Solar interfacial evaporation based oil/water separation from emulsion using a wood-melamine/calcium alginate composite structure

Abstract

Solar interfacial evaporation is an attractive phenomenon for water treatment using renewable energy without further environmental contamination. However, the existing researches mainly focus on improving water evaporation rate with diversified interfacial and porous materials for solar absorption and water transport. The oil/water separation from emulsion under solar interfacial evaporation is rarely investigated. Under these circumstances, a wood-melamine/calcium alginate composite structure with hydrophilic and oleophobic characteristics is designed and fabricated in the current work to realize solar interfacial evaporation based oil/water separation from emulsion. The corresponding oil/water separation process is experimentally analyzed under different material composite structures, solar intensities, and oil volume fractions. The wood-melamine/calcium alginate composite structure exhibits outstanding oil/water separation capability from emulsion under solar interfacial evaporation in comparison to the pure wood and wood-calcium alginate membrane structures owing to its fantastic oil resistance and water permeation properties. Through optimizing the thickness and aperture of hollow wood cylinder, a maximum interfacial water evaporation rate of 5.74 kg•m−2•h−1 is achieved under 5 sun solar intensity for oil/water separation. Besides, an outdoor experiment under natural sunlight (622 W•m−2 to 769 W•m−2) in summer time is also carried out for oil/water separation from emulsion using designed wood-melamine/calcium alginate composite under interfacial evaporation, and an average water evaporation rate of 0.965 kg•m−2•h−1 is obtained with condensed water on the hydrophobic glass cover for recovery. The current research paves an effective route for handling oil-in-water emulsion using renewable solar energy, contributing to the water resource protection and environmental sustainable development.