Influence of Na5P2O10-CaCl2-H2O Phase Equilibrium on Laundering of Cotton Fabric

Study of the phase equilibrium diagram for the CaCl2-Na5P2O10-H 2O system sug gested that washing phenomena would depend on the phase region as well as specific CaCl2 or Na5P2O10 concentration. Radioactive zirconyl phosphate was used as a redeposition soil, and tagged sodium alkyl aryl sulfonate was used for determination of detergent adsorption on cotton fabric. Ca ++ concentrations from 0 to 5.5 mmoles/l. were reacted with sodium tripolyphosphate concentrations from 0 to 32 mmoles/l. The quantity of radioactive ingredients deposited was measured after a 10-min. wash cycle in a Turg-O-Tometer. Desorption by a 5-min. rinse cycle was also evaluated. Both redeposition and rinsability depend upon the CaCl2-Na5P2O 10 phase region in which washing is performed. Higher tripolyphosphate concentrations in the wash cycle retard redeposition and promote the rinsing of detergent from cotton fabrics. Hardness of water definitely influences both redeposition and rinsability. The influence of tripolyphosphate on re deposition is most pronounced at low soil loads.