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MORPHOLOGICAL AND THERMAL PROPERTIES OF ALKALI TERATED BACTERIAL CELLULOSE FROM COCONUT WATER Indrarti, Lucia; Yudianti, Rike
Jurnal Sains Materi Indonesia Vol 13, No 3: JUNI 2012
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (365.66 KB) | DOI: 10.17146/jsmi.2012.13.3.4676

Abstract

MORPHOLOGICAL AND THERMAL PROPERTIES OF ALKALI TERATED BACTERIAL CELLULOSE FROM COCONUT WATER. Alkali treatment is one ofwide chemical treatment for removing non cellulosic materials and other impurities of bacterial cellulose (BC). Presently, BC produced by synthetic medium such as Schramm Hestrin or coconut water fermentation using pure culture of Acetobacter xylinum . In this research BC produced from coconut water fermentation using inoculums as suspension of mixture culture of bacteria A. xylinum in coconut water which commercialised inWest Java (Cianjur). Purpose of this research is to know the native and the effect of alkali treatment on the BC (heterofermentive) with evaluation of morphological, elemental analysis and thermal properties by Scanning ElectronMicroscope (SEM)-Energy Dispersive X-ray Spectroscopy (EDX) and Thermo-Gravimetry Analysis (TGA), respectively. Observation on morphological surface of native BC showes that there were noncellulosic materials entangled on the network of cellulose fibrils whichwere identified by EDX analysis as sodium(Na),magnesium(Mg), aluminium (Al), silica (Si) and potassium (K) in addition to carbon (C) and oxygen(O). On thermal analysis, stepwise of decomposition are observed on the native BC indicating the presence of non-cellulosic components which decomposed at different temperatures.While the alkali- treated BC sheet shows a single decomposition stage. The amount of residue formed after alkali treatment was relatively lower than native BC. Thermal degradation properties of the BC produced from coconut water was higher than that of BC belonging to synthetic medium. Based on this data, it is concluded that alkali treated cellulose can be used as a reasonable substitute for various non biodegradable synthetic polymers for large scale industrial in specific application
Pemurnian Carbon Nanotubes menggunakan Larutan HNO3 dengan metode Pencucian Biasa dan Reflux (Halaman 1 s.d. 4) Subagio, Agus; -, Pardoyo; -, Priyono; Yudianti, Rike; Rowi, Khasan; Imam Taufiq, M.
Jurnal Fisika Indonesia Vol 17, No 49 (2013)
Publisher : Department of Physics Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (483.309 KB) | DOI: 10.22146/jfi.24403

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Telah dilakukan penelitian berkaitan pemurnian carbon nanotubes (CNT) dengan metode pencucian biasa dan reflux menggunakan larutan HNO3. Pemurnian menggunakan metode pencucian biasa dilakukan dengan memasukkan CNT ke dalam 25 ml larutan HNO3 dengan variasi konsentrasi 25, 45 dan 65% di dalam gelas beker. Selanjutnya dilakukan pengadukan dan didiamkan selama 30 menit. Hasil pencucian disaring dengan kertas saring dan residunya dikeringkan di dalam oven dengan temperatur 120oC selama 1 jam. Sedangkan metode reflux dilakukan pada temperatur 100oC selama 4 jam menggunakan larutan HNO3 dengan variasi konsentrasi 25, 45 dan 65%. CNT hasil pemurnian selanjutnya dikeringkan di dalam oven dengan temperatur 120°C selama semalam. Carbon nanotube sebelum dan sesudah pemurnian dianalisis menggunakan Scanning Electron Microscopy (SEM) dan Energy Dispersive X-Ray Spectroscopy (EDS). Hasil penelitian menunjukkan bahwa tingkat kemurnian CNT yang paling baik dengan menggunakan metode pencucian reflux pada konsentrasi HNO3 sebesar 65%.  
KAJIAN KINERJA POLYMER ELECTROLYTE MEMBRANE FUEL CELL OPEN CATHODE TERHADAP VARIASI TEGANGAN KIPAS KATODA DAN VARIASI LAJUALIR HIDROGEN Irmawati, Yuyun; Indriyati, Indriyati; Onggo, Holia; Yudianti, Rike
Jurnal Sains Materi Indonesia Vol 13, No 3: JUNI 2012
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (565.059 KB) | DOI: 10.17146/jsmi.2012.13.3.4675

Abstract

KAJIAN KINERJA POLYMER ELECTROLYTE MEMBRANE FUEL CELL OPEN CATHODE TERHADAP VARIASI TEGANGAN KIPAS KATODA DAN VARIASI LAJUALIR HIDROGEN. Kajian untuk pengaruh variasi tegangan kipas dan laju alir gas hidrogen terhadap hasil rapat daya serta fitting kurva potensial untukmendapatkan parameter over potensial pada Polymer Electrolyte Membrane Fuel Cell (PEMFC) dengan sistem open cathode telah dilakukan. Pada stack PEMFC yang terdiri atas dua sel dengan aktif area 30 cm2, dipasang tegangan kipas dengan variasi 3Volt hingga 12Volt yang berasal dari tegangan listrik eksternal. Dari rapat daya yang diperoleh, variasi tegangan kipas, yang berfungsi sebagai pendingin stack dan mampu meningkatkan produksi rapat daya sebesar 47%hingga 67% dibandingkan bila tidak menggunakan kipas. Nilai rapat daya maksimal (73,26 mW/cm2) diperoleh pada tegangan kipas 3 Volt. Untuk variasi laju alir hidrogen yang rendah sebesar 20mL/menit hingga 40mL/menit, diperoleh adanya dead point disebabkan ketidak-seimbangan stoikiometri hidrogen dengan oksigen sehingga potensial sel turun tajam menuju nol. Pada laju alir hidrogen 50 mL/menit menghasilkan nilai rapat daya optimum sebesar 79 mW/cm. Berdasarkan hasil fitting kurva polarisasi dengan persamaan empiris, penambahan laju alir hidrogenmenyebabkan meningkatnya overpotensial aktivasi dan menurunnya over potensial difusi yang disebabkan oleh faktor hidrogen crossover dan dehidrasi membran, sedangkan untuk over potensial ohmik terlihat relatif konstan.
INFLUENCE OF FUNCTIONALIZED MULTI-WALLED CARBON NANOTUBES ON FILTERABILITY AND MECHANICAL PROPERTIES OF RAYON NANOCOMPOSITE FILAMENTS Onggo, Holia; Yudianti, Rike; Ruchiat, Endang
JURNAL SELULOSA Vol 3, No 01 (2013): JURNAL SELULOSA
Publisher : Center for Pulp and Paper

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (879.116 KB) | DOI: 10.25269/jsel.v3i01.41

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Carbon nanotube-rayon composite filaments was fabricated by spinning and coagulation of the mixture of 100mL functionalized carbon nanotube dispersion (containing 0.72 g FCNT) and cellulose xanthate in NaOH solution using viscose process. In the process, CNT was functionalized using mixture of acidic solution ( H2SO4/HNO3, 3:1 v/v). Influence of functionalized (FCNT) and non-functionalized carbon nanotubes (nFCNT) on the fabrication of rayon nanocomposite filament was studied. Physical and morphological properties of the nanocomposite filaments were characterized by single filament tenacity tester, photo micrograph, scanning electron microscope (SEM) and transmission electron microscope (TEM). Filterability and mechanical properties of FCNT-rayon nanocomposite filament greatly improved by reducing clogging constant from 1689 to 153 and increasing tenacity from 2.72 to 3.01 g/denier and decreasing elongation from 57.1 to 36.5% respectively compared with those of nFCNT-rayon nanocomposite filament.Keywords: functionalized multi-walled carbon nanotubes, nanocomposite filament, mechanical properties, filterability, dispersion  ABSTRAKRayon nanocomposite filaments telah dibuat melalui proses pemilinan (spinning) dan koagulasi (coagulation) dari campuran 100 mL larutan functionalized carbon nanotube dispersion (FCNT=0,72 g), selulosa santat dalam larutan NaOH melalui proses viskosa. CNT di functionalisasi (FCNT) menggunakan campuran larutan asam (H2SO4/HNO3, 3:1 v/v). Pengaruh fungsionalisasi CNT pada pembuatan rayon nanocomposite filaments dipelajari dengan cara membandingkannya dengan CNT tanpa fungsionalisasi (nFCNT). Sifat fisik dan morfologi dari rayon-nanocomposite filaments dikarakterisasi menggunakan tenacity tester, photo micrograph, scanning electron microscope (SEM) dan transmission electron microscope (TEM). Viskosa FCNT memiliki daya saring (Kw) cukup baik yaitu 155, sedangkan viskosa nFCNT  memiliki daya saring 1689 (tidak baik). Kekuatan mekanik dari FCNT-rayon nanocomposite filaments berturut turut adalah 3,01 g/denier (tenacity), dan 36,5% (elongation), lebih baik dibandingkan dengan nFCNT-rayon nanocomposite filament: 2,72 g/denier (tenacity) dan 57,1% (elongation).Kata kunci: fungsionalisasi multi-walled carbon nanotubes, rayon-nanocomposite filament, sifat mekanik, daya saring, dispersi
Chemical Compositions of Hydrocolloids Produced from Nutlets of Salvias Yudianti, Rike; Indrarti, Lucia; Karina, Myrtha; Sakamoto, Masahiro; Azuma, Jun-ichi
Jurnal Ilmu dan Teknologi Kayu Tropis Vol 5, No 1 (2007): Jurnal Ilmu dan Teknologi Kayu Tropis
Publisher : Jurnal Ilmu dan Teknologi Kayu Tropis

