The effect of liquid anhydrous ammonia in the structure and morphology of cotton cellulose

Abstract

The effect of liquid ammonia on cotton fabric was studied using x‐ray diffraction (XRD) and electron microscopy. A phase diagram is presented describing the relationship between disordered cellulose, cellulose I, and cellulose III. The transition from cellulose I to III proceeds through the liquid ammonia. Cellulose III is obtained upon drying the ammonia‐cellulose without the presence of water. Treatment of the cellulose III or of the ammonia‐cellulose with water brings about the formation of cellulose I. The degree of crystalline order achieved in water is enhanced by heating, which is consistent with a glass transition temperature between room temperature and 100°C. The cellulose III crystallites obtained are much smaller than those of cellulose I,16‐23Åas against 50‐80Å The interaction of ammonia with cotton cellulose is faster than with other swelling agents, such as ethylamine. The penetration of ammonia into the secondary wall of the cotton fiber is not only along the concentrical rings, as is the case with water, but also radially across the rings. Prolonged soaking in water increases the crystallite size with simultaneous rejection of swelling water.

Next-generation ammonia pretreatment enhances cellulosic biofuel production

“…High water concentration during pretreatment impedes CIII formation and reverts the ammonia-cellulose complex back into the allomorph CI. 2,5,7 Other ammonia-based pretreatments such as ammonia fiber expansion (AFEXt, trade mark of MBI International, Lansing, MI) and ammonia-recycle percolation (ARP) do not lead to CIII formation because they employ high moisture contents and/or low ammonia-to-biomass ratios. In the case of AFEX, heat generated by the exothermal reaction between ammonia and water is used to reach temperatures up to 140 1C.…”

Coconut Bagasse Treated by Thiourea/Amonium Solution for Cadmium Removal: Kinetic and Adsorption Equilibrium

“…According to research carried out by Zhou et al (2006) with the cellulose dissolution chemistry in NaOH/urea solution, the NaOH hydrates-urea hydrates-free water-cellulose and form a special complex in the solution. Lewin and Roldan (1971) observed that during liquid ammonia treatment the ammonia molecules penetrate cellulose and react with the hydroxyl groups, breaking the hydrogen bonds. The ammonia treatment is believed to yield a celluloseammonia complex (Barry et al 1937;Clark et al 1937).…”

Comparison of the Delignifiability and Hydrolysability of Wheat Straw and Corn Stover in Aqueous Ammonia Pretreatment

“…where λ is the wavelength of the incident X-ray (1.54 Å), θ is the Bragg angle corresponding to the (002) plane, β is the full-width at half maximum (FWHM) of the Xray peak corresponding to the (002) plane, τ is the X-ray crystallite size, and k is a constant with a value of 0.89 (Lewin and Roldan 1971).…”

“…Lewin and Roldan reported that ammonia penetrated the cellulose and reacted with the hydroxyl groups after breaking the hydrogen bonds. The interaction between cellulose and aqueous ammonia can cause changes in the interplanar distances of the 101 planes (Lewin and Roldan 1971;Mittal et al 2011). …”