Studies On The Catalitic Wet Air Oxidation Of Organic Pollutants

This paper developed the degradation method of paracetamol by catalytic wetoxidation with FeCl₃catalyst, and explored the study of different metal-doped TiO₂catalysts on catalytic wet oxidation of chlorophenols pollutants. Furthermore, thedecomposition of chlorophenols pollutants were investigated by using NaNO₂andLa₂O₃/TiO₂or CuO/TiO₂as associated heterogeneous catalysts on advanced wetoxidation.The concentration of paracetamol was higher and higher in aqueous environmentbecause of its massive consuming. In the conditions of temperature150oC,0.5MPaoxygen pressure, two hours reaction time and25mol%of FeCl₃and paracetamol,100%degradation ratio was achieved for5mM original paracetamol solution, and theremoval of chemical oxygen demand （COD） and total organic carbon （TOC） were49%and54%, respectively. Biochemical oxygen demand for5days （BOD5） and thetoxicity of disposal liquid in different reaction time was investigated too. and thereaction solution have good property of biochemical degradation, but the toxicity wasincreased after reaction for2h in the system. Through IC, LC-MS and GC-MSanalysis, the main by-product was formic acid (1.1mmolL^-1) and acetic acid (0.37mmolL^-1). N element of paracetamol was mainly exsited in the form of NH4+afterreaction. Benzoquinone and Hydroquinone which increasing toxicity were alsodetected. This result accorded with other research about the degradation ofparacetamol. But their COD and TOC removals were less than this catalytic system.This system was an alternative method to remove organic pollutants in waster waterand have good prospect for industry application.Based on wet oxidation system with different metal-doped TiO₂as catalyst,trichlorophenol was used as model pollutant to explore the activities of these solidcatalysts. La₂O₃/TiO₂and CuO/TiO₂have the highest catalytic activity. Furthermore,the removal of TCP increased after adding NaNO₂to these catalytic systems. In the best condition, i.e.,（CuO/TiO₂）+NaNO₂as catalyst, with100mol%of NaNO₂and3g/L CuO/TiO₂,96%of TCP removal and74%of chlorine mineralization was obtained.The removal of TOC and COD was reached to43%and73%under0.5MPa ofoxygen at150°C for2hours. The degradation of TCP was still efficient even repeateduse5-times for the catalyst CuO/TiO₂. This effective, inexpensive and practicalcatalytic oxidation system showed a significant step forward in fight againstrecalcitrant chlorinated organic pollutants and displayed potential promise for itspractical application in an industry setting.