Mechanisms And Process Of Dye Degradation Using Microwave Absorbing Material Assisted With Microwave Irradiation

With the rapid development of economy, the human values more and more high about environment, such as environmental pollution, the most direct and polluting industries and related industrial products. Most dyes and dye intermediates are carcinogenic, teratogenic, mutagenic, toxic biological characteristics, human health and ecosystems are causing serious harm. Exploring dye degradation method has become a top priority.We studied the absorbing materials AB2O4 (A=Sr, Ba, Fe, B=Fe, Co) as a catalyst, microwave irradiation degradation dye wastewater (crystal violet, methyl violet, malachite green) was studied. The influence of calcination temperature of AB2O4, initial dye concentration, the amount of catalyst, pH value of the dye solution, the microwave power, microwave irradiation time, interfering ions and other factors on the degradation efficiency were studied. Through a series of analytical methods for degradation mechanism AB2O4 would be revealed.Magnetic ferrite SrFe2O4 is synthesized by sol-gel method and is used XRD, SEM and VSM methods to characterize. The results showed prepared SrFe2O4 has spinel structure, and with good magnetic properties. Crystal violet and methyl violet are as the target pollutants to judge the catalytic property of SrFe2O4. Optimum degradation conditions is:the calcination temperature of SrFe2O4 is 400℃, added SrFe2O4 mass fraction of 0.1%, and 50 mL 10mg L-1 crystal violet and methyl violet solution in a microwave reactor with output power 500 W, the degradation efficiency of the microwave radiation for 8 min could reach more than 80%. The reaction kinetics of CV/MV obeyed the apparent pseudo-first-order model. The reaction rate was 0.22 min-1 and 0.17 min-1, respectively. Radicals trapping studies revealed the holes (h+), hydroxyl radicals (·OH) and superoxide radical (·O2-) were involved as the main active species in the reaction.Magnetic ferrite BaFe2O4 is synthesized by citrate-nitrate combustion method and use XRD, SEM and VSM methods to characterize. The results showed prepared has spinel structure, and with good magnetic properties. Crystal violet is as the target pollutants to judge the catalytic property of BaFe2O4. Optimum degradation conditions is:the calcination temperature of BaFe2O4 is 800℃, added BaFe2O4 mass fraction of 0.06%, and 50 mL 10 mg L’1 crystal violet solution in a microwave reactor with output power 500 W, the degradation efficiency of the microwave radiation for 8 min could reach 90%. The reaction kinetics obeyed the apparent pseudo-first-order model. The reaction rate was 0.44min-1. Radicals trapping studies revealed the holes (h+) and superoxide radical (·O2-) were involved as the main active species in the reaction.Magnetic ferrite FeCo2O4 is synthesized by thermal decomposition method and use XRD, SEM and VSM methods to characterize. The results showed prepared FeCo2O4 has spinel structure, and with good magnetic properties. Malachite green is as the target pollutants to judge the catalytic property of FeCo2O4. Optimum degradation conditions is:the calcination temperature of FeCo2O4 is 600℃, added FeCo2O4 mass fraction of 0.2%, and 50 mL 20 mg L"1 malachite green solution in a microwave reactor with output power 500 W, the degradation efficiency of the microwave radiation for 8 min could reach 90%. The reaction kinetics obeyed the apparent pseudo-first-order model. The reaction rate was 0.13min-1. Radicals trapping studies revealed the holes (h+) and superoxide radical (·O2-) were involved as the main active species in the reaction.The results show that, MW/AB2O4 system applied to the degradation of dye can greatly reduce the degradation time and increase the rate of degradation. Also by ion chromatography and UV measurement results, the refractory organic dye molecules have been completely mineralized to inorganic ions and other harmless substances. The MW/AB2O4 system will not cause secondary pollution. The degradation efficiency is still above 80% after four times, reducing the waste of resources and damage to the ecological environment.