Bacteria cell templated porous polyaniline facilitated detoxification and recovery of hexavalent chromium

In this study, bacteria cells served as a novel green pore-forming agent and template to fabricate porous polyaniline (Bac@PANI) by in situ oxidative polymerization. The achieved specific surface area of 51.2 m(2) g(-1) for Bac@PANI at a bacteria dosage of OD600 = 0.536 was far higher than that of the pristine PANI (27.5 m(2) g(-1)). The Bac@PANI presented an emeraldine form, hydrophilicity and decreased isoelectric point (4.2) after being modified by bacteria. All these properties contributed to an enhanced removal performance of hexavalent chromium (Cr(vi)), with a high removal rate of 0.5 mg (min(-1)g(-1)) and capacity of 835.06 mg g(-1) of Bac@PANI. Efficient removal was achieved in both acidic and neutral solutions due to its high H+ storage capacity. More than 90% of Cr(vi) can be reduced to trivalent chromium (Cr(iii)) by oxidation of amide groups in both acidic and neutral solutions. These Cr(iii) ions can be adsorbed by Bac@PANI simultaneously, resulting from the reversal of negative surface charge after treatment of Cr(vi); then Bac@PANI can be easily recovered in an acidic solution.