CytroCell: Valued Cellulose from Citrus Processing Waste

Abstract

Named herein “CytroCell”, the cellulosic material obtained via hydrodynamic cavitation of citrus processing waste in water is cellulose of low crystallinity, high porosity, good water holding capacity and good dispersibility in water. These properties, here demonstrated for the first time for lemon and grapefruit CytroCell, open the route to mass scale production of a useful functional material from a cheap and abundant biowaste. The process, indeed, does not require any pre-treatment of the raw material, and does not use acid, alkali, chemical oxidants or enzymes.

Emerging green routes to nanocellulose

“…Beyond enzymatic extraction, 39 three methods are ready for optimization, scale up and commercialization: the heterogeneously catalyzed oxidation over new generation solid TEMPO catalysts, 40 (including magnetically recoverable Karimi's nanocatalyst), 54 ball-milling in the presence of water of cellulose, 37 and (for applications in needd of nanocellulose of low crystallinity) acoustic and hydrodynamic cavitation. 41,44,45 All are promising considering that many of the aforementioned catalysts are now commercial (Karimi's nanocatalyst in the form of 50 nm beads easily recovered with a magnet); 55 whereas the safe and robust hydrodynamic cavitation process for the extraction of natural products such as waste orange peel is easily scaled-up. 56 Enzymatic extraction, too, is an eminently clean nanocellulose production process.…”

Pectin: New Science and Forthcoming Applications of the Most Valued Hydrocolloid

“…[46] Being reproducible and scalable, these acid-free and "green" extraction processes hold practical (commercial) applicative potential. For instance, extraction based on hydrodynamic cavitation-based directly carried out on a semi-industrial scale (>30 kg citrus biowaste in 120 L water), affords pectin in solution and micronized cellulose of high value (CytroCell) [47] as solid residue through an efficient, one-pot process requiring no chemical reactant (acid, alkali or enzyme) to promote the extraction. The safe and robust hydrodynamic cavitation process for the extraction of natural products is easily scaled-up.…”

“…Several alternative processes have been developed to extract less degraded pectin via acid-free technologies. [45,46,47] Whether or not these technologies will be commercialized will not be due to reduced environmental impact or better product quality (lesser degradation and higher purity), but to their higher profitability due to significantly lower capital and production costs.…”