Humic substances as surfactants

Humic substances from soils and sediments can be defined as surface active substances based on the surface tension measurements. Although there are several micellar structural models of humic substances currently available, few studies evaluating humic substances as surfactants have been conducted to date. Therefore, we evaluated the ability of humic substances and their derivatives to influence surface tension. We found that the ability of a humic substance to influence the surface tension of a solution depends on its origin. Many industrially produced humic materials exerted little or no impact on surface tension, whereas humic substances isolated from natural environments (water, soil, peat, sediments, sludge from wastewater treatment facilities) exerted a large impact on surface tension. These findings indicate that the modification of humic substances can enable their use as surfactants. In addition, these findings indicate that solutions of humic substances and their derivatives can be used to increase the solubility of organic compounds.