Jurnal Rekayasa Kimia & Lingkungan
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Hydrogen Absorbing Material in Carbonaceous-Metal Hydride
Full text linkOne of the most promising materials for storing hydrogen in solid state would be included in metal-carbon composites. In order to obtain nanocrystalline metal particles encapsulated by crystalline or amorphous carbon, mechanosynthesis of zirconium-carbonaceous composites and alkali metal-carbonaceous composites was performed. For zirconium-carbonaceous composites, only zirconium-carbon black composite absorbed more hydrogen than expected for a mere mixture with the same composition. The higher hydrogen capacity on the zirconium-carbon black composite would be due to some specific sites on the carbonaceous material created during the milling. Another effect of the composite formation was stabilization of zirconium, that is, the composites did not ignite in air. On alkali metal-carbonaceous composites, carbon black has superior effect in composite formation compared with graphite in which some cooperative effect was only detected on alkali metal-carbon black composite. The effect of the carbonaceous composite formation was resistance to air and anti-sticking characteristics to balls and the wall of the vial during the ball milling
Studi Oksidasi Etanol Menjadi Asetaldehida Menggunakan Katalis Molibdenum Oksida Berpenyangga Al2O3, TiO2, dan SiO2
Full text linkPenelitian ini bertujuan untuk mengevaluasi pengaruh penyangga Al2O3, SiO2, dan TiO2 pada MoO3 terhadap kinerjanya dalam oksidasi etanol menjadi asealdehida. Katalis disiapkan dengan metode impregnasi dengan kandungan MoO3 of 25% dan 50%. Hasil identifikasi dengan X-ray Difraction (XRD) menunjukkan bahwa komponen katalis terdiri dari kristal MoO3, TiO2, Al2O3, dan SiO2. Reaksi uji kinerja katalis dilangsungkan dalam reaktor pipa lurus berunggun tetap, beroperasi pada 150-300oC dan tekanan atmosfir. Produk dianalisis menggunakan gas kromatografi GC 8A buatan Shimadzu dengan kolom porapak Q 80/100 mesh. Konversi etanol tertinggi diperoleh 83% menggunakan katalis 50%MoO3/TiO2. Selektivitas asetaldehida tertinggi dihasilkan 96% menggunakan katalis 25%MoO3/SiO2. Yield asetadehida tertinggi dicapai 51% menggunakan katalis 25%MoO3/TiO2.Kata kunci: katalis MoO3/TiO2, Al2O3, SiO2, impregnasi, oksidasi etanol, asetaldehid
Rapid Determination of Microbial Quinones using Supercritical CO2 Extraction
Full text linkThe supercritical CO2 extraction of microbial quinones from activated sludge samples obtained from various activated sludge was investigated and compared to the conventional method using organic solvent extraction. The extraction was carried out in a supercritical fluid extraction (SFE) system in the temperature range of 25 to75 oC and the pressure up to 30 MPa. Different extraction conditions, such as the temperature, pressure, extraction time and modifier were employed to maximize the SFE efficiency. Significant amount of microbial quinones (ubiquinones and menaquinones) could be extracted rapidly with supercritical CO2. Results on the value of diversity and dissimilarity suggested that the SFE with supercritical CO2 extraction was a reliable technique for quinones extraction