Evaporation kinetics of surfactant solution droplets on rice (Oryza sativa) leaves

PLoS One. 2017 May 4;12(5):e0176870. doi: 10.1371/journal.pone.0176870. eCollection 2017.

Abstract

The dynamics of evaporating sessile droplets on hydrophilic or hydrophobic surfaces is widely studied, and many models for these processes have been developed based on experimental evidence. However, few research has been explored on the evaporation of sessile droplets of surfactant or pesticide solutions on target crop leaves. Thus, in this paper the impact of surfactant concentrations on contact angle, contact diameter, droplet height, and evolution of the droplets' evaporative volume on rice leaf surfaces have been investigated. The results indicate that the evaporation kinetics of surfactant droplets on rice leaves were influenced by both the surfactant concentrations and the hydrophobicity of rice leaf surfaces. When the surfactant concentration is lower than the surfactant CMC (critical micelle concentration), the droplet evaporation time is much longer than that of the high surfactant concentration. This is due to the longer existence time of a narrow wedge region under the lower surfactant concentration, and such narrow wedge region further restricts the droplet evaporation. Besides, our experimental data are shown to roughly collapse onto theoretical curves based on the model presented by Popov. This study could supply theoretical data on the evaporation of the adjuvant or pesticide droplets for practical applications in agriculture.

MeSH terms

  • Hydrophobic and Hydrophilic Interactions
  • Kinetics
  • Microscopy, Electron, Scanning
  • Oryza / chemistry*
  • Plant Leaves / chemistry*
  • Plant Leaves / ultrastructure
  • Surface Tension
  • Surface-Active Agents / chemistry*

Substances

  • Surface-Active Agents

Grants and funding

This study was supported by the National Natural Science Foundation of China (NSFC), no. 31471805, Prof. Qi-Liang Huang, and the National Natural Science Foundation of China (NSFC), no. 31601673, Dr. Chong Cao.