Biodegradable Mechanically Robust PCL/Oligomeric PCL-Diol/Laponite Antifouling Porous Membrane as a Versatile Adsorbent of Water Contaminants: A Sustainable Approach to Membrane Disposal

Abstract

Biodegradable polymeric membranes can reduce the environmental impact of polymer waste from discarded membranes used in water treatment and desalination. Poly(ε-caprolactone) (PCL), a promising biodegradable material, faces limitations due to its hydrophobicity, affecting salt and contaminant adsorption. To overcome this, PCL was blended with oligomeric PCL-diol (PCL-D) in ratios of 90:10, 80:20, and 70:30. Additionally, 12 wt% laponite (Lap), an anionic synthetic clay, was incorporated to enhance mechanical strength and functionality. The addition of PCL-D improved porosity, hydrophilicity, and antifouling properties, while Lap enhanced mechanical strength and performance. The pure water flux (PWF) increased from ~188 Lm−2 h−1 for neat PCL to 1124 Lm−2 h−1 for the 70:30 PCL blend with 12 wt% Lap (P7D3-L12), and the water contact angle (WCA) decreased from ~96° to ~49°. The P7D3-L12 membrane exhibited excellent adsorption of heavy metals (Pb2+ ~84.9 and Cd2+ ~90.6 mg/g) and dyes (MB ~45 and NR ~57 mg/g). It also showed ~36%–40% salt retention after multiple cycles and a fouling recovery rate (FRR) of ~82% after five cycles. Additionally, P7D3-L12 demonstrated 78% weight loss in compost over 54 days, indicating enhanced biodegradability. These modified membranes offer a promising solution for sustainable water treatment.