Judul: Optimasi Suhu Dan Lama Inkubasi Pada Hidrolisis  In Situ Minyak Jarak Pagar Untuk Produksi  Surfaktan Mono- Dan Digliserida
Abstrak: The increasing of people population in the world and also the increasing of technology development can support the invention of human need products. Surfactant is a component that can be used as mixing solution for many products. Its amphiphilic character can be used widely in many applications and have increasing usage for each year. Surfactant production based on vegetable oil such as mono- and diglyceride can be obtained from Jatropha oil because it has high productivity and high vegetable oil component. Effective and efficient method to produce mono- and diglyceride can be done with in situ hydrolysis method that is affected by temperature and incubation time. The research purposes are to obtain the effect of temperature and incubation time of Jatropha seed on in situ hydrolysis on surface tension, interfacial tension, emulsion stability, acid value, saponification value, and refractive index parameter, and also to determine optimum condition of physical characteristic of the surfactant (surface tension). The eksperimental design of this research is two level factorial design with two factors, wich were temperature and incubation time. The lowest temperature of incubation is at 33○C and incubation time of 3 days, the highest temperature of incubation is at 37○C and incubation time of 7 days. Meanwhile, the method used to find optimum condition is Response Surface Method. Surfactant M-DG that was produced can decrease water surface tension of 34−40 dyne/cm. It has interfacial tension value about 8−12 dyne/cm, emulsion stability of 48.1−59.49%, acid value of 25.81−67.11 mg KOH/g of oil, saponification value of 135.38−199.57 mg KOH/g of oil, and refractive index about 1.3777−1.4762. The microbiological analysis showed the increasing number of Mucor sp., the producer of lipase 1,3-regiospecific in Jatropha seed after incubation process. Based on the statistical analysis of factors involved, it can be concluded that incubation temperature has negative correlation to surface tension (93.87%), interfacial tension (93.79%), acid value (82.61%), and refractive index (63.93%). It has positive correlation to emulsion stability (92.72%) and saponification value (99.23%). The incubation time has negative correlation to surface tension (92.64%), interfacial tension (89.67%), and refractive index (65.76%), and has positive correlation to emulsion stability (69.98%), saponification value (97.67%), and acid value (96.77%). From Response Surface Method analysis, it can be obtained at the best condition to decrease surface tension to a minimum value of 33.42 dyne/cm with incubation temperature at 36.11○C and incubation time of 7.32 days.
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Judul: Kajian kinerja Surfaktan Mes (Metil Ester Sulfonat) dari Jarak Pagar (Jatropha Curcas L.) untuk enhanced waterflooding
Abstrak: Year by year, the production of petroleum decreases but its demand increases. The world will get the energy crisis if that condition happens continously. The main cause of low production of petroleum in Indonesia is the majority Indonesia’s oil wells being mature field/brown field and the discovery of new oil field in small scale. Indonesia focuses on maximize oil recovery in brown field because its oil production decreases naturally up 15% in total production. In recent years, the field of enhanced oil recovery has grown became more popular due to a combination of stagnant oil production and low recoveries by conventional methods. Many fields use unconventional method like enhanced oil recovery (EOR) which is tertiary oil recovery phase. One way of EOR is chemical flooding which uses surfactant for injection. Surfactant is injected to water and it is known as enhanced waterflooding. Generally, surfactant of petroleum sulfonates is used for oil recovery. This surfactant has many weaknesses such as resistance to water hardness, susceptible detergency to high salinity and being imported with expensive price. Due to these weaknesses, therefore it trigger to get surfactant substitute like MES (methyl ester sulfonates) that is synthesized by biooil. One of biooil is Jatropha oil. The study was aimed to know experimental of surfactant formula for enhanced waterflooding in fluida sample of oil field and synthetic core sandstone. The result showed that injection of surfactant 0,2 PV gave the influence differently to oil recovery. The best condition was surfactant 0,2 PV with the soaking time of 12 hours. This formula gave the highest of incremental total oil recovery 61,07%. The number were resulted from 47,73% waterflooding and 13,34% surfactant injection. Surfactant formula gave the good performance of compatibility, thermal stability, phase behavior and filtration test.
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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