Development of a PTFE membrane with photo-thermal activated carbon nanomaterials for improved solar-driven membrane distillation

Abstract

Tackling global water scarcity requires effective desalination with renewable energy. This paper explores direct solar membrane distillation (MD). This technology uses photothermal nanoparticles. These nanoparticles capture sunlight and convert it into heat. This creates a thermal driving force at the membrane surface. This approach improves MD's energy efficiency. It also addresses temperature polarization. Polytetrafluoroethylene (PTFE) membranes with a PP backing layer were used. These were coated with membranes containing photothermally activated carbon (AC). The AC was integrated into polyvinyl alcohol (PVA) and glutaraldehyde (GA). GA acted as a cross-linker. The goal was to maintain water flow after coating. The performance of the PTFE/PVA–AC/GA membranes was tested. A synthetic saline solution was used. Adding hydrophilic PVA–AC improved the membrane's scaling resistance compared to PTFE. Increased PVA loading decreased water flow. The optimized PVA–AC–GA (0.25 wt% + 1 wt% + 1 wt%) membrane exhibited a stable vapor flux of 0.51 kg m⁻² h⁻¹ °C⁻¹, which is comparable to the commercial PTFE membrane (0.58 kg m⁻² h⁻¹ °C⁻¹), while providing enhanced photothermal activity and anti-wetting stability under simulated solar illumination. The membrane showed promising performance. They suit solar desalination off-grid for fluids prone to scaling.