Synthesis of Nanostructured ZnO on HZSM-5 Zeolite: Characterization and Photocatalytic Properties

Nanostructured semiconductor particles prepared in polymeric, zeolite, and other organized media have drawn considerable interest in recent years because of their interesting photophysical and photochemical properties. It is suggested that encapsulating the semiconductor cluster in the porous support is a possible way to inhibit or to retard the electron-hole recombination [1, 2].Zinc Oxide (ZnO) an important semiconductor material with a band gap of 3.37 ev and exciton Bohr radius of 1.8 nm, has attracted much attention due to its promising applications in commercial devices such as a solar cell, photocatalysis, light emission, gas sensor, and other optical devices [1].The preparation of fine ZnO particles in solution has been carried out using various processes. However,these processes have many problems such as poor reproducibility, low yield, particle size control, distribution and shape, etc. The overall properties of the particles depend not only on their chemical nature but also their size and distribution. One of the most important factors for preparing the desired fine particles is controlling the reaction during the preparation of ZnO particles [3].Nitrophenols (4-NPh) are some of the most refractory pollutants, which can be present in industrial wastewater. These pollutants have high toxicity and carcinogenic character [4]. ZnO has been reported sometimes to be more efficient than TiO2 for the photooxidation of phenol and nitrophenol [5, 6].In this work, different amounts of ZnO nanoparticles were prepared on HZSM-5 (MFI type) microporous zeolites by the precipitation method. Photocatalitic efficiency of ZnO/HZSM-5 samples with 7% and 20% ZnO loading amounts was investigated under advanced oxidation process.