Single-step synthesis and modification of CTAB-hectorite for efficient adsorption of methyl orange dye

Hectorite modified with cetyltrimethylammonium bromide (CTAB) using a single-step synthesis and modification produced an efficient adsorbent for water treatment. Characterization analysis revealed that incorporating CTAB at 5–10 wt/wt increased the basal distances and the mesopore area of hectorite. The high concentration at 20–40 wt/wt deposited CTAB on the external surface of hectorite, consequently reducing the surface area. TGA-DTG analysis revealed that the surface-bound CTAB has lower thermal stability than the interlayered CTAB. CTAB-modified hectorite (40-Hec) showed the adsorption capacity of methyl orange at 164.28 mg/g, with 98.57% removal efficiency, significantly higher than hectorite. The adsorption of methyl orange followed the pseudo-second order kinetic and the Sips models. The Sips isotherm was suitable to describe the adsorption mechanism by monolayer physisorption. For thermodynamic studies, parameters such as the Gibbs free energy (ΔG°), the enthalpy (ΔH°) and the entropy (ΔS°) revealed that the adsorption of methyl orange on CTAB-modified hectorite is a spontaneous exothermic process and affected by the entropy of adsorption.