Rice Husk-Derived Materials for Solar Driven Interfacial Water Evaporation: A Short Review

Abstract

The increasing demand for sustainable freshwater production has driven interest in solar-driven interfacial evaporation (SDIE) as an energy-efficient desalination and wastewater treatment technology. Among various photothermal materials, rice husk is an abundant agricultural byproduct that offers a low-cost, carbon-rich, and porous alternative to synthetic absorbers. This short review summarizes recent advances in rice husk-derived materials for SDIE, focusing on their key photothermal properties, fabrication strategies, and evaporation performance. Rice husk-derived carbon (RHC) exhibits excellent light absorption (up to 99.4% across the solar spectrum), ultra-low reflectance (<5%), high light-to-heat conversion (temperature rise of 20.9 °C under 0.4 kW·m⁻²), and improved hydrophilicity and porosity when appropriately modified. Fabrication approaches are broadly classified into filler-based methods (e.g., membrane composites, coated cellulose papers) and foam-based strategies (e.g., self-standing foams, melamine sponge composites). The evaporation performance of rice husk-derived materials varies depending on structural design: standalone RHC coatings achieve evaporation rates of 2.09 kg·m⁻²·h⁻¹ with ~93.5% efficiency, while advanced architectures such as hydrogels, Janus evaporators, and trilayered composites (SiC/C + silica aerogel + carbonized wood) reach up to 4.21 kg·m⁻²·h⁻¹ and 94.9% efficiency. Some designs also improve long-term stability (>84 hours in brine), salt resistance (edge-only crystallization), and dual-mode functionality (nocturnal atmospheric moisture adsorption coupled with daytime evaporation). In conclusion, rice husk-derived carbon materials offer tunable, cost-effective, and sustainable solutions for SDIE. Future research should prioritize real-world testing, scalable fabrication, and further enhancement of cycle stability and salt management.