Leaching of triphenyl phosphate and tri-n-butyl phosphate from polystyrene microplastics: influence of plastic properties and simulated digestive fluids.

Abstract

Microplastics have gained considerable attention as a growing environmental problem owing to their potential to serve as vectors for harmful chemicals. However, the leaching of these chemicals from microplastics is unclear. In this study, we investigated the leaching of two organophosphate flame retardants, triphenyl phosphate and tri-n-butyl phosphate, from polystyrene microplastics in simulated digestive fluids and water, and polypropylene microplastics were simultaneously used for comparison with polystyrene microplastics. The results indicated that the first-order kinetic model best explained the leaching process, suggesting that leaching was related to the release of organophosphate flame retardant molecules at the polymer surface. Additionally, the size and crystalline state of the microplastics had a significant effect on the leaching, whereas organophosphate flame retardant content had a minimal impact. Simulated digestive fluids facilitated the leaching to a different extent, and under these influencing conditions, leaching percentages from polystyrene microplastics did not exceed 0.51%. Therefore, leaching from PS microplastics may not be an important source of OPFRs in the environment. However, the release of organophosphate flame retardants can be considerably enhanced with the breakdown of polystyrene microplastics to polystyrene nanoplastics.