Screening of Significant Factors in Uranium Biosorption from Aqueous Solutions Using Pseudomonas Putida Immobilized on Chitosan

Heavy metal sequestration from industrial wastewater is a serious environmental problem especially in developing countries. Among various treatment technologies, it seems that biosoprtion is a promising alternative method. Microbial–based biosorbents are effective and applicable for heavy metals removal from aqueous solutions. The present study investigated the ability of Pseudomonas putida immobilized on chitosan to adsorb uranium (VI) from the aqueous solution. The biosorption process factors were screened using Plackett–Burman design. The results showed that the biosorbent dosage, initial concentration, biosorbent particle size, bacteria wt.% in the biosorbent and pH were the most significant parameters, respectively while temperature was the only insignificant parameter in the biosorption process. Maximum practical biosorption capacity was 536.08 mg g–1 obtained from 15 wt.% of the bacterial cells immobilized on chitosan. Biosorption equilibrium isotherms were analyzed by Langmuir, Freundlich and Dubinin–Radushkevhch models. For Pseudomonas putida immobilized on chitosan, the Langmuir isotherm model (R2=0.983) was proved to fit the equilibrium data best with the maximum capacities of 588.23 and 454.54 mg g–1 for the biosorbent and pure chitosan, respectively. In conclusion, the present study indicated that the prepared composite biosorbent could be a suitable candidate for uranium (VI) biosorption.