Regeneration and mass transfer simulation for remazol brilliant violet dye adsorption by pineapple peel–based adsorbent

Abstract

The successful preparation of pineapple peel activated carbon (PineAC) using a low–cost and environmentally friendly method presented a promising alternative for the utilization of pineapple peel (PineP) waste. The remarkable regeneration capability of PineAC significantly enhances its possible reusable adsorbent for the effective Remazol Brilliant Violet 5 R (RBV 5 R) dye adsorption. The Polymath software was employed to gain deeper insights into the mass transfer process and optimize the adsorption kinetics. PineAC's performance was investigated using characterization techniques such as surface analyzer, Energy Dispersive X–ray (EDX), Fourier Transform Infrared (FTIR) spectroscopy, and X–Ray Diffraction (XRD) analysis. The optimal conditions for the adsorption of PineAC–RBV 5 R dye were at 60°C, in an acidic medium, and at 300 mg/L. The Langmuir isotherm model successfully described the monolayer behaviour of RBV 5 R dye adsorption onto PineAC at 30 and 45°C. In contrast, the Freundlich isotherm model was applicable at 60°C. The PineAC–RBV 5 R dye exhibited a maximum adsorption capacity (qmax) of 66.300 mg/g. The kinetic data demonstrated excellent agreement with the Polymath Mass Transfer (PMT) model, successfully capturing adsorption behavior. The rate constant, kPTM, displayed an increasing trend as the RBV 5 R initial concentration rose from 25 mg/L to 300 mg/L. Furthermore, the PMT model accurately predicted the adsorption surface area, aPMT, to be 466.6560 m2/g, closely matching the actual mesopores surface area of 547.8500 m2/g. This remarkable accuracy highlights the reliability and robustness of the PMT model in describing the adsorption process. PineAC–RBV 5 R dye adsorption exhibited consistent thermodynamic behaviour characterized by endothermic adsorption (ΔH°=28.49 kJ/mol), a physisorption mechanism (Ea=24.02 kJ/mol), and spontaneity (ΔG°=10.74 kJ/mol). The potential mechanisms involved in the PineAC–RBV 5 R dye adsorption included n–π interactions, hydrogen bonding, and π–π interactions. The regeneration effectiveness of PineAC–RBV 5 R dye adsorption was 72.30% for the third cycle without causing any surface morphological alterations in agreement with SEM images and EDX spectra. Investigating the adsorption mechanisms and the potential for further functionalization of PineAC could provide opportunities for enhanced performance and expanded applications in sustainable wastewater treatment.