Organobentonite fabrication assisted by surfactant octadecylamine intercalation under hydrothermal/solvothermal condition for effective direct yellow dye removal

Abstract

This study utilizes a hydrothermal-solvothermal method to facilitate the fabrication of organobentonite (OB) by intercalating the surfactant octadecylamine (ODA) using several solvents (water (OB-Aq), ethanol (OB-Et), and mix 50% water/ethanol (OB-Aq/Et)). The physicochemical features of the materials were investigated using X-ray diffraction, Fourier transform infrared, scanning electron microscopy, Brunauer-Emmett-Teller surface analyzer, and thermogravimetry differential thermal analysis characterization. The study of structural properties found that surfactant intercalation transformed the basal spacing. This was shown by a lower x-ray diffraction value of 2θ at <6° and the presence of peeled-off layers in the scanning electron microscope image. The thermogravimetry analysis and regeneration adsorption evaluated the structural stability of OB, demonstrating its capacity to withstand temperatures up to 300 °C and undergo three cycles of adsorption. In addition, the adsorption processes on direct yellow are mainly characterized by the pseudo-first-order kinetic and Langmuir isotherm models. The interaction between alumina-silica bentonite and ODA chains in this investigation influenced the adsorption mechanism. The adsorption system is influenced by pH, temperature, and ion competition, which can induce the disintegration of the direct yellow structure from the surfaces of the adsorbent. The mesoporous structures obtained have the highest Langmuir chemisorption capacities for OB-Aq, OB-Et, and OB-Aq/Et, with values of 270.27 mg/g, 108.696 mg/g, and 2000 mg/g, respectively. This work suggests using an efficient method to fabricate OB for anionic dyes removal, specifically direct yellow.