Optimization of process variables for hexavalent chromium biosorption by psychrotrophic Pseudomonas putida SKG-1 isolate

Hexavalent chromium, a priority pollutant, is well known for its carcinogenicity, mutagenicity, and teratogenicity in humans, animals, and plants. Biosorption is an attractive technique for the treatment of chromium pollution. This study was aimed to optimize the effect of various process parameters on biosorption of Cr6+ by Pseudomonas putida SKG-1 employing conventional one-factor-at-a-time and response surface methodology (RSM) approaches in a batch process. In conventional method, the maximum Cr6+ biosorption (97%) was achieved at 6.0gdeadcellbiomassl(-1), pH 3.0, and 35 degrees C during 195min contact time with an initial Cr6+ concentration of 50mgl(-1) under shaking (150rpm). Whereas in RSM approach, a slightly enhanced Cr6+ biosorption (98%) was obtained only in 180min by P. putida cells (8.0gl(-1)). The correlation coefficient (R-2) of biosorption data to Cr6+ simulated by the Langmuir, Freundlich, and D-R isotherm models was 0.9953, 0.8482, and 0.8916, respectively. The best fit was obtained for Langmuir model which suggests the binding of chromium as a monolayer on the surface of the biomass.