1,720,964 research outputs found
Dehidrasi Etanol Pada Kolom Fixed Bed Menggunakan Adsorben Pelet Dari Limbah Abu Dasar Pembakaran Batubara
Full text linkCoal Bottom Ash (CBA) merupakan limbah dasar hasil pembakaran batubara pada Pembangkit Listrik Tenaga Uap. CBA mengandung silika dan alumina yang dapat digunakan sebagai adsorben untuk dehidrasi etanol. CBA terlebih dahulu dihaluskan hingga ukuran 200 mesh. Kemudian ditambahkan perekat berupa tepung terigu dan dibentuk menjadi pelet. CBA kemudian dikalsinasi dengan suhu 500° C selama 2 jam. Adsorben pelet yang terbentuk dikarakterisasi menggunakan XRF, XRD, FTIR, BET dan SEM. Hasil analisis XRF menunjukkan adsorben pelet didominasi alumina (28,156%) dan silika (53,978%), hasil analisis XRD menunjukkan bahwa adsorben pelet didominasi oleh kristal quartz dan albite, hasil analisis BET menunjukkan adsorben mempunyai luas permukaan sebesar 2,8419 m2/g. Proses adsorpsi dilakukan secara kontinyu dalam kolom adsorpsi berdiameter 3 cm yang berisi adsorben pelet dengan tinggi 10 cm dan dilakukan variasi laju alir umpan sebesar 6, 10 dan 14 ml/menit dengan konsentrasi umpan larutan etanol sebesar 91,805%. Kapasitas dan kinetika adsorpsi dihitung menggunakan tiga persamaan model kinetika adsorpsi yaitu model kinetika adsorpsi Adam-Bohart, Yoon-Nelson dan Thomas. Didapatkan nilai R2 tertinggi pada model persamaan Adam Bohart pada laju alir 10 ml/menit yakni dengan nilai R2 sebesar 0,981 dengan konsentrasi tertinggi dicapai pada konsentrasi 98,813%
Sintesis Zeolit A Dari Coal Bottom Ash Dengan Metode Step Change Of Synthesis Temperature Dengan Variasi Suhu Kalsinasi Diaplikasikan Untuk Dehidrasi Etanol
Full text linkTelah dilakukan penelitian mengenai pembuatan zeolit A yang diaplikasikan untuk dehidrasi etanol dengan menggunakan metode step change of synthesis temperature dengan temperatur awal 90oC selama 1,5 jam kemudian dinaikkan menjadi 95oC selama 2,5 jam. Bahan baku yang digunakan adalah coal bottom ash PLTU Tarahan Lampung Selatan, yang dikalsinasi pada suhu yang bervariasi yaitu 500oC, 600oC, 700oC dan 800oC. Tahapan yang dilakukan adalah kalsinasi, sintesis dan adsorpsi. Penelitian ini bertujuan untuk mendapatkan zeolit A sintesis dari variasi suhu kalsinasi agar didapatkan persen kristalinitas yang tinggi yang diharapkan dapat menyerap air dalam campuran etanol dengan optimal, sehingga etanol memiliki kemurnian >99% (Fuel Grade Ethanol). Karaktersiasi zeolit A sintesis menggunakan difraktometer sinar-x (XRD), spektrometer inframerah (FTIR), scanning electron microscope (SEM) dan brunnaur, emmet dan teller (BET). Berdasarkan analisis XRD didapatkan persen kristalinitas tertinggi pada variasi suhu kalsinasi 500˚C yaitu sebesar 34,79 %, hasil analisis FTIR menunjukkan telah terbentuk produk Zeolit A yang ditandai dengan adanya karakteristik Zeolit A pada bilangan gelombang 950-1250cm-1, 650-750cm-1, 500-650cm-1, 420-500cm-1 dan 300-400cm-1, hasil analisis SEM menunjukkan semua variasi suhu kalsinasi terlihat bahwa bentuk partikel didominasi bentuk kubus, berdasarkan analisis BET diketahui Zeolit A berukuran mesopori yang memiliki kisaran diameter 2-50 nm. Telah dilakukan penelitian mengenai pembuatan zeolit A yang diaplikasikan untuk dehidrasi etanol dengan menggunakan metode step change of synthesis temperature dengan temperatur awal 90oC selama 1,5 jam kemudian dinaikkan menjadi 95oC selama 2,5 jam. Bahan baku yang digunakan adalah coal bottom ash PLTU Tarahan Lampung Selatan, yang dikalsinasi pada suhu yang bervariasi yaitu 500oC, 600oC, 700oC dan 800oC. Tahapan yang dilakukan adalah kalsinasi, sintesis dan adsorpsi. Penelitian ini bertujuan untuk mendapatkan zeolit A sintetis dari variasi suhu kalsinasi agar didapatkan persen kristalinitas yang tinggi yang diharapkan dapat menjerap air dalam campuran etanol dengan optimal, sehingga etanol memiliki kemurnian >99% (Fuel Grade Ethanol). Karaktersiasi zeolit A sintetis menggunakan difraktometer sinar-x (XRD), spektrometer inframerah (FTIR), scanning electron microscope (SEM) dan brunnaur, emmet dan teller (BET). Berdasarkan analisis XRD didapatkan persen kristalinitas tertinggi pada variasi suhu kalsinasi 500˚C yaitu sebesar 34,79 %, hasil analisis FTIR menunjukkan telah terbentuk produk Zeolit A yang ditandai dengan adanya karakteristik Zeolit A pada bilangan gelombang 950-1250cm-1, 650-750cm-1, 500-650cm-1, 420-500cm-1 dan 300-400cm-1, hasil analisis SEM menunjukkan semua variasi suhu kalsinasi terlihat bahwa bentuk partikel didominasi bentuk kubus, berdasarkan analisis BET diketahui Zeolit A berukuran mesopori yang memiliki kisaran diameter 2-50 nm. Dari hasil uji adsorspsi etanol-air diperoleh kemurnian etanol akhir tertinggi pada variasi suhu kalsinasi 500˚C yaitu sebesar 99,202 %.
