Effect of degree of sulfonation in nanocellulose/chitosan composite on adsorption of cationic dye as opioid simulant

In this study, the effect of nanocellulose sulfonate group content on adsorption of an opioid simulant was tested. The opioid simulant used was Victoria blue R, an amine dye. Nanocellulose filters were fabricated by crosslinking cellulose nanocrystals (CNCs) with chitosan to improve the mechanical stability of freeze-dried CNCs. Thermogravimetric analysis confirmed the filter's thermal stability and operating temperatures. Conductometric titration, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques were used to characterize the degree of nanocellulose functionalization. Lastly, the adsorption performance of the sulfonated nanocellulose filter was tested and fitted to kinetic models and adsorption isotherms. The adsorption of the dye by the sulfonated nanocellulose followed pseudo-second order kinetics and the Langmuir isotherm. The maximum adsorption of Victoria blue R dye by sulfonated nanocellulose (68.56 mg/g) is significantly higher than those of other adsorbents, like activated carbon (0.59-2.97 mg/g) and magnetic microparticles (40.98 mg/g). Thus, sulfonated cellulose nanocrystals are a promising material for the sequestration of opioids from water.