Background: Pentachlorophenol is an organic compound and one of the primary pollutants and is carcinogenic. Extensive use of pentachlorophenol in the world has created a lot of pollution in soil and water. The aim of this study was to evaluate the efficiency of pentachlorophenol removal process using UV/ZnO and investigate the influence of parameters is to remove pentachlorophenol.

Methods: This is a fundamental study, which was conducted in the laboratory scale. Factors affecting such as concentrations of pentachlorophenol, pH, time and ZnO dose in removal pentachlorophenol from aqueous solution selected and evaluated. The measurement of pentachlorophenol was done by high-performance liquid chromatography. Data analysis was performed using the SPSS v. 16 software. 

Results: The results showed that by reducing the pentachlorophenol concentration and pH, increasing the amount of nanoparticles, pentachlorophenol removal efficiency has increased (89% for pH=3 VS 60% for pH=8). According to the results, UV radiation alone has little effect on the removal of pentachlorophenol. Ultraviolet radiation on zinc oxide nanoparticles, pentachlorophenol removal efficiency increases by about 90%. The kinetic analysis of the photoreduction showed that the removal of PCP is according to the Langmuir–Hinshelwood model (R2=0.979). The adsorption isotherm data (in the first 30 min without UV) were fitted to Freundlich isotherm model. FTIR analysis revealed that O-H and C-O-H play an important role in the sorption of pentachlorophenol.    

Conclusion: According to the results, the photocatalytic process UV/ZnO in acidic conditions can be used as an effective method for removal of pentachlorophenol from water sources.