Tailored cellulose-based flocculants for microplastics removal: Mechanistic insights, pH influence, and efficiency optimization

This study explores the performance of novel cellulose-derived sustainable flocculants in the flocculation of different model microplastics (MPs), including polyethylene (PE), polyethylene terephthalate (PET) and polyvinyl chloride (PVC). The influence of key parameters, such as pH, flocculant structure and concentration was evaluated by Laser Diffraction Spectroscopy (LDS) and optical microscopy to access their effects on flocculation performance, kinetics and floc structure. The results reveal that a bioflocculant concentration of 0.001 g·mL −1 is ideal for effective flocculation, as lower concentrations lead to insufficient floc growth. While electrostatic interactions are a dominant factor in the flocculation process, the study also highlights the role of hydrophobic interactions, its contribution depending on the characteristics of the MPs. Overall, this research highlights the importance of understanding the key interactions governing the flocculation process. It further paves the way for designing and fine-tuning cellulose-based flocculants with improved efficiency and optimized dosages for effective MPs removal strategies. • Cellulose derivatives developed were used as flocculants in microplastics removal. • Bio-flocculants developed included both cationic and hydrophobic moieties. • MPs flocculation kinetics and evolution of flocs structure with time assessed by LDS. • It was possible to design the bio-flocculants to remove different types of model MPs.