On the Pb2+ ions adsorption onto microplastics

Abstract

Microplastic (MP) pollution has emerged as a critical environmental challenge with significant implications for ecosystems and human health. MPs are commonly found in aquatic environments ranging in size from 100 nm to 5 mm. Due to their small size and large specific surface area, MPs can adsorb and accumulate various chemical contaminants in aquatic systems . In particular, the adsorption of toxic metals onto MPs has gained increasing attention, as MPs not only act as pollutant adsorbents but also as vectors for the transport of hazardous substances [3]. Once ingested by marine organisms, MPs can induce toxic effects, including growth inhibition, reproductive toxicity, and genetic damage, ultimately threatening biodiversity. Here is investigated the adsorption of Pb²⁺ ions onto polystyrene (PS), carboxyl-functionalized polystyrene (PS-COOH), and polylactic acid (PLA) microplastics. Adsorption experiments were conducted in pure water, in NaNO₃ or NaCl 0.1 mol L⁻¹, and with the addition of sodium dodecyl sulfate (SDS) as a surfactant. Metal ion concentrations were determined using atomic spectroscopy and voltammetry. Furthermore, electrochemical impedance spectroscopy (EIS), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), zeta potential (ξ-potential), and Fourier-transform infrared spectroscopy (FT-IR) analyses were performed to elucidate the adsorption mechanisms. The results demonstrate that the adsorption of Pb²⁺ ions onto MPs strongly depends on the experimental conditions, highlighting the complex interactions between microplastics, metal ions, and environmental factors.