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研究报告

Synthesis of ZnO-PMMA composites for photocatalytic removal of ammonia nitrogen at low concentration

摘要：通过水热法制备纳米ZnO，采用热粘固法成功地将其负载于聚甲基丙烯酸甲酯（PMMA）微球表面，并对ZnO-PMMA复合材料光催化去除水中低浓度氨氮的能力进行了考察.同时，探究了负载比例、初始氨氮浓度、催化剂浓度和pH对低浓度氨氮去除效率的影响.实验结果显示，PMMA改善了纳米ZnO的分散性和光催化能力，ZnO-PMMA能够有效地催化去除氨氮废水.在汞灯照射下，当pH=12、温度为30℃时，1 g·L^-1的催化剂（ZnO-PMMA）对50 mg·L^-1的氨氮废水去除率达到66%，且反应产物硝氮和亚硝氮含量较低，体现了该催化剂具有将氨氮转化为N₂的良好的光催化降解能力.同时，纳米材料可以简单方便地回收，减轻了对环境的潜在影响，符合绿色化学的原则.

Abstract：A new kind of photocatalyst composite, ZnO-PMMA was produced by immobilizing ZnO nanoparticles synthesized by the hydrothermal method onto methyl methacrylate (PMMA), following the thermal attachment method.The properties of the as-prepared ZnO-PMMA were further characterized by X-ray diffraction, scanning electron microscopy, UV-Vis diffuse reflectance spectroscopy and flam atomic absorption spectrophotometer.Meantime, the ability of ammonia-nitrogen removal of composite was evaluated along the gradients of pH, load ratio, the initial concentrations of ammonia nitrogen and photocatalyst dosage.It is found that ZnO nanoparticles were evenly anchored on PMMA surface, which could mitigate the agglomeration of ZnO nanoparticles and promote their recovery in the reaction system.The highest ammonia-nitrogen removal efficiency (around 66%) was observed at the condition of the initial 50 mg·L^-1 of ammonia nitrogen, 1 g·L^-1 of ZnO-PMMA, at 30℃ and pH 12 under UV irradiation.The final product was almost exclusive nitrogen, indicating the excellent catalytic selectivity of ZnO-PMMA.in summary, our investigation indicates that ZnO-PMMA is a kind of the environmentally friendly and highly efficient photocatalyst complex for the removal of ammonia nitrogen at low concentration.