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

Abstract

Copper 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.

Solubilization of cuprous oxide in water using biosurfactant extracts from corn steep liquor: a comparative study

“…In addition, as it can be observed in Table 1 , the CMC values of all BS extracted from CSL were also evaluated, ranged from 424.1 to 442.1 mg/L for BS1 and BS2, respectively. These results are in concordance with those found in previous works for BS extracted from different CSL, with values ranged from 425.0 to 440.4 mg/L when they were extracted with chloroform or ethyl acetate, respectively 25 . Moreover, CMC of the chemical surfactants was evaluated as well, resulting in values over a wider range than those obtained for BS from CSL.…”

“…Moreover, Table 2 shows, as well, the effect of three different chemical surfactants (Tween 80, SDS and CTAB) on the solubilization of Cu-Ox, resulting in a negligible effect, which is in consonance with the results obtained in a previous work where BS from CSL were used to solubilize Cu-Oxy 25 . The solubility of commercial Cu-Ox pesticide (containing 75% of Cu-Ox) in ultrapure water resulted in 0.53% compared to 0.09% obtained for pure Cu-Ox, which can be attributed to the addition of solubilization agents such as chemical surfactants or other adjuvants in the formulation of commercial fungicides 27 .…”

“…The higher capacity of solubilization of a BS extracted from CSL with ethyl acetate was also observed in a previous work with copper oxychloride (Cu-Oxy) 25 , where the results showed values of 96.5% of copper dissolved at a concentration of 16.1 g/L of BS extracted with ethyl acetate from CSL. This increase in the solubility for the BS2 can be attributed to a high abundance of lipopeptides, as it can be observed in Fig.…”

Biosurfactants: Properties and Applications in Drug Delivery, Biotechnology and Ecotoxicology

“…The properties of biosurfactants are specific to the substrate, solubilizing or emulsifying different hydrocarbons at different rates [ 59 ]. Biosurfactants are more effective solubilizing agents than synthetic surfactants [ 60 ]. For example, a biosurfactant obtained from Rhodococcus erythropolis HX-2 exhibited a higher solubilization for petroleum and polycyclic aromatic hydrocarbons than synthetic surfactants sodium dodecyl sulfate (SDS), polysorbate (Tween 80), Triton X-100, and rhamnolipid [ 61 ].…”

Possibility of biologizing technology for protecting apple and plum trees based on the use of inorganic copper compounds

“…Another area of research is the use of new formulations while maintaining high efficiency, since otherwise the quality and quantity of the crop may be under threat [5,6]. Of the group of inorganic copper compounds, copper oxychloride, copper sulfate and copper hydroxide are the most widely used practically all over the world [7][8][9][10][11][12]. On an apple tree in Russia, the effectiveness of preparations based on copper hydroxide against scab has not been sufficiently studied.…”