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Recently,incineration technology has been widely used for the disposal of municipal solid waste(MSW).MSW incineration as a new anthropogenic source plays a important role in arsenic emission to the atmosphere in China.At the operating temperature of MSW incineration,arsenic is easily volatile which tends to release into the flue gas.CaO is usually used for the removal of hazardous materials in the flue gas and the interactions between arsenic vapors and CaO could effectively facilitate arsenic capture at high temperatures.However,the mechanism of arsenic capture by CaO is unclear,especially for the effects of temperature,acid flue gases.Thus,its difficult to chose the proper site for the injection of CaO to control the arsenic release in the flue gas.In the present study,arsenic capture by CaO was studied at 300 – 1050 ℃ in the simulated MSW incineration flue gas.The results show that arsenic capture was attributed to physical adsorption by CaO at low temperatures and was mainly determined by chemical oxidation at high temperatures.Increasing temperature stimulated arsenic capture through the chemical adsorption.Acid gases in the flue,i.e.SO2 and HCl,reacted with CaO and less active sites were available in CaO for the reacting with arsenic vapors.As a result,arsenic capture by CaO was suppressed at the presence of high content of SO2 and HCl.