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: Penentuan Kondisi Proses Pemisahan Sitronelal dan Rhodinol dari Minyak Sereh Wangi dengan Distilasi Fraksinasi Vakum
Abstrak: Minyak sereh wangi merupakan salah satu minyak atsiri yang memiliki komponen utama sitronelal dan rhodinol. Komponen utama tersebut dapat dipisahkan dengan metode distilasi fraksinasi. Proses distilasi fraksinasi dengan alat dan kondisi proses berbeda berpengaruh terhadap proses pemisahan fraksi minyak sereh wangi. Oleh karena itu, perlu diketahui pengaruh suhu dan rasio refluks pada proses pemisahan sitronelal dan rhodinol minyak sereh wangi dari unit distilasi fraksinasi vakum kapasitas 7L yang telah di desain dengan spesifikasi tertentu. Proses pemisahan dilakukan pada tekanan 60 mmHg dengan umpan 5L dan dilanjutkan proses redistilasi fraksi kaya sitronelal dan rhodinol. Fraksi sitronelal dan rhodinol yang dihasilkan dilakukan analisis GC-MS untuk mengetahui konsentrasi masing-masing fraksi. Variasi refluks yang digunakan pada pemisahan sitronelal yaitu 12:4, 6:4, 6:2 dan 10:10. Suhu dan rasio refluks berpengaruh terhadap kemurnian fraksi. Kemurnian fraksi sitronelal tertinggi yang dihasilkan yaitu sebesar 50,55% dan fraksi rhodinol sebesar 37,09% pada rasio refluks 6:4. Proses redistilasi fraksi kaya sitronelal dan rhodinol menghasilkan konsentrasi senyawa sitronelal sebesar 42,72% dan senyawa rhodinol sebesar 32,51% dengan rasio refluks 10:10. Kemurnian sitronelal meningkat dan waktu proses lebih singkat dikarenakan pada suhu dan rasio refluks yang digunakan, alat bekerja lebih baik sehingga menghasilkan kemurnian lebih tinggi. Kata kunci: distilasi fraksinasi vakum, minyak sereh wangi, refluks, rhodinol, sitronelal, Citronella oil is one of the essential oils that has the main components of citronellal and rhodinol. The main components can be separated by fractional distillation method. Fractional distillation process with different tools and process conditions affect the separation process of citronella oil fraction. Therefore, it is necessary to know the effect of temperature and reflux ratio on the separation process of citronellal and rhodinol of citronella oil from a 7L capacity vacuum fractionation distillation unit which has been designed with certain specifications. The separation process was carried out at a pressure of 60 mmHg with 5L feed and continued with the redistillation process of the citronellal and rhodinol-rich fractions. The resulting citronellal and rhodinol fractions were analyzed by GC-MS to determine the concentration of each fraction. Reflux variations used in citronellal separation are 12:4, 6:4, 6:2 and 10:10. Temperature and reflux ratio affect the purity of the fraction. The highest purity of the citronellal fraction produced was 50.55% and the rhodinol fraction was 37.09% at a reflux ratio of 6:4. The redistillation process of citronellal and rhodinol-rich fractions resulted in a concentration of citronellal compounds of 42.72% and rhodinol compounds of 32.51% with a reflux ratio of 10:10. The purity of citronellal is increased and the processing time is shorter because at the temperature and reflux ratio used, the tool works better resulting in higher purity. Keywords: citronella oil, citronellal, rhodinol, reflux, vacuum fractional distillation
Keyword: distilasi fraksinasi vakum, minyak sereh wangi, refluks, rhodinol, sitronelal

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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