2019 Amoroso L.
Fast production of cellulose nanocrystals by hydrolytic-oxidative microwave-assisted treatment
Amoroso L, Muratore G, Ortenzi MA, Gazzotti S, Limbo S, *Piergiovanni L
In contrast to conventional approaches, which are considered energy and time intensive, expensive and not green, herein we report an alternative microwave-assisted ammonium persulfate (APS) method for cellulose nanocrystals (CNCs) production, under pressurized conditions in a closed reaction system. The aim was to optimize the hydrolytic-oxidative patented procedure (US 8,900,706), replacing the conventional heating with a faster process that would allow the industrial scale production of the nanomaterial and make it more appealing to green economy. Microwave-assisted process was performed according to different time-temperature programs, varying the ramp (from 5 to 40 min) and the hold heating time (from 60 to 90 min), at fixed reagent concentration and weight ratio of raw material/APS solution. Differences in composition, structure and morphology of the nanocrystals, raising from traditional and microwave methods, were studied by several techniques (TEM, FTIR-ATR, DLS, ELS, TgA, XRD), beside the extraction yields were calculated. Fine tuning the microwave treatment variables, it was possible to realize a simple, cost-effective way for faster materials preparation, that allowed to get high quality CNCs, with defined hydrodynamic diameter (150 nm) and zeta potential (-0,040 V), comparable to those obtained using conventional heating, in only 90 min instead of 16 hours.