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: Study of biodiesel production by in situ transesterification of jatropha seed (jatropha curcas l.) on pilot scale
Abstrak: At present, energy demands have been steadily increasing along with growth of human population and industrialization. Common sources of energy are fossil-based fuels. This growing consumption of energy has rapidly depleted non-renewable sources of energy. The increasing cost and depletion of fossil fuels have motivated researchers to find an alternative source of renewable energy. Moreover, there are many disadvantages of fossil-based fuels, such as atmospheric pollution and environmental issues. Biodiesel (fatty acids methyl esters, FAME) is a promising alternative fuel to replace petroleum-based diesel that is obtained from renewable sources as vegetable oil, animal fat, and waste cooking oil. Vegetable oil are more suitable source for biodiesel production compared to animal fat and waste cooking since they are renewable in nature. Jatropha curcas L. (JCL) is an acceptable choice for biodiesel production because it is non-edible and can be easily grown. Conventional production of biodiesel from Jatropha seeds involve two main processing steps : oil extraction and transesterification to FAME. In this study, feasibility in situ transesterification of Jatropha seeds was investigated on pilot plant. It was found that methanol/hexane/seed ratio effected the yield significantly. With the following reaction conditions: reaction periode 6 hours, 600 rpm stiring speed, 400C reaction temperature, methanol/hexane/seed ratio 3:3:1, and 7 wt% of KOH, the biodiesel yield can reached 89.19%. This single step of in situ alkaline transesterification process therefore can be a potential route for biodiesel production that reduces processing steps and cost.
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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