Biosorption of Congo red and Indigo carmine by nonviable biomass of a new Dietzia strain isolated from the effluent of a textile industry

A new bacterial strain, PD1, was isolated from the effluent of a textile industry. Phylogenetic analysis based on 16S rRNA gene sequence showed that the strain belonged to the genus Dietzia. The efficacy of the dried bacterial biomass as biosorbent for removal of acid dyes, namely Congo red (CR) and Indigo carmine (IC), from aqueous solutions was studied by performing batch equilibrium tests under different operating parameters such as initial dye concentration, pH, and temperature. The amount of dye adsorbed onto Dietzia sp. PD1 decreased with increasing pH while it increased with increasing temperature. The equilibrium biosorption data showed excellent fit to Langmuir isotherm as compared to Freundlich isotherm. The maximum biosorption capacity, calculated using the Langmuir model, were 170.34 and 188.71mgg(-1) for CR and IC, respectively. Analysis of kinetic data showed that the biosorption processes followed pseudo-second-order kinetics. The numerical value of the thermodynamic parameters (G(0), H-0, and S-0) indicated that biosorption of CR and IC was feasible, spontaneous, and endothermic under the examined conditions. The study shows that the isolated Dietzia strain can be used as an inexpensive and efficient biosorbent for removal of acid dyes from aqueous solution.