2003 Volume 52 Issue 6 Pages 317-329
Investigation of the distribution of calcium ions in the wash system was conducted to clarify the interaction between calcium ions and surfactant, builder and cotton fabric in the range of low water hardness. In the presence of cotton fabric, sodium alkyl ether sulfate (AES) was clearly hard to compound salt with calcium than linear alkyl benzene sulfonate (LAS). Polyoxyethylene alkyl ether (AE) showed the lowest ability to compound with calcium ions. The data also suggest that some of the calcium ions in the solution were adsorbed into cotton fabric prior to compound with surfactant or to be bound by builder in the solutions. The relationship of calcium ion distribution to detergency clearly indicated less calcium to remain in solution with greater detergency. Detergency was greatest for the solution containing both 0.022% AE and 0.015% sodium tripolyphosphate (STPP), and equivalent to that of using 0.023% Zeolite. For greater detergency, AES or AE should be used as surfactant and Zeolite concentration should be at least 0.023%.
