Judul: Pengaruh cara delignifikasi terhadap sakarifikasi limbah lignoselulosik
Abstrak: Delignifikasi merupakan suatu proses pembebasan lignin dari suatu senyawa kompleks. Proses ini penting dilakukan sebelum hidrolisis bahan selulosik, sebab lignin dapat menghambat penetrasi asam atau enzim sebelum hidrolisis berlangsung. Tujuan penelitian ini adalah untuk mempelajari pengaruh cara delignifikasi terhadap sakarifikasi limbah lignoselulosik serta meningkatkan pemanfaatan limbah tersebut. Untuk maksud tersebut dipilih bahan lignoselulosik jerami, onggok dan pod cokelat dan empat cara delignifikasi kimiawi. Cara pertama yaitu perendaman dalam NaOH 1% selama 24 jam dan dilanjutkan dengan pemanasan selama 3 jam pada suhu 120°C. Kemudian dilanjutkan dengan perendaman dalam H202 1% selama 12 jam. Cara Kedua dilakukan dengan pemanasan dalam H₂SO₄ 4% selama 1 jam pada suhu 120°C. Cara ketiga yaitu pemanasan selama 4 jam pada suhu 90°C dalam H2SO4 5% dan dilanjutkan dengan perendaman dalam larutan feri natrium tartrat. Cara keempat yaitu pemanasan selama 3 jam pada suhu 120°C dalam larutan Ca(HSO3)2 1%. Pemanasan pada masing- masing cara di atas dilakukan dengan menggunakan autoklaf.
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Judul: Delignifikasi Limbah Tanaman Jagung Menggunakan Kalsium Hidroksida.
Abstrak: Since the 90’s, lignocelluloses began aggressively to become a source of energy by researcher of the world. In Indonesia, the actual potential for the development of this material is quite good if viewed from its energy needs. In addition, the supply for this material is relatively abundant, one of which is corn stover. The production of corn stover is about 18.9x1013 ton/year. Although, lignocellulose is relatively abundant, its utilization requires special treatment because of the complex structure of celluloses, hemicelluloses, and lignins. Various treatments have been developed included physical, biological, or chemical. One of the treatments is delignification with lime to minimize damage to the celluloses and hemicelluloses. This study aims to determine the effect of lime addition, water addition, heating temperature, and heating time on delignification, and to find the best condition in the delignification process of corn stover with lime. The experimental result shows that significant factor in delignification is heating temperature, whereas lime addition, water addition, and heating time did not have significant influence in delignification. In the tested range also has detected the existence of curvature, and obtained the equation: LR * = − 0.24197 + 0.007951 x3 – 5.3∙10-5 x3 2. The best condition of this process is estimated at 74.6 oC, with lignin removal is 0.055 g/g corn stover, delignification level is 0.25, and delignification selectivity is 0.40.
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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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