Biosorption of cesium(I) from aqueous solution by a novel exopolymerssecreted from Pseudomonas fluorescens C-2: Equilibrium and kinetic studies
Yanli Mao , Hongwei Hu , Yongsheng Yan
DOI:
Received January 22, 2010,Revised May 15, 2010, Accepted , Available online
Volume 23,2011,Pages 1104-1112
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The biosorption characteristics of Cs(I) ions from aqueous solution using exopolymers (PFC02) produced from Pseudomonas
fluorescens C-2 were investigated as a function of pH, biosorbent dosage, contact time and initial concentration. pH played a major role
in the adsorption process, and the optimum pH for the removal of Cs(I) was 8.0. Langmuir, Freundlich and Dubinin-Radushkevich (D-R)
models were applied to describe the biosorption isotherm of the Cs(I) ions by PFC02. The Lagergren first-order, pseudo second-order
kinetic and intraparticle diffusion models were used to test the kinetic data. Langmuir model and D-R model fitted the equilibrium data
better than the Freundlich isotherm. The monolayer adsorption capacities of PFC02 as obtained from Langmuir isotherm at 25°C was
found to be 32.63 mg/g. From the D-R isotherm model, the mean free energy was calculated as 26.73 kJ/mol, indicating that the
biosorption of cesium was chemisorption. The biosorption process was rapid, and the kinetic rates were best fitted to the pseudo
second-order model, which indicated the biosorption process operated through chemisorption mechanism. FT-IR analysis of PFC02
showed the possible functional groups responsible for cesium adsorption were hydroxyl, carboxyl, carbonyl and sulphonate groups.
SEM analysis showed the porous structure of the material while EDX analysis confirmed the adsorption of Cs(I) on PFC02. Cesium
adsorbed onto the PFC02 could be desorbed efficiently using 1 mol/L HNO3, and the enrichment factor was 50.0. Furthermore, PFC02
could be reused five times with only about 8.25% regeneration loss. The developed method was successfully utilized for the removal of
Cs(I) ions from aqueous solution.
