SOLVENT-DEPENDENT KINETICS OF POLYPHOSPHATE GLASS HYDROLYSIS

Abstract

Understanding the dissolution kinetics of phosphate glasses is essential for designing materials with tailored durability, optimizing their performance across various applications, and minimizing their environmental impact. The hydrolysis of phosphate glass refers to its degradation in the presence of water, where phosphate bonds break, leading to the gradual dissolution of the glass network. This process is influenced by factors such as composition, pH, temperature, and the presence of ions within the glass matrix. This study investigates the hydrolysis kinetics of polyphosphate glass in deionized water and a 2% citric acid solution, focusing on how solvent properties affect the dissolution process. Experimental results indicate that ion release rates range from 8.74 × 10⁻⁴ to 5.44 × 10⁻² g·m⁻²·h⁻¹ in deionized water, while in a 2% citric acid solution, they vary from 9.44 × 10⁻³ to 6.92 × 10⁻² g·m⁻²·h⁻¹. The activation energies for ion release during hydrolysis are 41.5 to 65.2 kJ·mol⁻¹ in deionized water and 49.1 to 85.3 kJ·mol⁻¹ in the citric acid solution. Additionally, this paper presents the results of EDS analyses of the surfaces of compact polyphosphate glass samples after dissolution in both solvents, providing further insight into the material’s degradation behavior.