Catalytic oxidation of o-chloroaniline in hot compressed water: Degradation behaviors and nitrogen transformation

Abstract Catalytic oxidation of o-chloroaniline (o-ClA) in hot compressed water (HCW) was investigated in a fused quartz tube reactor (FQTR) to determine the effects of catalyst, temperature, oxygen stoichiometric ratio (OSR) and reaction time on o-ClA mineralization, total nitrogen (TN) removal rate and nitrogen-containing products distribution. The results showed that o-ClA can be effectively degraded in HCW. With the increased of OSR, retention time and temperature or added of Mn2O3 as catalyst, the mineralization rate of o-ClA and the removal rate of TN increased. Ammonia-N was the main nitrogen-containing intermediate product of o-ClA degradation, however, when the oxidant was excessive, ammonia-N was oxidized to form nitrate-N. Althought the catalytic effect of Mn2O3 on the mineralization of o-ClA was not outstanding, it promoted the removal of ammonia-N from the benzene ring, improved the degradtion of ammonia-N, and inhibited the production of nitrate-N. GC–MS analyzed results indicated that o-chlorophenol was the main degradation intermediate product of o-ClA in HCWO process. Meanwhile, the potential degradation pathway of o-ClA was proposed. This work thus provides basic knowledge about o-ClA catalytic oxidation removal in HCW process.