Removal of heavy metal Ions in aqueous solution by Exopolysaccharides from Athelia rolfsii

This study aimed to evaluate the removal of heavy metal ions in aqueous solution by extracellular polysaccharide (EPS) extracted from Athelia rolfsii. The removing mechanism was further analyzed by Fourier transform infrared spectroscopy (FT-IR). Three heavy metal ions (Cd2+, Cu2+ and Zn2+) were removed from the aqueous solution. And the effect of pH, contact time and initial EPS concentrations and metal iron concentrations on the metal uptake (qe) was illustrated. The results showed that the clearance ability of EPS to Cd2+, Cu2+ and Zn2+ all reached best at 25 °C, pH 5–7 and 60 min reaction time. The biosorption isotherm was also studied. Compared with Freundlich adsorption isotherm, biosorption datas for Cd2+, Cu2+and Zn2+ all fitted better with the Langmuir adsorption isotherm and according to the qmax value in Langmuir adsorption isotherm, the maximal metal uptakes (qmax) of EPS were 116.28, 103.09 and 153.85 mg/g for Cd2+,Cu2+ and Zn2+, respectively. According to FT-IR, Cd2+ mainly reacted with –CHO and –NH– in EPS, and Cu2+and Zn2+ mainly reacted with –NH– and –OH, respectively. The results indicated that EPS could be employed as a promising biosorption for industrial wastewater treatment.