Microplastic and heavy metal interactions (adsorption and desorption) at different salinities

Abstract

Heavy metals and microplastics (MPs) are two pollutants that are currently gaining a lot of attention, and it has been observed that they can interact. The objective of this research was to observe the adsorption and desorption of heavy metals concerning various types of MP particles, different heavy metals and concentrations, and salinity. The findings demonstrate that among all particle types, PP particles absorb heavy metals at the highest rate. Contrarily, PP particles release lower heavy metals and more slowly than other particles. Pb consistently absorbed more metal by MPs than Cu, Zn, or Cd. Cd had the highest rate of heavy metal desorption, followed by Pb, Cu, and Zn. The adsorption capacity of MPs particles increases together with the concentration of heavy metals, whereas the adsorption rate decreases. Salinity has an enormous impact on how MPs and heavy metals interact. The adsorption and desorption of heavy metal in MPs particles decreases and takes longer to reach equilibrium at increased salinities. Between the three different salinities, even the adsorption and desorption results demonstrate a significant difference (p<0.05). Finally, our results indicate that MPs particles have the potency as a vector for heavy metal in freshwater, brackish water, and ocean.