Recent Advances on Density Separation Techniques for Microplastic Recovery from Sediments

Microplastics are small plastic fragments commonly less than 5 mm in size (Khatmullina et al., 2016), making up about 92% of the total plastic pollution. Since these plastics are transparent due to their small size, they cause invisible plastic pollution. Due to their adsorptive properties, they can potentially harm marine and human life if ingested. Microplastic extraction is used to isolate microplastics from their original matrix using various methods and instruments to ease the process. Electrostatic separation, magnetization, and pressurized fluid extraction are among the established microplastic extraction methods, but these separation techniques require more effort and use a more advanced setup than density separation. Salt-assisted density separation of microplastics has been demonstrated to provide modest to excellent recovery rates. This review survey reported different salt solutions used in microplastic extraction via density separation in the last five years. Among the inorganic salts used in density separation, sodium dihydrogen phosphate (NaH2PO4) holds promise in separating microplastics because of its high extraction efficiency while being cost-effective and non-hazardous.