Treatment of organosilicon wastewater by UV-based advanced oxidation processes: Performance comparison and fluorescence parallel factor analysis

Abstract Organosilicon wastewater, generally contains plentiful silicone polymers, high salinity and high chemical oxygen demand (COD), and therefore, has great impact on the environment. This study explored the degradation of organosilicon wastewater by UV-based advanced oxidation processes: UV/H2O2, UV/peroxydisulfate (PDS) and UV/peroxymonosulfate (PMS). At natural pH of wastewater and 100 mM of oxidant concentration, UV/PDS achieved a higher COD removal (90.6%) than UV/PMS (80.8%) after a 240 min reaction time, whereas only half time was required for UV/H2O2 to reach nearly the same COD removal (89.7%) as UV/PDS. Electron paramagnetic resonance (EPR) analysis indicated hydroxyl and sulfate radicals were the main reactive species for COD removal. Parallel factor analysis (PARAFAC) of excitation emission matrix (EEM) fluorescence spectroscopy was employed to monitor the transformation of dissolved organic matter (DOM) present in the organosilicon wastewater. The results illustrated that the tyrosine-, tryptophan- and humic-like substances were three components of DOM and all of them were significantly degraded into smaller molecular weight fractions.