Adsorption of methyl violet from aqueous solution using β-cyclodextrin immobilised onto mesoporous silica

Abstract

ABSTRACT β-cyclodextrin(β-CD) was immobilised onto mesoporous silica using 1,1′-carbonyldiimidazole and tetraethyl orthosilicate as raw materials to construct adsorbent in dye wastewater treatment. The mesoporous structure of β-CD@SiO2-1 was characterised by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), specific surface area measurement (BET), thermogravimetric (TG) and scanning electron microscopy (SEM). The adsorption experiments were studied by response surface method (RSM) to optimise various parameters such as initial concentration, contact time and adsorbent dosage on the adsorption property of β-CD@SiO2-1 to methyl violet. The optimum process conditions were initial concentration 34 mg/L, contact time 13 h and adsorbent dose 5 mg. The adsorption rates correspond to the pseudo-second-order kinetic model. The adsorption isotherm was suited to the Langmuir isotherm model. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were obtained. As a result, it was found that the adsorption process was exothermic and spontaneous.