Detergency of Oily Soil: Effects of Hardness and Builders
The objective of this study was to investigate the effects of hardness and builders on both phase diagrams of microemulsions with motor oil and the detergency performance of oily soil removal. A mixed surfactant system of 0.1wt% branch alcohol propoxylate sulfate sodium salt (Alfotera 145-3PO) and 5wt% 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 in the phase diagrams of microemulsions slightly changed with increasing hardness and the microemulsion diagrams did not change with hardness. From the detergency results, %oil removal decreased with increasing hardness for all three types of fabrics (pure cotton, polyester/cotton (65/35) blend and pure polyester) and %oil removal was improved with increasing hydrophilicity of the fabric with cotton fabric being cleanest and polyester fabric being the most difficult to clean. When the hardness increased, the adsorption isotherm slightly decreased but the interfacial tension increased. For the effect of builders on the detergency performance, an amount of builder added was found to be several times of the hardness in order to react with the other divalent and monovalent cations in the system.