Solar nanophotocatalytic pretreatment of seawater: process optimization and performance evaluation using response surface methodology and genetic algorithm

Abstract

In reverse osmosis seawater treatment process, membrane fouling can be mitigated by degrading organic pollutants present in the feed seawater. The present study evaluates the effectiveness of employing solar photocatalysis using TiO2/ZnO/H2O2 to pretreat reverse osmosis (RO) feed seawater under solar irradiation. Process optimisation and performance evaluation were undertaken using response surface methodology-desirability function and RSM integrated with genetic algorithm (RSM-GA). Statistical analysis was performed to determine the interactive relationships and main effects of input factors such as TiO2 dosage, H2O2 dosage, pH, reaction time and ZnO dosage. The performance evaluation was determined in terms of percentage removal of total organic carbon (TOC) and chemical oxygen demand (COD). The obtained optimum values using RSM-GA evaluation for TOC and COD removal were found to be 76.5% and 63.9%, respectively. The predicted RSM-GA results correspond well with the experimental results (TOC removal = 73.3%, COD removal = 61.2%). Utilization of renewable solar energy coupled with optimum utilisation of nanophotocatalysts enables this technique to be a unique treatment process for RO pretreatment of seawater and membrane fouling mitigation.