Synthesis and physicochemical characterization of ZnMgNiAl-CO₃-layered double hydroxide and evaluation of its sodium dodecylbenzenesulfonate removal efficiency

Abstract

In this study, the adsorption of anionic surfactant by uncalcined ZnMgNiAl-CO₃ was examined using sodium dodecylbenzenesulfonate (SDBS) as a model compound in an aqueous solution. The synthesized adsorbent (ZnMgNiAl-CO₃) was characterized by FTIR, X-ray diffraction, and BET. The capacity of ZnMgNiAl-CO₃ to adsorb surfactant was evaluated at different contact times, pH values, mass effect, and initial surfactant concentrations. According to the obtained results, the adsorption processes could be described by a pseudo-second-order kinetic model. The adsorption isotherm was well fitted by the Sips model. Maximum adsorption capacity for SDBS on ZnMgNiAl-CO₃ was found to be 191.7 mg/g which was in accordance with the experimental value. Thermodynamic parameters were estimated as well, and their values indicated that the adsorption process was spontaneous and endothermic. The values of ΔH° and ΔS° of the adsorption process were 7.9 and 0.102 kJ/mol, respectively. The low value of ΔH° (<40 kJ/mol) indicated that adsorption process occurs mainly through a physical means.

Keywords:

• Removal
• Surfactant
• Sodium dodecylbenzenesulfonate (SDBS)
• ZnMgNiAl-CO₃