Waste semi-coke/polydopamine based self-floating solar evaporator for water purification

Abstract

Solar steam generation as a green and sustainable technology has recently attracted significant interest for relieving the longstanding challenge of clean water resources. However, the large-scale preparation of low cost photothermal materials for solar steam generators is highly desired yet still challenging. Herein, semi-coke (SC), a solid byproduct of coal industrial, was first demonstrated as an efficient photothermal material and successfully applied in solar steam generation system by depositing SC on melamine sponge with the assistance of polydopamine. Then, the modified melamine sponge was functionalized by hydrophobic methyl trichlorosilane to fabricate the self-floating semi-coke/polydopamine@photothermal melamine sponge (SPMS). Based on their outstanding light absorption, good wettability, and effective thermal location, the SPMS performs a high evaporation rate of 1.41 kg m −2 h −1 with a solar thermal conversion efficiency of 90.56% under 1 sun irradiation. Meanwhile, the SPMS has remarkable cycle stability and water purification abilities for seawater, dyeing wastewater and heavy metal solution. By turning “waste” to “wealth”, the SPMS shows great potential for sustainable applications in synergetic solar clean water production. • The waste semi-coke was first applied for solar steam generation. • A self-floating system inspired by ducks was fabricated. • Extremely low cost and abundant resources made this absorber stand out. • Excellent water purification capacity.