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Nitrogen-Phosphorus co-doped Zinc Oxide activated carbon (NPZAC) composite was prepared in this study. The prepared photocatalyst was characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The removal of 4-Nitrophenol (4-NP); by the modified ZnO based catalyst was studied and the effects of operational parameters such as 4-NP initial concentration, catalyst loading, pH and irradiation time were studied using full factorial experimental design. The reusability of NPZAC was also investigated. The investigation revealed that doping increased the removal efficiency of the catalyst by a factor of 0.35 (35 %) while addition of activated carbon further increased it to a factor of 1.82 (182 %) under the same condition. The statistical analysis of the experimental results showed that some model terms were significant (p<0.05) and the interactions plots revealed that catalyst loading was the most significant factor affecting the removal efficiency. This study revealed that optimum removal value of 100 % was achieved at low initial 4-NP concentration (10 mg/L), high catalyst loading (0.5 g), high pH (11) and long irradiation time (150 min). Also, the reusability test revealed that the composite can be used up to fifth cycles. Therefore, NPZAC can be used for the removal of 4-NP phenol pollutant.
Keywords: Photocatalytic removal, 4-Nitrophenol, Full factorial experimental design