Humic acid solubilization effect on pesticides Humic acid has been widely used as a surfactant in many industries at home and abroad. It is reported that the surface tension of alkali metal salts of peat humic acid and weathered coal humic acid is lower than the surface tension of water to varying degrees, and the surface tension of water reduced by humic acid in aqueous solution can reach 7-26 dynes/cm. In contrast, weathered coal humic acid reduces the surface tension of water less, but it has a larger molecular weight and a higher content of hydrophilic groups, and can be regarded as a high molecular surfactant, which can play a good dispersing and emulsifying role on pesticides. In the article “Interaction between pesticides and natural organic matter” reported in foreign literature, the surface tension of aqueous solutions of sodium humate with different concentrations was measured. The measured data showed that humic acid has a moderate surface activity. Its effect of reducing the surface tension of water may also increase the solubility of soluble pesticides. The experimental case shows that the solubility of DDT in 0.5% sodium humate solution is at least 20 times that in water. This example illustrates the degree of solubility of humic acid on pesticide solubilization.
