Adsorption of Sodium Hexadecyl Sulfate and Triton X from Binary Aqueous Solutions at Thermally Graphitized Carbon Black

Olga Kochkodan,Victor Maksin,Tetyana Semenenko

doi:10.3311/ppch.15085

Abstract

Adsorption of anionic sodium hexadecyl sulfate (SHS) and nonionic Triton X surfactants with different ethoxylation degree: TX-45, TX-100 and TX-300 from their individual and mixed aqueous solutions at the surface of thermally graphitized carbon black (CB) was studied. It was found that at low solution concentrations addition of the nonionic surfactant increases the amount of SHS adsorbed from SHS/Triton X mixtures compared to SHS amount adsorbed from its individual solution. These findings might be explained by decreasing in electrostatic repulsion between SHS ions due to inclusion of the molecules of the nonionic surfactant in the mixed adsorption layer. At higher solution concentrations, adsorption of SHS decrease as a result of displacement of SHS ions from the mixed adsorption layer by Triton X molecules. It was established that the composition of the mixed adsorption layer at CB surface notably differ from the composition of the surfactant mixture in the bulk solution. The mixed adsorption layer is enriched with the molecules of the nonionic surfactants and this conclusion is confirmed by the results of measuring zeta potential of CB particles with the adsorbed surfactants.

Highlights

Surfactants adsorption at a solution/solid interface is very important phenomenon in many colloid-chemical processes, including flotation of ores, oil recovery, foam forming, detergency, stabilization of the colloids, emulsification, chemical synthesis and water treatment
Values of the nonionic surfactants from sodium hexadecyl sulfate (SHS)/Triton X mixtures practically do not change at low solution concentrations, but adsorption of Triton X surfactants increase at higher solution concentrations
It is shown that at low solution concentrations addition of the nonionic surfactant increases SHS adsorption from SHS/Triton X mixtures compared to SHS adsorption from its single solution

Summary

Introduction

Surfactants adsorption at a solution/solid interface is very important phenomenon in many colloid-chemical processes, including flotation of ores, oil recovery, foam forming, detergency, stabilization of the colloids, emulsification, chemical synthesis and water treatment. The use of surfactant mixtures allows to more effectively affect the properties of dispersed systems than the individual components. These features are due to the essential variation in the component properties in the mixture, including enhancement or attenuation of surfactants adsorption at an interface. Wetting and adsorption from binary surfactant mixtures at solid surfaces of diverse nature are significantly different compared to the solutions of the individual surfactants [2, 3, 5]. It is still challenging to predict the magnitude and mechanism of adsorption of surfactant mixtures at solid surfaces, especially given that adsorption of surfactant mixtures is a complex process affected by many factors such as chemical nature of the surfactant and adsorbent, temperature, feed pH, concentration, etc. [1, 9]

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Conclusion