Electro-chemical mineralization of recalcitrant indole by platinum-coated titanium electrode: multi-response optimization, mechanistic and sludge disposal study
Journal
International Journal of Environmental Science and Technology
Journal Volume
15
Journal Issue
2
Pages
349-360
Date Issued
2018
Author(s)
Abstract
Indole is a highly recalcitrant aromatic heterocyclic organic compound consisting of a five-membered nitrogen-containing pyrrole ring fused to a six-membered benzene ring. This study presents the results of the electro-chemical mineralization of indole in an aqueous solution using platinum-coated titanium (Pt/Ti) electrode. A central composite design was used to investigate the effect of four parameters namely initial pH (pHo), current density (j), conductivity (k) and treatment time (t) at 5 levels. Multiple responses namely chemical oxygen demand (COD) removal (Y1) and specific energy consumption (Y2) were simultaneously maximized and minimized, respectively, by optimizing the parameters affecting the mineralization of indole by using the desirability function approach. At the operating conditions of pH 8.6, j = 161 A/m2, k = 6.7 mS/cm and t = 150 min, 83.8% COD removal with specific energy consumption of 36.3 kWh/kg of COD removed was observed. Ultra performance liquid chromatography, UV–visible spectroscopy, Fourier transform infrared spectroscopy and cyclic voltammetry of the indole solution were performed at the optimum condition of the treatment so as to report a plausible mechanism of indole degradation. Field emission scanning electron microscopy analysis of electrodes before and after treatment was performed for determining the changes on anode surface during the treatment. Thermal analysis of the solid residue (scum) obtained was also performed for exploring its disposal prospects. Present study shows that electro-chemical oxidation can be used for mineralization of nitrogenous heterocyclic compounds such as indole. © 2017, Islamic Azad University (IAU).
Subjects
COD removal; Electro-chemical treatment; Multiple-response optimization; Specific energy consumption
SDGs
Other Subjects
Aromatic compounds; Chemical compounds; Chromatography; Cyclic voltammetry; Degradation; Electrodes; Energy utilization; Field emission microscopes; Fourier transform infrared spectroscopy; Liquid chromatography; Mineralogy; Organic compounds; Platinum; Polycyclic aromatic hydrocarbons; Scanning electron microscopy; Sludge disposal; Solutions; Thermoanalysis; Titanium; Waste disposal; Chemical oxygen demand removals; Chemical treatments; COD removal; Field emission scanning electron microscopy; Heterocyclic organic compounds; Multiple response optimization; Specific energy consumption; Ultra performance liquid chromatography; Chemical oxygen demand; aqueous solution; biomineralization; chemical oxygen demand; electrochemical method; electrode; optimization; organic compound; pollutant removal; sludge; waste disposal
Type
journal article