Study On Adsorption Of Cadmium In Water By Biomass Power Plant Ash Using Microwave Modification

In recent years,the rapid development of economy and industry in our country,the heavy metal pollution problem has been aggravated due to the large amount of waste discharge.More and more attention has been paid to the pollution of heavy metal Cd in soil.As a low-cost and stable heavy metal remediation agent,Biofuel Ash has initially shown its good passivation effect on Cd.Through laboratory simulation,this paper studied the use of sodium hydroxide and sodium meta-aluminate Biofuel Ash were modified to further improve the Biofuel Ash adsorption capacity of heavy metal Cd,thereby preparing a more efficient heavy metal Cdmodifiedremediationagent.Theeffectsofdifferentmicrowave intensities,adsorption time,initial concentration of Cd²⁺and other factors on the Cd²⁺removal efficiency were investigated.The adsorption kinetics and adsorption isotherms of Cd²⁺in modified Biofuel Ash were studied.Through a series of characterization tests,Adsorption mechanism was initially discussed,the following findings were obtained:1.The optimum conditions for the adsorption of Cd²⁺?initial concentration of40mg/L?by microwave-NaOH modified Biofuel Ash?NABFA?were as follows:the microwave intensity was 500W and the adsorption time was 24h;The adsorption kinetics was in accordance with quasi-second-order kinetic equation.The adsorption isotherms were in accordance with Fruandlich equation.The maximum adsorption capacity of Cd²⁺was 14.247mg/g,which was 50%higher than that of pure Biofuel Ash.The desorption analysis of adsorbed NABFA by Tessier extraction method showed that the exchangeable form Cd content was only 2.564mg/g,the residual form of non-direct use of biological form Cd was 9.356mg/g,accounting for 78.49%of the total adsorption amount.Indicating that this modified method of Cd passivation effect is significant.2.The optimal conditions for the adsorption of Cd²⁺?initial concentration 40mg/L?by microwave-NaAlO₂ modified Biofuel Ash?NLBFA?were as follows:the microwave intensity was 500W and the adsorption time was 24h;the adsorption kinetics was in accordance with quasi-second-order kinetic equation.The adsorption isotherms were in accordance with Fruandlich equation.The maximum adsorption capacity of Cd²⁺was 19.837mg/g,which was100%higher than that of pure Biofuel Ash.The desorption analysis of adsorbed NLBFA by Tessier's extraction method showed that the exchangeable form Cd content was only 2.062mg/g,and the residual form of non-direct use of biological form Cd was 9.714mg/g,accounting for 82.49%of the total adsorption amount.The newly formed crystallizd Si-Al structure on the NLBFA surface enhances the adsorption properties of Cd.