title: Biosorption of cadmium and chromium in duckweed Wolffia globosa.
abstract: The biosorption of cadmium (Cd) and chromium (Cr) by using dried Wolffia globosa biomass were investigated using batch technique. The effects of concentration and pH solution on the adsorption isotherm were measured by determining the adsorption isotherm at initial metal concentrations from 10 to 400 mg/L and pH 4 to 7 for Cd, and pH 1.5 to 6 for Cr. The adsorption equilibria were found to follow Langmuir models. The maximum adsorption capacity (Xm) at pH 7 in W. globosa-Cd system was estimated to be 80.7 mg/g, while the maximum removal achieved at pH 4, pH 5, and pH 6 were 35.1, 48.8, and 65.4 mg/g, respectively. The Xm at pH 1.5 in W. globosa--Cr system was estimated to be 73.5 mg/g, while the maximum removal achieved at pH 3, pH 5, and pH 6 were 47.4, 33.1, and 12.9 mg/g, respectively. The effects of contact times on Cd and Cr sorption indicated that they were absorbed rapidly and more efficiently at lower concentrations.
authors.affiliation: Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: E Suchart
authors.initials: ES
authors.lastname: Upatham
authors.forename: Benjaporn
authors.initials: B
authors.lastname: Boonyapookana
authors.forename: Maleeya
authors.initials: M
authors.lastname: Kruatrachue
authors.forename: Prayad
authors.initials: P
authors.lastname: Pokethitiyook
authors.forename: Krisna
authors.initials: K
authors.lastname: Parkpoomkamol