Preparation of composite coagulant for the removal of microplastics in water

In this work, a composite flocculant (polyferric titanium sulfate-polydimethyldiallylammonium chloride [PFTS-PDMDAAC]) with a rich spatial network structure was prepared for the treatment of simulated wastewater containing polystyrene (PS) micro-nanoparticles. Characterization results showed that the surface of the PFTS-PDMDAAC was a three-dimensional network polymer of chain molecules that exhibited good thermal stability and formed an amorphous polymer containing multiply hydroxyl-bridged titanium and iron. When n(OH-) : n(Fe) = 1:2, n(PO43-) : n(Fe) = 0.35, n(Ti) : n(Fe) = 1:8, n(DMDAAC) : n(Fe) = 5:100, and the polymerization temperature is 60 degrees C, the prepared composite flocculant has the best effect. The effects of dosage, pH, and agitation intensity on the flocculation properties of PFTS-PDMDAAC were also studied. The optimal removal rates of PS-mu m and haze by PFTS-PDMDAAC were 85.60% and 90.10%, respectively, at a stirring intensity of 200 rpm, a pH of 9.0, and a PFTS-PDMDAAC dosage of 20 mg/L. The flocs produced by the PFTS-PDMDAAC flocculation were large and compact in structure, and the flocculation mechanism was mainly based on adsorption bridging. Kaolin played a promoting role in the process of PS-mu m removal by PFTS-PDMDAAC floc and accelerated the formation of large and dense flocs. This study provided a reference for the coagulation method to remove micro-nanopollutants in the actual water treatment process.Practitioner PointsA composite flocculant with rich spatial network structure (PFTS-PDMDAAC) was prepared.PFTS-PDMDAAC can effectively remove micro-nano polystyrene (PS) in wastewater.The floc produced by PFTS-PDMDAAC is large and compact in structure.The flocculation mechanism of PFTS-PDMDAAC is mainly adsorption bridging. A new composite flocculant (PFTS-PDMDAAC) was prepared for effectively removing micro-nanoparticle contaminants. Kaolin assisted coagulation in the removal of PS-mu m particles by PFTS-PDMDAAC flocculation, which could accelerate the formation of large and dense flocs.image