Surfactants assisted synthesis of CuAl-sodium dodecyl sulfate layered double hydroxide and its adsorptive removal of methyl red dye from aqueous solution

Abstract

The versatile nature of layered double hydroxide (LDH) has made it the most widely used potential adsorbent for the decontamination of azo dye-polluted wastewater. Recently, the assembling of organic molecules on LDH structure to improve its physicochemical characteristics is given more attention by researchers. In this present work, the adsorption property of the CuAl-LDH was enhanced by modification with anionic surfactants sodium dodecyl sulfate and the synthesized materials were applied for the examination of methyl red removal from its aqueous solution. Both the pristine and surfactants modified LDH were synthesized by a facile co-precipitation method and characterized by X-ray diffraction, Brauner-Emmet-Teller surface area, thermogravimetric analysis, infrared spectroscopy, scanning emission microscopy, and energy dispersive x-ray spectroscopy. The obtained experimental data were analyzed by different isotherm and kinetics models and it shows higher degree of coefficient correlation with Langmuir isotherm and pseudo-second-order kinetic model. However, the study of thermodynamic parameters reveals that the adsorption process is spontaneous and endothermic in nature for both the adsorbents. The adsorption efficiency of surfactant fabricated CuAl/SDS-LDH was increased compared to pristine LDH and the maximum monolayer adsorption capacity qmax (mg g−1) for CuAl-LDH and CuAl/SDS-LDH were 209.9 mg g−1 and 411.47 mg g−1, respectively. The reusability of the materials indicates impressive results and can be repeated for up to four cycles. The synthesized sorbents CuAl-LDH and CuAl/SDS-LDH can significantly remove the target organic pollutant over a broad range of dye concentrations.