Robert Milbradt

Emulsification Performance Used for NPE Replacement in Solvent-Based Formulations

The increase in the world’s population has led to an increased demand for agricultural products, which in turn calls for more intensive farming and higher crop yields. To minimize the impact on the environment, society demands more environmentally-friendly products to be used. Regulatory authorities have answered the public’s call for “greener” chemistries by applying pressure to not only replace the more harmful active ingredients, but also the formulation inerts. The Crop Protection Industry has used nonylphenol ethoxylates (NPEs) as inert ingredients in pesticides and spray adjuvants for decades. The implementation of European Directive 2003-53 EC, which bans the use of NPEs, has caused many American markets to look for alternatives for nonylphenol-based surfactants as well. Substitute chemistries typically are chosen based on hydrophile-lipophile balance (HLB) values and cloud points. This study uses an alternative method of selection by evaluating the emulsifier performance in commonly used solvents in emulsifiable concentrates (ECs), emulsion oil-in-water (EW), and oil dispersion (OD) formulations. A modified cylinder test is used for the evaluation of a wide range of surfactants. The emulsifier, solvent, and hard water are placed in a glass cylinder, inverted multiple times, and allowed to stand undisturbed for 24 h. The emulsification performance is then calculated based on the phase height of each emulsion, which is then compared to the performance of the systems, which includes NPEs. The solvents used in the study are not only the common naptha-based solvents as seen in many ECs, but also in the more environmentally-friendly formulation types such as EWs and ODs, which use mineral oils, seed oils, and seed oil methyl esters. This method offers an easy way to reformulate NPE-containing formulations with regard to sustainability and an emulsifier selection guide for environmentally-friendly formulations in general.