Expired yogurt-derived, three-dimensional water evaporator with sustainable self-cleaning and high mechanical properties for the desalination and purification of oil-contaminated seawater

Abstract

In this study, expired yogurt-derived three-dimensional water evaporators were developed using a freeze-drying calcination technique and applied to the desalination and purification of oil-contaminated seawater. By mixing polyvinyl alcohol and a super absorbent polymer, the maximum pressure of the expired yogurt-derived water evaporator is capable of being maintained at 2.5 MPa, which is much greater than any previously reported values. Moreover, super absorbent polymer and polyvinyl alcohol can also adjust the pyrrolic nitrogen content, thereby increasing light-to-heat efficiency by reducing the evaporation enthalpy of water. The optimized water evaporator exhibited an excellent solar evaporation rate of 3.25 kg m−2 h−1 and a high light-to-heat efficiency value of 96.47 % under one-sun irradiation. After desalination, the concentrations of Na+, K+, Mg2+, and Ca2+ ions satisfied drinking water standards. The optimized water evaporator exhibited excellent salt inhibition and antibacterial properties during the water evaporation process, resulting in a sustainable self-cleaning capability. The optimized water evaporator can purify oil-contaminated seawater because of its unique wetting characteristics and microporous structure. The expired yogurt-derived, three-dimensional water evaporator developed in this study shows great potential for the purification of oil-contaminated seawater.