Sorption of cadmium by rice husk char, bamboo char, and coconut shell char in aqueous solutions

[摘要] Cadmium (Cd) is a byproduct of zinc production. It has a high solubility, mobility and biological accumulation leading to a risk of bone and kidney damage after long-term exposure. Sorption is an effective method to treat Cd-contaminated water. As a great potential contaminant sorbent, biochar can be produced from rice husk, coconut shell and bamboo under their respective optimum conditions for the sorption of toxic metal ions were used as representatives. Sorption models of kinetics and isotherms were used to fit the experimental results. Pseudo-first-order models fitted the data better than pseudo-second-order for all types of biochar. The Cd2+ sorption capacity of coconut shell char and bamboo char was higher than rice husk char (7.3723 mg/g ≈ 7.3835 mg/g > 5.0345 mg/g). Freundlich model fitted the results of coconut shell biochar and bamboo biochar better than Langmuir model, which indicate a strong bond for Cd2+ sorption. In contrast, for rice husk biochar Langmuir model fitted the results better than Freundlich model indicating monolayer sorption mechanism dominated the sorption.

[发布机构] Department of Water Conservancy and Civil Engineering, Beijing Vocational College of Agriculture, No. 5, Daotiannanli, Beijing, Changyang, Fangshan District; 102442, China^1;School of Environment and Energy Engineering, Key Laboratory of Urban Stormwater System and Water Environment, Ministry of Education, Beijing University of Civil Engineering and Architecture, Yongyuan Road 15, Beijing, Daxing District; 102616, China^2

[学科分类] 环境科学（综合）

[关键词] Contaminated water;Long term exposure;Optimum conditions;Potential contaminants;Pseudo second order;Pseudo-first-order;Sorption capacities;Sorption mechanism