Study on the Passivation of Heavy Metals in Municipal Sludge by Attapulgite Modified at High Temperature
YIN Meng
LIU Hong
LIU Mengjia
WANG Qian
ZHANG Huiling
Abstract：For the problem that the content of heavy metal cadmium,zinc and arsenic in some municipal sludge exceeded the discharge standard of Grade A,the effects of calcination temperature and doping ratio of attapulgite on the passivation efficiency of heavy metals were investigated by using attapulgite modified at high temperature as passive material.The passivation mechanism of cadmium,zinc and arsenic was explored.The results showed that the optimal passivation effect was achieved by attapulgite calcined at 700 ℃ and doped as 15％,and the highest passivation rate of cadmium,zinc and arsenic reached 99.6％,92.7％ and 87.6％,respectively.After being calcined at 700 ℃,the chemical bonds in the crystal lattice of attapulgite were broken,and attapulgite decomposed to some alkaline oxide like CaO and MgO,which increased the alkalinity of sludge and thus resulted in the change of occurrence form of cadmium and zinc.The passivation of arsenic was realized owing to the formation of complex with Al and arsenate after the A1-OH bond in attapulgite was broken.
Keywords：attapulgitemodification at high temperaturemunicipal sludgeheavy metalspassivation
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：5( 93-97 )