1,720,963 research outputs found
PEMANFAATAN TEKNOLOGI AIR SUB KRITIS DALAM PROSES HIDROLISIS DAN EKSTRAKSI PADA SINTESIS BIODIESEL DAN GULA REDUKSI DARI DEDAK PADI
Get PDFMetode terintegrasi pembuatan biodiesel dan gula dengan menggunakan
bantuan air sub kritis dalam konsep biorefinery dikembangkan dalam penelitian ini.
Pengaruh berbagai kondisi operasi seperti suhu reaksi ,waktu reaksi, ratio air:
methanol, jenis gas penekan terhadap penggunaan air sub kritis dalam tahapan
pembuatan biodiesel dan hidrolisis karbohidrat untuk mendapatkan gula dari dedak
padi akan dipelajari secara sistematis. Proses konversi dedak padi menjadi biodiesel
biasanya menghasilkan produk samping berupa deffated rice bran yang jarang
dimanfaatkan. Kandungan karbohidrat yang tinggi dalam deffated rice bran dapat
dikonversi menjadi gula yang merupakan bahan baku pembuatan bioethanol. Adanya
perbedaan kondisi operasi untuk produksi biodiesel dan gula dalam air sub kritis
maka kombinasi proses dilakukan untuk mendapatkan hasil terbaik. Dua rute proses
digunakan dalam penelitian ini yaitu pembuatan biodiesel bersama dengan
pembuatan gula dan pembuatan gula dilanjutkan dengan pembuatan biodiesel.
Dengan menggunakan rute proses pertama, pembuatan biodiesel dilakukan
dengan metode in situ dalam air dan methanol sub kritis. Dedak padi , air dan
methanol secara bersamaan dimasukkan ke dalam reactor dengan kondisi operasi
yang telah ditetapkan. Fase terlarut dalam hexane dan air untuk selanjutnya
dipisahkan untuk dilakukan analisa. Kemurnian FAMEs dalam produk sebesar 73,53
% diperoleh dengan kondisi operasi : ratio methanol : H2O = 30 : 10 suhu 200 C
selama 3 jam, tekanan 40 bar dengan CO2 sebagai gas penekan dan persen yield
FAMEs terbaik sebesar 67,39 % diperoleh dengan kondisi operasi : ratio methanol :
H2O = 20 : 20 suhu 200 C selama 3 jam, tekanan 40 bar dengan CO2 sebagai gas
penekan.
Rute kedua didesain untuk mengetahui pengaruh waktu hidrolisis terhadap
total gula yang diperoleh. Rute kedua terdiri dari dua tahapan kerja dimana tahap
pertama untuk produksi gula reduksi sementara tahap kedua untuk produksi
biodiesel. Total gula tertinggi sebesar 1.68 g/L diperoleh dengan kondisi tahap
pertama sebagai berikut : ratio dedak : H2O = 1 : 6 suhu 200 C selama 25 menit,tekanan 40 bar dengan CO2 sebagai gas penekan dilanjutkan dengan tahap kedua dengan kondisi operasi ratio methanol : H2O = 20 : 20 suhu 200 C selama 3 jam, tekanan 40 bar dengan CO2 sebagai gas penekan. Dari hasil penelitian didapatkan bahwa penggunaan gas CO2 sebagai gas penekan dapat meningkatkan perolehan yield FAMEs serta total gula. Hal ini disebabkan oleh kemampuan gas CO2 yang dapat mengasamkan media reaksi sehingga dapat meningkatkan laju esterifikasi dan hidrolisis. ==================================================================================== An integrated method for producing biodiesel and sugar with employing subcritical
water in a biorefinery concept has been developed in this study. The
influences of various operating conditions such as reaction temperature, reaction
time, ratio of water: methanol towards the utilization of subcritical water in the
stages of biodiesel production and hydrolysis of carbohydrates to gain the sugar from
rice bran would be studied systematically. The conversion of rice bran into biodiesel
typically produces byproducts such as deffated rice bran which is underutilized. High
carbohydrate content in deffated rice bran can be converted into sugar which is the
raw material for bioethanol. The big differences in the operating conditions for the
production of biodiesel and sugar in sub-critical water then the combination process
is performed to obtain the best results. Two processes were designed in this study i.e.
biodiesel production along with sugar production and sugar production is followed
by biodiesel production.
