螯合剂固化生活垃圾焚烧飞灰中重金属的机理研究进展

填埋是目前处理生活垃圾焚烧飞灰的主要方式之一，然而飞灰中重金属随渗滤液浸出会对环境产生污染隐患，药剂固化飞灰中重金属是主要预处理方式. 其中，化学药剂中的螯合剂类对飞灰中重金属的固化效果较好，国内外使用广泛. 本文通过对比多种有机螯合剂的重金属固化率发现，具有不同官能团(醛基、羟基、羧基、磷酸官能团和含硫基官能团)的螯合剂的固化效果有明显差异，其中含有磷酸官能团和硫基官能团的螯合剂对飞灰中重金属的固化效果普遍优于含醛基、羟基、羧基官能团的螯合剂. 因此，可根据填埋场渗滤液的酸碱性，通过添加羧基、羟基或磷酸官能团改性有机螯合剂，使填埋场渗滤液达到中性. 同时，螯合固化体形成正四面体结构最为稳定，可以降低飞灰中重金属浸出率，减少填埋场污染隐患. 

Review on Mechanisms of Chelating Agents to Solidify Heavy Metals in Municipal Solid Waste Incineration Fly Ash

Landfill is one of the main ways to dispose of municipal solid waste incineration fly ash (MSWIFA). However, the potential leaching of heavy metals from fly ash (FA) with leachate poses a significant risk to the environment. The main pretreatment method is the solidification of heavy metals in the fly ash with chemicals. In particular, chelating agent-based solidifying agents are more effective in curing heavy metals in fly ash and are widely used at home and abroad. In this paper, by comparing the heavy metal curing rates of various organic chelating agents, it is found that chelating agents with different functional groups (aldehyde group, hydroxyl group, carboxyl group, phosphate functional group, and sulfur-containing functional group) have significant differences in the solidification effects. For solidifying heavy metals in FA, the chelating agents with phosphate and sulfur functional groups are generally more effective than the chelating agents with aldehyde, hydroxyl, and carboxyl functional groups. Therefore, according to the acidity and alkalinity of the landfill leachate, the landfill leachate can be made neutral by adding carboxyl, hydroxyl, or phosphate functional group modified organic chelating agent. After solidification, the solidified product forms an orthotetrahedral chelate to achieve the most stable structure, thus reducing the leaching rate of heavy metals from the MSWIFA and reducing landfill pollution.