Colloidal and Thermal Behaviors of Some Venezuelan Kaolin Pastes for Therapeutic Applications

Ana C Hernández,César Viseras,Fátima García-Villén,Gema González,Mahmoud E Awad,Williams Meléndez,Rita Sánchez-Espejo,Alberto López-Galindo

doi:10.3390/min9120756

Abstract

This work contributes to the knowledge of colloidal and thermal properties of some important primary-originated kaolin deposits from Bolivar State, Venezuela, and their possible use as semisolid formulations in medicinal muds for topical applications. Eight selected high purity kaolin samples were characterized. Rheological and thermal properties were correlated to physico-chemical characteristics of the clay suspensions (pH, Ca2+, and Mg2+ cation desorption and surface charge). Most of the studied kaolin pastes showed adequate viscosities, acceptable skin safe pH, and good thermal properties for pelotherapeutic uses. Three of the studied samples, in particular, showed very high kaolinite purities (>92% kaolinite), elevated viscosities (>1 Pa·s), and good thermal and pH performances for topical application.

Highlights

Clay minerals have been widely used to develop products and functionalities in a large variety of areas, including materials, pharmaceuticals, food sciences, and biotechnology
Samples essentially consisted of kaolinite, with contents ranging from 73% to 99%, with an average of 88.3%
Contents of trace elements in the global kaolin deposits were attributed to their substitutions in the crystal structures of the associated titanium oxides and iron oxy-hydroxide minerals

Summary

Introduction

Clay minerals have been widely used to develop products and functionalities in a large variety of areas, including materials, pharmaceuticals, food sciences, and biotechnology. Mixtures of clays and mineral waters are used in health mud therapies, either for thermotherapeutic or cosmetic purposes, and constitute the basis of most of the muds used in healing and spa centers. The ever-increasing use of clay minerals in pelotherapeutic applications is due to the versatility and peculiarity of their physical and chemical properties and the suitability of their colloidal and thermal behaviors [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]. Kaolinite is the main clay mineral of the kaolin group, and it has attracted great interest in pharmaceutics and therapy fields based on their properties [27]. In addition to the influence of water content and solid fraction composition in the quality and healing activity of the thermotherapeutic muds, Awad et al [29]

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