Agglomeration–Flotation of Microplastics Using Kerosene as Bridging Liquid for Particle Size Enlargement

Abstract

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.

The preliminary investigation on the microplastic removal using column flotation: effects of kerosene on the floatability of microplastics

“…It was observed that the removal rates for PP, PE, ABS, and PS decreased to 89.6%, 90.6%, 92.8%, and 87.8%, respectively. This decline can be attributed to the excessive dosage of kerosene, which might adhere to the column walls and diminish the floatability of the MPs [17]. Furthermore, both PET and PVC exhibited a significant reduction in their removal rates, decreasing to 77.5% and 77.8%, respectively.…”

Conventional and recent advances in gravity separation technologies for coal cleaning: A systematic and critical review

“…Hornn and co-workers, for example, showed that by combining surfactants, oil and sufficient mixing before flotation, agglomeration of chalcopyrite could be induced that improved copper recovery [ 85 , 281 , 282 ]. Oil-agglomeration of fine particles can also be applied for the quantification and removal hydrophobic microplastics from contaminated soils, sediments, and water [ 283 ]. Lares et al (2019), for example, used canola oil to improve the recovery and measurement of microplastics from wastewater treatment plant sewage sludge [ 284 ].…”

Chlorinated plastics offer unique opportunities and challenges in upcycling

“…Despite these issues, it would be a misconception to classify PVC as non-recyclable, 6 especially with the fact that PVC waste sorting 7 and recycling technologies are in constant advancement. Nonetheless, the investigation of chemical recycling methods for PVC is worthwhile to pursue in parallel.…”