Magnetically recyclable 3D water evaporator for desalination and purification of oil-contaminated seawater

Abstract

Desalination using solar-driven water evaporation is one of the most efficient, green, and sustainable approaches. However, the purification of oil-contaminated seawater, salt inhibition, and recovery of water evaporators remain challenging. Herein, a water evaporator based on a C/ZnFe2O4-x composite deposited on floral foam (FF) was developed, and its water evaporation performance was optimized by adjusting the reaction and calcination temperatures, concentration of deposited C/ZnFe2O4-x, and height of the FF. Owing to the excellent optical properties of C/ZnFe2O4-x, the water evaporator absorbed more than 96 % of sunlight in the wavelength range of 280–2500 nm, and its excellent magnetic properties promoted the recycling of the evaporator using a magnetic drive. The evaporator exhibited an excellent solar evaporation rate of 4.06 kg m−2 h−1, and a high light-to-heat conversion efficiency of 95.4 % under one-sun irradiation. The water evaporator exhibited excellent salt inhibition properties, and no salt crystals formed during the water evaporation process. The total organic carbon and organic dissolved matter in the purified water were significantly lower than those of the oil-contaminated seawater. Because of its low cost, high evaporation rate, and excellent durability, recyclability, and salt inhibition properties, the 3D evaporator can be a reliable device for purifying oil-contaminated seawater.