Can Microplastics Accumulate Toxic dye in Water? An adsorption-desorption Study under Different Experimental Conditions.

The adsorption/desorption of Rhodamine B (RhB) on Polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC) microplastics (MPs) was investigated in this study. The results showed that RhB adsorption on the selected MPs was fast. The adsorption coefficients (K) of RhB were 2036 ± 129, 1557 ± 91, and 63 ± 8.5 L kg for PS, PP, and PVC, respectively. RhB adsorption on PS and PP increased with increasing temperature and decreasing ionic strength, whereas RhB adsorption on PVC showed a completely opposite trend. The binding strength of RhB on the three types of MPs was weak as demonstrated by the high total desorption percentage, which ranged from 79.59 ~ 89.39%. This study shows that PP and PS MPs can accumulate RhB in the aquatic environment and their potential combined toxic risks should be taken seriously.