Interactions between microplastics and phthalate esters as affected by microplastics characteristics and solution...

Area of Science:

• Environmental Chemistry
• Polymer Science
• Environmental Science

Background:

• Microplastics are emerging environmental contaminants.
• Microplastics can act as vectors for pollutant transport.
• Phthalate esters (PAEs) are common environmental pollutants.

Purpose of the Study:

• To investigate the sorption behavior of diethyl phthalate (DEP) and dibutyl phthalate (DBP) on microplastics.
• To determine the primary sorption mechanism of PAEs on microplastics.
• To assess the influence of microplastic type and environmental factors on PAE sorption.

Main Methods:

• Sorption experiments were conducted using three microplastic types: polyvinyl chloride (PVC), polyethylene (PE), and polystyrene (PS).
• Sorption isotherms were analyzed to determine the sorption mechanism and partition coefficients (Kd).
• The effects of solution pH, natural organic matter, and salinity (NaCl, CaCl2) on sorption were investigated.

Main Results:

• Sorption isotherms for DEP and DBP on microplastics were highly linear, indicating partitioning as the dominant mechanism.
• Hydrophobic interactions governed the partition mechanism, with higher Kd values observed for dibutyl phthalate (DBP) compared to diethyl phthalate (DEP).
• Sorption followed the order: polystyrene (PS) > polyethylene (PE) > polyvinyl chloride (PVC), highlighting the role of microplastic chemical properties.
• Salinity (NaCl, CaCl2) enhanced PAE sorption via the salting-out effect, while pH and natural organic matter showed no significant impact.

Conclusions:

• Microplastics effectively sorb PAEs through partitioning, with sorption influenced by microplastic type and salinity.
• Understanding these interactions is crucial for assessing the environmental fate and transport of PAEs and microplastics.
• The findings provide insights into the environmental behavior of microplastic-pollutant complexes.