Batch‐Scale Study to Assess the Adsorption Potential of Locally Available Clay for Cationic Azo Dye from Water

Abstract Basic blue 41 (BB41) dye discharge to water bodies is a potential concern to public health. In this study, an eco‐friendly and cost‐effective approach for removing BB41 dye from water using locally available raw clay (RC) was proposed. RC was characterized using X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), Fourier‐transform infrared (FTIR) spectroscopy, laser granulometry, and X‐ray fluorescence (XRF). The average particle size was 26.42 µm, with a high silica (SiO₂: 32.08%) and alumina (Al₂O₃: 10.82%) contents. The effect of various experimental parameters such as pH, solid/liquid ratio, initial dye concentration, and temperature on adsorption performance were investigated. Isotherm studies followed the Langmuir isotherm model, with a maximum monolayer adsorption capacity (q m ) of 85.54 mg/g. Kinetic modelling confirmed the applicability of pseudo‐second‐order model, with intraparticle diffusion as the rate‐limiting step. Thermodynamic modelling parameters such as standard free energy (ΔG ° ), standard enthalpy change (ΔH°), and standard entropy change (ΔS°) indicated a spontaneous and exothermic adsorption process, with an activation energy (E a ) of 26.24 kJ/mol, confirming BB41 was through physical adsorption. These findings demonstrate the potential of RC as an efficient and sustainable adsorbent for BB41 removal, providing a cost‐effective alternative for wastewater treatment applications.