Judul: Aplikasi Response Surface Method untuk Optimasi Kondisi Proses Produksi Biodiesel Jarak Pagar Melalui Transesterifikasi In Situ
Abstrak: A conventional jatropha seeds biodiesel production is conducted through many stages and long time process. It requires high production cost where 70% of production cost is used for extraction and purification. In situ transesterification can be an alternative solution for conventional biodiesel production problems. This study aims to optimize the process conditions of the jatropha seeds biodiesel production through in situ transesterification using RSM, and to determine the influence of the process conditions on the yield and quality of the biodiesel. The variables of process conditions optimized were the ratio of hexane to total solvent (X1), reaction temperature (X2), reaction time (X3), and agitation speed (X4), where the response was yield, viscosity, acid value, saponification value, and ester value. The optimum process conditions for biodiesel yield were obtained on X1= 0, X2= 57.9 °C, X3= 5.4 hours, and X4= 206.5 rpm. The optimum process conditions for biodiesel quality (viscosity; acid value; saponification value; ester value) were obtained on X1= 0.33, X2= 55.8 °C, X3= 3.2-5.2 h, and X4= 300-600 rpm. Polynomial model for biodiesel yield was first order polynomial model or linier and for biodiesel quality was third order polynomial model or cubic. The ratio of hexane to total solvent (X1) affected significantly biodiesel yield and quality. The optimum process conditions with multi response was obtained on X1= 0.06, X2= 53.3 °C, X3= 6 h, and X4= 392.4 rpm, with y1= 81.3%, y2= 0.14 mg KOH/g, and y3= 3.2 cSt. The validation on this optimum process conditions resulted y1= 77.5%, y2= 0.16 mg KOH/g, and y3= 3.6 cSt. The difference between the results of validation and model prediction was less than 5%, the model was thus good.
Keyword: Bogor Agricultural University (IPB), response surface method, optimization, in situ, jatropha seeds, biodiesel

Judul: Kajian Proses Produksi Biodiesel Melalui Transesterifikasi in situ Biji Jarak Pagar (Jatropha curcas L.) Pada Berbagai Kondisi Operasi
Abstrak: Biodiesel production is generally carried out through several stages of process. They are oil extraction, oil purification, and oil transesterification. Several steps that must be passed in the biodiesel production causing low efficiency and high energy consumption, resulting in high cost of biodiesel production. Therefore, it is necessary to develop a process that simplify the steps in biodiesel production, more efficient, low cost and low energy consumption, also be able to produce high quality of biodiesel through in situ transesterification. This study purposes to investigate on in situ transesterification of Jatropha curcas L. under various operating condition by studying the influence of temperature, stirring speed, and reaction time on the yield and quality of biodiesel. In situ transesterification of Jatropha seeds was carried out under the following process conditions : the moisture content of Jatropha seeds less than 1%, the particle size of 35 mesh, the methanol to hexane to seeds ratio of 6:1:1 (v/v/w), and the KOH concentration of 0.075 mol/L methanol. Operating conditions of in situ transesterification was varied at temperature of 40, 50, and 60ºC, reaction time of 3, 4, and 5 hours, and mechanical stirring of 700, 800, and 900 rpm. Analysis of variance showed that temperature, stirring speed, and reaction time did not significantly affected the yield and viscosity of biodiesel. Temperature, reaction time, and interactions between temperature, stirring speed, and reaction time significantly affected acid value of biodiesel. Temperature and interaction between temperature and stirring speed significantly affected saponification value and ester value of biodiesel. The experimental results showed that in situ transesterification conditions which recommended for commercial scale was at temperature of 40ºC, mechanical stirring of 700 rpm, and reaction time of 3 hours (A1B1C1). That condition was choosen because this condition used low energy than other operating condition. This was also supported by the results of statistical analysis showed that the yield and viscosity of biodiesel were not significantly different at all operating conditions, and biodiesel’s characteristics meets Indonesian Biodiesel Standard. The value of acid value, saponification value, ester value, and viscosity at A1B1C1 are 0.49 mg KOH/g, 201.36 mg KOH/g, 200.87 mg KOH/g, and 3.49 cSt.
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Judul: Karakteristik Anatomi Skelet Kepala Buaya senyulong (Tomistoma schlegelii).
Abstrak: Buaya sepit atau senyulong (Tomistoma schlegelii) merupakan jenis buaya asli Indonesia yang berhabitat di sungai-sungai Sumatera, Kalimantan, dan juga pedalaman Sulawesi. Salah satu ciri khas buaya senyulong adalah bentuk moncong yang runcing dan sempit, namun hingga saat ini informasi mengenai struktur skelet kepala buaya senyulong sangat terbatas. Penelitian ini bertujuan untuk mempelajari karakteristik anatomi skelet kepala buaya senyulong yang dikatikan dengan fungsi dan perilakunya. Penelitian dilakukan secara eksploratif dengan melakukan pengamatan, pencatatan, dan pengambilan gambar dari skelet kepala buaya senyulong. Skelet kepala berukuran panjang 70 cm, lebar 29 cm, dan tingggi 17 cm dengan permukaan kasar pada os nasale, os frontale, os maxilla, os mandibula, os lacrimale, os jugale. Jumlah gigi pada buaya ini sebanyak 78 buah, terdiri dari 4 buah gigi premaxila, 16 buah gigi maxila, dan 19 buah gigi mandibula. Pada regio orbitalis ditemukan dua pasang fenestrae temporales yang berkembang baik. Fenestra supratemporale merupakan lubang oval yang membentang di sepanjang os parietale. Fenestra infratemporale berbentuk segitiga dan dibatasi oleh os squamosum, os postorbitale, os jugulare, dan os quadratum. Os mandibula hewan ini mempunyai symphysis mandibularis yang panjang yaitu garis yang melintang di corpus mandibulae. Secara fungsional ukuran symphysis mandibularis berkaitan dengan adaptasi hewan terhadap diet makan.
Keyword: kepala, moncong, Tomistoma schlegelii