Sustainable Deep Eutectic Solvent Modified Multi-Walled Carbon Nanotubes for Ibuprofen Removal from Pharmaceutical Effluents

Abstract

The increasing occurrence of pharmaceutical residues such as ibuprofen in aquatic systems poses a growing environmental concern. In this study, oxidized multi-walled carbon nanotubes (MWCNTs) were functionalized using an ecofriendly deep eutectic solvent prepared from tetrabutylammonium bromide and glycerol. The modified nanotubes were thoroughly characterized and evaluated for their adsorption performance towards ibuprofen removal from aqueous media. Batch experiments were carried out to investigate the influence of pH, temperature and contact time. The process was optimized through response surface methodology (RSM), and the results were validated using an artificial neural network (ANN) model. Fourier transform infrared and field emission scanning electron microscope analyses verified the surface modification and morphological variation after deep eutectic solvent (DES) coating. Optimum adsorption occurred at 35 °C, pH 4 and 90 min, resulting in a removal efficiency 94.9%. The kinetic data followed the pseudo second order model (R² = 0.9715) and the Langmuir Isotherm gave the best fit with R² = 0.9602 and a capacity 86.2 mg/g). In addition, desorption studies demonstrated high regeneration efficiency (>96%), indicating that the adsorption process is largely reversible and that the DES-functionalized MWCNTs possess strong potential for repeated use in wastewater treatment applications. Both RSM and ANN predictions closely matched experimental outcomes (R² > 0.998), confirming their reliability. To the best of our knowledge, this is the first study that employs TBAB-glycerol DES functionalization of MWCNTs for ibuprofen removal combined with dual ANN-RSM modeling, demonstrating a uniquely green and high-efficiency adsorption system.