The cloud point of aqueous solutions of ethoxylated monoalkylphenols in the individual state and in the presence of electrolytes

The cloud points t(cp) of aqueous solutions of ethoxylated monoalkylphenols, AF9-n (n=8,9,10,12), were measured in the concentration (C) range of 0.25-40wt.%. t(cp) increased as C decreased at C<1wt.%. At 1<10wt.%, t(cp) changed insignificantly; t(cp)/t(cp) did not exceed 5%. Solutions transformed into the gel state at C>10-20wt.% and t(cp) sharply increased. The dependence of t(cp) on the length of the oxyethylene chains of ethoxylated nonylphenols at C=1wt.% can be described by the equation t(cp)=bln(n-n(0)), where n(0)=6. The cloud points of aqueous solutions (C=1wt.%) of the ethoxylated nonylphenols were measured at different concentrations of NaI, NaCl, NaF, Na2CO3, and Na2SO4 salts. For all of these solutions, t(cp) decreased in the presence of NaCl, NaF, Na2CO3, Na2SO4 and increased in the presence of NaI. To describe the dependence of t(cp) on the salt concentration, the equation and t(cp) are the cloud points of a neat aqueous solution of ethoxylated nonylphenols and of the solution in the presence of electrolytes, respectively. [GRAPHICS] .