Nanocellulose from citrus processing waste using water and electricity only

Abstract

Along with a water-soluble fraction rich in pectin, the hydrodynamic cavitation of citrus processing waste carried out in water directly on a semi-industrial scale affords an insoluble fraction consisting of a new nanocellulose of high quality. Lemon and grapefruit nanocellulose powders isolated upon filtration and mild drying consist, respectively, of 100-500 nm wide cellulose nanorods, and of 500-1,000 nm wide ramified microfibrils extending for several μm. The process is general and can be applied to any citrus processing biowaste. These findings establish a long-sought technically viable route to a material whose numerous potential applications in fields ranging from biomedicine to composite production have been limited by the harsh conditions required for the extraction of nanocellulose via acid or enzymatic hydrolysis following pretreatment of lignocellulosic biomass with acid-chlorite or alkali.

Emerging green routes to nanocellulose

“…Grapefruit CytroCell is comprised of ramified microfibrils whose diameter varies from 500 nm to 1 μm (Figure 2). 46 Both new "CytroCell" materials consist of cellulose of low crystallinity index (0.33 for lemon and 0.36 for grapefruit). The one-pot process requires no subsequent mechanical treatment of the fibrillated nanofibers.…”