Electrospun bio-polymeric nanofibrous membrane for membrane distillation desalination application

Polylactic acid (PLA) has been explored as a sustainable material for membrane distillation (MD) membranes using electrospinning for the first time. Adjusting the electrospinning parameters of PLA nanofiber, such as concentration, voltage, collector distance, humidity, and flow rate, resulted in uniformly distributed and smaller nanofibrous structures. Heat treatments were also performed to enhance the tackiness and fusibility of the fibers within the nanofibrous structure, optimizing the pore size, hydrophobicity, and surface roughness of the PLA membranes. The hierarchical structure of the PLA membranes improved the liquid entry pressure (LEP) and mechanical strength by 320 % and 230 %, respectively. The membrane characteristics were assessed in terms of porosity, pore size, surface roughness, and contact angle, which determined the impact of the wettability of the membrane under different conditions. The results showed that under certain constraints, PLA membranes could be effectively used in the air gap membrane distillation (AGMD) process, achieving a permeated flux of ~2 kg/m2h and a salt rejection of 99 %. However, PLA-based nanofibrous membranes are unsuitable for MD applications at feed temperatures above 60 °C and a flow rate of 60 LHP. This study provides a strong basis for developing and manufacturing eco-friendly bio-based nanofibers materials for desalinating saltwater.