微/纳米ZnO绒球的制备及其在自然光下催化降解有机染料性能

以谷氨酸氟硼酸(GluBF₄)离子液体水溶液为反应介质,以物质的量比为1:6的二水合醋酸锌[Zn(Ac)₂·2H₂O]和氢氧化钠为原料,室温下制备前驱体,再微波辅助加热制备了纳米氧化锌粉体,获得了纳米结构微米尺寸纳米ZnO绒球.利用场发射扫描电镜(FESEM)、X射线衍射(XRD)、比表面(BET)、能量色散谱(EDS)等对产物进行了表征.所得产物为六方晶系纤锌矿结构,粉体粒径20.4 nm,绒球比表面积为28.3 m²·g^-1,产物纯度较高,收率95.3%.同时探讨了纳米ZnO绒球生成的可能机理.该纳米材料在日光下显示较高的光催化活性和稳定性.分别配制浓度为10 mg·L^-1的100 mL甲基橙(MO)和甲基紫(MV)水溶液, 30 mg纳米氧化锌为光催化降解催化剂,太阳光激发下5 h脱色率分别达到74.3%和96.9%;溶液总有机碳(TOC)含量随光降解的进行缓慢下降;光催化剂重复利用5次,催化剂形貌不变、颜色不变,质量基本未发生变化.

Preparation of Micro/Nano ZnO Pompons and Their Catalytic Activity for the Solar Degradation of Organic Dyes

A novel, high-yielding synthesis of micro/nano ZnO pompons using glutamic acid fluoborate (GluBF₄) ionic liquid is reported. The precursor was prepared with zinc acetatedihydrate [Zn(Ac)₂·2H₂O] and sodium hydroxide (molar ratio = 1:6) as starting materials in an aqueous solution of the GluBF₄ ionic liquid at room temperature, which was then heated by microwave to form nano-ZnO powder. The ZnO pompons were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), specific Brunauer-Emmett-Teller (BET) surface area method, and energy dispersive spectrometry (EDS). The product displayed a hexagonal wurtzite structure. The pompon diameter was determined to be 20.4 nm, with a pompon specific surface area of 28.3 m²·g^-1. A possible mechanism for the formation of the nano-ZnO pompons is discussed. The ZnO pompons displayed high photocatalytic reactivity and photostability under sunlight. Aqueous solutions of methyl orange (MO) and methyl violet (MV) containing the ZnO pompons were exposed to sunlight and the decolorization rates were determined by monitoring the drop in color intensity. After 5 h, the solutions reached 74.3% and 96.9% degradation, respectively. The total organic carbon (TOC) content decreased as the photodegradation process occurred. The morphology, color, and weight of the ZnO pompons remained unchanged even after being reused five times.