Carbide Slag/Aluminate Cement Non-calcined Filler:Preparation and Study on Cadmium Removal Performance
A non-calcined artificial wetland filler(CSAC filler)was prepared using carbide slag and aluminate ce-ment,and its cadmium adsorption capacity was investigated.The results showed that CSAC fillers(80％calcium carbide slag,20％aluminate cement)have good cadmium adsorption performance.When the initial Cd2+concentration was 50 mg/L,the cadmium adsorption amount can reach 299.8 mg/g,and the results were influenced by various factors(pH,initial concentration,reaction time,temperature).The adsorption kinetics analysis showed that the adsorp-tion process was more in line with the quasi second order kinetic model,and the heterogeneous chemical adsorp-tion process was the main process of cadmium adsorption on CSAC fillers.The adsorption isotherm analysis showed that the adsorption process can be fitted using the Sips model,and the theoretical maximum adsorption ca-pacity obtained from the Sips model was 341.33 mg/g(30 ℃).The characterization results indicated that the adsorp-tion mechanism of CSAC fillers for cadmium includes the combination of Cd2+with Ca(OH)2 and CO2,forming CdCO3 precipitation;Cd2+undergoes intergranular substitution and complexation reactions with hydration products.CSAC filler has good mechanical and physical properties,and all indicators meet the requirements.The research results provided strong reference for the development of cadmium removal fillers in constructed wetlands and the resource utilization of carbide slag.
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