Comparison of catalysis and high energy irradiation for the intensification of wet oxidation as process wastewater pretreatment

摘要

Enhancing reaction rate in wet oxidation (WO) with catalysis and high energy irradiation was tested by comparing them with the usual thermal reaction. Total organic carbon and chemical oxygen demand (COD) conversion values of phenol degradation in the thermal WO were <20 % (150 degrees C, 20 bar, 2 h); in the catalytic reaction, they were nearly 60 %. Irradiation assisted oxidation produced more than 80 % COD conversion (30 min, absorbed dose similar to 18 kGy). This considerable increase in the oxidation rate at relatively low temperature is suggested to be due to temperature independent oxidation chain initiation by irradiation. Both the catalytic and especially the irradiation assisted reaction (at and above 125 degrees C) proved to be much more effective than the thermal WO. The condition of the application of Ti mesh monolith catalyst is the preparation of more leaching-resistant Ti mesh/Ru/Ir oxide catalyst with acceptable lifetime (>1000 h), that of the electron beam irradiation is the solving the problem of the introduction of the electron beam into the reaction mixture under high oxygen pressure without significant loss of intensity.