Application of Dubinin-Radushkevich Isotherms and Density Functional Theory to Phenolic Contaminant Remediation Using Mg-Activated Snail Shell Biochar
Year: 2026
Type: article
Abstract: This study applies the Dubinin-Radushkevich-Misra (DRM) isotherm and density functional theory (DFT) to investigate the adsorption and molecular interactions of phenol (PNL) and para-chlorophenol (PCP) on Mg-modified snail shell biochar (Mg@SSB). The Langmuir model provided good fits, with values of 0.9860-0.9970 for PNL and 0.9834-0.9921 for PCP, and maximum adsorption capacities (qmax) of 11.16-11.85 and 12.64-13.30 mg/g, respectively. The DRM model showed stronger correlations (R2), with predicted maximum adsorption amounts of 14.84 mg/g for PNL and 57.81 mg g for PCP. The corresponding DRM adsorption energies (Eads) were 9.42 and 13.61 kJ mol, respectively, indicating stronger adsorption of PCP. Kinetic analysis showed that the Weber-Morris intraparticle diffusion model provided the highest correlations for both PNL and PCP, exceeding those obtained from the pseudo-first-order, pseudo-second-order, and Elovich models. DFT calculations further supported preferential PCP adsorption, with adsorption energies of -1.1683 eV for PCP–Mg@SSB and -0.8163 eV for PNL–Mg@SSB. For the pristine Mg@SSB surface, the calculated HOMO, LUMO, and HOMO–LUMO gap were -4.978, -2.997, and 1.981 eV, respectively. The consistently stronger DRM and DFT adsorption characteristics of PCP demonstrate its greater affinity for Mg@SSB, while the high DRM correlations provide additional mechanistic information beyond the Langmuir model. These findings show Mg@SSB's potential for remediating phenolic contaminants and highlight the complementary value of DRM modelling and DFT in elucidating adsorption behaviour.
Source: FUDMA Journal of Sciences
Institution: University of Calabar
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7214432203