By using the first process, biodiesel production was carried out with in situ
method in sub-critical water and methanol. Rice bran, water and methanol were
simultaneously inserted into the reactor with predetermined operating conditions.
Hexane and water phase were then separated for analysis. The highest purity of
FAMEs 73,53% was obtained with following operating conditions: ratio of methanol:
H2O = 30: 10 at 200oC for 3 hours, pressure 40 bar with CO2 as pressurized gas and
the highest yield of FAMEs (67,39%) was obtained with operating conditions: methanol ratio : H2O = 20: 20 at 200oC for 3 hours, pressure 40 bar with CO2 as pressurized gas.
The second process was designed to determine the effect of hydrolysis time on the obtained total sugars. The second process consists of two phases where the first phase for sugar production while the second stage for the production of biodiesel.
The highest total sugar of 1,68 g / L was obtained with the following first phase conditions: rice bran: H2O ratio = 1: 6, temperature of 200°C for 25 minutes,
pressure 40 bar with CO2 as pressurized gas followed by a second phase operating
conditions methanol: H2O ratio = 20: 20 at 200°C for 3 hours, pressure 40 bar with
CO2 as pressurized gas. The result showed that the use of CO2 as pressurized gas can
enhance the obtained FAMEs and total sugar. This is due to the ability of CO2 to
acidify the reaction medium so that it can increase the rate of esterification and
hydrolysis
PRODUKSI BIODIESEL DARI MINYAK JELANTAH MENGGUNAKAN KATALIS KALSIUM OKSIDA
No full textThe transesterification reaction has performed to convert waste cooking oils into biodiesel with assistant of heterogen catalyst of calcium oxide using reactor in a laboratory . The reaction was performed in two stages that is the esterification followed transesterification reaction. The aim of research is to study the effect of temperature and time reaction on viscosity and biodiesel yield. The results showed that obtained biodiesel had viscosity value in accordance with SNI 04-7182-2006 about diesel-fuel viscosity. At lower temperature (40, 45, and 50oC), the longer reaction time could lead to the increasing of biodiesel yield. Meanwhile, at higher temperature reaction (55oC and 60oC) the longer reaction time could reduce biodiesel yield. The highest biodiesel yield was obtained at following reaction condition: temperature reaction 50oC, 6 hours reaction time, ratio oil:MeOH= 1:48 molar ratio, % wt CaO = 8% to weight of waste cooking oil
TRANSESTERIFIKASI MINYAK DEDAK PADI SECARA IN-SITU DENGAN BANTUAN GELOMBANG MIKRO
No full textRice bran as rice milling waste is very promising to be used as raw material of oil producer such as biodiesel oil. The production process by using of microwaves has been studied in this research. The production process was carried out in-situ where the extraction process of rice bran oil and the biodiesel formation reaction occured simultaneously in microwave radiation. Rice bran was obtained from Lamongan area with IR 64 type. The reaction was carried out in modified microwaves with variation of operating conditions on reaction times (10, 30 and 50 min) and weight ratio of rice bran to methanol (1:4, 1:8, 1:12, 1:16 and 1:20). The results obtained were then analyzed by product yield and free fatty acid content. The optimum condition was obtained in the highest yield of the product with the lowest free fatty acid. The results showed that the optimum condition was obtained at reaction time of 30 minutes with the ratio of ricebran:methanol at 1:12.
Keywords: Microwave, In-situ, Rice Bran Oil, Transesterification
The effect of pretreatment process on lignocellulosic materials with a combination of microwaves and alkaline solvents on solid products.
