Abstract:
The goal of this research is to develop zinc oxide (ZnO) photocatalysts using zinc-dust wastes from the hot-dip galvanizing process as starting materials via a hydrothermal method. Effects of acid types for zinc-dust dissolving process and concentration of NaOH for ZnO precipitation on their phase, morphology, specific surface area (SBET), and photocatalytic activities through the degradation of rhodamine B dye (RhB.) under UV irradiation were investigated. The ZnO rod-shaped particles prepared by dissolving zinc-dust with nitric acid, then precipitating with 6 M NaOH (ZnO(N-6M)), and hydrothermal at 170 oC for 8 h exhibited the highest dye degradation efficiency (89.7%). This is comparable to that of commercial ZnO (92.7%). This research also studies the enhancement of photocatalytic performance under visible light irradiation of the synthesized ZnO through preparing composites with graphitic carbon nitride (g-C3N4). The ZnO/g-C3N4 composites prepared by physical grinding, dispersion mixing, and co-calcination showed remarkably lower photocatalytic activities for the degradation of RhB. under visible light irradiation, compared to those of pristine g-C3N4. Contrarily, the ZnO/g-C3N4 composites synthesized via the solvothermal method at 150 °C for 4 h (1Z/gCN_Solv.150) exhibited the best photocatalytic activity (97.9%). This is due to higher SBET (68.4 m2/g) and the heterostructure formation in 1Z/gCN_Solv.150, leading to lower recombination rate of e- and h+.