Judul: Fraksinasi Minyak Sereh Wangi Menggunakan Distilasi Vakum Skala Pilot
Abstrak: Citronellal and rhodinol are the main compound of citronella oil that has higher price than crude citronella oil. Citronellal and rhodinol can separate using fractionation process. Therefore, it is necessary to know the process conditions of citronella oil fractionation using 50 L vacuum distillation unit. Fractionation process carried out at 20 mmHg by using 25 L of citronella oil. Crude citronella oil is separated into initial fraction, citronellal fraction, intermediate fraction, and rhodinol fraction. The fractions were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) to determine the composition. The result of process 1 is then used to regenerate the process condition of process 2 by lowering the temperature setting used in process 2. The citronellal fraction of process 1 and process 2 has purity level of 51.22% and 50.40%, respectively. Similarly, the rhodinol fraction of process 1 and process 2 has purity level of 62.33% and 59.40%, respectively. Meanwhile, there was a decreased concentration of citronellal in the initial fraction of process 1 and process 2. Whereas the intermediate fraction in process 1 and process 2 were contained quite high concentrations of citronellal and rhodinol compounds. Low purity of main fraction indicates that the reflux ratio used in the process was inefficient., Citronellal dan rhodinol merupakan senyawa utama dalam minyak sereh wangi yang memiliki harga lebih tinggi dibanding minyak sereh wangi. Citronellal dan rhodinol dapat diperoleh menggunakan proses fraksinasi. Oleh karena itu perlu untuk mengetahui kondisi proses yang optimal dalam proses fraksinasi minyak sereh wangi dengan menggunakan alat distilasi vakum dengan kapasitas 50 L. Proses fraksinasi dilakukan pada tekanan 20 mmHg dengan menggunakan minyak sereh wangi sebanyak 25 L. Minyak sereh wangi mentah dipisahkan menjadi fraksi awal, fraksi citronellal, fraksi antara, dan fraksi rhodinol. Hasil fraksinasi dianalisis menggunakan Gas Chromatography-Mass Spectrometry (GC-MS) untuk mengetahui komponen yang terkandung. Hasil dari proses 1 digunakan untuk memperbaiki kondisi proses pada proses 2 dengan menurunkan pengaturan suhu pada proses 2. Fraksi citronellal pada proses 1 dan proses 2 memiliki kemurnian sebesar 51.22% dan 50.40%. Begitu pula fraksi rhodinol pada proses 1 dan proses 2 memiliki kemurnian sebesar 62.33% dan 59.40%. Sementara terdapat penurunan konsentrasi senyawa citronellal dalam fraksi awal pada prosess 2. Sedangkan fraksi antara pada proses 1 dan proses 2 masih mengandung senyawa citronellal dan rhodinol dengan konsentrasi yang cukup besar. Rendahnya kemurnian fraksi utama ini menunjukkan bahwa rasio refluks yang digunakan tidak efisien.
Keyword: citronella oil, citronellal, rhodinol, vacuum distillation fractionation

Judul: Pemisahan Fraksi Kaya Sitronelal, Sitronelol, dan Geraniol Minyak Sereh Wangi Menggunakan Distilasi Fraksinasi Vakum
Abstrak: The main compounds of citronella oil are citronellal, citronellol, and geraniol, all of which determine the fragrance intensity and price of the citronella oil it self. Separation of those compounds increased the value of citronella oil. The aim of this research is to obtain the optimum amounts of citronellal, citronellol, and geraniol fractions by vacuum of fractional distillation technology. Conditioning process using 30:1 reflux ratio obtioned purer citronellal, citronellol, and geraniol than conditioning process with 10:1 reflux ratio. The separation process was held in 5 - 4 mBar vacuum pressure and the variation of reflux ratio 10:10, 20:10, 30:10. The optimum amounts of citronellal, citronellol, and geraniol was obtioned in the variation of reflux ratio 10:10, they are 90.670 % of 620 ml, 41.101 % of 160 ml, and 53.581 % of 500 ml respectively
Keyword: vacuum fractional distillation, geraniol, citronellol, citronellal, citronella oil

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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