热活化耦合铁负载改性埃洛石吸附剂联合脱除气态铅和铬的实验与机理研究OA

High concentrations of lead and chromium in combustion flue gas pose serious risks to human health and the environment.Therefore,their emissions require effective control.A modified halloysite(Fe-HNT)adsorbent was prepared using a composite modification method combining thermal activation at 900 ℃ with 20％iron loading.The combined removal performance and adsorption mechanisms of Fe-HNT for lead and chromium were systematically investigated through a combination of experiments and density functional theory(DFT)calculations.The experimental results show that the adsorption efficiencies of Fe-HNT for lead and chromium first increase and then decrease as the temperature increases from 800 ℃ to 1 100 ℃.The optimal adsorption temperature is 1 000 ℃,with adsorption efficiencies of 77.59％for lead and 75.10％for chromium.During the combined removal of lead and chromium,the adsorption efficiencies of Fe-HNT decrease slightly,reaching 71.49％for lead and 73.39％for chromium.The crystalline phase composition of the adsorption products was further analyzed by XRD.During the adsorption process,Fe-HNT reacts chemically with lead and chromium.The adsorption products mainly consist of lead and chromium silicoaluminates,ferrites,and iron chromate.The adsorption mechanism of lead and chromium on the surface of Fe-HNT was revealed at the microscopic level using DFT calculations.The results indicate that the Al,O and Fe atoms on the Fe-HNT surface are active adsorption sites for lead and chromium.There is competitive adsorption between lead and chromium because they share the same active sites on the adsorbent.Lead preferentially binds to halloysite,whereas chromium exhibits a stronger binding affinity for Fe2O3 on Fe-HNT,making it more readily adsorbed onto Fe2O3.