Microplastics (MPs), defined as plastics with diameters between 1 and 5000 µm, are problematic pollutants in the environment, but their removal is challenging because of their minute size. One promising approach for their removal is flotation because MPs are inherently hydrophobic. However, the very small particle size of MPs lowers the probability of MPs-bubble collision and attachment that in turn affects the efficiency of the process. To address this challenge, we propose the use of agglomeration-flotation, a technique using kerosene as a bridging liquid to enlarge the particle sizes of MPs and make them amenable to flotation. In this study, the effects of kerosene dosage on particle size enlargement and floatability of six types of MPs with 100–1000 µm size fractions were investigated. The results showed that MPs with lower density compared with water could easily float in water without bubble attachment and particle agglomeration required. So, the effects of agglomeration on removal were negligible. In contrast, agglomeration using kerosene enhanced the floatability of MPs with high-density plastics. Moreover, image analysis was used to determine the agglomerated MPs’ particle size. The results indicate that kerosene could agglomerate the MPs and enhanced the removal of MPs by agglomeration-flotation.

Microplastics (MPs), the plastic particles with size fraction smaller than 5 mm, are recently becoming one important problem worldwide due to their ubiquitous distribution in the environment, especially in water. In this study, the separation techniques in mineral processing (i.e., magnetic separation and surface-based separation) were applied to remove MPs from contaminated water. Five kinds of model MPs samples (+38−2000 μm); polypropylene (PP), polyethylene (PE), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC) were used and magnetite (Fe3O4) powders (−75 μm) were modified using hexadecyltrimethoxysilane (HDTMS) to change their surface from hydrophilic to hydrophobic for MPs recovery. The results showed that MPs could be attached on the surface of modified magnetite due to the hydrophobic interaction and could be recovered together with modified magnetite by magnetic separation.