Electron beam crosslinked PVA/PAM/GO/SA hydrogel for high-efficiency solar desalination: Synergistic design and performance optimization

To address the global freshwater scarcity challenge, this study presents a photothermal hydrogel composite composed of polyvinyl alcohol (PVA), polyacrylamide (PAM), graphene oxide (GO), and silica aerogel (SA), fabricated using electron-beam (e-beam) crosslinking as a clean and additive-free process. Material characterization methods, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), contact angle analysis, swelling behavior, and compressive loading, demonstrated the formation of a structurally resilient, anisotropic hydrogel with uniform nanomaterial dispersion and an asymmetric wettability gradient. Response surface methodology (RSM) was employed to maximize the evaporation rates in saline systems by optimizing the concentration of GO and SA in the second cycle under saline conditions. The optimized condition with 0.3 % (w/v) GO and 1.4 % (w/v) SA delivered one-sun–normalized evaporation rates of 1.54 ± 0.02 kgm⁻²h⁻¹ in the distilled water and 1.50 ± 0.03 kg m⁻²h⁻¹ in the saline water under ambient sunlight. GO incorporation enhanced photothermal absorption and improved the mechanical stability of the hydrogel matrix, while SA provided buoyancy and helped limit heat loss. The hydrogel retained structural strength under load, demonstrated high water uptake, and enabled sustained surface heating. These synergistic features supported stable and efficient solar-driven interfacial evaporation. E-beam irradiation is a scalable and green crosslinking process that avoids toxic chemical additives required in conventional chemical crosslinkers. This work demonstrates a practical, stable, lightweight, high efficiency polymer hydrogel platform for solar desalination, supporting deployment in energy-limited settings and contributing to sustainable freshwater production.