RISM-Assisted Analysis of the Role of Alkali Metal Hydroxides in the Solvation of Cellulose in Alkali/urea Aqueous Solutions

The three-dimensional reference interaction site model theory with the Kovalenko-Hirata closure (3D-RISM-KH) combined with the Kirkwood-Buff integral (KBI) was used to clarify the role of alkali metal hydroxides (MOHs) in cellulose solvation in alkali/urea aqueous solutions. The KBI and excess number of MOHs showed that their access and affinity to cellulose were both in the order LiOH > NaOH > KOH. The cavity and interaction volumes for cellulose indicate that the alkali metal ions closer in proximity to cellulose induce thermal fluctuations of cellulose molecules more easily and cause more electrostatic interactions and hydrogen bonding with cellulose. These calculation results support the hypothesis of cellulose charging up, which claims that cellulose-ion interactions cause cellulose solvation. The energy and chemical potential of cellulose solvation confirmed the affinity and interaction of MOHs with cellulose. Solvent reorganization, whose energy primarily determined the solvation energy, was found to be facilitated by the more proximal MOH when in the presence of urea. 3D-RISM-KH combined with KBI produced quantitative information regarding the distribution and attractive interaction of MOHs (especially LiOH) with cellulose, which clarified their role in cellulose solvation in alkali/urea aqueous solutions.

SYNTHESIS OF CROSPOVIDONE DIFFERENT PROCESS

ABSTRACT Crospovidone is a super-disintegrant and is a thermal polymer; crospovidone is a homopolymer of N-Vinyl-2- pyrrolidone; it is a random polymer of N-Vinyl-2-pyrrolidone cross-linked with (Z)-3-ethylidene-1- vinylpyrrolidone-2-one. In this article, the overview is how to synthesise crospovidone by different processes like the main theme, is direct heating of N-Vinyl-2-pyrrolidone with alkali metal hydroxides in the presence of water. Key Words: Crospovidone, Thermal Polyme

Thermodynamic description of alkali metal hydroxides over a wide range of temperatures, pressures and densities of aqueous fluids

All available experimental data on dissociation constants of aqueous hydroxides of Na, K, and Li were critically assembled and together with quantum chemical estimations used to evaluate parameters of the AD EoS [1] for corresponding aqueous molecules NaOH(aq), KOH(aq), and LiOH(aq). Use of the proposed approach allows proper prediction of the whole set of thermodynamic properties of these hydroxides over a wide range of temperatures (0 – 800 °C), pressures (0.1 – 800 MPa) and solvent densities (0.03 – 1.1 g·cm-3).

Corrosion of Hydrogen Storage Metal Alloy LaMm-Ni4.1Al0.3Mn0.4Co0.45 in the Aqueous Solutions of Alkali Metal Hydroxides

Corrosion of pristine AB5-type metal alloy LaMm-Ni4.1Al0.3Mn0.4Co0.45 in the aqueous solutions of alkali metal hydroxides of diverse composition and concentration was tested. Correlation was observed between the alloy corrosion intensity in various hydroxide solutions, and its electrochemical capacity in these electrolytes. Mm(OH)3, CoO(OH), and nickel metal aggregates were detected among the products of selective oxidation of the alloy. High intensity corrosion of the alloy was observed in RbOH and CsOH solutions leading to formation of ternary oxides at the surface of the alloy. Presence of rubidium and cesium ions in the electrolyte were found to create an additional driving force for lanthanides (La and Ce) to leave the lattice of the alloy, thus, enhancing its corrosion. Corrosion, together with mechanical degradation, were found to be the main reasons of deactivation of LaMm-Ni4.1Al0.3Mn0.4Co0.45 alloy upon elongated electrochemical treatment.