⅲ)，从而去除Cr(Ⅵ). 从经济环保角度考虑，宜选择柠檬酸作为二次清洗剂. 

Screening of Washing Agents for the Removal of Chromium from Contaminated Construction Waste

The removal efficiencies of six different agents on chromium-contaminated building waste collected from Haibei Chemical Plant were analyzed by using microwave-assisted digestion,alkaline digestion co-precipitation and modified BCR.The amounts of total chromium,hexavalent chromium(Cr(Ⅵ)) and chromium in other forms in samples with different grain diameter were investigated.Through comparison of the washing results of the six different agents,the most effective washing agent was selected.The results showed that grain diameter had little impact on contents of total chromium,Cr(Ⅵ) or chromium in various forms,and had no impact on the desorption of total chromium and Cr(Ⅵ).After washing once by water,the removal efficiencies of total Cr and Cr(Ⅵ) were 75.24% and 77.59%,respectively.In the secondary washing by the six agents individually,citric acid,high concentration hydrochloric,and high concentration acetic acid showed the highest washing efficiencies for total Cr and Cr(Ⅵ),which were all above 94%.These results indicated that these three acids can remove Cr(Ⅵ) by reducing Cr(Ⅵ) to Cr(Ⅲ).Considering economics and environmental protection,citric acid would be the best choice for secondary washing of chromium-contaminated construction waste.