Performance of a multistage rotating mesh support photoreactor immobilized with TiO2 on photocatalytic degradation of PNP: Reactor construction and optimization

Abstract

In this study, a novel multistage rotating mesh support photoreactor was designed and employed for investigation of photocatalytic degradation of p-Nitrophenol (PNP) in aqueous solution under UV irradiation. Electrophoretic deposition (EPD) method was applied for TiO2 immobilization on the stainless steel mesh supports and surface characterizations were carried out by XRD, SEM, and BET. Central composite design (CCD) method was employed to model and optimize the process. Based on the model prediction, maximum predicted and experimental photocatalytic degradation percent of PNP under the optimum conditions of recirculating flow rate = 6 l/min, rotational speed =76 rpm and number of TiO2 immobilized meshes = 24 were obtained to be 95.7% and 95.48%, respectively. Under the optimum condition, the effect of initial solution pH on the photocatalytic degradation process was investigated and the results indicated that the PNP degradation efficiency was enhanced by reducing the initial pH to 3.5. The reduction in TOC content under optimum condition was about 55% after 5 h. Moreover, pseudo-first-order model fitted the process kinetics perfectly.