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Ultrasound-assisted preparation and characterization of crystalline cellulose–ionic liquid blend polymeric material: A prelude to the study of its application toward the effective adsorption of chromium

Kalidhasan, S., Santhana KrishnaKumar, A., Rajesh, Vidya, Rajesh, N.
Journal of colloid and interface science 2012 v.367 no.1 pp. 398-408
Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, adsorbents, adsorption, ambient temperature, ascorbic acid, biopolymers, carcinogenicity, cellulose, chromium, crystal structure, energy-dispersive X-ray analysis, heat production, hydrogen bonding, ionic liquids, models, nuclear magnetic resonance spectroscopy, scanning electron microscopy, sorption isotherms, stable isotopes, surface area, ultrasonic treatment, van der Waals forces
The molecular interaction of biopolymers with an array of substrates offers interesting insight into the adsorption phenomenon. The present work proposes the preparation and characterization of cellulose–methyltrioctylammonium chloride (MeTOACl)–a room temperature ionic liquid (IL) blend polymeric sorbent and its application for the adsorption of carcinogenic chromium(VI). The blend adsorbent material was synthesized in a relatively green solvent (methylisobutylketone) medium by ultrasonication. The mechanism of interaction of biopolymer with the ionic liquid could be conceptualized as electrostatic attraction, hydrogen bonding, and Van der Waals force of attraction with the hydroxyl groups of cellulose as a bilayer assembly. The composition, crystallinity, and the surface area of the prepared material were comprehensively characterized using FT-IR, solid-state ¹³C NMR, TGA, XRD, SEM, EDX, XPS, and BET isotherm study. The adsorption capacity of chromium(VI) calculated from Langmuir isotherm model was found to be 38.94mgg⁻¹ with adherence to the second-order kinetics. The study of thermodynamic parameters that affect the sorption process indicated the spontaneity and exothermic nature of adsorption. The green aspect in the methodology is brought out in the regeneration of the adsorbent, where Cr(VI) could be effectively reduced to the less toxic Cr(III) using ascorbic acid.