BIOSORPTION OF CD(II) FROM AQUEOUS SOLUTION BY A NOVEL EXTRACELLULAR BIOPOLYMER SECRETED FROM PSEUDOMONAS FIUORESCENS C-2: EQUILIBRIUM AND KINETIC STUDIES

摘要

The biosorption characteristics of Cd(II) from aqueous solution using the extracellular biopolymer (PFC02) secreted from Pseudomonas fiuorescens C-2 were investigated as a function of pH, adsorbent dosage, contact time and initial concentration. The optimal solution pH for the removal of Cd(II) was determined to be 6.0. The Lagergren-first-order, pseudo-second-order kinetic and intraparticle diffusion models were used to test the kinetic data. The pseudo-second-order kinetic model was found to be well suited for the entire adsorption process of Cd(II) on PFC02. Langmuir and Freundlich models were applied to describe the biosorption isotherm of the Cd(II) ions by PFC02. Langmuir model fitted the equilibrium data better than Freundlich isotherm. The maximum adsorption capacity of PFC02 for Cd(II) according to Langmuir isotherm was 37.17 mg g~(-1) at pH 6.0 and 25 °. FT-IR analysis of PFC02 showed the possible functional groups of PFC02. Responsible for the cadmium adsorption were hydroxyl, carboxyl and phosphate groups etc. SEM analysis demonstrated the microporous structure of the material while EDX analysis confirmed the adsorption of Cd(II) on PFC02. Furthermore, PFC02 could be re-sed five times with only about 9.15% regeneration loss, and the enrichment factor was 50.0. The developed method was successfully utilized for the removal of Cd(II) ions from environmental and industrial wastewater samples analyzed by inductively coupled plasma-atomic emission spectros-copy (ICP-AES).