Liquid-phase synthesis of advanced ceramic sorbents with high functionalization and morphological control

Abstract

Sorption properties, induced by surface reaction such as adsorption, absorption, and ion-exchange reactions, of ceramics are affected by crystallographic properties, including crystallinity, structure, size, and morphology. Through the hydrothermal process, which is a part of the liquid-phase synthesis, crystals with various morphologies can be synthesized in a relatively short time and at low temperatures. Therefore, this process is an effective technique for the enhancement of sorption properties as it facilitates morphology control of ceramics-based purification materials. Herein, morphology-control-based techniques based on the hydrothermal processes for achieving high functionalization of ceramic materials, such as hydroxyapatite (HAp) and sodium titanate (ST) are reviewed, and their applicability for the development of environmental purification materials is verified. An overview of the process design for the morphology control of HAp crystals prepared through the hydrothermal process based on changes in the driving force for crystal growth, i.e., the degree of supersaturation, during the liquid-phase synthesis is presented. Furthermore, the high functionalization (in terms of adsorption and ion-exchange properties) of HAp-based materials prepared through the hydrothermal synthesis is demonstrated. In addition, the effects of unique seaweed-like nanostructures, a higher-order structure composed of ST nanofibers, of ST on its sorption properties are discussed, and the applicability of ST as an inorganic ion exchanger is also investigated.