Simple vapor sorption method for determination of water in liquids

Abstract The objective of this study was to understand the chemical modification impact on interactions between water and cellulosic fiber. In that respect, cotton (C), flax (F), viscose (V) and cellulose acetate (CA) were analyzed by using a dynamic vapor sorption analysis. The sorption and desorption isotherms and kinetic curves were modelled using the Park model and the “Parallel Exponential Kinetics” (PEK) model-which allowed an accurate fitting on the whole range of water activity. The obtained sorption properties were correlated to the accessibility and the amount of sorption sites and also to the crystallinity level of the fibers. It was found that V exhibited the highest water sorption capacity due to a higher hydroxyl groups accessibility and a high amorphous fraction, followed up by F, C and CA. In contrast, higher kinetic sorption rate was obtained for CA due to a decrease of the hydroxyl groups within the fibers. Regardless the fiber, the determination of characteristic times showed that the kinetic rate was higher for sorption than desorption.

Download Full-text

Size Analysis Based on Sorption Study Data for Hydroxyapatite Nanoparticles

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1031.172 ◽

2021 ◽

Vol 1031 ◽

pp. 172-177

Author(s):

Evgeniya Maraeva ◽

Kamilya Khalugarova

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Chemical Deposition ◽

Study Data ◽

Size Analysis ◽

Hydroxyapatite Nanoparticles ◽

Sorption Method ◽

Sorption Study

This work is devoted to the study on the possibility of applying the method of analyzing the particle size of hydroxyapatite at various stages of synthesis. A series of hydroxyapatite powders obtained by chemical deposition using microwave radiation is considered. Determination of the size of hydroxyapatite nanorods is carried out on the basis of data on the density and specific surface area. The specific surface area is analyzed by the sorption method. Determination of the ratio "length / diameter" of nanorods is based on the analysis of images obtained by scanning electron microscopy.

Download Full-text

AMORPHOUS PHARMACEUTICAL SOLIDS: A REVIEW

INDIAN DRUGS ◽

10.53879/id.50.07.p0005 ◽

2013 ◽

Vol 50 (07) ◽

pp. 5-13

Author(s):

B. V Dhokchawle ◽

◽

S. J. Tauro ◽

A. B Bhandari

Keyword(s):

Freeze Drying ◽

Amorphous State ◽

Vapor Sorption ◽

Pharmaceutical Solids ◽

Preparation Methods ◽

Continuous Increase ◽

Amorphous Pharmaceuticals ◽

Drug Molecules ◽

Sorption Method ◽

Quench Cooling

Amorphous pharmaceutical solids have recently attracted the interest of pharmaceutical scientists because of a continuous increase in the number of developmental drug molecules that are insoluble. Amorphous state of the drug provides several pharmacokinetic advantages over the crystalline state. In this review preparation methods, characterization techniques and applications of amorphous pharmaceuticals have been discussed. Quench cooling, melt extrusion, spray drying and freeze drying are important methods for amorphization of solids. Amorphous pharmaceutical solids are characterized by diffraction technique, spectroscopy, vapor sorption method and thermal analytical methods. Stability of amorphous solids is important as their advantage of improved solubility might not be long lasting.

Download Full-text