Effect of Surfactant Systems, Alcohol Types, and Salinity on Cold‐Water Detergency of Triacylglycerol Semisolid Soil. Part II

Abstract

AbstractOur prior work found that detergency of coconut oil was relatively poor using C14‐15‐8PO‐SO4Na alone but showed promising improvement with the presence of linear intermediate‐chain alcohols (C7–C9 alcohols) in the surfactant formulation. The maximum detergency exceeded 90% removal using 0.1 w/v% C14‐15‐8PO‐SO4Na/0.2 w/v% 1‐octanol/4 w/v% NaCl (final optimized surfactant system) at 10 °C. The current work thus seeks to further investigate surfactant formulations capable of providing improved detergency performance. Different 50% linear anionic extended surfactant structures (LC14‐15‐8PO‐SO4Na, LC14‐15‐8PO‐3EO‐SO4Na, and LC14‐15‐8PO‐7EO‐SO4Na) were compared with the branched C14‐15‐8PO‐SO4Na previously studied. Detergency of coconut oil using C14‐15‐8PO‐SO4Na at 8 w/v% NaCl (S*) still performed more effectively than these new surfactant systems. The addition of octanol as a detergency additive was further studied, and it showed that S* reduced from 8 w/v% NaCl to 4 w/v% NaCl for 1‐octanol and to 2 w/v% NaCl for 2‐octanol and 2‐ethyl‐hexanol in the C14‐15‐8PO‐SO4Na surfactant formulation. Coconut oil removal significantly improved detergency from roughly 49% for no alcohol with 8 w/v% NaCl, to 83% for 2‐ethyl‐hexanol with 2 w/v% NaCl, to 95% for 1‐octanol with 4 w/v% NaCl, and to 98% for 2‐octanol with 2 w/v% NaCl. Further studies on octanol concentration showed that decreasing 1‐octanol from 1.2% (90 mM) to 0.2% (15.3 mM) and 2‐octanol from 1.2% (90 mM) to 0.5% (38.5 mM) still maintained detergency over 90% removal. In this work, cold‐water detergency was found to correlate with low interfacial tension above the melting point, improved wetting of the semisolid soil, and oil solubilization in surfactant micelles.