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Journal : Makara Journal of Science

Grass-Like Structured Mesoporous Carbon as an Acid Red 119 Dye Adsorbent Krisnandi, Yuni Krisyuningsih; Priantini, Tania; Faisal, Muhammad; Yunarti, Rika Tri; Saragi, Indah Revita; Gunlazuardi, Jarnuzi
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

Grass-like structured mesoporous carbon was prepared by the soft-template method using triblock copolymer Pluronic F127, affording an organic–organic composite structure between phloroglucinol and formaldehyde. Thermogravimetric analysis revealed that the as-synthesized mesoporous carbon is stable to 900 °C, and X-Ray Diffraction (XRD) analysis confirmed the presence of carbon material structures at 2θ values of 22.020° and 42.420°. A hysteresis loop at relative partial pressures (P/Po) between 0.45 and 0.85 was observed in the N2 adsorption isotherm, indicating that the solid material exhibits mesoporous characteristics, with a homogeneous pore size distribution of 8.863 nm. Scanning Electron Microscope (SEM) images revealed that the bulk carbon surface exhibits a uniform grass-like structure. Furthermore, the as-synthesized mesoporous carbon was investigated for the adsorption of a diazo dye Acid Red 119, and it exhibited an adsorption capacity of 217.7389 mg/g; this capacity is 1.53 times greater than that of commercial activated carbon. Therefore, this mesoporous carbon is a potential adsorbent for the treatment of synthetic coloring waste.
ZnO/SiO2 Composite as Catalyst for the Transformation of Glycerol to Glycerol Carbonate Krisnandi, Yuni Krisyuningsih; Eckelt, Reinhard; Atia, Hanan; Adam, Martin; Saragi, Indah Revita; Martin, Andreas; Richter, Manfred
Makara Journal of Science Vol. 24, No. 1
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Abstract

Zinc oxide/porous silica (ZnO/SiO2) composite was used as a catalyst to transform glycerol to glycerol carbonate (GC), a chemical intermediate and monomer for the synthesis of new functionalized polymers. The ZnO/SiO2 catalyst was prepared using the direct precipitation method by mixing zinc sulfate solution with Aerosil 300 silica suspension and adding potassium oxalate solution. Catalytic transformation used glycerol and urea (molar ratio = 1:1) at 140 °C, 40 mbar, and various reaction times (1–6 h). The ZnO catalyst exhibited a high percentage of glycerol conversion of 82.38%; however, the yield of GC and selectivity toward GC were relatively low (i.e., 33.33% and 40.46%, respectively). The presence of silica support (ZnO/(x)SiO2 increased the selectivity toward GC and yield of GC to 74.40% to 77.83% and 57.86% to 64.30%, respectively. Furthermore, although its crystallinity decreased, the reused ZnO/(60)SiO2 catalyst still exhibited a high activity. The scanning transmission electron microscopy image indicated the migration of ZnO on the surface of the composite and the possibility of ZnO-glycolate formation, which were also confirmed by FTIR measurement. Nevertheless, these results showed that ZnO/SiO2 is a promising catalyst for the transformation of glycerol to GC.
Natural Aluminosilicate-based Y Zeolite for Catalytic Cracking of n-Hexadecane Khatrin, Irena; Saragi, Indah Revita; Ekananda, Rizki; Hanna, John Vincent; Griffith, Benyamin E; Krisnandi, Yuni Krisyuningsih
Makara Journal of Science Vol. 24, No. 2
Publisher : UI Scholars Hub

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Abstract

Natural zeolite and kaolin are abundant in Indonesia especially in Java and Belitung islands. These materials generally contain high aluminosilicate minerals that can be used as silica and alumina sources for the formation of NaY zeolite. This research aimed to identify the modification of NaY zeolite structure using Bayat natural zeolite as alumina source and Belitung kaolin as silica source and its catalytic activity for n-hexadecane cracking. Pretreatment of materials were performed in several steps: activation, purification, fragmentation for Bayat–Klaten natural zeolite, and silica extraction for Belitung kaolin. The synthesis of NaY was performed hydrothermally using seed-assisted method with crystallization times of 24 and 48 h. The surface area analysis showed a typical surface area of microporous zeolite (i.e., a pore diameter of 1.897 nm) and surface area of 309.4 cm2/g. Meanwhile, powder X-ray diffraction characterization showed that the as-synthesized materials have the structure of NaY zeolite. The optimum crystallization time was 24 h with Si/Al ratio of 4.10. Furthermore, both synthetic and natural sourced NaY zeolites were converted into HY zeolites and employed as cracking catalyst of n-hexadecane in a fixed-bed reactor at 500 °C for 75 s. The natural sourced HY resulted in 59.80% conversion and 59.80% yield of gasoline product (C9–C12). These values were lower than the results given by synthetic HY (80%).