Judul: Produksi Biodisel Secara Transesterifikasi In Situ dari Mikroalga Chlamydomonas sp. dan Synechococcus sp. yang Dikultivasi dengan Media Teknis
Abstrak: During the time being, the world’s oil supply is going to be less. In the other side, enviroment pollution derived from fosil fuel combustion is going tobe more extensive. Indonesia has 9 billion barrel of oil reserve which will be run out in 23 years. Therefore, alternative source of energy should be developed, such as biodiesel. Microalgae have a high productivity and potential to be developed as biodiesel. This development need a high cost. This study is intended to find an alternativeof biodiesel production from microalgae which is more cost efficient. We developed a new improvement by using technical grade culture nutrient and in situtransesterification process. The study consisted of three stages. The first was regeneration and providing four isolates in BG 11 medium. The second was cultivation in lab scale, aquarium scale using N2P1, N2P2 or N3P3 medium, and analyses of lipid, water, ash, yield, free fatty acid (FFA), and characterization of the fatty acid. The last was biodiesel production byin situtransesterification process,yield measurement and characterization of the biodiesel. Isolate Chlamydomonas sp. ICBB 9114 produced the highest yield of biomass (0.44 g/L) with low water content, whileChlamydomonas sp. ICBB 9112 produced the lowest biomass (0.19 g/L) with the highest water and FFA content. Synechococcus sp. ICBB 9111 had the highest ash content, whileChlamydomonas sp. ICBB 9113 had the lowest ash and FFA content. Fatty acid content with C18:3 type was dominant in Synechococcus sp. ICBB 9111 (47.03%), Chlamydomonas sp. ICBB 9113 (42.57%), and Chlamydomonas sp. ICBB 9114 (34.42%). While, C16:0 type was dominant in Chlamydomonas sp. ICBB 9112. It marked that Chlamydomonas sp. ICBB 9112 had a good quality of FA which could be used as biodiesel needing a low melting point, high cetan number, and unoxidizable. After lipid extraction, the process was continued with convertion to fatty acid metyl ester (FAMEs) through transesterification process. Chlamydomonas sp. ICBB 9114 produced the highest FAMEs (3523.20 mg/100 g). The characteristics of the biodiesel originated fromChlamydomonas sp. ICBB 9114 producedby in situ transesterficationwere suitable with SNI biodiesel criteria except for the acid value.
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Judul: Identification and optimization of growth media of microalgae originated from Cipanas hot spring water West Java that is potential for biodiesel source
Abstrak: The increasing use of fossil fuel leads to the depletion of fuel sources and increases CO2 emission level into the environment that affects global warming. Microalgae is an alternative biodiesel source that is renewable and environmentally friendly. The objective of the research was to identify and optimize the growth media of microalgae isolate originated from Cipanas hot spring water. Identification was done based on morphological and 18S rDNA gene sequence approaches. Growth media experiment was designed as a factorial randomized block design. First factor was water media composition containing aquades and hot spring water with five level of aquades:hot spring water ratio, which were 1:0, 0:1, 1:1, 2:1, and 1:2 (v/v). The second factor was P concentration, which were 40, 80 and 120 ppm. The result showed that the morphologically a microalgae isolate had similarity to Chroococcus sp prokaryotic, but molecular data indicated that the microalgae was similar to uncultured freshwater eukaryote clones. The highest cell density of microalgae culture was 2.19 and 2,21 which were achieved when microalgae was cultured in aquades:hot spring water medium 1:2 (v/v) and in P concentration 120 ppm, respectively. The highest dry weight average of biomass (175 mg) was obtained in aquades:hot spring water 1:0 (v/v) with P concentration 120 ppm. Hot spring water could be substituted by aquades to gain high lipid content microalgae. Growth media containing aquades:hot spring water 1:0 (v/v) with P concentration 40 ppm produced the highest average of lipid content (21%) and highest average of lipid productivity, 17 mg l-1 day-1.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular