Spektra: Jurnal Fisika dan Aplikasinya
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STUDY OF NYLON MEMBRANE AS A FILTER FOR CLARIFICATION OF SUGARCANE JUICE
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Membran nilon merupakan lapisan semipermeabel yang terbuat dari jenis polimer poliamida untuk memisahkan partikel tertentu dari larutannya. Pada artikel ini, membran nilon berperan sebagai filter untuk penjernihan nira tebu dengan mengkaji kinerja, efektivitas, dan efisiensi membran. Penelitian dilakukan dengan sistem aliran dead-end pada proses ultrafiltrasi menggunakan empat tekanan transmembran yang berbeda yaitu 1.0, 1.5, 2.0, dan 2.5 bar. Konsentrasi nira tebu sebelum dan sesudah proses ultrafiltrasi dikarakterisasi menggunakan Spektrofotometer UV-Vis. Membran nilon dengan variasi massa 4.5, 5.0, 5.5, 6.0, dan 6.5 gram, menunjukkan fluks air yang sesuai pada rentang 15 – 38 L/m2.jam.bar pada tekanan transmembran. Hasil penelitian menunjukkan bahwa membran nilon yang memiliki kinerja paling baik adalah membran dengan massa benang nilon 4.5 gram karena memiliki nilai fluks paling besar dan nilai koefisien rejeksi paling kecil. Membran dengan massa benang nilon 6.5 gram memiliki efektivitas dan efisiensi penurunan sukrosa yang paling besar. Sedangkan membran dengan massa benang nilon 4.5 gram memiliki efektivitas dan efsiensi penurunan konsentrasi sukrosa yang paling rendah.
Kata-kata kunci: membran nilon, nira tebu, kinerja membran, efektivitas, efisiensi.
Abstract
Nylon membrane is a semipermeable layer made of a type of polyamide polymer to separate certain particles from the solution. In this article, nylon membrane is presented as a filter for clarification of sugarcane juice concerning study on performance evaluation, effectiveness, and efficiency of the membrane. The experiments were conducted according to the principle of the dead-end in an ultrafiltration process using four different transmembrane pressures of 1.0, 1.5, 2.0, and 2.5 bar. The concentration of sugarcane juice before and after ultrafiltration process was characterized using UV-Vis Spectrophotometer. Nylon membranes, which consist of 4.5, 5.0, 5.5, 6.0, and 6.5 gram various mass, showed matched water flux in the range of 15 – 38 L/m2.jam.bar at the transmembrane pressures. The results showed that the best performance nylon membrane was a nylon membrane with a mass of 4.5 gram nylon, because it has the largest flux and the smallest rejection coefficient. Nylon membrane with a mass of 6.5 gram has the biggest effectiveness and efficiency in the reduced of sucrose concentration. Meanwhile, nylon membrane with a mass of 4.5 gram has the lowest effectiveness and efficiency in the reduced of sucrose concentration.
Keywords: nylon membrane, sugarcane, membrane performance, effectiveness, efficiency
TWO STATIC FLUID DARK MATTER MODEL WITH ADDITIONAL COSMOLOGICAL CONSTANT
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Pada persamaan medan gravitasi Einstein terdapat konstanta kosmologi sebagai konstanta alam yang menjelaskan model mengembangnya alam semesta dan yang paling dominan terdapat di jagad raya ini adalah dalam bentuk energi gelap (dark energy). Kami meninjau model objek dua fluida tidak terkopel, seperti layaknya materi gelap (dark matter) atau bintang yang memiliki karakteristik tensor energi-momentum dan kecepatan-4 nya yang berbeda serta bersifat anisotropik, kemudian disatukan sebagai model dua fluida untuk ditinjau persamaan TOV (Tolman-Oppenheimer-Volkoff) dan persamaan geodesiknya dalam menunjukkan sifat gerak dan model dua fluida tersebut. Hasil perhitungan menunjukkan bahwa model ini dapat menjelaskan persamaan potensial efektif dengan tambahan konstanta kosmologi sebagai karakteristik gerak dan kecepatan tangensial partikel uji dalam orbit lingkaran stabil.
Kata-kata kunci: konstanta kosmologi, anisotropik, potensial efektif, kecepatan tangensial.
Abstract
In Einstein's gravitational field equation has been found the cosmological constant as the natural constant that describes the universe's expansion model and the most dominant in the universe is the dark energy form. We review the two objects of fluid models are not coupled, like dark matter or stars which has the different characteristic energy-momentum tensor and four velocities and anisotropic tend, then combined as two-fluid models for TOV (Tolman-Oppenheimer-Volkoff) equation and the geodesic equation to characterize the movement and the two fluid models. The calculation result shows that this model can explain the potential equation with an addition of an effective cosmological constant as the movement characteristic and tangential velocity of a tested particle in a stable circular orbit.
