Judul: Transformation of jatropha seeds (Jatropha curcas L.)  into biodiesel by in situ transesterification
Abstrak: Biodiesel is defined as mono-alkyl esters from transesterification reaction of triglycerides with alkyl alcohol. In situ transesterification is a method to produce biodiesel from oil sources of material by eliminating process steps of oil extraction and refining. The purpose of this research is to study the transformation process of Jatropha seeds into biodiesel by in situ transesterification on the 10 liters scale by studying the influence of reaction time, stirring speed and ratio methanol/hexane/material on the yield and quality of biodiesel. In situ transesterification of Jatropha seeds was carried out under the following process condition: the moisture content of Jatropha seeds were less than 2%, the particles size were ± 20 mesh and KOH concentration was 0.075 mol/L methanol. Operating condition of in situ transesterification was varied at 4 and 6 hours reaction time, 200 and 600 rpm stirring speed and ratio methanol/hexane/material (v/v/w) were 3:3:1, 4:2:1 and 5:1:1. Analysis of variance showed that reaction time, stirring speed and ratio methanol/hexane/material did not significantly affected the yield, acid value, saponification value, ester value, viscosity and ash content of biodiesel. The biodiesel yield was produced between 82.54-87.57%. The best biodiesel yield on all of treatments was 87.57% with condition treatment were reaction time of 6 hours, stirring speed 600 rpm and ratio methanol/hexane/material (v/v/w) of 4:2:1. Acid value, saponification value and ester value of biodiesel were 0.20-0.26 mg KOH/g, 185.49-194.30 mg KOH/g and 185.29-194.10 mg KOH/g respectively. Viscosity of biodiesel was 3.49-6.36 cSt. The ash content of biodiesel was 0%, but the condition treatment, were reaction time of 4 hours, stirring speed of 600 rpm and ratio methanol/hexane/material (v/v/w) of 5:1:1, had ash content of 0.007%. Jatropha cakes had total volatile matter content 1.80-3.64% and extracted material content 3.94-11.42%.
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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: Perbandingan Karakteristik Anatomi Skelet Kepala Komodo (Varanus komodoensis) dan Biawak Air (Varanus salvator).
Abstrak: Komodo dan biawak air diklasifikasikan dalam Ordo Squamata dan Famili Varanidae. Meskipun kedua hewan ini termasuk dalam ordo dan famili yang sama tetapi perannya di alam berbeda. Komodo sebagai predator utama memiliki ukuran tengkorak yang lebih besar dibandingkan dengan ukuran tengkorak biawak air yang berperan sebagai predator opportunistik. Penelitian ini bertujuan untuk mempelajari komparasi karakteristik struktur skelet kepala komodo (Varanus komodoensis) dengan skelet kepala biawak air (Varanus salvator). Struktur kepala ini dikaitkan dengan fungsi skelet kepala untuk mendukung perilaku sehari-hari. Penelitian ini dilakukan dengan cara mengamati dan mengukur tulang-tulang penyusun skelet kepala komodo dan biawak air, serta mengamati perilaku sehari-hari kedua hewan melalui pengamatan video. Hasil penelitian menunjukkan ukuran skelet kepala komodo memiliki panjang 21.9 cm, lebar 11.6 cm, dan tinggi 8.9 cm. Skelet kepala biawak air memiliki panjang 16.0 cm, lebar 7.0 cm, dan tinggi 5.0 cm. Komodo memiliki gigi marginal dan lingual dengan tipe gigi pleurodont dan ziphodont, yaitu bentuk gigi seperti pedang dan melengkung ke arah lateral. Biawak air memiliki gigi marginal dengan tipe pleurodont yang tumbuh disamping rahang dengan satu gigi pengganti pada setiap gigi marginal. Hubungan antar tulang penyusun skelet kepala komodo relatif longgar dan memiliki os temporale yang sangat berkembang, sehingga pembukaan mulut komodo sangat lebar dibandingkan biawak air yang tidak memiliki kraniokinesis. Kedua hewan ini memiliki canalis intercisivum yang terdapat pada palatum durum menghubungkan cavum oris dan cavum nasi. Secara fungsional, saluran ini dikaitkan dengan kemampuan penciuman yang tajam karena saluran ini berhubungan dengan organ vomeronasale. Perbedaan struktur skelet kepala komodo dan biawak air berperan dalam melakukan aktifitas sehari-hari kedua hewan ini.
Keyword: perbandingan skelet kepala, komodo, biawak air