Combined membrane separation and photocatalysis process for the recovery and decomposition of micro/nanoplastics from polyester fabrics

The mismanagement of plastic waste has had a disastrous impact on the aquatic and terrestrial environment This study aims to develop and evaluate an innovative system for treating polyester-polluted water by combining membrane separation and photocatalytic processes. The research objective is to concentrate polyester fibers using membrane technologies and subsequently decompose them through a photocatalytic process using different oxidants, such as hydrogen peroxide and sodium peroxodisulfate. The results, compared in terms of permeate flux, water permeability, fouling index (FI %) and cleaning efficiency (CE %), indicated nanofiltration as the membrane process that allowed not only the complete recovery of fibers from water as with all processes used, but also the almost complete recovery of the initial performance of the membrane used (CA 2 kDa NF) with a cleaning efficiency of 98 % and a low fouling index (16 %). Preliminary photocatalytic tests on some recovered polyester fibers by membrane process showed a decrease in their length and thickness with a weight loss of 13.52 % in 48 h, highlighting the potential of the photocatalytic process to degrade polyester fibers. Furthermore, these results indicated that the photocatalytic process can be tuned to allow the decomposition of polyester avoiding the use of dangerous and costly methods such as the thermal process that can produce toxic by-products. The proposed system, which combines the membrane separation process and the photocatalysis process, could lead to an effective integrated process for the treatment of MPs/NPs from polluted water.