Efficient microplastics extraction from sand. A cost effective methodology based on sodium iodide recycling

•The impact of storage on sodium iodide quality have been monitored during ten life cycles.•The results show that NaI solutions are recyclable without any density alterations.•The recycling of sodium iodide solutions leads to decrease the quantities used.•The use of recycling methods allows for a significant cost reduction.•The relevance of this method is especially useful to extract dense microplastics from sand.

Evaluating the microplastics pollution on the shores requires overcoming the technological and economical challenge of efficient plastic extraction from sand. The recovery of dense microplastics requires the use of NaI solutions, a costly process. The aim of this study is to decrease this cost by recycling the NaI solutions and to determine the impact of NaI storage. For studying the NaI recyclability, the solution density and the salt mass have been monitored during ten life cycles. Density, pH and salt mass have been measured for 40 days to assess the storage effect. The results show that NaI solutions are recyclable without any density alterations with a total loss of 35.9% after the 10 cycles of use. During storage, chemical reactions may appear but are reversible. Consequently, the use of recycling methods allows for a significant cost reduction. How far the plastic extraction by dense solutions is representative is discussed.