title: Biosorption studies on copper (II) and cadmium (II) using pretreated rice straw and rice husk.
abstract: This study investigated the adsorption and removal behaviour of copper (Cu) (II) and cadmium (Cd) (II) ions using rice husk and rice straw in aqueous solutions. Different parameters were used to investigate their adsorption performance in saline conditions and the optimal level of biosorption at different pH levels. The main parameters were pH (3, 6 and 9), initial concentration level of heavy metals (Cu (II) 5, 10, 20, 40 and 60 mg/L and Cd (II) 0.5, 1, 2, 4 and 8 mg/L, respectively), salinity (0, 50 and 100 mM NaCl) and contact time (ranging from 3 to 60 min). Langmuir and Freundlich isotherm models were applied to analyse the removal efficiency and sorption capacity of the pretreated rice husk and rice straw. The removal efficiency and adsorption capacity generally increased with the pH and reached a plateau in alkaline conditions. The percentage removal of Cu (II) by rice husk reached 97 % at pH 9 and 95 % by rice straw at pH 6. Biosorption performance increased in the absence of NaCl. Kinetic studies for both metals revealed that the biosorption of Cu (II) and Cd (II) onto rice straw and husk was pseudo-second order.
authors.affiliation: The Centre for Education in Environmental Sustainability, and Department of Science and Environmental Studies, The Hong Kong Institute of Education, Hong Kong, SAR, China. waichin@ied.edu.hk.
authors.forename: W C
authors.initials: WC
authors.lastname: Li
authors.affiliation: The Centre for Education in Environmental Sustainability, and Department of Science and Environmental Studies, The Hong Kong Institute of Education, Hong Kong, SAR, China.
authors.forename: F Y
authors.initials: FY
authors.lastname: Law
authors.affiliation: The Centre for Education in Environmental Sustainability, and Department of Science and Environmental Studies, The Hong Kong Institute of Education, Hong Kong, SAR, China.
authors.forename: Y H M
authors.initials: YH
authors.lastname: Chan
mesh_terms: D000327:Adsorption; D002104:Cadmium; D003300:Copper; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012275:Oryza; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium; D003300:Copper
keywords: Biosorption; Isotherm; Kinetic; Rice husk; Rice straw