In search of a Consensus Method for the Isolation of Microplastics from Freshwater Sediments

Description

Considering the rise in use of plastics, and their indiscriminate disposal into the environment, the quantification of microplastics (MPs) in aquatic systems remains vital. Several analytical approaches have been employed. However, there is a lack of consensus in these methods, especially for the isolation of MPs from freshwater sediments. In this work, a sediment matrix was simulated using sand and peat with addition of virgin polyamide (PA), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polytetrafluoroethylene (PTFE), and polyvinyl fluoride (PVF) microplastics. Comparative flotation experiments were conducted on similar-sized MPs and on three size fractions (<1 mm; 1-2 mm; >2 mm) of MPs using aqueous solutions of NaCl, CaCl2, ZnCl2, and NaI. Organic matter removal was compared for HNO3, NaOH, and Fenton’s reagent at selected concentrations, temperatures, and times. Results for the tested solutions showed that only NaI solution resulted in 100 % flotation of all groups of MPs tested for similar-sized MP, while flotation patterns varied significantly (p<0.05) for size separated fractions in all solutions, with recovery ranging between 4 and 80 %. Digestion efficiencies ranged from 6-78 % (HNO3), 4-45 % (NaOH), and 49-80 % (Fenton’s reagent) with temperature and time noted to affect efficiency. In conclusion, NaI was identified as the best salt for MP flotation and recommended for future studies. Other particle properties besides density were noted to affect flotation. Also, Fenton’s reagent was recommended for organic matter removal at the optimized conditions of 30℃ for 360 mins, and at ambient temperature for 24 h digestion period.

Period	1 Jul 2024 → 4 Jul 2024
Event title	39th International Conference on Environmental Geochemistry and Health – SEGH 2024
Event type	Conference
Conference number	39th
Location	Abuja, NigeriaShow on map
Degree of Recognition	International