聚环氧琥珀酸对污泥中铅的萃取研究

以上海市桃浦污水厂污泥为对象,研究了易生物降解的聚环氧琥珀酸(PESA)对污泥中重金属Pb的萃取作用,重点考察了萃取体系的pH值和萃取剂PESA的用量对重金属Pb萃取的影响.研究发现,PESA对污泥中的重金属Pb具有较好的萃取效果,形态分析结果表明,被PESA萃取的锌主要来自水溶态、酸溶态、可还原态和可氧化态4种形态.当萃取体系的pH=4且PESA与污泥中重金属总量的摩尔比为4∶1时,Pb的萃取效率可达73%.实验结果还表明,萃取体系的pH值和PESA用量是影响污泥中Pb萃取的重要因素.随着萃取体系pH值的降低,Pb的萃取效率总体呈现逐渐下降的趋势;随着PESA用量的增加,Pb的萃取效率逐渐提高,且对体系pH值的依赖性减小.

Extraction of Pb from Sewage Sludge with PESA

Poly-epoxy-succinic acid (PESA), as a novel biodegradable chelant, has been used to remove the heavy metals from the sewage sludge based on chemical extraction technology. For the sewage sludge from Shanghai Taopu Municipal Wastewater Plant, the influence factors including pH and the concentration of PESA on the extraction efficiency has been investigated. It is found that PESA had a higher efficiency for the extraction of Pb from sludge than that of other heavy metals. The analysis of species distribution shows that the extracted Pb mainly comes from the following states, water soluble, acid soluble, reducible and oxidizable fractions.The extraction efficiency of Pb reached 73% when the molar ratio of PESA to total heavy metals was 4:1 and system pH was 4. The concentration of PESA and system pH have a significant effect on the extraction efficiency of Pb. The extraction efficiency of Pb decreases gradually with pH increasing, and the dependency of the extraction efficiency on pH decreases with the molar ratio increasing.