废弃口罩基ZIF-8/Ag/TiO2复合材料的制备及其光催化降解染料性能

针对废弃口罩和印染废水处理难题,利用金属有机骨架ZIF-8高度可调的孔径、大的比表面积、优异的吸附和光催化活性,基于化学共沉淀法和煅烧技术制备出ZIF-8/Ag/TiO₂异质结,并将其负载到废弃的口罩上。对颗粒物和口罩复合材料的形貌、结构、比表面积、键合状态、能带结构和热稳定性进行了分析,测定了吸附、光催化降解亚甲基蓝和刚果红染料性能。研究结果表明:较原始口罩,废弃口罩基ZIF-8/Ag/TiO₂复合材料的吸附、可见光光催化降解亚甲基蓝染料能力分别提高了12.9倍和4.8倍,且可多次重复使用;较ZIF-8和ZIF-8/TiO₂,ZIF-8/Ag/TiO₂异质结吸附能力和可见光光催化活性增强。Ag掺杂ZIF-8/ZnO与C、N掺杂TiO₂使得ZIF-8/Ag/TiO₂异质结带隙变窄,且有孔的中空结构能够更加充分地吸收可见光。

Preparation of discarded mask-based ZIF-8/Ag/TiO2 composite and its photocatalytic property for dye degradation

Aiming to use discarded masks for purifying printing and dyeing wastewater, ZIF-8/Ag/TiO₂ heterojunction was prepared based on the chemical co-precipitation and calcination methods using metal organic framework ZIF-8 as the supporting material, making use of the characteristics of ZIF-8 being highly adjustable pore size, large specific surface area, excellent adsorption capability, and high photocatalytic activity. The synthesized ZIF-8/Ag/TiO₂ particles were loaded on the surface of discarded mask. The morphology, structure, specific surface area, chemical bonding state, electronic energy band structure, and thermal stability of the resultant particles and mask-based composite were systemically characterized. The properties of adsorption and visible light photocatalytic degradation of methylene blue and Congo Red dyes were investigated. Experimental results indicated that in comparison with the untreated mask, the adsorption and photocatalytic degradation capabilities towards methylene blue by the mask-ZIF-8/Ag/TiO₂ composite were improved by 12.9 and 4.8 times respectively with good reusability. ZIF-8/Ag/TiO₂ heterojunction exhibited stronger adsorption capacity and visible light photocatalytic activity as compared with ZIF-8 and ZIF-8/TiO₂. The band-gap of ZIF-8/Ag/TiO₂ was narrowed due to the doping of Ag into ZIF-8/ZnO and the doping of C and N into TiO₂. In addition, the hollow-structured ZIF-8/Ag/TiO₂ with holes could absorb more visible lights.