纳米ZnO的制备及其光催化降解印染废水-《深圳大学学报理工版》

文章信息/Info

Title:: Preparation of nano-ZnO and its photocatalyticdegradation of dyeing wastewater

作者:: 王丽娟1; 李晓宁1; 陈爱武2; 王莹1; 江卜涛1; 1) 河北工业大学土木与交通学院，天津 300401；2) 天津市武清自来水公司，天津 301700

Author(s):: WANG Lijuan1; LI Xiaoning1; CHEN Aiwu2; WANG Ying1; and JIANG Butao1; 1) School of Civil Engineering and Transportation, Hebei University of Technology, Tianjin 300401, P.R.China 2) The Water Supply Company of Wuqing District, Tianjin 301700, P.R.China

Keywords:: municipal engineering; direct precipitation method; nano-ZnO; photocatalytic; methylene blue; catalytic mechanism; water treatment; dyeing wastewater

摘要:: 采用直接沉淀法将氯化锌与氨水反应合成纳米ZnO粉末，通过X射线衍射和扫描电子显微镜进行表征．在模拟紫外光和可见光条件下，以亚甲基蓝(methylene blue，MB)为印染废水中目标污染物，考察了纳米ZnO的光催化活性，研究制备纳米ZnO时的煅烧温度、纳米ZnO投加量、光催化反应时间、溶液的初始pH值和初始质量浓度对MB去除率的影响．结果表明，在煅烧温度为400 ℃(此时ZnO形貌为球状与片状混合)、纳米ZnO的投加量为2 g/L、溶液的初始质量浓度为5 mg/L、pH=9时，紫外光和可见光分别照射3 h后纳米ZnO对MB最大去除率为93.11％和65.49％；紫外光照下纳米ZnO循环使用4次后对MB的去除率仍达到88.00％；自由基猝灭实验表明，空穴是纳米ZnO降解MB的主要因素．纳米ZnO粒径小、比表面积大、禁带宽度小、重复利用率高，且绿色环保，可广泛用于水处理领域．

Abstract:: The nano-ZnO powder is synthesized by using the direct precipitation method through the reaction between zinc chloride and ammonia water, and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Under the simulated ultraviolet and visible light conditions, methylene blue (MB) is used as the target contaminantin dyeing wastewater to investigate the photocatalytic activity of nano-ZnO. The effects of the calcination temperature, nano-ZnO dosage, photocatalytic reaction time, initial pH and initial concentration on the MB removal efficiency are studied. The results show that when the calcination temperature is 400 ℃ (the morphology of ZnO is spherical and flake-likemixed), the nano-ZnO dosage is 2 g/L, the initial mass concentration of the solution is 5 mg/L, and pH=9, the maximum removal rate of MB by nano-ZnO can reach 93.11% after UV irradiation for 3 h, and the maximum removal ratio of MB is 65.49% after exposure to visible light for 3 hrs. The removal ratio of MB after nano-ZnO recycling for 4 times under ultraviolet light can still reach 88%. The results of free radical quenching experiments show that the holes are the primary controlling factor for the degradation of MB by nano-ZnO. Because nano-ZnO is small in size, large in specific surface area, small in forbidden band gap, high in recycling rate, and environmentallyfriendly, it would have broad application prospects in water treatment.