Study On Microwave-Induced Catalytic Degradation Of Aqueous Methyl Orange Solution With Mineral Bearing Chromium

Mineral resources are important elements for society's survival and development. Mining industry possesses a significant postion in our country. But there is much pollution resource from it. It is worthwhile to investigate the catalyst from mining waste for organic wastewater treatment. Employed mineral bearing chromium, microwave and advance oxidation processes (AOPs) were integrated for degradation of azo dyestuff wastewater in order to find a new way to purify the environment.Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of wastewaters containing non-easily removable organic compounds. Methyl orange (MO) is a typical azo dyestuff. Researchs were carried out in the following aspects: (1) Feasibility of degradation of methyl orange solution was studied with microwave - H2O2 system. (2) To improve the efficiency of oxidation process, microwave-Fenton process was investigated; in the meanwhile, comparative research was done among Fenton, heating-Fenton and ultrasonic-Fenton. (3) Wastewater containing chromium and chromium slag are toxic heavy metal waste and it becomes a public concerned problem. Moreover, some azo dyestuff wastewater also bears chromium compounds. From the strategy of recycle economy, minerals bearing chromium including Cr3+, Cr6+ and chromium slag were selected as catalysts instead of Fe2+, and combined with H2O2 to form a new Fenton-like catalytic system. Feasibility and decolorization mechanism were studied for degradation of methyl orange solution with microwave assisted catalytic oxidation of minerals bearing chromium.From the investigation, main results were obtained as following:(1) Microwave or H2O2 could not effectively decolorize methyl orange solution separately. Microwave can induce conversion of H2O2 to·OH, and it is helpful to the degradation of methyl orange solution. Microwave has a great potential application value because of its thermal and non-thermal effect.(2) The hydroxyl radical generated by the decomposition of hydrogen peroxide under the microwave irradiation could make MO solution to degrade availably. Its behavior was submitted to the pseudo-first order kinetics, lnC/[C] = -2.473t-2.738. At pH<3.1, decolorization ratio came to nearly 100%; While pH value of MO solution was over 3.1, the decolorization process was inhibited.(3) Microwave-Fenton process for degradation of MO solution had had higher...