Persulfate-assisted electrochemical system for pharmaceuticals and personal care products removal: Performance evaluation, kinetics and energy assessment

• Application of persulfate assisted electrochemical system for PPCPs removal • Fe electrodes demonstrated superior performance over SS electrodes in DIC and MNZ removal • Optimal conditions were found to be 120 min, 15V, 500 mg/L PS dose with 4 electrodes • First-order kinetic model better represented the experimental data • Simultaneous removal of DIC and MNZ exhibited synergistic effect in multi-pollutant system Pharmaceutical and personal care products (PPCPs) are emerging contaminants of concern, posing significant risks to both human health and aquatic ecosystem due to limitations of conventional treatment systems. This study presents novel approach by evaluating performance of persulfate-assisted electrochemical system (PS-ECS) equipped with stainless steel (SS) and iron (Fe) electrodes for removal of metronidazole (MNZ) and diclofenac (DIC). The investigation covers MNZ and DIC removal from mono-pollutant (DIC/MNZ) and multi-pollutant (DIC+MNZ) systems. Performance of Fe and SS electrodes was evaluated under various operational conditions, focusing on kinetics, energy consumption and economic feasibility. This research explores PPCPs removal from spiked secondary effluent, providing unique insight into practical applications. Results revealed that Fe electrodes significantly outperformed SS, achieving higher removal efficiencies in mono-pollutant systems i.e. 99.1% for DIC and 94.3% for MNZ, compared to multi-pollutant conditions, where removal was 76.3% for DIC and 84.7% for MNZ. Optimal performance was obtained using four electrodes at 15V for 120 min, with 1 cm electrode spacing and PS dose of 500 mg/L. Removal of both pollutants followed first-order kinetics across all experimental conditions. Fe electrodes also proved more energy-efficient and cost-effective, with treatment costs of 0.32 USD/m 3 for DIC and 0.35 USD/m 3 for MNZ. Radical scavenging experiments using p-benzoquinone, ethanol and tert-butanol resulted in reduced rate constants, indicating that reactive species such as hydroxyl, sulfate and superoxide radicals play a dominant role in oxidation mechanism. Overall, study demonstrated that PS-ECS as promising, energy-efficient and economically viable method for simultaneous removal of PPCPs from wastewater.