Judul: Studi pengaruh ukuran pori-pori filter terhadap kualitas biodiesel jarak pagar (Jatropha curcas Linn.) yang dimurnikan menggunakan adsorben
Abstrak: Biodiesel merupakan salah satu bahan bakar terbarukan yang marak dibicarakan akhir-akhir ini. Biodiesel dibuat dari bahan-bahan berupa minyak nabati dan lemak hewani. Untuk keperluan penggunaan selanjutnya, biodiesel kasar harus dimurnikan terlebih dahulu. Metode pemurnian yang biasa digunakan adalah metode wet washing atau pencucian biodiesel menggunakan air hangat. Metode ini disinyalir memiliki beberapa kelemahan dan tidak terlalu efisien dalam menghilangkan pengotor dari biodiesel. Limbah hasil cuci biodiesel juga menjadi masalah tersendiri dalam konteks lingkungan. Metode yang akhir-akhir ini dikembangkan sebagai substituen dari metode water washing adalah metode dry washing atau pemurnian dengan adsorben. Metode ini memanfaatkan adsorben sebagai bahan pemurni biodiesel, yang diyakini lebih efisien dan murah dalam penggunaannya. Filtrasi merupakan salah satu cara yang digunakan untuk memisahkan antara biodiesel yang telah murni dan adsorben. Untuk lebih mengefisienkan hasil pemisahan antara biodiesel murni dan adsorbennya, maka ukuran pori dari media filter harus ditentukan. Penelitian ini dikembangkan untuk menentukan ukuran pori filter yang paling efisien dalam proses filtrasi, tergantung dari karakteristik biodiesel jarak pagar dan jenis adsorben yang digunakan. Penelitian ini terbagi menjadi tiga tahapan, yaitu persiapan bahan baku, penelitian pendahuluan dan penelitian utama. Pada tahapan persiapan bahan baku dilakukan proses pembuatan biodiesel kasar jarak pagar dan proses aktivasi hidrat alumunium silikat dan hidrat magnesium silikat sebagai adsorben. Penelitian pendahuluan dilakukan untuk mencari jenis dan perbandingan antara hidrat alumunium silikat dan hidrat magnesium silikat sebagai adsorben. Penentuan jenis dan perbandingan adsorben dilakukan melalui analisis karakteristik biodiesel seperti bilangan asam, kadar katalis, kadar sabun, kadar gliserol bebas, gliserol total dan gliserol terikat.…
Keyword: Biodiesel, Jatropha, Filtration, Filter, Pores

Judul: Pengaruh Penggunaan Adsorben  Dan Penggunaan Ulang Adsorben Hasil  Recycling Pada Proses Pemurnian Biodiesel  Minyak Jarak Pagar (Jatropha Curcas L.)
Abstrak: Biodiesel is an alkyl esther which potentially as renewable alternative energy. It could be produced from plant oil derivates such as jathropa pagar oil. Jathropha biodiesel is produced by estrans (esterification-transesterification) reaction. But, in the end of its making, there would be produced dirty biodiesel and another contaminants such as; residue of glycerol, non-reacted methanol, KOH residue and soap produced from the reaction between alkali and free fatty acid during the transesterification. That contaminant will impact the quality of its fuel and has been loosen from the product. Because of that, biodiesel has to be purified in order to have standardized quality that approximately with SNI 04- 7182-2006. The biodiesel purification is commonly used water (water washing method), but this washing method is still having so many weakness that in this research was done the biodiesel purification using adsorbent (dry washing method). This research was aimed to know the impact of adsorbent using and regenerated adsorbent reusing in jathropa biodiesel purification. This research is divided into two stage; introduction and main research. The introduction research was done to know the best adsorbent formulation between silica alumina and silica magnesium. The adsorbent formulation decision was done by some biodiesel characteristic analysis such as acid value, catalyst percentage, soap percentage, free glycerol, total glycerol and bounded glycerol. The experimental designed used in this stage was completely randomized design with one factor, that is adsorbent formulation (Z). The factor (Z) consisted of 8 treatment level, include silica alumina 100%, silica magnesium 100%, and the combination of those two with various comparation; that was 1:1, 1:2, 1:3, 2:3, 2:1, 3:1, and 3:2. In the main research, variety and adsorbent comparation that chose in the former research used for several times and looked the impact of quality characteristic of biodiesel. Before reused, the chosen adsorbent regenerated with water in the temperature of 65-70oC and recovery methanol. The characteristic biodiesel parameter that tested includes acid value, soap value, free glycerol, total glycerol and bounded glycerol. The process of adsorbent activation in biodiesel was significantly reduced the impurities of biodiesel. Based on previous research, best performance was the variety and comparation of 100% silica alumina. The characteristic of purified biodiesel which has been purified by the 100% silica alumina was having the acid value 0.4373 mg KOH/g biodiesel, undetected catalyst, soap contain 53,37 ppm, free glycerol 0,0054%, bounded glycerol 0.2490%, total glycerol 0.2544% and water contain. The result of the main research showed that silica alumina could be used for several times but there was reduction to the quality of the biodiesel. The reduction of biodiesel was significant until the third reuse but it still accomplish the SNI standards. The regeneration process of silica alumina with water 65-70oC produced better methanol compared with recovery methanol. The characteristic of purified biodiesel using first regenerated silica alumina with water in the temperature of 65-70oC was acid value 0.4211 mg KOH/ g biodiesel, undetected catalyst contain, soap contain 1034.5 ppm, free glycerol 0,0079%, bounded glycerol 0.0842%, and total glycerol 0.0921%. The characteristic of the biodiesel in second stage was having the acid
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Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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