Microcrystalline-Cellulose Hydrolysis with Concentrated Sulphuric Acid

Abstract

The effects of temperature (25–40°C), H2SO4 concentration (31–70% (w/v)) and the acid/substrate relationship (1–5 cm3 of H2SO4 per g−1 of cellulose) on the solubilization rate of microcrystalline cellulose and on the glucose production rate have been analysed. The solubilization process was by determining reducing groups present in solution. For acid/substrate relationships of more than 1 cm3 g−1 and H2SO4 concentrations of greater than 62% (w/v), the acid promoted the total solubilization of the cellulose in the form of chains with a low degree of polymerization within 4 h. The solubilization demonstrated zero‐order kinetics in which the specific rate and time of total solubilization are a function of the variables in operation. Glucose was produced according to a mechanism of two consecutive first‐order pseudo‐homogeneous reactions. The values of the kinetic constants k1 and k2 have been correlated with temperature, the H2SO4 concentration and the acid/substrate relationship.

Effect of fibre spinning conditions on the electrical properties of cellulose and carbon nanotube composite fibres spun using ionic liquid as a benign solvent

“…To overcome the first challenge, room temperature ionic liquids such as EMIMAc can be employed as environmentally benign solvent, which is safer and easier to handle than traditionally used solvents such as carbon disulphide [9], sulphuric acid [10] and N-methylmorpholine-N-oxide (NMMO) [11]. A number of researchers have used ionic liquids for fibre stretching/spinning of cellulose [12][13][14][15][16][17][18], wool [19,20], chitin [21][22][23][24] and other natural polymers [25][26][27][28], as well as composite fibres of cellulose [8,29].…”

Fractionation of lignocellulosic biomass with the ionic liquid 1-butylimidazolium hydrogen sulfate

“…Water was then removed in 75 vacuo at 50 ºC, usually for 48 h. ILs were obtained as colourless viscous liquids. Composition and purity of the ILs were confirmed by 1 H-NMR, 13 C-NMR and mass spectroscopy; these data are given in the electronic supplementary information.…”

Products of Cellulose Hydrolysis Made by Treatment of Feedstock with Concentrated Solutions of Sulfuric Acid

“…These early investigations showed that at room or lower temperatures, the sulfuric acid with concentrations greater than 63 wt.% caused swelling and dissolving of cellulose samples that was accompanied by hydrolysis process. Increased temperatures of the acidic treatment promoted both to hydrolysis and dissolving of cellulose [1,2] . At increased concentrations >63wt.% molecules of sulfuric acid are capable to break the hydrogen bonds and penetrate into noncrystalline and crystalline domains of the polymer with forming of the complexes [1] .…”

“…However, in the other papers [1,2,9,20,21] it was found that, the sulfuric acid at concentrations greater than 63-64 wt.% causes swelling and dissolving of cellulose samples. When the acidic solution of cellulose was diluted with water the soluble cellulose was regenerated and precipitated in a form of low molecular amorphized flocs having crystalline polymorph of CII-type [9,20,21,22] .…”