THE EFFECT OF CRYSTALLIZATION AND AGING TIME IN ZEOLITE SYNTHESIS USING COAL FLY ASH AS SILICA AND ALUMINA SOURCE

Silica and alumina were extracted from coal fly ash (CFA) using a reflux method with an alkaline solution. The resulting coal fly ash extract (CFAE) served as the primary material for synthesizing zeolites through a hydrothermal method at 150°C, with variations in crystallization time (ranging from 10 to 120 hours) and aging time (ranging from 0 to 24 hours). Hence, this study aims to utilize CFA waste to synthesize zeolite without adding external silica and alumina while evaluating the optimal crystallization and aging time synthesis conditions using the hydrothermal method. XRF characterization revealed increased alumina and silica composition in CFAE, from 16.7669% and 30.8462% to 42.04% and 53.42%, respectively. Analysis of FTIR spectra showed characteristic absorptions indicative of zeolite structures, while XRD data analysis confirmed the presence of zeolite ZK-14 (SOD) phase in all synthesized samples. The %yield, crystallinity, and particle size of the synthesized materials were significantly influenced by variations in crystallization and aging times. %Yield showed slight variation, with the highest achieved at 48 hours of crystallization time (37.83%). Crystallinity increased with prolonged crystallization time, peaking at 72 hours (50.73%), while particle size reached its maximum at 120 hours (23.82 nm). Aging time exhibited an inverse relationship with crystallinity and particle size but did not affect %yield. Overall, longer crystallization times led to higher %yield, crystallinity, and larger particle size in the synthesized zeolite materials.