Study of Hydrophilic Properties of Polysaccharides

In this research, the structural characteristics, specific surface area, sorption of water vapor, and wetting enthalpy of various polysaccharides (cellulose, hemicelluloses, starch, pectin, chitin, and chitosan) have been studied. It was confirmed that crystallites are inaccessible for water, and therefore water molecules can interact only with polar groups in noncrystalline (amorphous) domains of biopolymers. The isotherms of water vapor sorption for various polysaccharides had sigmoid shapes, which can be explained by the absorption of water molecules in heterogeneous amorphous domains having clusters with different packing densities. The method of contributions of polar groups to sorption of water molecules was used, which allowed to derivate a simple calculating equation to describe the shape of sorption isotherms. The wetting of biopolymers with water was accompanied by a high exothermic thermal effect, in direct proportion to the amorphicity degree. The sorption values and wetting enthalpies of amorphous domains of biopolymers were calculated, which allowed to find the hydrophilicity index and compare the hydrophilicity of the various polysaccharides.

Study of the diffusion process in films sodium salt of carboxymethyl cellulose – drug

The transport properties of medicinal films based on sodium salt of carboxymethylcellulose and the antibiotic amikacin sulfate have been studied in this work. It has been shown that the process of sorption of water vapor by such films and the release of a drug from them proceeds in an abnormal diffusion mode, which is explained by the slowdown of relaxation processes in glassy polymers, which include the sodium salt of carboxymethylcellulose. An increase of the amount of the introduced drug is accompanied by a regular decrease in the diffusion coefficients of both the process of sorption of water vapor and the release of amikacin from the films. It is noted that the formed films of sodium salt of carboxymethylcellulose-amikacin sulfate dissolve in water during the day and do not provide a prolonged release of the drug. To reduce the solubility of the films in water, the surface modification of the polymer film with calcium chloride has been carried out. It has been found that the modification does not lead to a change in the diffusion mode, but is accompanied by a regular change in the diffusion coefficients – the longer the formed films were kept in a calcium chloride solution, the lower the diffusion coefficients of the sorption of water vapor by medicinal films and the diffusion coefficients of the release of the drug amikacin from the film. It is argued that the surface modification of polymer films based on the sodium salt of carboxymethylcellulose is an effective way of imparting to them the effect of prolonging the release of a drug.

Anisotropic properties of nanofiber porous materials of fibroin silk and cotton cellulose

This paper presents the results of a study on the production of nanofiber anisotropic nanoporous materials based on silk fibroin and cotton cellulose by electrospinning using a rotating screen-receiver of nanofibers in the form of a thin material. The difference in the anisotropic properties of the nanofiber material is shown by the method of birefringence, sorption of water vapor and filtration of a liquid-phase mixture. The possibility of using nanofiber nanoporous fibroin and cotton cellulose materials as a nanofilter of gaseous and liquid-phase mixtures has been shown.

Photocatalytic Decomposition of N2O Over Ceramics Cordierite/CeO2 Nanoparticles

The study is focused on the testing of the photocatalytic ability to decompose nitrous oxide (N2O) over cordierite/CeO2 nanoparticles ceramic photocatalysts. The activity of ceramic materials was compared with the activity of industrially produced TiO2 (Evonik photocatalyst). Photocatalytic decomposition of N2O over the ceramic samples and the TiO2 Evonik was performed in annular batch reactor illuminated with 8 W Hg lamp (λ ═ 254 nm wavelength). Reaction kinetics was well described by pseudo 1st rate law. Photocatalytic activity of cordierite/CeO2 was better in comparison with TiO2 Evonik P25. The highest N2O conversion (56%) after 20 h of irradiation in inert gas was achieved over the sample with higher amount of CeO2. This photocatalyst sample was examined for photocatalytic activity in the decomposition of N2O in the three various gaseous feed mixtures. The gaseous feed mixtures were: N2O enriched with O2 (6.5 mol.%); N2O enriched with H2O(25 mol.%) and N2O enriched with mixture of O2 and H2O(6.5 mol.% and 25 mol.%, respectively). It is assumed that the reduced conversion of N2O (47%) observed in the flow of the mixture of N2O and H2Ocould be affected by the sorption of water vapor on/onto the photocatalyst “active sites” causing less penetration of light and thus reducing the efficiency of photocatalytic decomposition of N2O. The presence of oxygen in the N2O mixture had only little effect to photocatalytic decomposition of N2O.