Detergency of oily soil : effects of hardness and builders

Abstract

The objective of this study was to investigate the effects of hardness and builders on both the phase diagrams of microemulsions with motor oil and the detergency performance of soil removal. A mixed surfactant system of 0.1 wt.% branched alcohol propoxylate sulfate sodium salt (Alfoterra 145-3PO) and 5 wt.% secondary alcohol ethoxylate (Tergitol 15-S-5) was used to form microemulsions with motor oil under the presence and absence of hardness and/or builders. Under this mixed surfactant system, the optimum salinity slightly decreased with increasing hardness and the microemulsion diagrams did not change with hardness. From the detergency results, the total oil removal decreased with increasing hardness for all three types of fabrics (pure cotton, polyester/cotton [65/35] blend and pure polyester) and the total oil removal was improved with increasing hydrophilicity of the fabric. When the hardness increased, the adsorption of a mixed surfactant decreased but the interfacial tension increased. For addition of the builder under the presence of hardness, the total oil removal was improved at a certain level.