Judul: Sintesis glukosa oleat dari metil oleat dan glukosa pentaasetat menggunakan katalis zeolit alam cikembar
Abstrak: Zeolit merupakan suatu kelompok mineral yang telah menyita perhatian banyak pihak. Hal ini terkait dengan cirinya yang selektif terhadap suatu zat selain sifat asambasa yang dimilikinya. Zeolit dapat digunakan sebagai penjerap, zat penukar ion, dan katalis. Salah satu reaksi yang dikatalisis oleh zeolit adalah interesterifikasi metil oleat dengan glukosa pentaasetat untuk memperoleh glukosa oleat. Pada reaksi ini, zeolit berperan sebagai katalis heterogen yang mudah dipisahkan dari campuran reaksinya. Penelitian ini merupakan pengaplikasian zeolit alam Cikembar sebagai katalis pada sintesis ester glukosa oleat. Bobot zeolit diragamkan untuk mengetahui bobot zeolit yang paling tepat digunakan dalam sintesis glukosa oleat. Tabapan penelitian terdiri atas lima tabap, yaitu sintesis glukosa pentaasetat (GPA), aktivasi zeolit, sintesis metil oleat, sintesis glukosa oleat menggunakan katalis zeolit, dan pemisahan ester glukosa oleat.
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Judul: Sintesis ester glukosa oleat dari glukosa pentaasetat dan metil oleat
Abstrak: Dewasa ini, perkembangan industri farmasi, kosmetika, dan detergen meningkat pesat sehingga kebutuhan bahan aditif seperti surfaktan juga meningkat. Selain minyak bumi, sumber daya alam yang dapat digunakan sebagai bahan baku surfaktan adalah minyak nabati (asam lemak) dan karbohidrat (glukosa). Ester asam lemak-glukosa merupakan surfaktan nonionik yang memperlihatkan sifat mudah terdegradasi dan tidak beracun. Penelitian ini dilakukan melalui empat tahapan, yaitu sintesis metil oleat, sintesis glukosa pentaasetat (GPA), sintesis ester glukosa oleat, serta pemisahan ester glukosa oleat. Rendemen rerata metil oleat yang dihasilkan sebesar 88.36%, sedangkan rendemen rerata GPA sebesar 48.11% dengan kisaran titik leleh 108-112 oC. Rendemen rerata ester glukosa oleat yang didapatkan pada nisbah mol GPA: metil oleat 1:1; 1:2; dan 1:3, masing-masing sebesar 65.55; 57.77; dan 70.64% dengan kisaran titik leleh masing-masing sebesar 98-110; 110-112; dan 84-98 oC. Berdasarkan hasil analisis spektrum infra merah ester glukosa oleat, terdapat puncak serapan ulur C-H dari gugus alkil rantai panjang yang kuat pada bilangan gelombang 2800-2900 cm-1, yang tidak dimiliki oleh GPA. Hal tersebut menunjukkan bahwa telah terjadi reaksi interesterifikasi antara metil oleat dan GPA menghasilkan ester glukosa oleat.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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