Self-assembly behavior in systems containing surfactants and chelating agents

Sammanfattning

Cleaning products play a crucial role in effectively maintaining a healthy andhygienic living environment. In all cleaning formulations ingredients like chelatingagents and surfactants are essential for the products’ performance. This studyinvestigates the self-assembly of surfactants in the presence of chelating agents andtheir influence on the physicochemical properties and cleaning efficiency ofcleaning formulations. The formulations consist of a nonionic surfactant, achelating agent and a secondary surfactant. Three amine-based secondarysurfactants were evaluated, including an amphoteric surfactant, an amine oxide,and a quaternary ammonium compound (quat). The chelating agents evaluatedwere L-glutamic acid N,N-diacetic acid tetrasodium salt (GLDA), methylglycineN,N-diacetic acid trisodium salt (MGDA), ammonium citrate and citric acid.The study focuses on how these components affect clouding temperature, viscosity,foaming, wettability, and surface tension. Results show that clouding temperature,viscosity, and foaming are notably impacted by the choice of secondary surfactantand chelating agent, whereas surface tension remains unchanged. Amphotericsurfactants, in particular, reduce the salting-out effect of chelating agents likeMGDA and GLDA, likely due to the similarity between their molecular structures.This interaction is hypothesized to lower the critical packing parameter (CPP),leading to smaller, more spherical micelles that increase solubility, raise cloudingtemperature, decrease viscosity, and improve foaming. These changes could enablehigher concentrations of active ingredients, resulting in more concentrated,energy-efficient products with reduced packaging needs.Cleaning performance tests on model soils revealed that formulations combiningamphoteric or amine oxide surfactants with GLDA or MGDA were most effectiveacross various surfaces and soil types, especially at higher concentrations of chelatingagents. These findings suggest that combining amphoteric surfactants with GLDAor MGDA could lead to the development of more concentrated, sustainable cleaningproducts.