In-situ ultrasonic monitoring of zeolite A crystallization from coal fly ash

In this study, high phase purity of zeolite A was prepared from coal fly ash precursors. The molar regime of both the clear solution extract and unseparated fly ash slurry was adjusted to achieve the right composition for zeolite A crystallization. The formation process for zeolite A from coal fly ash precursors was monitored in detail using an in situ ultrasonic system and was complemented by use of ex situ techniques such as XRD, FTIR, SEM and FTIR. The findings from both the in situ ultrasonic monitoring process and ex situ techniques clearly contributed significantly in unmasking the formation process of zeolite A from coal fly ash compared to previous studies reported in the literature. The study also enriches the existing body of literature by deeply investigating the gel–solution–crystal interactions starting from this complex feedstock. Comparable ultrasonic signals were generated when both clear and unseparated fly ash based precursor solutions were used during the zeolite synthesis process.Web of Scienc

Synthesis of zeolites from coal fly ash using mine waters

In this study mine waters obtained from coal mining operations in South Africa were used as a substitute for pure water during the synthesis of zeolites from South African coal fly ash. Procedures that had been optimized to produce single phase zeolite Na-P1 and X using pure water were employed independently. The use of circumneutral mine water resulted in similar quality zeolite Na-P1 and X whereas the use of acidic mine drainage led to the formation of a single phase hydroxysodalite zeolite. Since these two wastes (fly ash and mine waters) are found in close proximity to each other, this study demonstrates that they can be used to ameliorate each other and at the same time produce saleable zeolitic products that can be used to offset their costs of disposal and treatment.Web of Scienc