Keywords: cosmological constant, anisotropic, effective potential, tangential velocity
UV-VISIBLE OPTICAL ABSORBANCE OF GRAPHENE OXIDE IN COPPER IONIC LIQUID SYNTHESIZED VIA ELECTROCHEMICAL METHOD ASSISTED BY A COPPER COIL
Get PDFAn optical absorbance study using Ultraviolet-Visible (UV-Vis) spectrophotometer device has been conducted on graphene oxide (GO) in copper (Cu) ionic liquid using electrochemical exfoliation combined with a direct current (DC) electrical circuit of copper coil given inside the electrolyte solution. The electrolyte solutions used are sulfuric acid (H2SO4) and chloride acid (HCl). The UV-Vis spectrum of the samples shows absorbance peaks at around 214 nm to 218 nm and shouldering peaks around 245 nm to 249 nm. The first peak corresponds to the existence of copper (Cu) ionic liquid in the solution, whereas the shouldering peak is related to the occurrence of GO material. A comparison between UV-Vis spectral of graphite in dimethylformamide (DMF) and GO in Cu ionic liquid in DMF resulted in the existence of a blue shift which signifies the production of Cu ionic liquid from the Cu coils inside the electrolyte solution. Increasing the concentration of the solution increases the absorbance peaks. Furthermore, raising the number of loops yields in the increase of the absorbance value at the first peaks that show Cu ionic liquid, but tends to decrease the absorbance value of the shouldering peaks of the GO material
INTEGRATED AVO, ELASTIC SEISMIC INVERSION AND PETROPHYSICAL ANALYSIS FOR RESERVOIR CHARACTERIZATION: A CASE STUDY OF GAS FIELD, SOUTH SUMATERA BASIN
Get PDFIntegrated Amplitude Versus Offset ( AVO), elastic seismic inversion and petrophysical analysis have been successfully applied to estimate the elastic parameters of the reservoir for a case study of the gas field in south Sumatera basin. This paper aims to have better understanding the petrophysical properties of the reservoir. The petrophysical analysis was carried out by performing routine formation evaluation that includes calculation of shale volume, porosity, and water saturation of basic well log data. Sensitivity analysis was conducted to evaluate the sensitivity parameters of the log for changing in lithology, porosity, and fluid content in the reservoir. For completing the availability of elastic parameter from well log data, shear wave logs were derived from Castagna’s mudrock line relationship. Further, P-impedance, S-impedance, VpVs ratio, LambdaRho (λÏ), MuRho (μÏ) and density(Ï) were then calculated through a Lambda-Mu-Rho (LMR) transformation. Prior to performing AVO analysis and elastic seismic inversion, super gather technique was applied to improve the reliability of pre-stack seismic data. Elastic seismic inversion was carried out to extract the lateral elastic properties to capture lithology and fluid changes in the reservoir. In addition, AVO analysis of pre-stacked data was applied to identify hydrocarbon-bearing sandstone at target zone. The petrophysical analysis shows that porosity versus density crossplot is able to distinguish sand-shale based on 34% shale volume cutoff, while LMR crossplot is able to delineate hydrocarbon zone at water saturation value under 65%. The predicted lateral elastic parameter shows slightly higher value compare to overlying layer
IMAGING OF 3-D SEISMIC TOMOGRAPHY FOR INTERNAL STRUCTURE UNDER THE MOUNTAIN MERAPI USING THE LOTOS-10 SOFTWARE
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Telah dilakukan penelitian pencitraan tomografi seismik 3D untuk stuktur internal di bawah Gunung Merapi dengan empat stasiun pencatat gempa dan gempa vulkanik sebagai sumber sinar gelombang. Penelitian ini menggunakan perangkat LOTOS-10 (Local Tomography Software 10) untuk inversi tomografi seismik 3D. Karakteristik medium bawah Gunung Merapi dapat digambarkan oleh parameter fisis seperti kecepatan gelombang primer dan sekunder. Hasil pengolahan data seismograf menunjukkan metoda tomografi seismik dapat mengungkap struktur bawah permukaan Gunung Merapi melalui distribusi anomali deviasi kecepatan dan Vp/Vs ratio. Kualitas citra yang dihasilkan dengan menggunakan gelombang primer lebih jelas resolusinya dan waktu yang digunakan lebih efesien, sehingga dapat digunakan sebagai informasi mitigasi bencana sebelum gempa erupsi terjadi. Daerah anomali negatif yang diperoleh terletak di bawah puncak Gunung Merapi pada kedalaman 3 - 5 km mempunyai karakter fisis yaitu zona lemah, kurang kompak, panas dan heterogen. Daerah anomali tersebut dapat diinterpretasikan sebagai keberadaan zona materi panas yang berasosiasi dengan sisa dapur magma dangkal.
Kata-kata kunci: Gunung api Merapi, sifat fisis, tomografi seismic, lotos-10.
Abstract
3D seismic tomography imaging research conducted for internal structures under Merapi Volcano with four earthquake recording and volcanic earthquake stations as a source of wave rays. This study used LOTOS-10 (Local Tomography Software 10) for 3D seismic tomography inversion. Characteristics of the medium under Merapi Volcano described by physical parameters such as primary and secondary wave velocities. The result of seismograph data processing shows seismic tomography method can reveal the subsurface structure of the Merapi Volcano through the distribution of deviation anomaly speed and Vp / Vs ratio. Image quality generated by using primary wave more clearly the resolution and time used more efficient, so that can be used as disaster mitigation information before earthquake eruption happened. The negative anomaly area obtained under the peak of Merapi Volcano at a depth of 3 - 5 km has the physical characteristics of weak, less compact, hot and heterogeneous zones. The anomalous region can interpret as the existence of a zone of heat material associated with the rest of the shallow magma kitchen.
Keywords: Mount of Merapi, physical character, Seismic of Tomography, lotos-10