Optimization, kinetics, and thermodynamics aspects in the biodegradation of reactive black 5 (RB5) dye from textile wastewater using isolated bacterial strain, Bacillus Albus DD1

This study is aimed to model and optimize the decolorization of reactive black 5 (RB5) dye using Bacillus Albus DD1. The response surface methodology (RSM) along with rotatable central composite design (rCCD)is used to optimize the response, % decolorization with four input variables: (i) pH (5-9), initial dye concentration (50-500 ppm), the composition of yeast extract as nitrogen source (0.2-1%) and amount of bacterial inoculum (5-25% v/v). The % decolorization is predicted approximate to 98% at the optimized condition (pH = 7.6, Dye concentration = 200 ppm, Bacterial Inoculum = 20 v/v% and Yeast Extract = 0.4%). Furthermore, the kinetics and thermodynamics of RB5 degradation are also determined. The kinetic order of bio-degradation of RB5 is found to follow the first-order kinetics with a kinetic rate constant = 0.0384. The activation energy, E-a and frequency factor, A values are calculated as 34.46 kJ/mol and 24,343 (1/Day). The thermodynamic study is also carried out at different temperatures (298 K, 308 K, 310 K, 313 K, and 318 K) using optimized conditions. The values of the and Delta S are found to be +30.79 kJ/mol, and -0.1 kJ/mol/K, respectively using Eyring Polanyi equation. The values of Delta G are also calculated at all temperatures.