Electrochemical and microbial treatment of bromophenol blue dye in aqueous solution

Bromophenol blue (BB) is an important triphenylmethane derivative widely used in research and industry as a dye or colorant for silk, leather, and drugs. BB has a high proclivity for water contamination because of its high solubility and stability, causing damage to living organisms even in low quantities. This study assessed the feasibility of electrochemical and biological for the decolorization of BB using graphite-copper electrode and indigenous microorganisms, respectively. It was found that effectiveness of electrochemical treatment improves with higher electrolysis time, current density, and electrolyte concentration, drops with rising pH, and shows a nonlinear pattern with temperature. The microbial strains identified as Acinetobacter baumaniu, Serratia marcescens, Aspergillus niger, Aspergillus flavus, Bacillus megaterium, Rhizopus stolonifer, and Bacillus subtilis performed poorly, irrespective of the dye/mineral salt ratio. The electrochemical technique was much more effective for decolorizing bromophenol blue dye-contaminated water. The computational results showed clearly that bromine atoms are the most susceptible sites for attack by oxidizing species and, thus, the onset of BB-decolorization.