Catalytic oxidation of various aromatic compounds in supercritical water: Experimental and DFT study

Catalytic supercritical water oxidation (CSCWO) has sprung up as a promising technique to eliminate refractory aromatic compounds, which are difficult to be removed by conventional wastewater treatment processes. Decompositions and degradation mechanisms of 18 aromatic compounds, including benzene, phenol, bisphenol A (BPA) etc., were investigated using CSCWO in this study. It was found that TOC removal efficiencies of the aromatic compounds were significantly enhanced, when CSCWO temperatures raised from 325 to 525 °C and reaction time prolonged from 0.5 to 6 min, with the addition of Cu(NO3)2. The correlationships among TOC degradation rates (kTOC), temperature at TOC removal rate of 90% (T90) and 19 molecular descriptors were studied. The results indicated that BOn and q(H)x could greatly impact the degradation behaviors. Fukui indices based density functional theory (DFT) method was applied to reveal the conceivable degradation pathway of BPA during CSCWO process.