Low-cost and facile hydrophilic amplification of raw corn straws for the applications of highly efficient interfacial solar steam generation

Highlights: • The solar evaporator was constructed under the skeleton made of cheap corn straws. • Citric acid was employed to amplify hydrophilic of corn straws. • The carbon layer was obtained via sulfuric acid carbonization method. • The solar steam generation device performs reliable reusability and high-efficient water purification capacity. Solar steam generation-is an emerging water purification technology because it is environment-friendly and cost-effective. Continuous efforts have been made to improve its efficiency, but there are still challenges in terms of material costs, manufacturing processes, recycling, and scalable production. In this paper, inspired by the spontaneous transpiration of corn straw, the interfacial solar steam generation device was constructed under the skeleton made of cheap corn straws. Owing to outstanding hydrophilicity improved by citric acid (the water absorption rate of corn straw is 1.4 times that of natural straw), corn straw enjoys feasible water transport with vascular bundles and screens. Besides, it has excellent light absorption and photothermal conversion properties due to carbon black layer formed after sulfuric acid carbonization. The experimental results show that, based on the modified corn straws, the solar evaporator achieved an evaporation rate of 1.422 kg m⁻² h⁻¹ and corresponding solar conversion efficiency of 89.3%under 1 sun (1 kW m⁻²) illumination. Moreover, the evaporator performed reliable reusability and excellent desalination capacity. Therefore, using cost-effective corn straws as high efficiency solar steam generator is promising in water purification and wastewater treatment.