Detergency of mixed oily and particulate soils by single and mixed surfactant systems

Abstract

This research studies the detergency performance of mixed surfactants of (anionic and nonionic surfactants) for mixed oily and particulate soils on polyester/cotton blend fabric, and compares with a commercial liquid detergent. Palm oil and kaolinite are used as representatives of oily soil and particulate soil, respectively. The anionic surfactants used in this study are methyl ester sulfonate (MES), linear alkyl benzene sulfonate (LAS) and sodium dodecyl sulfate (SDS). The nonionic surfactants are alcohol ethoxylate 7EO (AE7) and alcohol ethoxylate 9EO (AE9). The effect of surfactant concentrations, NaCl concentration, and mixing ratios of the selected surfactant formulations on detergency performance are investigated. The mixed surfactant system of LAS and AE7 with a 0.3 wt. % total surfactant concentration provides the maximum detergency performance at low salinity of 2 wt. % NaCl. Interestingly, the particulate soil removal for any mixing ratios of all selected surfactant systems could exceed 85%, which is higher than those from either any single surfactant or the commercial liquid detergent. This is possibly because of the synergistic effect between the ethoxylated head group of AE7 and sulfonate head groups of LAS that balance the electrostatic repulsion, leading to lowering the free energy of the system. In addition, the percentages of detergency and total oil removal are relatively constant with the ratio of mixed surfactants.