Claim Missing Document
Check
Articles

Found 5 Documents
Search

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)

Show Abstract | Download Original | Original Source | Check in Google Scholar

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
Variasi Jarak Antar Layer Bentonit Pada Pembuatan Nanokomposit Pla-Bentonit Sebagai Kemasan Makanan Wonoputri, Vita; Emanuella, Natasha; Angelica, Evelyn; Sitompul, Johnner
Indonesian Journal of Chemical Research Vol 8 No 1 (2020): Edisi Bulan Mei (Edition for May)
Publisher : Jurusan Kimia, Fakultas Sains dan Teknologi, Universitas Pattimura

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/ijcr.2020.8-vit

Abstract

In this study, bentonite was used as a filler in the synthesis of polylactic acid (PLA) nanocomposite. The mechanical property of PLA-Bentonite nanocomposite was treated using two different surfactants, namely octadecyl amine (ODA) and trimethyl stearyl ammonium chloride (TSC) at two different concentration (20 mmol and 40 mmol). The treatments of ODA and TSC in the matrix with regards to the basal spacing of bentonite stacks measured by X-Ray Diffraction (XRD) analysis. The results showed a significant increase in basal spacing was obtained when TSC 40 was applied for treatment. Data of Fourier Transform Infrared Spectroscopy (FTIR) suggested that this increase was caused by the incorporation of surfactant into the bentonite stacks. Most of the PLA-Bentonite nanocomposite can form intercalation structure, while a sample containing TSC 40 formed exfoliation structure. This exfoliation structure resulted in a film with the best tensile strength and water vapor permeability compared to the others. The film containing TSC 40 showed the lowest reduction in water activity, almost similar to the bread sample wrapped using conventional plastic. The bread wrapped with TSC 40 film was not grown by fungi as opposed to the conventional plastic, showing the potential of the nanocomposite film as food packaging.
Novel Study of Reaction Kinetics and Mass Transfer in Bioreactor Modelling: Prediction of Bioethanol Fermentation Performance by Saccharomyces cerevisiae on Continuous Fixed Bed Biofilm Plug Flow Reactor Aslan, Christian; Devianto, Hary; Wonoputri, Vita; Harimawan, Ardiyan
Bulletin of Chemical Reaction Engineering & Catalysis 2024: BCREC Volume 19 Issue 4 Year 2024 (December 2024)
Publisher : Masyarakat Katalis Indonesia - Indonesian Catalyst Society (MKICS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.20230

Abstract

Bioethanol implementation as a renewable fuel has yielded economic, social, and environmental benefits, including reduced fossil fuel consumption, enhanced energy diversity and supply security, lower greenhouse gas emissions, and support for agricultural communities. These impacts underscore the importance of advancing innovation and optimizing processes to increase bioethanol production. Therefore, basic knowledge of chemical engineering in bioethanol fermentation is important to be learnt as a preliminary study, such as reaction kinetics and transport phenomena. This work studies the reaction kinetics and mass transfer in continuous fixed bed biofilm plug flow reactor modelling to predict anaerobic Saccharomyces cerevisiae fermentation performance, which is still not studied comprehensively. This modelling provides an overview of the influence of various independent variables, namely temperature, initial substrate concentration, cell concentration, superficial flow rate, reactor diameter, and solid particle diameter on various dependent variables, namely final product concentration, residence time, reactor length, reactor volume, product productivity, and pressure drop. The most sensitive parameters related to product productivity are temperature and cell concentration, so in its implementation, the temperature must be controlled at its optimum temperature, and the inoculum must be prepared with high cell concentration. For the next study, it is recommended to study the optimization of reactor design and operation (i.e. the pumping system, cooling system, and pH control of the reactor) and the implementation of the reactor on the plant scale. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Role of Deagglomeration in Particle Size and Antibiofilm Activity of ZnO Nanoparticles Synthesized with Averrhoa bilimbi Extract Wonoputri, Vita; Samadhi, Tjokorde Walmiki; Khairunnisa, Shafira; Rahayu, Eka
Journal of Engineering and Technological Sciences Vol. 56 No. 6 (2024)
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2024.56.6.5

Abstract

Averrhoa bilimbi fruit extract was utilized as a reducing and capping agent in the biosynthesis of zinc oxide nanoparticles, with an emphasis on the effects of in-situ deagglomeration on physical properties and antibiofilm activity against Escherichia coli. The study explored various biosynthesis parameters, namely deagglomeration method (physical vs chemical), temperature (30, 60 ℃), and zinc precursor-to-extract volumetric ratio (0.5 and 2). High purity crystalline ZnO nanoparticles were obtained by calcining biosynthesis precipitates at 375  ℃. The resulting particles consisted of the wurtzite ZnO phase, with diameters ranging from 18 to 30 nm. The hydrodynamic mean particle diameters were 1.0 to 3.5 µm, suggesting the formation of soft agglomerates. Physical deagglomeration was more effective at higher temperatures, while chemical deagglomeration was more efficient at lower temperatures, owing to the interaction between the deagglomeration method and biosynthesis temperature. The biosynthesized ZnO nanoparticles exhibited good antibiofilm activity, achieving a 61% reduction in biofilm population at 50 ppm ZnO, which increased to 78% at a dose of 200 ppm. This activity was improved by lower biosynthesis temperature and precursor:extract ratio, likely due to the preservation of bioactive molecules. The results demonstrate the potential of biosynthesized ZnO nanoparticles as antibiofilm agent, offering enhanced effectiveness compared to commercial ZnO nanoparticles