Surface innovation for fabrication of superhydrophobic sand grains with improved water holding capacity for various environmental applications

Abstract

The extreme evaporative loss of water from topsoil complicates cultivation in arid areas, and artificial plastic mulches that imitate sand mulches may minimize such water losses. However, the application of such plastic mulches is limited by their high cost and non-biodegradability. In this study, we developed superhydrophobic sand grains to reduce evaporative water loss from soil. Sea sand (SS) was coated with silica sol, which was prepared by the hydrolysis of tetraethoxysilane (TEOS) under alkaline conditions, followed by treatment with perfluorodecyltrichlorosilane (FDTS). A facile step was optimized for fabricating hydrophobic sand grains with contact angle of 151° and rolling-off angle of 9.5° to confirm the hydrophobicity and anti-droplet properties of the modified sand grains. The sands modified with engineered nanomaterials have shown the enhanced water holding and storage efficiency, and they can be applied as an oil sorbent scaffold to absorb oil (chloroform) from water selectively due to their water repelling properties. The coated superhydrophobic sand grains displayed anti-droplet and self-cleaning features, and withheld water for extended periods of time, which could benefit agriculture in arid regions and various environmental applications.