Comprehensive analysis of hazardous dye adsorption onto a green adsorbent: Experimental profiling, theoretical modeling, and deciphering potential molecular interactions

This work explores the pomegranate peel’s potential in the guise of a green adsorbent to eliminate harmful dyes present in aqueous media, especially methylene blue (MB). To assess the biomass’s ability to remove MB, adsorption experiments were executed in batches under different conditions. The finding demonstrated that the best adsorption occurred at neutral to basic pH levels. The kinetic and equilibrium isotherm data were analyzed mathematically, and several statistical error functions were used to verify the most accurate models. The model of pseudo-second-order offered a precise characterization of the kinetic data. In contrast, the model of Redlich-Peterson was deemed the most reliable to describe the isotherm adsorption data. Scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction were utilized to elucidate the studied biomass’s morphological and structural attributes before and after adsorption. Furthermore, the Gaussian 09 W program was used to examine the molecular structure of MB and to determine its potential interaction mechanisms with the adsorbent. The quantum descriptors extracted from the analysis supported the experimental findings reported in this study. • Valorizing agricultural waste as green adsorbent for methylene blue removal. • Characterizing the adsorbent with pH PZC , Boehm titrations, ATR-FTIR, DRX, and SEM. • Utilizing statistical errors for kinetic and isotherm model adequacy analysis. • Performing DFT calculations to optimize MB molecule geometry. • Integrating experimental and theoretical studies to reveal adsorption mechanisms.