PNNL

Abstract

Biodegradable plastics can reach full degradation when disposed of appropriately and thus alleviate plastic pollution caused by conventional plastics. But additives can be released into the environment during degradation, and the fate of these additives can be aected by the degradation process. In this study, we characterized TiO2 particles released from a biodegradable plastic mulch during composting and studied the transport of the released TiO2 particles in inert sand and agricultural soil columns under unsaturated flow conditions. TiO2 microparticles were released from the biodegradable plastic mulch in both single particle and cluster forms. The released TiO2 microparticles were fully retained in unsaturated soil columns due to its ne texture, slow flow rate, and favorable attachment conditions. But in unsaturated sand columns, the released TiO2 microparticles were highly mobile. Comparison with the pristine TiO2 microparticles revealed that the enhanced mobility of the released TiO2 microparticles was caused by the presence of compost residues which blocked attachment sites on the sand surface. This study demonstrates that TiO2 microparticles can be released during composting of biodegradable plastics, and the transport potential of the released TiO2 microparticles in the terrestrial environment can be enhanced by the presence of compost material.