针铁矿对垃圾焚烧飞灰中重金属离子的固化作用及机理分析

The Curing Effect of Goethite on Heavy Metal Ions in Fly Ash from Waste Incineration and Mechanism Analysis

垃圾焚烧飞灰是一种危险固体废弃物,必须经过固化稳定化,满足《生活垃圾填埋场污染控制标准》后方能填埋。针铁矿是一种表面带有丰富羟基功能基的固体表面活性剂,利用其表面羟基对金属离子的络合作用能够对垃圾焚烧飞灰进行固化。本论文探讨了工艺参数对针铁矿固化飞灰毒性浸出效果的影响;又利用酸碱滴定表征了针铁矿表面羟基化特性;用格氏图处理酸碱滴定数据,计算出针铁矿表面羟基活性位点密度。结果表明:在针铁矿添加量为15%、液固比为0. 4、固化时间为3 d的条件下,固化后的飞灰能够满足生活垃圾填埋场进场要求;金属离子能够进入针铁矿表面stern层被紧密吸附,碱性条件下则更加有利于离子在针铁矿双电层的扩散层中吸附。

Fly ash from municipal solid waste incineration is a kind of hazardous solid waste.It must be cured and stabilized to meet the"Standard for Pollution Control of Domestic Waste Landfills"before it can be landfilled.Goethite is a kind of solid surfactant with abundant hydroxyl functional groups on its surface,which can be used to solidify waste incineration fly ash by complexing metal ions with hydroxyl groups on its surface.In this paper,the influence of technological parameters on toxic leaching effect of goethite cured fly ash was discussed,and the hydroxylation characteristics of goethite surface were characterized by acid-base titration,and the density of hydroxyl active sites on goethite surface was calculated by processing acid-base titration data with Gran diagram.The results show that under the conditions of15%goethite,0.4liquid-solid ratio and3days solidification time,the cured fly ash can meet the entry requirements of domestic refuse landfill;metal ions can enter stern layer on goethite surface and be adsorbed tightly,while alkaline conditions are more conducive ion to adsorb on diffusion layer on goethite double layer.