Microplastics are widely regarded as an emerging pollution owing to ubiquitous environmental distributions and toxicological characteristics. The adsorption kinetics of microplastic particles with polyelectrolytes is vital to improve the removal efficiency of microplastics, however, the adsorption kinetics of polyelectrolytes onto the particle surface is far from well understood near the isoelectric point. The adsorption of high and low charge density polyelectrolytes was investigated near the isoelectric point based on the measurement of the electrophoretic mobility. The mobility of particles adsorbing high charge density polyelectrolytes reaches the plateau in several seconds, whereas low charge density polyelectrolyte takes about dozens of seconds to reach the plateau of zero. The adsorption of high charge density polyelectrolyte is enhanced with the decrease of ionic strength, whereas, low charge density polyelectrolyte demonstrates the opposite tendency against ionic strength. All results will facilitate the analysis of the flocculation process of microplastic particles.
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