Get PDFThe pretreatment process is important in treating lignocellulosic-rich biomass such as sugarcane bagasse. The lignocellulosic structure is strong, and the proportion of crystals is high, complicating the fermentation process. Still, it needs to be converted to a more amorphous structure for easy access to fermenting enzymes. The pretreatment process is carried out with alkaline solvents and microwaves in this study. The process begins by standardizing the size of the bagasse powder used. Sugarcane bagasse powder and NaOH alkaline solvent were mixed in a three-necked round-bottom flask. The reactor used in this study was a modified domestic microwave equipped with a temperature controller and condenser. The results showed that this modification was significant to reduce the weight of the residual solid product compared to the initial weight of the raw material. Process variables such as reaction time and solvent concentration significantly affect the cellulose content of solid products. However, hemicellulose content showed different results. The results of the XRD analysis showed that the crystallization index of the effect decreased with increasing pretreatment time. Pretreatment with microwaves and alkaline solvents was successful with satisfactory structural changes in the cellulosic solid
Pengaruh Gelombang Mikro terhadap Proses Stabilisasi Dedak Padi
Get PDFProses stabilisasi dedak padi sebagai limbah utama dari proses penggilingan padi dengan bantuan gelombang mikro telah dilakukan. Proses ini meliputi dua tahapan, tahapan pertama berupa proses stabilisasi dedak padi menggunakan gelombang mikro dikuti tahapan kedua yaitu proses ekstraksi minyak dedak padi. Pengaruh variabel proses yaitu waktu stabilisasi dan masa simpan dedak padi terhadap perolehan minyak dedak padi dan kadar asam lemak bebas dipelajari secara sistematis. Hasil penelitian menunjukkan bahwa dengan menggunakan daya microwave daya 3, dan waktu stabilisasi 1-3 menit, kadar asam lemak bebas minyak dedak padi yang diperoleh cenderung konstan selama 2 minggu masa simpan dedak padi. Hal ini menunjukkan bahwa proses stabilisasi dengan menggunakan microwave efektif untuk menonaktifkan enzim lipase yang ada di dalam dedak padi. Massa minyak tertinggi sebesar 7,58% diperoleh pada waktu stabilisasi selama 5 menit dengan masa simpan dedak padi 1 minggu pada daya 3
PROSES PERLAKUAN AWAL AMPAS TEBU DENGAN PELARUT ASAM DAN GELOMBANG MIKRO SEBAGAI BAHAN BAKU BIOETHANOL
Get PDFProses pretreatment perlu dilakukan pada penggunaan ampas tebu sebagai bahan baku generasi kedua pembuatan bioethanol. Hal ini dikarenakan sebagian besar kandungan ampas tebu adalah lignoselulosa yang memiliki struktur yang kuat dan susah difermentasi. Proses pretreatment ampas tebu dengan menggunakan senyawa asam dan pemanasan gelombang mikro dilakukan dalam penelitian ini. Penelitian itu bertujuan untuk mengetahui pengaruh varibel proses yaitu konsentrasi senyawa asam (0,1; 0,4 dan 1,0 M) dan waktu reaksi (10-30 menit) terhadap komposisi produk solid yang diperoleh. Penelitian ini dilakukan dengan menggunakan reaktor microwave yang diperoleh dengan memodifikasi microwave domestik dengan alat pengatur suhu dan kondensor refluk. Hasil penelitian menunjukkan bahwa metode yang dirancang pada penelitian ini telah berhasil mengubah struktur selulosa dan hemiselulosa pada produk yang diperoleh. Kenaikan waktu reaksi menurunkan persentase kandungan selulosa dan hemiselulosa pada produk. Pengaruh yang sama juga ditunjukan oleh perubahan konsentrasi pelarut. Kenaikan konsentrasi pelarut menyebabkan semakin kecilnya persentase selulosa dan hemiselulosa yang diperoleh. Hasil penelitian menunjukkan bahwa ukuran kristal pada ampas tebu sebelum dan sesudah reaksi mengalami penurunan. Kata Kunci: perlakuaan awal, asam, gelombang mikro, ampas tebu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
