Cellulose nanocrystal isolation from tomato peels and assembled nanofibers

Pure cellulose has been successfully isolated from tomato peels by either acidified sodium chlorite or chlorine-free alkaline peroxide routes, at 10.2-13.1% yields. Negatively charged (ζ = -52.4 mV, 0.48 at% S content) and flat spindle shaped (41:2:1 length:width:thickness) cellulose nanocrystals (CNCs) were isolated at a 15.7% yield via sulfuric acid hydrolysis (64% H2SO4, 8.75 mL/g, 45 °C, 30 min). CNCs could be facilely assembled from dilute aqueous suspensions into highly crystalline (80.8%) cellulose Iβ fibrous mass containing mostly sub-micron fibers (ϕ = 260 nm) and few interconnected nanofibers (ϕ = 38 nm), with 21.7 m(2)/g specific surface and 0.049 m(3)/g pore volume. More uniformly nanofibers with average 42 nm width and significantly improved specific surface area (101.8m(2)/g), mesoporosity and pore volume (0.4m(3)/g) could be assembled from CNCs in 1:1 v/v tert-butanol/water mixture.