We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Surface functional group dependent enthalpic and entropic contributions to molecular adsorption on colloidal microplastics
Summary
This chemistry study measured how different organic molecules (charged and neutral) stick to the surface of various microplastic particles in water, finding that the plastic's surface chemistry strongly influences the strength and nature of these interactions. The work reveals that both electrostatic attraction and water structure at the plastic surface play a role in determining what contaminants microplastics can carry. This matters because microplastics act as "carriers" for other pollutants, and understanding the binding chemistry helps predict which toxins hitchhike with plastics into ecosystems and organisms.
Molecular interaction with micro- and nano-plastics (MNPs) is an important chemical process that dictates the fate and transport of organic contaminants, and that of MNPs, within the aquatic environment. In this study, adsorption of cationic, anionic, and neutrally charged organic molecules from aqueous solution to model microplastics (MPs) is presented. Second harmonic generation, an interfacial selective laser-based technique that allows in situ measurements of adsorption isotherms, has been used. Polystyrene (PS) and polymethyl methacrylate (PMMA) microplastic particles with distinct charge characteristics were chosen. PS MPs investigated include distinct surface functional groups such as -OSO3, -COOH, mixed -NH2/-COOH, and amidine. Thus, the effect of different types of electrostatic interactions on adsorption have been analyzed. Comparison of adsorption Gibbs free energy for these MPs reveals that Coulombic attraction is important for spontaneous adsorption. However, distribution of water at the interfacial region, and functional group dependent interactions determine the magnitude of binding strengths. Entropic (ΔSads) and enthalpic (ΔHads) contributions to spontaneous adsorption have been determined by analyzing temperature-dependent adsorption isotherms. We show that ΔHads and ΔSads are dependent on the interfacial chemical composition of MPs and are not constant with respect to temperature. Although of varying degrees, MPs studied show an increase in entropy upon adsorption of organic molecules. These findings hint at a plausible influence of hair-like structure, common in polymeric soft matter, on the adsorption mechanism. This systematic study thus underscores unique colloidal features of the plastic/aqueous interface that are critical in adsorption of organic molecules by microplastics.
Sign in to start a discussion.
More Papers Like This
Adsorption behavior of organic pollutants on microplastics
This review summarizes the main mechanisms by which microplastics adsorb organic pollutants, including hydrophobic interactions, electrostatic forces, and hydrogen bonding. Researchers found that particle size, surface area, aging, and environmental factors like pH and temperature significantly influence how much pollution microplastics can carry. The study highlights the need for more field-based research to understand how microplastics behave as pollutant carriers in real environmental conditions.
Microplastic properties and their interaction with hydrophobic organic contaminants: a review
This review examines the physical and chemical properties of microplastics that determine how they interact with hydrophobic organic contaminants in the environment. Researchers found that factors like polymer type, particle size, weathering, and surface chemistry all influence how strongly microplastics bind to co-occurring pollutants. The findings suggest that microplastics can serve as carriers for harmful chemicals, potentially increasing exposure risks for organisms that ingest them.
Investigating the adsorption of organic compounds onto microplastics via experimental, simulation, and prediction methods
This review systematically examined experimental, simulation, and predictive modeling approaches for studying the adsorption of organic compounds onto microplastics, synthesizing findings on how molecular interactions, environmental conditions, and plastic aging affect microplastic vector behavior for organic pollutants.
Sorption of pharmaceuticals on the surface of microplastics
Researchers tested the ability of four common microplastic types to adsorb nine pharmaceutical compounds frequently found as water pollutants. They found that sorption involved both hydrophobic and electrostatic interactions, but under natural environmental conditions the binding was relatively weak. The study suggests that while microplastics can interact with pharmaceutical residues, their role as carriers of these contaminants in real aquatic environments may be more limited than previously assumed.
Sorption of representative organic contaminants on microplastics: Effects of chemical physicochemical properties, particle size, and biofilm presence
This study examined how organic pollutants like flame retardants and industrial chemicals attach to microplastics in saltwater conditions. Smaller microplastic particles absorbed more contaminants per unit weight, and natural biofilms growing on the plastic surfaces changed how much pollution they could carry. The findings help explain how microplastics act as carriers of toxic chemicals through the environment and potentially into the food chain.