Judul: Characteristics of Hydrochar from Kenaf  (Hibiscus cannabinus L.) Fiber with Hydrothermal Carbonization
Abstrak: Karbonisasi hidrotermal (KHT) lebih dipilih karena memiliki keuntungan yaitu energi yang digunakan rendah dan ramah lingkungan. KHT bahan berlignoselulosa menghasilkan produk berupa arang hidro. Arang hidro sangat baik untuk dijadikan arang aktif dan dapat dimanfaatkan sebagai adsorben berbagai polutan. Dalam penelitian ini, KHT dilakukan menggunakan bahan baku serat kenaf. Penelitian ini bertujuan untuk mengevaluasi pengaruh KHT terhadap karakteristik arang hidro serat kenaf dan menentukan suhu dan waktu KHT terbaik. Suhu yang diterapkan yaitu 130, 150, dan 170 ºC dengan waktu proses selama 3, 4, dan 5 jam. Karakteristik yang diteliti dalam penelitian ini antara lain komponen kimia, analisis proksimat, daya jerap iodin dan daya jerap polutan. Hasil menujukkan karbon terikat, daya jerap iodin dan daya jerap polutan arang hidro meningkat seiring peningkatan suhu dan waktu KHT. Arang hidro terbaik didapat dari hasil KHT 170 ºC selama 4 jam berdasarkan total bilangan iodin dan daya jerap polutan yang cenderung lebih tinggi dibandingkan perlakuan lainnya., Hydothermal carbonization (HTC) is preferred nowaday because it used lower energy and environmentally friendly. Hydrothermal carbonization of lignocellulosic material produces hydrochar. Hydochar is an excellent raw material for activated charcoal and also can be used as an adsorbent of various pollutants. In this study, HTC was carried out using kenaf fiber as raw material. This study aims to evaluate the effect of HTC on the characteristics of kenaf fiber hydrochar and determine the optimal temperature and time for HTC. The temperatures applied were 130, 150, and 170 ºC with processing times of 3, 4, and 5 hours. The characteristics studied in this study include chemical components, proximate analysis, iodine number test, and pollutants adsorbtion test. The result shows that fixed carbon, iodine number, and pollutans adsorbtion of hydrochar increased with increasing of temperature and time. HTC 170 ºC for 4 hours produces the optimal hydrochar based on the total iodine number and pollutant adsorption which tended to be higher than other treatments.
Keyword: Arang hidro, daya jerap iodin, daya jerap polutan, karbonisasi  hidrotermal, serat kenaf, Hydrochar, hydrothermal carbonization, iodine number, kenaf fiber, pollutants adsorbtion

Judul: Characteristics of Pyrolysis Charcoal from Kenaf (Hibiscus cannabinus L.) Stem with Pyrolysis Carbonization
Abstrak: Karbonisasi pirolisis dipilih dalam penelitian ini karena metode ini memiliki kelebihan, yaitu tidak diperlukannya bahan tambah pada saat proses karbonisasi. Karbonisasi pirolisis menghasilkan produk berupa arang pirolisis. Limbah batang kenaf yang cukup banyak dan belum dimanfaatkan dengan optimal, mendasari penggunaan batang kenaf pada penelitian ini. Penelitian ini bertujuan untuk mengetahui pengaruh karbonisasi terhadap karakteristik arang pirolisis batang kenaf, serta mengetahui suhu dan waktu yang terbaik dalam melakukan karbonisasi pirolisis. Pada penelitian ini karbonisasi dilakukan dengan variasi suhu 175 °C, 200 °C, dan 225 °C dengan waktu karbonisasi 3, 4, dan 5 jam. Karakteristik yang diuji meliputi komponen kimia bahan, analisis proksimat arang hasil karbonisasi, daya jerap polutan, dan daya jerap iodin. Hasil pada penelitian ini menunjukkan bahwa, daya jerap polutan dan daya jerap iodin dari arang batang kenaf menjerap dengan baik dibandingkan dengan daya jerap batang kenaf sebelum dijadikan arang. Berdasarkan hasil pengujian daya jerap polutan dan total bilangan iodin, didapatkan arang terbaik pada suhu 225 °C selama suhu 4 jam., Pyrolysis carbonization was chosen in this study because this method has an advantage that it does not require additional materials during the carbonization process. Pyrolysis carbonization produces a product in the form of pyrolysis charcoal. There is a lot of kenaf stems and it has not been used optimally, underlies the use of kenaf stems in this study. This study aims to determine the effect of carbonization on the characteristics of pyrolysis charcoal from kenaf stems, as well as to determine the best temperature and time to carry out pyrolysis carbonization. In this study, carbonization was carried out with variations in temperature of 175 °C, 200 °C, and 225 °C with carbonization times of 3, 4, and 5 hours. The characteristics tested include the chemical components of the material, proximate analysis of carbonized charcoal, pollutant adsorption capacity, and iodine adsorption capacity. The results of this study indicate that the adsorption capacity of the pollutant and the iodine adsorption capacity of the kenaf stem charcoal is better than the adsorption capacity of the kenaf stem before being made into charcoal. Result showed that pollutant adsorption test and the total number of iodine, the best charcoal was obtained at a temperature of 225 °C for 4 hours.
Keyword: Arang pirolisis, batang kenaf, daya jerap iodin, daya jerap polutan, pirolisis, Charcoal pyrolysis, iodine number, kenaf stem, pollutants adsorbtion, pyrolysis

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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