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Electrochemical and microbial decolourization of Congo Red dye-contaminated wastewater: experimental and computational studies

Chikwado E. Anene, Kanayo L. Oguzie, Toochukwu E. Ogbulie, Chris O. Akalezi, and Emeka E. Oguzie

Africa Centre of Excellence in Future Energies and Electrochemical Systems (ACE-FUELS), Federal University of Technology, Owerri, Nigeria



Received: 22 May 2023  Accepted: 20 August 2023


The aim of this study was to investigate the degradation of Congo Red (CR) dye in aqueous solution through two different processes: electrochemical oxidation (EO) and microbial degradation. In the electrochemical degradation experiment, several electrochemical parameters were examined to determine their influence on the degradation of CR dye. These parameters included the type of anode used, current density, supporting electrolytes, electrolyte concentrations and pH. Concurrently, microbial degradation was carried out using various indigenous isolates, namely Bacillus megaterium, Lactobacillus delbrueckii, Bacillus sphaericus, Pseudomonas sp., Bacillus lentus, Erwinia sp., Bacillus pumilus, Aspergillus flavus and Aspergillus niger. The effects of mineral salt and time on CR dye degradation were also investigated in the microbial degradation process. Additionally, density functional theory (DFT) computation was employed to analyse the degradation mechanism of CR dye. The results of the electrochemical degradation experiment indicated that the copper anode exhibited superior effectiveness in degrading CR dye compared to the graphite anode. Furthermore, the degradation rate of the dye increased as current density, electrolyte concentration and pH were elevated. In the microbial degradation process, the degradation of CR dye increased over time, and the presence of mineral salt enhanced the degradation rate. The DFT computations revealed that the degradation of the dye initiated at the azo chromophore, sulfonate molecule and ultimately the amide group.

Keywords: Electrochemical oxidation; Microbial degradation; Percentage decolourization; Density functional theory; Congo Red

Full paper is available at

DOI: 10.1007/s11696-023-03045-2


Chemical Papers 77 (12) 7761–7774 (2023)

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