Removal of anionic surfactants from aqueous solutions using Fe-aluminosilicate sorbents

Abstract

Fe-aluminosilicate sorbents were obtained by modifying bentonite clay with iron polyoxocations and heat treatment at 400°C and 500°C. The specific surface of the sorbents determined by the method of low-temperature nitrogen adsorption was 118-136 m2 · g–1. The iron content in sorbents was equal 7.8 %. The adsorption properties of the obtained sorbents were studied with respect to anionic surfactants (sodium dodecyl sulfate and sodium dodecylbenzenesulfonate) in aqueous solutions. It was shown that the modification of clay leads to a significant increase in anion-exchange capacity. The value of the adsorption capacity was in good agreement with the increase in the number of the basic groups of Fe – OH and the value of the specific surface of the sorbents. Adsorption isotherms of sodium dodecyl sulfate on bentonite clay and on Fe –aluminosilicate sorbents are described by the Langmuir adsorption isotherm equation which describes monolayer adsorption on a homogeneous surface with a correlation coefficient of 1.000 at initial surfactant concentrations of 10-1000 mg · l–1. The adsorption capacity of Fe-aluminosilicate sorbents was more than 3 times higher than the capacity of the original clay in the adsorption of sodium dodecyl sulfate and was about 5 times higher in the adsorption of sodium dodecylbenzenesulfonate. The results of the study suggest that the Fe-aluminosilicate sorbents can be effective for removing anionic surfactants from wastewater.