Adsorption of Organic Pollutants onto Microplastics
Microplastics (MPs) are small plastic pieces with sizes ranging from 1 mm to 5 mm in diameter. Polyethylene (PE) is a common polymer used in plastic material and eventually breaks down to MP size overtime in the environment through a process called weathering. Weathering of MPs alters their surface chemistry and chemical composition, breaking the polymer down to smaller sizes and creating oxygen containing functional groups. MPs can be found ubiquitously throughout the environment and are capable of adsorbing organic pollutants, acting as vectors of transport. Their small size allows for more surface area for contaminates to adsorb onto. Weathering of MPs also allows for stronger interactions between contaminates due to new carbonyl groups on the MPs surface. Ethylparaben (EtP) and oxybenzone (BP-3) are two common organic pollutants found in personal care products (PCPs) and are frequently released into the environment where they can interact with MPs. The adsorption of EtP and BP-3 onto PE MPs was analyzed using ultra-high performance liquid chromatography (UHPLC). The UHPLC parameters and figures of merit for EtP and BP-3 were established. The adsorption experiments used size of MPs, weathering of MPs, and time as the experimental variables. Pristine small and large MPs were used to show how the larger surface area of the small MPs sorb more than the large MPs. The adsorption of organics to artificially weathered MPs versus pristine MPs was performed to see how mimicking MPs found in the environment affects adsorption. The weathering of MPs did not increase adsorption of organics due to the increase in hydrophilicity of the MPs. Time was also a factor to show that if MPs were stirring in the organic pollutant solution for longer periods of time, there is more sorption.
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