A multifunctional waste biomass-derived solar evaporator for efficient and sustainable solar-driven clean water evaporation

Abstract

Universal and unlimited access to clean water resources represents one of the global priorities. Solar-driven interfacial evaporation using low-cost and eco-friendly biomass-derived photothermal conversion materials has emerged as a key, widely applicable, and energy-efficient strategy for freshwater production. Herein, a multifunctional waste biomass-derived photothermal (MWBP) evaporator was first developed using carbonized vinegar residue, an abundant waste biomass material, via a convenient and scalable method combining KOH activation and high-temperature pyrolysis. Benefiting from its synergistic advantages in efficient light harvesting, superior photothermal energy conversion, and optimized water transport pathways, the MWBP evaporator achieved a solar-to-vapor conversion efficiency of 91.5% and an optimal evaporation rate of 1.45 kg m⁻² h⁻¹, maintaining unaffected evaporation efficiency in seawater or wastewater under various pollution conditions. Additionally, the MWBP evaporator effectively removed 99% of typical organic pollutants, such as methylene blue, methyl orange, and heavy metals, facilitated by chelation and hydrogen bonding interactions with –OH and –NH₂ groups on its surface. Moreover, antibacterial functional groups, including oxygen-containing functional groups and amino groups, primarily contributed to the good biological cleanliness of the recycled water by disrupting the cellular structure of bacteria or interfering with their metabolic processes. Hence, the as-prepared MWBP evaporator exhibits tremendous potential as an innovative system for interfacial water evaporation and purification, which is particularly beneficial for economically deprived regions with multisource pollution.