Investigation of water vapor adsorption kinetics on hydroxyapatite/magnetite/chitosan biocomposites

Abstract

The work is devoted to the investigation of the morphology and adsorption properties of powder composites based on biogenic hydroxyapatite modified by magnetite (1, 5, 25, 50 wt. %) of various types (synthesis methods) and chitosan. The morphology of the powders evaluated using SEM micrographs and AMIS software is characterized by a uniform distribution of particles size and shape. It was established that the use of magnetite synthesized by chemical precipitation in the amount of 1-5% allows to obtain composite materials with a particle size in a narrower size range. Analysis of the kinetics of adsorption-desorption processes showed that the adsorption of water vapor is directly related to the ratio of hydroxyapatite and magnetite, increasing with increasing magnetite content. In addition, it is shown that the adsorption process for composites modified by magnetite obtained by the chemical precipitation method proceeds uniformly, while for composites containing magnetite obtained by the thermal decomposition method, three consecutive stages of the adsorption process are characteristic: rapid linear increase in mass, gradual inhibition of the adsorption process and stabilization of the mass of the material. The evaluation of the increase in mass also indicates a connection with the ratio of hydroxyapatite and magnetite, increasing with increasing magnetite content, which confirms the presence of physicochemical processes of interaction of gas molecules with the active centers of the molecules of the studied materials. DTGA also shows that the type of magnetite in an amount of more than 25% significantly affects the mass loss of composites during heat treatment up to 1000 °C, which is related to the initial characteristics of the magnetite used. The presented results in combination with previously obtained physicomechanical and biochemical properties testify to the prospects of biogenic hydroxyapatite/magnetite/chitosan composite materials for medicine.