Combining nanofiltration and electrooxidation for complete removal of nanoplastics from water

Abstract

Nanoplastics (NPs) have emerged as significant water contaminants, attracting increasing attention due to their potential impacts on aquatic ecosystems and human health. In addressing the environmental and health hazards posed by NPs in water, this new study explores a combined nanofiltration (NF) and electrooxidation (EO) approach. The proposed process begins with NF to concentrate the NPs in the water, followed by EO to degrade the NPs in the NF rejection. The results indicated that the employed NF system could completely eliminate NPs at different transmembrane pressures and times. The study also highlighted the influence of NP concentrations on recovery rates, showing a reduction in recovery at higher concentrations. Moreover, following the NF process, the EO process was examined for its efficiency in removing NPs over time and at various initial NP concentrations. The results revealed that the most effective durations were 20, 30, and 40 min for NP concentrations of 10, 22.5, and 35 mg/L, respectively. As a kinetic study, the rate of NPs degradation by the EO process was modeled using Langmuir–Hinshelwood (L-H) as well as power law models. The comparison between the models' predictions and the experimental data demonstrated that the power law and L–H models had good predictability for NP concentrations exceeding 10 mg/L and 2 mg/L, respectively. At concentrations below the 2 mg/L, deviations from the model were observed, likely due to changes in the reaction mechanism. It can be concluded from these results that, at low concentrations, the surface reactions were no longer the rate-determining step.