title: Eco-friendly and facile integrated biological-cum-photo assisted electrooxidation process for degradation of textile wastewater.
abstract: The present article reports an integrated treatment method viz biodegradation followed by photo-assisted electrooxidation, as a new approach, for the abatement of textile wastewater. In the first stage of the integrated treatment scheme, the chemical oxygen demand (COD) of the real textile effluent was reduced by a biodegradation process using hydrogels of cellulose-degrading Bacillus cereus. The bio-treated effluent was then subjected to the second stage of the integrated scheme viz indirect electrooxidation (InDEO) as well as photo-assisted indirect electro oxidation (P-InDEO) process using Ti/IrO2-RuO2-TiO2 and Ti as electrodes and applying a current density of 20 mA cm(-2). The influence of cellulose in InDEO has been reported here, for the first time. UV-Visible light of 280-800 nm has been irradiated toward the anode/electrolyte interface in P-InDEO. The effectiveness of this combined treatment process in textile effluent degradation has been probed by chemical oxygen demand (COD) measurements and (1)H - nuclear magnetic resonance spectroscopy (NMR). The obtained results indicate that the biological treatment allows obtaining a 93% of cellulose degradation and 47% of COD removal, increasing the efficiency of the subsequent InDEO by a 33%. In silico molecular docking analysis ascertained that cellulose fibers affect the InDEO process by interacting with the dyes that are responsible of the COD. On the other hand, P-InDEO resulted in both 95% of decolorization and 68% of COD removal, as a result of radical mediators. Free radicals generated during P-InDEO were characterized as oxychloride (OCl) by electron paramagnetic resonance spectroscopy (EPR). This form of coupled approach is especially suggested for the treatment of textile wastewater containing cellulose.
authors.affiliation: Corrosion and Material Protection Division, CSIR-Central Electrochemical Research Institute (CECRI), Karaikudi 630 003, India. Electronic address: priya.bdu07@gmail.com.
authors.forename: Priyadharshini
authors.initials: P
authors.lastname: Aravind
authors.affiliation: Electro-inorganic Chemicals Division, CSIR-Central Electrochemical Research Institute (CECRI), Karaikudi 630 003, India.
authors.forename: Vasudevan
authors.initials: V
authors.lastname: Subramanyan
authors.affiliation: Department of Life Sciences and Biotechnology, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Ferro
authors.affiliation: Chlor-alkali Division, CSIR-Central Electrochemical Research Institute (CECRI), Karaikudi 630 003, India.
authors.forename: Rajagopal
authors.initials: R
authors.lastname: Gopalakrishnan
mesh_terms: D001409:Bacillus cereus / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D002482:Cellulose / Q000737:chemistry / Q000378:metabolism; D004396:Coloring Agents / Q000737:chemistry / Q000378:metabolism; D017753:Ecosystem; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D007220:Industrial Waste; D010084:Oxidation-Reduction / Q000528:radiation effects; D010782:Photolysis / Q000528:radiation effects; D066244:Proton Magnetic Resonance Spectroscopy; D013784:Textiles; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D004396:Coloring Agents; D005609:Free Radicals; D007220:Industrial Waste; D002482:Cellulose
keywords: Cellulose degradation; Molecular docking; Oxychloride radicals; Photo-assisted electrooxidation; Textile effluent