【作者】 王洁；

【导师】 陈建林； 卢宁川；

【作者基本信息】 南京大学 ， 环境工程（专业学位）， 2018， 硕士

【摘要】 光催化技术因在治理污染方面具有节能高效、绿色环保的优势,成为当前的研究热点。研究发现,g-C₃N₄具有无毒、化学性质稳定、成本低廉等优点,是一种非常有潜力的光催化材料,但其电子-空穴复合迅速、对太阳能利用率低,导致在实际应用时光催化效果不佳。因此,本文考虑将其与另一种窄带隙半导体SnWO₄复合,以提高其可见光催化活性。以g-C₃N₄、Na2WO₄和SnCl2为原料,通过溶剂热法合成SnWO₄/g-C₃N₄复合光催化剂。通过XRD、SEM、TEM、BET、UV-visDRS等手段对催化剂进行表征分析,以亚甲基蓝为探针污染物,考察制备条件对SnWO₄/g-C₃N₄光催化活性的影响,筛选出光催化活性最好的催化剂的制备条件。并进一步考察影响光催化降解亚甲基蓝、曙红B和孔雀石绿的因素,同时考察SnWO₄/g-C₃N₄的重复使用性能。本论文研究结果表明:（1）前驱液pH=7,热处理温度为180℃、反应时间为12h、复合比例n（SnWO₄）:n（g-C₃N₄）=0.1:l的条件下制备的SnWO₄/g-C₃N₄光催化活性最好,相比g-C₃N₄和SnW04,在相同条件下降解亚甲基蓝的效率分别提高了 91.9%、46.7%。（2）通过降解亚甲基蓝、曙红B和孔雀石绿,表明SnWO₄/g-C₃N₄具有较好的光催化活性。光照180min后,1.0g/L的催化剂光催化降解15mg/L亚甲基蓝的脱色率可达94.2%;光照50min时,0.6g/L的催化剂光催化降解20mg/L的曙红B的脱色率为99.9%;光照180min时,1.5g/L的催化剂光催化降解20mg/L的孔雀石绿的脱色率为88.7%。（3）NaCl的加入对光催化降解亚甲基蓝、曙红B和孔雀石绿起抑制作用。（4）SnWO₄/g-C₃N₄具有良好的稳定性,重复使用5次后,对亚甲基蓝、曙红B和孔雀石绿仍具有较高的光催化活性。（5）亚甲基蓝、曙红B和孔雀石绿的光催化降解过程基本符合一级反应动力学规律,表观反应速率常数k随溶液初始浓度的增大而逐渐减小。本课题研究将进一步拓宽类石墨相氮化碳和钨酸盐的研究领域,研究成果对于处理染料废水及难降解有机物具有一定的理论指导和现实意义。更多还原

【Abstract】 Photocatalysis as an efficient and environmental-friendly way to manage pollution has received extensive attention in recent years.G-C₃N₄ is a very potential catalytic materials because of its many advantages,sach as non-toxic,stable chemical properties and low cost.Nevertheless,the high recombination rate of photo-generated electron-hole pairs and low utilization of sunlight are two main issues limiting the significant photocatalytic efficiency of g-C₃N₄.In order to improve its photocatalytic activity in visible light,we considered to combine g-C₃N₄ with another traditional narrow band semiconductor catalyst SnWO₄.Using g-C₃N₄,Na2WO₄ and SnCl2 as the raw materials,the visible-light photocatalyst SnWO₄/g-C₃N₄ was synthesized by solvothermal process.The prepared photocatalysts were characterized by XRD,SEM,TEM,UV-vis DRS and BET surface area analysis.The preparation conditions of the SnWO₄/g-C₃N₄ photocatalysts with better visible light photocatalytic activity were screened through the degradation of methylene blue,and the influencing factors of photocatalytic degradation of methylene blue,eosin B and malachite green and the reuse performance of the photocatalysts were also investigated.The results of this study show that:（1）The optimum synthesis condition of SnWO₄/g-C₃N₄ was selected as:solvothermal synthetic temperature-180℃,solvothermal holding time =12 h,the pH value of solvothermal precursor =7,and n（SnWO₄）:n（g-C₃N₄）=0.1:1.The degradation rate methylene blue compared with pure g-C₃N₄ and pure SnWO₄ increased by 91.9%and 46.7%.（2）The SnWO₄/g-C₃N₄ photocatalyst has splendid photocatalytic activity to photodegrade methylene blue,eosin B and malachite green.The decolorization rate could reach about 94.2%after visible-light illumination for 180mins,when the initial concentration of methylene blue was 15mg/L,the catalyst dosage was 1.0g/L;The degradation rate of 20mg/L eosin B could amount to 99.9%within 180 mins using 0.6g/L compound catalyst;And the degradation rate of 20mg/L malachite green can reach about 88.7%within 180 mins using 1.5g/L compound catalyst.（3）NaCl inhibited the degradation of methylene blue,eosin B and malachite green.（4）The SnWO₄/g-C₃N₄ photocatalyst has excellent photocatalytic activity to photodegrade methylene blue,eosin B and malachite green after 5 times of repeated use.（5）Photocatalytic degradation of methylene blue,eosin B and malachite green accord with the first-order reaction kinetics model,and the apparent reaction rate constant decreased with the increase of initial concentration of solution.This topic research will further broaden the research field of graphite phase nitride carbon and tungstate photocatalyst,and the research result has a certain theories guides and realistic meaning to the treatment of dye wastewater and other refractory organic pollutants.更多还原