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Microwave-assisted catalytic technology is potentially promising in the application of water treatment due to its merits of high reaction rates, simple equipment and operations. In case of the cartap wastewater rarely studied, the easy transformation of cartap into metabolites could induce higher toxicity. This study aimed to develop a novel catalyst Ce/Co/γ-Al2O3 to dispose cartap effectively. The catalyst was prepared by loading Ce and Co on the surface of the support Al2O3, followed by characterization with X-ray diffraction, scanning and transmission electron microscopies. Based on the treatment results, the microwave-induced catalytic oxidation procedure over Ce/Co/γ-Al2O3 could decompose the contaminants efficiently and fast in the case of a low oxidant dosage and a wide pH range. Under the conditions of pH of 5, microwave power of 450 W, catalyst dosage of 0.7 g and hydrogen peroxide dosage of 0.2 mL, the activity of Ce/Co/γ-Al2O3 catalyst could reach up to 86.08%. Importantly, the Ce/Co/γ-Al2O3 catalyst displayed excellent stability after using for 6 times in the degradation process. This work paved a new way for the effective catalyst design for efficient microwave-induced oxidative degradation.

Abstract. Presently, the preparation of high pure manganese sulfate solution shows a long and complex process with low efficiency from the low grade manganese ore. The complete removal of calcium and magnesium ions coordinating with high recovery rate of manganese becomes one of the challenges for the conventional preparation of manganese sulfate. In the paper, the general removal methods of Ca 2+ and Mg 2+ including crystallization, electrolysis, extraction and chemical precipitation were reviewed at first. Moreover, a novel approach was proposed herein with the aid of theoretical calculation, in which Ba(OH) 2 was used to adjust the pH value of manganese sulfate solution and BaF 2 was used to completely remove Ca 2+ and Mg 2+ . The initial experimental results show that the calcium and magnesium removal rate reached 95.11% and 97.93%, respectively, and the recovery rate of manganese keeps 96%, which shows the prospect of industrial application.