Dynamic extraction of microplastics from simulated and natural freshwaters using a rotating coiled column

Abstract

At present, microplastics pollution of aquatic environments raises increasing concerns in terms of risks for human health. The efficiency of existing water treatment technologies, which are based on different physical principles, is still insufficient for the removal of microplastics from aqueous media, so novel methods are needed. So far, liquid-liquid extraction has not been used in processes of water treatment, however, it has a great potential for removing microplastics from water. The present study is aimed at the development of a novel method based on dynamic liquid-liquid extraction in a rotating coiled column for the removal of microplastics from aqueous samples. It has been demonstrated that liquid-liquid extraction in a rotating coiled column (inner capacity 25 of mL) using castor oil as a stationary phase provides more than 96 % recovery of five most abundant in the environment microplastics (μPE, μPP, μPS, μPVC, and μPET) of different size (<63, 63–100, and 100–250 μm) from simulated freshwater (sample volume of 20 mL). The recovery of a mixture of five microplastics from spiked natural river water is on the average 100 %. The recovery is not dependent on the size and type of microplastics under study. It has been also found that in the column with a tubing bore of 1.6 mm, the flow rate of the aqueous suspension of microplastics (mobile phase) can be increased up to 5 mL min−1 without decreasing the extraction efficiency. Scale-up of the extraction process is possible.