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摘要
The effects of particle size and soil moisture on water repellency (WR) from hydrophobized sand are studied in this research. Quartz sand samples were separated into three sieve fractions: 0.5-2 mm (coarse sand, CS), 0.25-0.5 mm (medium sand, MS), and 0.05-0.25 mm (fine sand, FS). WR of sand was induced using different concentrations of stearic acid (SA; 0.5, 1, 5, 10, 20 and 30 g kg(-1)). Moist samples have been exposed to two types of drying: air-drying at standard laboratory conditions and oven-drying at 50 degrees C. Change in moisture content, and water repellency has been monitored every 24 h for 10 days. After 1 day of drying, SA concentrations %26gt;= 10 g kg(-1) caused extreme WR in oven-dry samples, independently of sieve fraction. In air-dried samples, time of drying and decreasing soil moisture content increased WR, but an erratic behaviour was observed in MS and FS samples. All air- and oven-dried samples became extremely water repellent after 7 days of treatment. At all SA concentrations and drying temperatures, WR was extreme in the CS fraction after one day. Superhydrophobicity of CS samples is suggested as a possible explanation of this response. In MS and FS samples, water repellency showed an erratic behaviour at lower SA contents, which may be due to contact of water droplets with a high proportion of areas not covered by hydrophobic coatings. The higher severity of WR observed in CS is in agreement with the idea of hydrophobicity associated with coarser particles. Coarse-textured soils have a lower specific surface than fine-textured soils, and a limited amount of organic matter may cause higher WR than in finely textured soils.
- 出版日期2013-11
