柠檬酸及柠檬酸铵电场强化水洗脱除垃圾焚烧飞灰中重金属

Heavy metals removal from municipal solid waste incineration fly ashes by electric field enhanced washing with citric acid/ammonium citrate

为进一步强化城市生活垃圾焚烧飞灰中重金属电场水洗脱除效果,详细研究柠檬酸和柠檬酸铵强化洗脱效果,分析了初始pH、辅助剂浓度和电流密度对飞灰中重金属去除率的影响,探讨了处理后飞灰的浸出毒性。结果表明,柠檬酸和柠檬酸铵辅助剂的电场强化水洗均能显著去除飞灰中重金属,且去除率随着初始pH的减少、辅助剂浓度的增加和电流密度的增加而增大。在最佳条件下,添加柠檬酸辅助剂,飞灰中铅、镉和镍的去除率均高于90%,锌、铜和砷的去除率分别为83.12、72.68和71.86%;以柠檬酸铵为辅助剂时,镉、铜、镍、锌、砷和铅的去除率分别为91.51%、88.18%、86.43%、77.94%、69.57%和69.07%;2种辅助剂处理后的飞灰重金属浸出浓度符合国家标准。本研究结果可为飞灰中重金属电场水洗脱除强化提供参考。

Citric acid and ammonium citrate were applied to further enhance the removal of heavy metals from municipal solid waste incineration fly ashes by electric washing.The effects of initial pH,auxiliary agent concentration and current density on the removal rate of heavy metals from fly ash were studied,and the leaching risk of treated fly ash was discussed.These results indicate that both citric acid and ammonium citrate aided electric enhanced washing could significantly remove heavy metals from fly ashes,and the removal rate increases with the decrease of initial pH and the increase of auxiliary agent concentration and current density.At optimum conditions,with the addition of citric acid auxiliary agent,the removal rates of Pb,Cd and Ni in the fly ash are all higher than 90%,while the removal rates of Zn,Cu and As are 83.12%,72.68%and 71.86%respectively.When ammonium citrate is used as an auxiliary agent,the removal rates of Cd,Cu,Ni,Zn,As and Pb removal rates are 91.51%,88.18%,86.43%,77.94%,69.57%and 69.07%,respectively.The fly ash treated with the two auxiliary agents has no leaching toxicity since their leaching concentrations either could not be detected or at an extremely lower level.The results provide references for electric field washing removal and enhancement of heavy metals in fly ash.