National Institute of Technology Durgapur, Department of Chemical Engineering, Durgapur- 713209, India Prince Mohammad Bin Fahd University, Department of Mechanical Engineering and Deanship of Research, Alkhobar, Kingdom of Saudi Arabia E-mail: susmita.dutta@che.nitdgp.ac.in Manuscript received online 01 June 2020, revised and accepted 20 September 2020 The critical challenge for the cost-effective application of seawater reverse osmosis systems is membrane fouling due to organic pollutants.

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... s study evaluates the effectiveness of employing solar photocatalysis of TiO2-ZnO process to pretreat reverse osmosis (RO) feed seawater under solar irradiation. Process optimization and performance evaluation were undertaken using the central composite design (CCD) with response surface methodology (RSM) techniques. Statistical analysis was performed to determine the interactive relationships and effects between input factors such as TiO2 dosage, pH, reaction time (RT) and ZnO dosage. Process optimization and performance evaluation were determined in terms of degradation efficiency of total organic carbon (TOC) and chemical oxygen demand (COD). The quadratic models developed for TOC and COD responses were found to be significant with very low probabilities (<0.0001). Organic removal with a reaction time of 90 minutes, pH 4.0, TiO2 dosage of 0.6 gL-1 and ZnO dosage of 0.39 gL-1 were found to be optimum by achieving 60.97% degradation of COD and 64 % degradation of TOC. The experimental results (COD removal = 58.09% and TOC removal = 62.25%) correspond well with the predictions. The optimum validation degradation efficiencies without changing original pH of seawater (at pH= 8) were obtained as: COD removal = 51.23 % and TOC removal = 59.65%.