Abstract
Sand, a cheap and naturally abundant particulate material, was modified with photocatalytic and hydrophobic coatings to reduce evaporation loss and facilitate the purification of water. The first-level photocatalytic coatings (TiO2 or ZnO nanocrystals) rendered nanoscale roughness on the surface of the sand. The additional second-level hydrophobic coating of a self-assembled monolayer of octyltrimethoxysilane (OTS) made the sand particles superhydrophobic because of the nanoscale roughness imposed by the nanocrystals. The superhydrophobic sand particles, floating on the free surface of water due to their superhydrophobicity, significantly reduced the evaporation loss of water by 60%–90% in comparison to an uncovered water surface. When the outer hydrophobic coatings are weathered or disengaged, the inner photocatalytic coatings become exposed to water. Then, the sand particles act as photocatalysts to degrade the contaminants in water under solar radiation.
Highlights
Water is the most important resource on earth and it has become a more valuable commodity as concerns increase about its scarcity and sustainability [1]
As much as 40%, of water stored in a farm dam can be lost through evaporation, depending on the condition of the dam and the local weather [2]
The Fourier-Transform Infrared Spectroscopy (FTIR) was collected with the Smart iTRTM Attenuated Total Reflectance (ATR) sampling accessory attached to the
Summary
Water is the most important resource on earth and it has become a more valuable commodity as concerns increase about its scarcity and sustainability [1]. The run-off water stored in ponds, ditches, and dams is extensively used as a water supply for industrial, agricultural, and even domestic applications. As much as 40%, of water stored in a farm dam can be lost through evaporation, depending on the condition of the dam and the local weather [2]. The evaporation loss can be reduced through both physical and chemical strategies. The evaporation loss can be significantly decreased through specialized dam design, including reducing the surface area to volume ratio (e.g., using deeper and narrower dams) and planting windbreaks to provide shade and diminish wind turbulence. The construction of water dams with such structures is challenging and a serious financial burden for many developing countries and districts
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