Vita Wonoputri
Research Group of Chemical Engineering Process Design and Development, Faculty of Industrial Technology, Institut Teknologi Bandung

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Determination of Kinetic Parameters for Methane Oxidation over Pt/γ-Al2O3 in a Fixed-Bed Reactor Wonoputri, Vita; Effendy, Mohammad; Budhi, Yogi Wibisono; Bindar, Yazid; Subagjo, S.
Journal of Engineering and Technological Sciences Vol 45, No 2 (2013)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (518.085 KB) | DOI: 10.5614/j.eng.technol.sci.2013.45.2.7

Abstract

This paper describes akinetic study for the determination of the kinetic parameters of lean methane emission oxidation over Pt/γ-Al2O3 in a dedicated laboratory scale fixed bed reactor. A model ofthemechanistic reaction kinetic parameters has been developed. The reaction rate model was determined using therate-limiting step method, which was integrated and optimized to find the most suitable model and parameters. Based on this study, the Langmuir-Hinshelwood reaction rate model with the best correlationis the one where the rate-limiting step is thesurface reaction between methane and one adsorbed oxygen atom. The pre-exponential factor and activation energy were 9.19 x 105 and 92.04 kJ/mol, while the methane and oxygen adsorption entropy and enthalpy were –17.46 J/mol.K, –2739.36 J/mol,–16.34 J/mol.K, and –6157.09 J/mol, respectively.
Variasi Antioksidan dalam Pembuatan Protected Active Dried Yeast Purwadi, Ronny; Wonoputri, Vita; Fitriana, Febri Ulfa; Choliq, Najwa Shufia
Jurnal Teknik Kimia Indonesia 2020: Article in Press
Publisher : ASOSIASI PENDIDIKAN TINGGI TEKNIK KIMIA INDONESIA (APTEKIM)

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Abstract

Abstrak. Penggunaan antioksidan pada pembuatan protected active dried yeast (PADY) dapat memperpanjang umur simpan ragi kering. Antioksidan yang sering digunakan adalah antioksidan sintestis BHA dan BHT yang diduga bersifat karsinogenik. Penelitian ini bertujuan untuk mencari alternatif antioksidan yang lebih aman. Lima antioksidan yaitu asam sitrat, asam askorbat, tokoferol, natrium eritrobat, dan askorbil palmitat pada rentang konsentrasi 0,025-0,5% diuji pada suspensi ragiuntuk mempelajari efek inhibisi dari antioksidan tersebut. Uji laju produksi CO2 menunjukkan sifat noninhibisi dari asam askorbat, natrium eritorbat, asam sitrat, dan tokoferol, sedangkan sifat inhibisi askorbil palmitat dan BHT perlu diteliti lebih lanjut. Formulasi antioksidan terpilih untuk produksi PADY adalah asam sitrat 0,5%, asam askorbat 0,5%, dan tokoferol 0,5%. Pengeringan ragi dengan spray dryer menghasilkan PADY dengan kadar air sesuai standar. PADY dengan sifat fisik terbaik adalah variasi asam sitrat 0,5% dan asam askorbat 0,5% karena kelarutan dalam air yang baik serta granula yang lebih halus. Stabilitas vitalitas PADY diukur selama 45-50 hari, dan didapatkan PADY dengan antioksidan asam askorbat 0,5% memiliki konstanta laju kematian terendah, yaitu 0,0492/hari, setara dengan umur simpan 20 hari. Dengan demikian, formulasi antioksidan asam askorbat 0,5% berpotensi untuk dikembangkan pada produksi PADY.  Kata kunci: Antioksidan, ragi kering, stabilitas, vitalitas Abstract. Variation of Antioxidant in Production of Protected Active Dried Yeast. The use of antioxidants in production of protected active dried yeast (PADY) can increase dried yeast’s shelf life. Usually, the antioxidants used are synthetic antioxidants such as BHA and BHT, which are known to be carcinogenic. Therefore, the aim of this research is to study antioxidant alternative that is safer. Five antioxidants, i.e. citric acid, ascorbic acid, tocopherol, sodium erythorbate, and ascorbil palmitate in concentration range of 0.025-0.5% were tested on yeast suspension to study its inhibitory effect. CO2 production rate test showed noninhibitory characteristic of ascorbic acid, sodium erythorbate, citric acid, and tocopherol, whereas ascorbyl palmitate and BHT showed inhibitory characteristic. Formulations of antioxidants selected are 0.5% citric acid, 0.5% ascorbic acid, and 0.5% tocopherol. Spray drying of yeast resulted in PADY with moisture content within standard. PADY with the best physical properties are 0.5% citric acid and 0.5% ascorbic acid variation due to good water solubility and finer granules. Vitality stability of PADY was measured for 45-50 days. PADY with 0.5% ascorbic acid had the lowest death rate constant, i.e. 0.0492/day, which is equivalent to 20-days shelf life. Thus, ascorbic acid antioxidant formulation of 0.5% can be developed in the production of PADY.Keywords: Antioxidant, dried yeast, stability, vitality