Investigation of Combined Effects of Xanthan Gum, Sodium Dodecyl Sulphate, and Salt on Some Physicochemical Properties of Their Mixtures Using a Response Surface Method

Abstract

Aqueous solutions containing sodium dodecyl sulphate, xanthan gum, and salt were characterized by ionic conductivity, viscosity, and surface tension methods. A preliminary experimental study was performed to evaluate the effect of the mixture compositions on the surface behavior of the mixed polymer/surfactant systems under different solution conditions. An experimental design using response surface method (RSM) was then applied to assess factors interactions and empirical models regarding the physicochemical responses variables (i.e., conductivity, surface tension and viscosity). The main effects of the three independent factors: SDS concentration (x₁), NaCl concentration (x₂) and xanthan concentration (x₃) were determined using in particular a D-optimal design. The results show an important effect of the factors on responses; they also indicate that the synergetic action of surfactant, electrolyte and biopolymer greatly influences these properties. Analysis of variance (ANOVA) showed high variance coefficient (R ² ) values, thus, ensuring a satisfactory adjustment of the second-order regression model with the experimental data.

Keywords:

• Interactions
• physicochemical properties
• polymer
• surface response method
• surfactant

Notes

^a R² = 0,995, .

^b R² = 0,982, .

^c R² = 0.990, R²(adj) = 0.976.

Abbr.: DF, degree of freedom; SS, sum of squares; MS, mean square; F, Fisher test; p, probability; SD, standard deviation.