Sintesis ZSM-5 dari Coal Fly Ash (CFA) dengan Sumber Silika Penambah yang Berasal dari Abu Sekam Padi: Pengaruh Rasio SiO2/Al2O3 Terhadap Kristalinitas Produk
Full text linkCoal Fly Ash and rice husk ash can be utilized by converting it into ZSM-5 synthetic zeolite. One of the influencing factors of ZSM-5 synthetis is ratio of SiO2/Al2O3. Synthesis of ZSM-5 was carried out in an autoclave at a temperature of 180°C with a variation of the ratio of SiO2/Al2O3, namely 20, 30, 40, 50 and 60 mol/mol during 24 hour crystallization using TPABr template. Characterization of ZSM-5 was conducted using X-ray Diffraction, Scanning Electron Microscopy, Adsorption-Desorption Analysis of Nitrogen and Acidity. The results showed that the ZSM-5 was formed in all the variations of SiO2/Al2O3 ratios with the highest percent crystallinity of 52.83%, at the ratio of 50 mol/mol. All products are still in accompany with the formation of side products such as Analsime and Silica Oxide. The ZSM-5 crystal product was in hexagonal shape. Results from Adsorption-Desorption Analysis of Nitrogen indicated that all products were mesoporous materials.
Keywords: crystallinity, mesopore, ZSM-5, silica, rice husk, SiO2/Al2O3 ratio
Limbah Coal Fly Ash dan abu sekam padi dapat dimanfaatkan dengan mengkonversi limbah menjadi zeolit sintesis ZSM-5. Salah satu faktor yang mempengaruhi sintesis ZSM-5 adalah rasio SiO2/Al2O3. Sintesis ZSM-5 dilakukan di dalam autoklaf pada suhu 180C dengan variasi rasio SiO2/Al2O3 yaitu 20, 30, 40, 50 dan 60 mol/mol selama waktu kristalisasi 24 jam menggunakan template TPABr. Karakterisasi ZSM-5 menggunakan metode Difraksi Sinar X, Scanning Electron Microscopy, Adsorpsi – Desorpsi Nitrogen dan Analisis Keasaman. Hasil penelitian menunjukkan bahwa ZSM-5 terbentuk pada semua variasi SiO2/Al2O3. Persen kristalinitas produk ZSM-5 sebesar 52,83%, ada pada rasio 50 mol/mol. Semua produk masih disertai terbentuknya produk samping seperti Analsime dan Silika Oksida. Kristal ZSM-5 yang dihasilkan berbentuk heksagonal. Hasil Analisis Adsorpsi-Desorpsi nitorgen mengindikasikan bahwa semua sampel adalah material mesopori.
Kata kunci: kristalinitas, mesopori, ZSM-5, sekam, rasio SiO2/Al2O
Peningkatan Produksi Gula Merah UKM Desa Purworejo Pesawaran Lampung Melalui Rancang Bangun Tungku SK32
Full text linkOne household business from the community in Purworejo Village, Pesawaran District, Lampung Province is producing brown sugar from coconut juice. Currently, the process of cooking coconut juice into brown sugar uses conventional stoves with biomass fuels such as rubber wood. There are several problems in this community furnace, which is wasteful of fuel consumption, long cooking time, environmental pollution, and its construction is fast cracking. The solution offered is to make a SK32 fire brick furnace that has an inlet air supply space, heat losses insulator, and exhaust gas channel with the community. The results obtained are the SK32 fire brick furnace is able to save fuel consumption by around 20%, cook time faster by 11.17%, and the construction is much more robust. This result means that the people's income increases because the production of brown sugar increases and saves fuel consumption, a clean and healthy work environment, and the community has the ability to make furnaces SK32
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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