Adsorption of dyes on microwave assisted activated stalks of pepper plants: Experimental, DFT and Monte Carlo simulation studies

This study focuses on the valorization of stalks of pepper plants (SPP), to produce efficient activated carbons for wastewater treatment. The activation process was done by potassium hydroxide for 30 min under microwave irradiation. Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) analyses were investigated. Adsorption performance was tested for the removal of methyl orange (MO) and methylene blue (MB). Experimental results show that the adsorption was correlated to the pseudo-second-order model. Equilibrium uptake of the both dyes were suitable to the Langmuir isotherm model. The adsorption reaction was endothermic of MB and exothermic for MO. Global reactivity descriptors of the dyes have been calculated and discussed. The adsorption behaviors of chemical compounds on graphite (104), CaCO3 (104) and activated carbon (104) surfaces were investigated using Monte Carlo simulation. The adsorption energies of the studied dyes on different surfaces followed the order: CaCO3 (104) > Activated carbon > Graphite (104) for MO and MB, respectively.