Humic Acid – ability to use as natural surfactants

Abstract

Surface-active agents (surfactants) belong to a group of substances that at low concentrations are adsorbed onto the surface or interfaces of a system altering the free energy of those systems. In the case of water as solvent, surfactant consists of a hydrophilic head and a hydrophobic tail. Inwater, surfactant molecules concentrate at the water–air interface, with the hydrophilic heads oriented towards the water and the hydrophobic tails oriented away from it. When surfactants arrange themselves along the water–air interface, the surface tension of the solution decreases with increasing surfactant concentration until the surface tension is below a critical point. The concentration at which the critical point occurs indicates the formation of micelle structures and it is defined as the critical micelle concentration (CMC). A hydrophobic molecule in contact with an aqueous solution containing surfactant tends to arrange itself within the core of the micelles. Therefore the hydrophobic core of the micelle structure enables the surfactant to enhance the aqueous solubility of hydrophobic organic compounds, increasing their apparent solubility.