Preparation of Ammonia Dealuminated Metakaolinite and Its Adsorption against Bixin

• Main Authors: Winda Rahmalia, Jean-Francois Fabre, Thamrin Usman, Zéphirin Mouloungui
• Format: Article
• Language: English
• Published: Universitas Gadjah Mada 2020-06-01
• Series: Indonesian Journal of Chemistry
• Subjects: ammonia; adsorption; bixin; metakaolinite
• Online Access: https://jurnal.ugm.ac.id/ijc/article/view/44706
• ISSN: 1411-9420; 2460-1578

This study aims to prepare dealuminated metakaolinite which has a high surface area by using NH4OH as an activator. The natural kaolinite sample was treated at 600 °C for 6 h in order to obtain metakaolinite. A dealuminated metakaolinite was then prepared by the repeated activation method using concentrated ammonia (5 M NH4OH) at room temperature. Depending on the nature of each type of material, natural kaolinite, NH4OH treated kaolinite, metakaolinite and NH4OH treated metakaolinite were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and Brunauer-Emmett-Teller (BET-N2) measurements. XRD and FTIR results confirmed that structural transformation from kaolinite to metakaolinite had occurred. According to SEM-EDS data, the activation of metakaolinite by NH4OH allowed the dealumination of metakaolinite. The increase in the Si/Al ratio was almost twice as high as in kaolinite. BET-N2 analysis showed that the specific surface area and the total pore volume increased significantly after activation. Its adsorption properties were tested against bixin. Bixin adsorption on dealuminated metakaolinite followed pseudo-second order kinetic where k2 = 0.20 g/mg min. The adsorption isotherm followed the Langmuir model where qm = 0.72 mg/g.