Adsorption of benzophenone-3 and octocrylene UV filters on polyethylene:analysis by HPLC-MS/MS and voltammetry with screen-printed electrodes

Abstract

Microplastics (MPs) are persistent pollutants that can adsorb contaminants, facilitating their accumulation inaquatic ecosystems. The presence of UV filters (UVFs) such as benzophenone-3 (BP3) and octocrylene (OC),exacerbates this issue, particularly in coastal areas. This study presents an innovative dual-method approachcombining high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and differentialpulse adsorptive stripping voltammetry (DPAdSV) to assess the adsorption of UVFs on polyethylene (PE), awidely found polymer in aquatic environments. Adsorption kinetics were analysed using pseudo-first-order(PFOM) and pseudo-second-order (PSOM) models, revealing a higher equilibrium sorption capacity for OCdue to its stronger hydrophobic interactions with PE. A central composite design (CCD) was employed to enhanceresources efficiency in experimentation and controlled experiments exposed the materials to both pure freshwater and synthetic seawater. The results indicate a higher adsorption affinity of OC on PE than BP3, attributedto its high octanol-water partition coefficient (log Kow 6.88) and stronger hydrophobic interactions. Exposuretime was the most influential variable across both media, while pH and temperature had a significant effect onBP3 adsorption in synthetic seawater. Hydrophobic partitioning, aided by van der Waals forces, was identified asthe dominant interaction mechanism for both UVFs, with π–π and electrostatic interactions playing minimal rolesdue to the nature of the polymer. The study provides new insights into how polymer–pollutant interactions varyacross environmental conditions and offers a novel voltammetric alternative for in-situ UVFs monitoring.