Effect Ageing Time on Structure and Surface Area of Zeolite Synthetic from Low Grade Bauxite and Rice Husk Ash Arif Rahman (a), Setia Budi (a), Y. Eko Adi Prasetyanto (b), Anwar Usman (c), Nur Kusumaningrum (a).
(a) Department of Chemistry, Faculty of Science and Mathematics, Universitas Negeri Jakarta, Rawamangun,
East Jakarta, Indonesia,
(b) Department of Pharmacy, School of Medicine and Health Sciences, Atma Jaya Catholic University of Indonesia, Jalan Pluit Utara no 2, Jakarta Utara, 14440, Indonesia
(c) Department of Chemistry, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410, Brunei Darussalam
Abstract
This study investigates the effect of ageing time on the structural evolution and surface area characteristics of synthetic zeolite prepared from low-grade bauxite as an alumina source and rice husk ash as a silica precursor. The utilization of low-quality mineral resources and agricultural waste offers a sustainable alternative for the synthesis of high-value zeolitic materials. Zeolite synthesis was carried out through an alkali fusion process followed by ageing and hydrothermal crystallization. Variations in ageing time were applied to evaluate their influence on phase transformation, crystallinity, morphology, and specific surface area of the synthesized products. Structural characterization using Fourier Transform Infrared (FTIR) spectroscopy indicated gradual changes in the Si-O-Al and Si-O vibrational bands associated with the evolution of aluminosilicate frameworks during the ageing process. X-ray diffraction (XRD) analysis demonstrated that prolonged ageing promoted the formation of more stable precursor phases prior to hydrothermal treatment. However, excessive ageing reduced the conversion efficiency toward Zeolite NaX formation, resulting in lower crystallinity of the Faujasite (FAU) framework. Surface area analysis based on the Brunauer-Emmett-Teller (BET) method revealed that longer ageing times caused a significant decrease in specific surface area, indicating reduced pore development and limited zeolitization. This behavior is attributed to the stabilization of precursor species that inhibited further transformation into highly porous zeolitic structures. Scanning electron microscopy (SEM) observations further confirmed the morphological evolution of the synthesized materials with increasing ageing duration. The results demonstrate that ageing time plays a critical role in controlling precursor stability, zeolite crystallization, and surface properties, thereby determining the quality of Zeolite NaX synthesized from low-grade bauxite and rice husk.
