Chitosan enhances poly aluminum chloride flocculation system removal of microplastics: Effective, stable, and pollution free

Microplastics are a new type of pollutant that may enter the human body through drinking water so the effective removal of microplastics in water is of great significance. In this paper, natural organic polymer flocculant chitosan (CTS) was used to strengthen the traditional flocculant poly aluminum chloride (PAC) to remove microplastics. Then this study chose polyethylene terephthalate (PET) as representative microplastics and investigated the performance and mechanism of CTS enhancing PAC flocculation system. The experimental results showed that under the normal dosage, the PET removal rate of the PAC-CTS system in pure water was nearly three times that of the PAC system, and the PAC-CTS system's PET removal rate in tap water was even close to 90 %. The strengthening mechanism was analyzed by scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results indicated that the introduction of CTS improved the charge neutralization, adsorption, and purge flocculation in the PAC system to varying degrees, mainly strengthening the charge neutralization and adsorption. And the PAC-CTS system showed better adaptability to different influencing factors. What's more, compared with other flocculation systems, the PAC-CTS system had a better comprehensive evaluation for removing different types of microplastics in water.