Research On Removal Of Toluene By Microwave Stepless Ultraviolet Advanced Oxidation Technology

Volatile organic compounds(VOCs)are one of the most important air pollutants for prevention and control.Their harm to the human body and environmental damage have caused widespread concern.The management of VOCs has been fully developed.At present,the commonly used VOCs processing technology has problems such as high cost,difficulty in maintenance,or failure to mineralize VOCs.Based on microwave technology,this thesis intends to develop a single microwave-induced composite advanced oxidation technology with low cost,easy maintenance and high mineralization rate for VOCs.The specific research contents are as follows:In this study,a microwave-induced composite advanced oxidation technology evaluation device was built,and the operating parameters of the device were tested.The results show that as the microwave power increases,the light intensity increases,and the temperature of the resonant cavity and the temperature of the photocatalyst Ti O2 increase,the ozone concentration first increases and then decreases.As the relative humidity and gas flow increase,the temperature of the resonant cavity decreases slightly,and the ozone concentration first increases and then decreases.At a microwave power of147.75 W,a relative humidity of 70 %,and a gas flow rate of 400 m L/min,the ozone concentration is at most 55.4 ppm.The performance of single process in composite oxidation technology was evaluated.The increase of microwave power,the increase of ozone to toluene concentration ratio and the increase of catalyst dosage,the decrease of gas flow rate and initial concentration of toluene were beneficial to the removal of toluene.When the relative humidity is 70 %,the toluene degradation rate and mineralization rate are maximized.When the microwave power is 147.75 W,the relative humidity is 70 %,the gas flow rate is 200 m L/min,and the initial concentration of toluene is 5 ppm,the mineralization rate is 31.4 % in the photo-oxidation process,and both benzene and chain organic substances are present in the product.In the catalytic ozonation process,the degradation rate of toluene reaches 63.5 %,the mineralization rate is 22.6 %,and only benzene series in the product.In the photocatalytic process,the degradation rate of toluene is 85.6 %,and the mineralization rate can reach 47.2 %.The product is mainly benzene series,as well as formic acid.The performance of the composite process in the composite oxidation technology was evaluated.In the composite process,the degradation rate of toluene is above 95 %.When the two processes are combined,the mineralization rate is higher than the sum of the individual processes.When the microwave power is 147.75 W,the relative humidity is 70 %,the gas flow rate is 200 m L/min,and the initial concentration of toluene is 5ppm,the mineralization rate can reach 55.3 % in the photooxidation-catalyzed ozone oxidation process.Only the benzene series and Long carbon chain organic matter is in the product.In the photooxidation-photocatalytic process,the mineralization rate can reach 81.5 %,the product is only benzene series.In the photooxidation-catalyzed ozone oxidation-photocatalysis process,the mineralization rate can reach 92.8 %,the product is basically benzene series,and the structure is more complicated.When the relative humidity is 70 %,the microwave power is 147.75 W,the gas flow rate is 200 m L/min,and the initial concentration of toluene is 20 ppm,the toluene degradation rate remains above 96 % for a long time of 50 h,and the mineralization rate is reduced from 70.3 %to 45.6 %.After the system is regenerated in situ with air,it can be reactivated,indicating that system maintenance is easy.