Removal of methyl red from wastewater using a NiO@Hyphaene thebaica seed-derived porous carbon adsorbent: kinetics and isotherm studies

Abstract

In this study, the adsorption of methyl red (MR) dye from wastewater on nickel oxide (NiO) doped in porous carbon derived from Hyphaene thebaica (HT) seeds (NiO@HT derived C) as an adsorbent material was investigated. The prepared NiO@HT derived C was characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). Moreover, the effects of solution pH, contact time, amount of the adsorbent, and the initial concentration of MR on the adsorption efficiency were consistently examined. The adsorption capacity of NiO@HT derived C at room temperature (25 °C ± 2) could reach 129.87 mg g⁻¹ in an acidic medium after shaking for 60 min. Furthermore, the adsorption kinetics and isotherms of adsorption were investigated. The results indicated that the adsorption isotherm of reactive MR on the NiO@HT derived C surface follows the Langmuir isotherm model, which revealed that the adsorption of MR is a chemisorption process. On the other hand, the kinetic data fit well with the pseudo-second-order kinetic model, indicating that both NiO@HT derived C and MR influence the adsorption process.