Cellulose engineering for eco-efficient Cr(VI) adsorption: Experimental and mathematical optimization

This study presents a novel, solvent-free methodology for enhancing cellulose adsorption of hexavalent chromium through citric acid crosslinking and microwave-assisted Aliquat-336 immobilization, yielding the CECAAL adsorbent. Structural changes were confirmed by FTIR, XRD, and SEM-EDX. Response surface methodology optimized adsorption to yield 74.04 mg g^-1 removal capacity at pH 3.0 with 100 mg adsorbent and 60 min contact time. Kinetic analysis demonstrated that adsorption data fitted exceptionally well to the pseudo-second-order kinetics confirm chemisorption-dominated uptake. Thermodynamic assessment confirmed spontaneous exothermic adsorption with favorable entropy changes. Bayesian uncertainty quantification provided robust 95 % credible intervals for Langmuir adsorption parameters, reinforcing model reliability. Green chemistry evaluation demonstrated exceptional sustainability: E-factor of 0.12, 89 % atom economy, 65 % reduction in energy demand (450 kJ kg-1), and 78 % lower carbon footprint (2.1 kg CO₂ eq kg-1) compared to conventional methods. CECAAL maintains consistent performance over 10 consecutive regeneration cycles, confirming its potential for sustainable industrial wastewater treatment.