Isotherm kinetics of Cr(III) removal by non-viable cells of Acinetobacter haemolyticus

The potential use of non-viable biomass of a Gram negative bacterium i.e. Acinetobacter haemolyticus to remove Cr(III) species from aqueous environment was investigated. Highest Cr(III) removal of 198.80 mg g−1 was obtained at pH 5, biomass dosage of 15 mg cell dry weight, initial Cr(III) of 100 mg L−1 and 30 min of contact time. The Langmuir and Freundlich models fit the experimental data (R2 > 0.95) while the kinetic data was best described using the pseudo second-order kinetic model (R2 > 0.99). Cr(III) was successfully recovered from the bacterial biomass using either 1 M of CH3COOH, HNO3 or H2SO4 with 90% recovery. TEM and FTIR suggested the involvement of amine, carboxyl, hydroxyl and phosphate groups during the biosorption of Cr(III) onto the cell surface of A. haemolyticus. A. haemolyticus was also capable to remove 79.87 mg g−1 Cr(III) (around 22.75%) from raw leather tanning wastewater. This study demonstrates the potential of using A. haemolyticus as biosorbent to remove Cr(III) from both synthetic and industrial wastewater.