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (173.587 KB)

Abstract

Hydrocolloids of three species of Salvias (S. miltiorrhiza, S. sclarea and S. viridis) was analyzed their chemical compositions after isolation of hydrocolloids from seed coats. Isolation was conducted after expanding out completely in water.  Hydrocolloids produced from S. miltiorrhiza, S. sclarea and S. viridis have cellulose contents about 18.6%, 25.3% and 35.4% and hemicelluloses contents about 80%, 73.4% and 62%, respectively. Native hydrocolloids produced from S. sclarea and S. viridis were rich in glucose about 48.6% and 55.4%, respectively, while the other one, S. miltiorrhiza, was rich in xylose, about 85.1%. Distribution of these polysaccharides in S. miltiorrhiza, S. sclarea and S. viridis were 86.5%, 71.0% and 63.2% (acidic polysaccharides) and 13.8%, 29.0% and 36.5% (neutral polysaccharide), respectively. Acidic polysaccharides of hydrocolloids produced from three species of Salvias contain high amount of xylose (88.8 ~ 91.9%). Neutral sugar compositions in neutral polysaccharides of hydrocolloids produced from three species of Salvias, however, were rich in glucose (25.7 ~ 37.5%) and galactose (31.3 ~ 60.4%), the ratio being changed depending on species. Acidic sugar in the acidic polysaccharides from three Salvia spp. was identified as glucuronic acid by High Performance Anion Exchange Chromatography (HPAEC). Glucuronic acid contents in the acidic fractions of S. miltiorrhiza, S. sclarea, S. viridis were estimated about 25%, 22% and 27%, respectively. These results elucidate that hydrocolloids have amorphous structure containing branch glucuronic acid in acidic polysaccharides structure. The present of glucuronic acid is predicted attach to xylan.
THE EFFECT OF Pt LOADING ON ELECTROCHEMICAL PERFORMANCE OF CNT-BASED ELECTROCATALYST Yudianti, Rike; Onggo, Holia
Teknologi Indonesia Vol 37, No 3 (2014)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (16.051 KB) | DOI: 10.14203/jti.v37i3.230

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Pt loading on CNT surface as electrocatalyst support affects electrochemical performance of electrocatalyst and proton exchange membrane fuel cell stability. In some recent study, Pt-loaded electrocatalyst was a synthesis using poliol method, undergone by controling weight ratio of Pt percursor and CNT in order to find out the importance of appropriate Pt loading and configuration on electrochemical performance. According to the analysis, Pt-loaded electrocatalyst 23.4 and 36.3% show good material properties and electrochemical performance. Electrocatalyst 23.4% Pt loading was selected for preparing low Pt-loaded electrocatalyst layer by screen printing techniques. Nafion ionomer on electrocatalytic film plays an important role to determine the morphological electrocatalyst surface and performance in changing hydrophobicity and electrochemical properties. Nafion ionomer consequently causes reduction on electrochemical properties from 338.6 to 31.6 m2/g whereas the highest electrochemical surface area (ECSA) is achieved by Pt loading 23.4% in average particle size 3.7 nm, corresponding to Pt activity on hydrogen desorption.
PENGARUH PENAMBAHAN POLY(TETRAFLUOROETHYLENE) PADA KARAKTERISTIK KOMPOSIT BACTERIAL CELLULOSE/ MULTI-WALLED CARBON NANOTUBES Onggo, Holia; Yudianti, Rike
Teknologi Indonesia Vol 35, No 1 (2012)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (16.051 KB) | DOI: 10.14203/jti.v35i1.173

Abstract

In order to obtain new materials as alternative carbon paper, the bacterial cellulose/multi-walled carbon nanotube (BC/MWCNT) composites were made with and without PTFE by helping agarose, via heating process. The effect of PTFE addition on characteristic BC/MWCNT composite have been studied using thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and impedance bridge. The electrically conductivity of BC / MWCNT/ AG composite (without PTFE addition) is 15.1 x 10-2 S/cm (in-plane) and 0.3 x 10-2 S/cm (through plane). Above 150oC, the composite tends to be destroyed leading to electrical conductivity measurements cannot be performed. In the BC/MWCNT/AG/PTFE composite, heating from 150 to 330oC increased electrically conductivityfrom 4.5 to 24.5 x 10-2 S/cm (in-plane) while through-plane electrically conductivity tend to be stable (0.020.03x10-2 S/cm). After heating at 400oC, the composite was seen better thermal stability but the electrically conductivity was decrease because of carbon particles from AG and BC were decomposed and coating of MWCNT. The PTFE addition was not only for increasing the thermal stability but also as coating material of BC/MWCNT composites.
PENGARUH KONSTANTA DIELEKTRIK DAN DISPERSITAS PARTIKEL TERHADAP HYDROPHOBICITY ELEKTROKATALIS BERBASIS CARBON NANOTUBE Yudianti, Rike; Onggo, Holia; Syampurwadi, Anung
Jurnal Sains Materi Indonesia Vol 14, No 1: OKTOBER 2012
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2465.928 KB) | DOI: 10.17146/jsmi.2012.14.1.4636

