Towards more Ecofriendly Pesticides: Use of Biosurfactants Obtained from the Corn Milling Industry as Solubilizing Agent of Copper Oxychloride

Abstract

AbstractCopper oxychloride (Cu‐Oxy) is a widely used copper‐based fungicide. A drawback of the product is its very low water solubility (around 0.2%) which limits its fungicide efficiency due to the low‐penetrating capacity in the fungal mycelia. In this study, we have explored the use of biosurfactants (BS), surface‐active compounds obtained by microbial production, to enhance the solubility of Cu‐Oxy in agrochemical formulations. A BS extracted from corn steep liquor (CSL), a residue from the corn‐milling industry, was evaluated as an additive to increase the solubility of Cu‐Oxy in water. Different types of synthetic surfactants (Tween® 80, sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB)) were included for comparison. Results showed that it was possible to dissolve around 90% of Cu‐Oxy at concentration of 4 g L−1 in 20 min of contact time when the BS was added at the concentration of 20 g L−1. In contrast, the synthetic surfactants were only able to dissolve less than 0.5% of Cu‐Oxy under the same conditions. In addition, a factorial design was carried out in order to evaluate the influence of BS concentration, Cu‐Oxy concentration and contact time, on the solubilization of Cu‐Oxy. Maximum percentage of solubilization (96.5%) was achieved at concentrations of 16.1 g L−1 of BS, 2 g L−1 of Cu‐Oxy, and 20 min of contact time. These results allowed to conclude that BS extracted from CSL could be included in agrochemical formulations as solubilizing agents improving the stability of hydrophobic active principles and reducing the concentration needed of chemical pesticides, giving eco‐friendlier formulations.