Cistus albidus L. cellulose-based bioadsorbent: An innovative eco-friendly method for removing basic fuchsin dye from water solutions and DFT mechanistic insights

Abstract

• Novel cellulose-based biosorbent from Cistus albidus L leaves for BF dye removal. • Adsorption capacity for BF dye: 12.01 mg/g at C 0 = 100 mg/L after 60 minutes. • DFT and NCI calculations show cellulose contribute to adsorption BF dye. • Adsorption mechanism involves hydrogen bonding and van der Waals forces. • Kinetic, thermodynamic, and isothermic studies conducted for BF dye adsorption. Synthetic dyes are widely used in various industries, but the discharge of dye-contaminated effluents poses significant environmental and health hazards due to the persistence and toxicity of many dyes. Traditional remediation methods often face challenges regarding cost, efficiency, and environmental impact. This study introduces a novel, unmodified bioadsorbent derived from the powdered leaves of Cistus albidus L . (CSP) for the removal of Basic Fuchsin (BF) dye from aqueous solutions. The bioadsorbent was characterized using scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis, revealing a well-structured mesoporous architecture with a surface area of 10.93 m²/g. Under optimal conditions (21°C, pH 10, initial BF concentration of 100 mg/L, contact time of 60 minutes, and a CSP dose of 5 g/L), the maximum adsorption capacity for BF dye reached 12.01 mg/g, demonstrating competitive efficiency relative to other plant-based adsorbents. The adsorption process was best described by the Freundlich isotherm model and pseudo-second-order kinetics, indicating multilayer adsorption on a heterogeneous surface. Density Functional Theory (DFT) calculations revealed that BF dye adsorbs onto the cellulose structure of CSP (R-CSP), with an interaction energy of E I n t e r a c t i o n = − 0.13 eV, confirming that the adsorption is thermodynamically favorable and exothermic. This energy therefore yields E b i n d i n g = 0.13 eV indicates a stable configuration for the R-CSP-BF complex. Furthermore, Non-Covalent Interaction (NCI) analysis highlighted the critical roles of hydrogen bonding and van der Waals forces in the adsorption of BF dye. These results underscore the potential of CSP as an effective and environmentally friendly bioadsorbent for removing dyes from wastewater.