Judul: The utilization of sawdust for ethanol production
Abstrak: Currently, Indonesia is in the middle of petroleum crisis. One of the alternative fuels which can be used as a petroleum substitute is ethanol. Ethanol can be produced from the timber waste (sawdust). Indonesia, in 2003, had timber waste potency of about 3 – 4 millions m3. Process of sawdust manufacturing become an ethanol can be conducted by simultaneous saccharificationfermentation method. However, ethanol production from sawdust has problem due to its lignin content. Therefore, research on bio-delignification treatment of sawdust prior to ethanol making process is required. The research was done by acted of growing white rot fungi Phanerochaete chrysosporium on three kinds of sawdust i.e. jati, meranti and sengon. The chemical contents (extractive contents, cellulose contents, holocellulose contents, ash contents and lignin contents) of these three of sawdust were analyzed previously. Then simultaneous saccharification-fermentation (SSF) process was done by using crude enzyme from Trichoderma viride and then followed by fermentation with Saccharomyces cerevisiae on shaker incubator with rate 12 rpm at temperature 30oC for 72 hours. The result as an ethanol was analyzed by using gas chromatography method. Analysis design used was completely randomized design using 2 factors of treatment i.e. type of wood (A) and time of incubation (B). Pretreatment with Phanerochaete chrysosporium on various types of sawdust and incubation time rises up ethanol contents up to about 26.68 – 76.90%. Chemical contents of sawdust having significant effect to ethanol contents was holocellulose, the higher holocellulose contents give higher ethanol contents. Ethanol contents resulted was about o.o16 – 0.448 g/l. Interaction between factor type of wood and time of incubation had significant effect to ethanol content. The best combination treatment was on sengon sawdust with incubation period of 30 days.
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Judul: Optimasi Proses Hidrolisis Kimiawi dan Enzimatis Tandan Kosong Kelapa Sawit Menjadi Glukosa untuk Produksi Etanol
Abstrak: Recently, energy especially from petroleum fuel become a serious problem for the whole countries in the world, including Indonesia. Decreasing world’s petroleum stock make its price is very high. So, it is urgent to search other alternative energy sources, such as bioethanol. Oil Palm Empty Bunches (OPEB) are found abundantly as waste of CPO production. It is rich in lignocellulose content. After delignification by white rot fungi Omphalina sp, cellulose from OPEB can be degraded to glucose as the raw material for etanol production by hydrolysis process. In this research, hydrolysis were done chemically using H2SO4 and HCl and enzymatically using cellulolytic bacteria and Trichoderma isolates. Chemical hydrolysis was carried out in autoclave at temperature of 121oC and varation in acid concentration (0.1N; 0.5N; 1N; and 2N) and hydrolysis time (20; 40; 60; 120; and 240 min). The condition was then reoptimalized by increasing the temperature to 200 0C and variation hydrolisis time (5;7,5;10;12,5; dan 15 min). Enzymatic hydrolysis were done by two methods, namely simultaneuos and separated bacth methods using Trichoderma or cellulolytic bacteria and Saccharomyces cereviceae. Delignification process increased cellulose content from 47.18% to 49.09%. The optimum condition by chemical hydrolisis with H2SO4 2N was resulted in sugar content (30,86%) with ethanol production 1.82%. By enzymatic methods, higher sugar content was obtained by Trichoderma isolate with incubation time 72 hours. The sugar content was 1.46 g/L and ethanol production was 0.33%. Ethanol production from simultaneuos process by cellulolytic bacteria was the same as ethanol production from Trichoderma by separated batch process i.e as much as 0.27 %
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf