期刊
WATER RESEARCH
卷 37, 期 20, 页码 4913-4923出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2003.08.020
关键词
heavy metal binding; cassava waste; wastewater treatment; thiolation; Manihot sculenta Cranz
The sorption of two divalent metal ions, Cd(II) and Zn(II), onto untreated and differentially acid-treated cassava waste biomass over a wide range of reaction conditions was studied at 30degreesC. The metal ion removal from the spent biomass was also measured. The batch experiments show that pH 4.5-5.5 was the best range for the sorption of the metal ions for untreated and acid-treated biomass. Time-dependent experiments for the metal ions showed that for the two metals examined, binding to the cassava waste biomass was rapid and occurred within 30 min and completed within I It. High sorption capacities were observed for the two metals. The binding capacity experiments revealed the following amounts of metal ions bound per gram of biomass: 86.68 mg/g Cd, 55.82 mg/g Zn and 647.48 mg/g Cd, 559.74 mg/g Zn for untreated and acid-treated biomass, respectively. It was further found that the rate of sorption was particle-diffusion controlled, and the sorption rate coefficients were determined to be 2.30 x 10(-1) min(-1) (Cd2+), 4.0 x 10(-3) min(-1) (Zn2+) and 1.09 x 10(-1) min(-1) (Cd2+), 3.67 x 10(-2) min(-1) (Zn2+) for 0.5 and 1.00 M differential acid treatment, respectively. Desorption studies showed that acid treatment inhibited effective recovery of metal ions already bound to the biomass as a result of stronger sulfhydryl-metal bonds formed. Less than 25% of both metals were desorbed as concentration of acid treating reagent increases. However, over 60% Cd and 40% Zn were recovered from untreated biomass during the desorption study. The results from these studies indicated that both untreated and acid-treated cassava waste biomass could be employed in the removal of toxic and valuable metals from industrial effluents. (C) 2003 Elsevier Ltd. All rights reserved.
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