Removal of linear alkyl benzene sulfonate from aqueous solutions by functionalized multi-walled carbon nanotubes

This paper explores the possibility of employing Oxidized Multiwalled Carbon Nanotubes (MWCNT-COOH) for the removal of toxic Linear Alkyl benzene Sulfonate (LAS). LAS is among the most toxic industrial and house hold waste surfactants. This study discusses the feasibility of removing LAS from aqueous solutions using MWCNT-COOH. The effects of operational parameters such as solution pH, LAS concentration and contact time on the removal of LAS were studied. The four linear forms of Langmuir, Freundlich, Dubinin Radushkevich (D-R) and Temkin models were applied to determine the best fit of equilibrium expressions. Our results showed that the experimental adsorption isotherm complies with Freundlich model. The maximum adsorption capacity was determined to be 62.5 mg/g with an initial LAS concentration of 4 mg/L at pH 3 in 45 min. Fitting of the experimental results to kinetic models showed the relevance of the pseudo second-order (R2 > 0.99) model for LAS. Our results confirmed that MWCNT-COOH would be promising adsorbents for LAS removal in aqueous solution.