Judul: Pembuatan Arang Aktif Tempurung Kelapa Sawit Sebagai Adsorben Dalam Pemurnian Biodiesel
Abstrak: Palm shell is one of solid waste from palm oil industries. To increase the added value and to reduce solid waste palm shell can be converted as activated charcoal. Application of activated charcoal could be done for purification process of biodiesel. Production of activated charcoal could be made through carbonization process at temperature of 450oC for five hours. The charcoal was soaked for 24 hours with the activator agent such as phosphoric acid activated with concentration of 15% and charcoal which was not soaked with phosphoric acid. Both of the charcoals were activated at temperature of 800oC with the variation time of 60, 90, and 120 minutes. The best quality of activated charcoal was the activation charcoal which were not soaked and activation time. The best quality of activated charcoal was the activation charcoal which were not soaked and activation time for 120 minutes with yield value of 56.5%, water content of 2.45%, volatile matter of 10.66%, ash content of 6.83%, fix carbon of 82.51%, adsorptive capacity of iodine 878.31mg/g, adsorptive capacity of benzene of 20,14%, and pH of 9.42. Crystalinity of activated charcoal of 39.89 %. Activated charcoal had been the standard of Standar Nasional Indonesia (SNI) 06-3730-1995. The ability of the best activated charcoal would be applicated for purification of biodiesel. Adding 3% of activated charcoal was better for purification of biodiesel so that was earned acid value of 0.22 mg KOH/g, pureness of 65.43%, pH of biodiesel of 7.29.
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Judul: Activated Charcoal Made from Kluwak, Palm Kernel, Coconut, and Candlenut Shells as an Adsorbent for Motor Vehicle Gas Emissions
Abstrak: Arang aktif biasa dipakai dalam proses pemurnian udara, gas, larutan atau cairan, dan proses perolehan kembali suatu logam. Arang aktif memiliki pori-pori yang lebih terbuka sehingga daya jerapnya lebih tinggi dibandingkan arang biasa. Bahan yang dapat digunakan sebagai bahan baku arang aktif adalah limbah perkebunan seperti tempurung kluwak, kelapa sawit, kelapa, dan kemiri. Penelitian ini bertujuan membandingkan arang aktif dengan mutu terbaik dari bahan dasar tempurung untuk menurunkan kadar gas pencemar udara seperti gas CO, NO2, dan SO2 yang berasal dari emisi kendaraan bermotor yang dapat merusak lingkungan dengan metode kajian literatur. Hasil penelitian menunjukkan keempat tempurung menghasilkan arang aktif dengan mutu yang baik. Tempurung kluwak menghasilkan arang aktif dengan kandungan karbon terikat tertinggi, yaitu sebesar 96,90% serta daya jerap iod sebesar 996,96 mg/g yang memenuhi SNI 06-3730-1995. Arang aktif tempurung kluwak memiliki efektivitas terhadap penurunan konsentrasi gas CO yang paling baik, yaitu sebesar 98,02%, sedangkan efektivitas terhadap penurunan konsentrasi gas NO2 dan SO2 yang paling baik dimiliki oleh arang aktif tempurung kelapa, yaitu 93,50% terhadap gas NO2 dan 76,79% terhadap gas SO2. Kata kunci: adsorpsi, arang aktif, emisi, karbon terikat, tempurung, Activated charcoal is commonly used to purify air, gas, solution, or liquid, and recover a metal. Activated charcoal has pores that are more open so that it has a higher adsorption capacity than ordinary charcoal. Raw materials used as activated charcoal include leftover shell from kluwak, palm kernel, coconut, and candlenut shell. This study compares and determines which shell-based activated charcoal has the best quality to reduce air pollutant gases such as CO, NO2, and SO2 gases from motor vehicle emissions that can damage the environment using a literature review method. The results showed that the four shells produced good quality activated charcoal. Kluwak shell produces activated charcoal with the highest fixed carbon content, 96.90% and iodine adsorption capacity of 996.96 mg/g, complying with SNI 06-3730-1995. Kluwak shell activated charcoal has the most excellent effectiveness in reducing the concentration of CO gas from motor vehicle emissions compared to activated charcoal from the other three shell types, which is 98.02%. Meanwhile, coconut shell-activated charcoal performs the best effectiveness in reducing NO2 and SO2 gas concentrations, which has 93.50% for NO2 and 76.79% for SO2. Keywords: activated charcoal, adsorption, emission, fixed carbon, shell
Keyword: Activated charcoal, Adsorption, Emission, Fixed carbon, Shell

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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