Investigation of Water Capillary Rise in Soil Columns Made from Clay Mineral Mixtures Pretreated with Cationic Surfactants

Abstract

The study of the environmental pollution effect of surfactants is very important. Surfactants modify the wetting, surface tension, and capillary pore system of soil grains depending on their characteristics. During the research, the surface modification effect of a cationic surfactant (hexadecyl–pyridinium–chloride) was analyzed on mineral mixtures series assembled in various ratios with decreasing clay content (bentonite–loess–sand, kaoline–loess–sand). Cationic surfactants are adsorbed on the inner and outer surfaces of phyllosilicates, which could result in swelling. Our results were evaluated on the basis of the interfacial (surface tension of liquid phase, contact angle) and soil physical characteristics of the examined samples. The wetting properties and structural changes (eliminating the surface modification effect of humic materials) of mineral mixtures treated with surfactants were studied on the basis of capillary water rise. The results of our research could be used to interpret the water features of surfactant-polluted soils.

Keywords:

• Capillary water rise
• contact angle
• surface modification
• surface tension
• surfactant adsorption

Acknowledgments

The financial and infrastructural support of the State of Hungary and the European Union in the framework of the TÁMOP-4.2.1/B-09/1/KONV-2010-0003 and TÁMOP-4.2.1/B-09/1/KONV-2010-0005 projects and the National Talent Program are gratefully acknowledged.