Production of a nascent cellulosic material from vegetable waste: Synthesis, characterization, functional properties, and its potency for a cationic dye removal

The present work reports the production of cellulose nanocrystals, CNC30 and CNC60, developed using vegetable waste, i.e., bottle gourd peel through sulfuric acid hydrolysis with a 30 and 60 min hydrolysis process coupled with ultrasonication. The FTIR confirmed the absence of hemicellulose and lignin, and XRD confirmed the crystallinity of the cellulose nanocrystals. DLS studies indicated the hydrodynamic diameter of CNC30 and CNC60 to be 195.5 nm and 192.2 nm, respectively. The TEM image and SAED pattern established the shape of CNC60 to be spherical, with an average particle size of 38.32 nm. CNC60 possessed lesser negative potential and higher thermal stability than CNC30, possibly due to the demolition of the crystalline regions containing sulfate groups. The functional properties, such as swelling power, water, and oil holding capacities of CNC60, were superior to that of CNC30. The adsorption batch parameters yielded 95.68 % methylene dye removal by CNC60 against the predicted value of 96.16 % by the RSM-PSO hybrid approach. The analyses of adsorption isotherms, kinetics, and thermodynamic parameters revealed the nature of the adsorbed layer and adsorption mechanism. Overall observations recommend that CNC60 could be a good and potent functional agent in paper technology, food technology, water treatment, and biomedical applications.