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. 4079 rscadv RSC Advances RSC Adv Royal Society of Chemistry PMC12576948 12576948 12576948 41181020 10.1039/d5ra06460k Development of a PTFE membrane with photo-thermal activated carbon nanomaterials for improved solar-driven membrane distillation El-Fattah Wesam Abd a Guesmi Ahlem a Ben Hamadi Naoufel a Ebraheem Bassant b Ding An c Ali Mohamed E A b ✉ a Chemistry Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), P. O. 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. These materials include plasmonic nanoparticles (NPs) and carbon-based materials. Activated carbon (AC) is an example. They must be in a coating layer. This layer permits the passage of water. Thermal energy is also captured from the photothermal agent. This indicates an equilibrium between coating thickness, boost light absorption, and water vapor flux, influenced by the coating's mass transfer resistance. 27–29 Many studies have investigated the concurrent use of activated carbon (AC) with ultrafiltration, RO, and DCMD. 30–33 The studies demonstrate that AC can effectively adsorb many different pollutants. Yet, they need more layers, making them less effective in flux and price. This design provides a hydrophilic surface that enhances anti-scaling resistance while the embedded activated carbon functions as a photothermal agent for localized solar heat generation. To the best of our knowledge, this is one of the first systematic studies to investigate the combined effects of PVA and AC concentrations on both photothermal performance and water flux stability in solar-driven MD systems. 28 2. Experimental 2.1. Materials and reagents A hydrophobic polytetrafluoroethylene (PTFE) membrane with a polypropylene (PP) support and a nominal pore size of 0.45 μm was obtained from Jian City Qing Feng Filter Equipment Material Co., Ltd (China) and used as a substrate for the PVA/activated carbon (AC) composite layer. ACROS Organics supplied The calculated value of E g for the AC sample is summarized in Table 3 . Table 3 Experimental and theoretical optical band gap values ( E g ) of activated carbon (AC) from literature compared with the present work (3.7 eV) Samples Determination method E g (eV) Ref. The presence of bands around 1420 cm −1 and 1090 cm −1 corresponds to CH 2 bending and C–O stretching, respectively, confirming the successful deposition of PVA onto the PTFE surface. With the incorporation of activated carbon, the PVA–AC composite membrane (blue curve) retains the key spectral features of PVA, but with increased intensity in the O–H stretching region. This enhancement may reflect additional hydroxyl groups or physisorbed water introduced by the porous AC structure. Also, the flux behavior of six different membrane formulations: a base membrane of 0.25% wt polyvinyl alcohol (PVA), this same PVA membrane with the addition of activated carbon (AC) at varying concentrations (0.25%, 0.5%, 0.75%, and 1% wt), and a pristine (unmodified) membrane. Fig. 7B clearly reveals the dynamic flux behavior of the membranes over time. The pristine membrane exhibits a relatively stable flux over the entire 1200-minute period. In contrast, the PVA 0.25% wt membrane shows a significantly lower and relatively stable flux compared to the pristine membrane. This indicates that higher AC concentrations may initially offer more pathways for vapor transport but are also more susceptible to fouling or blockage. Although the pristine PTFE membrane displayed a relatively higher flux, it lacks photothermal capability and tends to suffer from pore wetting during extended operation. The incorporation of activated carbon (AC) into the PVA matrix introduces photothermal functionality that enables efficient solar-to-thermal conversion, enhancing the thermal efficiency of the DCMD process. Moreover, AC contributes to improving the surface stability and anti-wetting properties of the coated membranes, which are crucial for long-term desalination performance.