Unveiling the potential: Thin film composite membranes and joule heating synergy for pervaporation desalination

Abstract

Pervaporation emerges as a promising technology for desalinating high-salinity water, yet its broader application is constrained by low productivity and significant energy requirements. This study introduces a unique thin-film composite membrane featuring a polyamide active layer atop a support membrane comprised of carbon nanostructures and networked cellulose. The carbon nanostructures, being electrically conductive, were crucial for enabling Joule heating, thereby significantly enhancing desalination efficiency. The membrane demonstrated a superior flux of 41.85 LMH and a rejection rate of around 99 % for a 3.5 g/L NaCl feed. Pervaporation desalination tests revealed that the Joule-heated membrane achieved higher fluxes than conventional heating methods. The enhanced flux is attributed to diminished temperature polarization and enhanced water and vapor diffusion facilitated by the membrane's elevated temperature. At a comparable permeate flux of around 17 LMH, Joule heating led to a 46 % reduction in specific heating energy consumption compared to conventional heating. This study provides valuable insights into developing efficient thin-film composite membranes with joule heating capabilities for pervaporation desalination, marking a significant step forward in addressing the challenges of high-salinity water treatment via pervaporation.