Abstract In a previous study, we presented a new method for preparing a mixture of sodium toluenesulfonates (STS), sodium xylenesulfonates (SXS), sodium benzenesulfonate (SBS) and Na 2 SO 4 by sulfonating the BTX fraction of a Tunisian natural gas. Such mixtures can be used as a hydrotrope agent for concentrated liquid detergents. In the present work, we performed a mixture design in order to study the effect of each of these four components on the clear point and the viscosity of a liquid detergent, and therefore, to determine the conditions allowing to improve the effectiveness of the hydrotrope. Twenty-eight combinations of the 4 components out of 51 candidate points are selected by the Nemrod-W software according to the D-optimal criterion to fit two polynomial models. The statistical study shows that the fitted models were adequate to describe the clear point and the viscosity responses. Optimal conditions allowing to lower the two responses are then looking for by examining the response surface both as a contour plot, and as three-dimensional surface plot and the response trace. We prove that Na 2 SO 4 exhibits a harmful negative effect, while SXS and STS exhibit, respectively, a strong and moderate positive effect on both clear point and viscosity responses. As expected, SBS has a harmful effect on the two responses but the magnitude of this effect is lesser than that predicted by the preliminary experiments carried out with SBS alone. This phenomenon is explained by the formation of heteroassociation between SBS, STS and SXS similar to what is found in surfactants. The effectiveness of the hydrotrope, obtained by sulfonation of the BTX fraction of the Tunisian natural gas, is really improved by removing sulfates either by adding lime to precipitate gypsum, or isopropanol to reduce the solubility of Na 2 SO 4 .
[1]
M. Deaton,et al.
Response Surfaces: Designs and Analyses
,
1989
.
[2]
M. S. Khots,et al.
D-optimal designs
,
1995
.
[3]
Virgil L. Anderson,et al.
Extreme Vertices Design of Mixture Experiments
,
1966
.
[4]
J. Cornell,et al.
Experiments with Mixtures
,
1992
.
[5]
Erik Johansson,et al.
Mixture design—design generation, PLS analysis, and model usage
,
1998
.
[6]
Nouna Kettaneh-Wold,et al.
Analysis of mixture data with partial least squares
,
1992
.
[7]
R. Carlson,et al.
Design and optimization in organic synthesis
,
1991
.
[8]
A. Kamoun,et al.
Chemometrics applied to the optimization of the preparation of hydrotropes for detergents starting from BTX fraction of natural gas
,
2000
.
[9]
S. Friberg,et al.
Hydrotropic action of a diacid
,
1981
.
[10]
Douglas C. Montgomery,et al.
Response Surface Methodology: Process and Product Optimization Using Designed Experiments
,
1995
.
[11]
Eric R. Ziegel,et al.
How to Run Mixture Experiments for Product Quality
,
1990
.
[12]
J. G. Otten,et al.
Anionic hydrotropes for industrial and institutional rinse aids
,
1986
.
[13]
Manish Sharma,et al.
Aggregation behavior of hydrotropic compounds in aqueous solution
,
1989
.