Abstract

PENGARUH KONSTANTA DIELEKTRIK DAN DISPERSITAS PARTIKEL TERHADAP HYDROPHOBICITY ELEKTROKATALIS BERBASIS CARBON NANOTUBE. Pada penelitian ini dilakukan pembuatan lapisan elektrokatalis berbasis Carbon Nanotube (CNT) dengan teknik filtrasi untuk meningkatkan sifat hydrophobicity. Sifat hydrophobicity elektrokatalis diperlukan untuk mengurangi penggunaan hydrophobic agent, yaitu PolyTetra Fluoro Ethylene (PTFE) yang ditambahkan pada elektrokatalis komersial Pt/C untuk mengatasi air yang dihasilkan di elektroda. Pembuatan lapisan elektrokatalis dilakukan dengan metode filtrasi dari elektrokatalis terdispersi menggunakan membran hidrofilik. Beberapa teknik pembuatan dan formulasi larutan dilakukan untuk meningkatkan hydrophobicity tanpa mengurangi performanya. Pada kondisi larutan padat antara pelarut yangmempunyai konstanta dielektrik (?) >10 dengan ionomer nafion akan menghasilkan hydrophobicity yang tinggi (>90°). Sedangkan pada kondisi colloidal state antara pelarut dengan konstanta dielektrik (?) <10 dan ionomer nafion cenderung tidak mengubah sifat hydrophobicity (<90°). Sifat hydrophobicity elektrokatalis diukur dengan teknik Half Angle menggunakan Contac Angle Meter. Perubahan morfologi permukaan lapisan elektrokatalis akibat penambahan nafion dan dispersi partikel CNT diamati dengan Scanning Electron Microscope. Hubungan antara penambahan larutan nafion dan hydrophobicity film dibahas pada makalah ini.
PEMBUATAN GAS DIFFUSION ELECTRODE DENGAN TEKNIK SCREEN PRINTING : PENGARUH MICROPOROUS LAYER TERHADAP STRUKTURMIKRO DAN KINERJA ELEKTROKATALIS Onggo, Holia; Syampurwadi, Anung; Yudianti, Rike
Jurnal Sains Materi Indonesia Vol 14, No 4: JULI 2013
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (825.546 KB) | DOI: 10.17146/jsmi.2013.14.4.4382

Abstract

PEMBUATAN GAS DIFFUSION ELECTRODE DENGAN TEKNIK SCREEN PRINTING : PENGARUH MICROPOROUS LAYER TERHADAP STRUKTURMIKRO DAN KINERJA ELEKTROKATALIS. Pembuatan Gas Diffusion Electrode (GDE) dengan teknik screen printing dilakukan untuk mengetahui efektivitas teknik ini terhadap kinerja dan strukturmikro elektrokatalis. Lapisan katalis dibuat dari Pt/C dan nafion ionomer dengan variasi rasio berat nafion ionomer/katalis (Pt/C) adalah 35/65; 25/75; dan 15/85. Perubahan morfologi permukaan lapisan katalis akibat perubahan rasio nafion/Pt/C diamati dengan Scanning Electron Microscope (SEM). Analisis komposisi elemen permukaan dan electrochemical surface area dari partikel Pt dilakukan berturut-turut dengan Energy Dispersive X-Ray Spectroscopy (EDS) dan voltametrik siklik.Hasil penelitian menunjukkan bahwa teknik screen printing cukup efektif untuk mendapatkan lapisan elektrokatalis dengan Pt loading rendah. Penelitian ini juga menjelaskan bahwa microporous layer yang dibentuk antara lapisan katalis dan carbon paper meningkatkan kinerja elektrokatalis.
DISPERSIBILITY OF MULTIWALL CARBON NANOTUBE IN A POLYANIONIC SURFACTANT BASED ON UV-VIS ANALYSIS Irmawati, Yuyun; Khaerudini, Deni Shidqi; Indriyati, Indriyati; Mardiyati, Mardiyati; Yudianti, Rike
Indonesian Journal of Chemistry ARTICLE IN PRESS
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (386.925 KB) | DOI: 10.22146/ijc.45567

Abstract

The degree of carbon nanotube (CNT) dispersion in an ink solution plays a critical role in the performance of CNT based devices. This is a challenging task in the CNT utilization due to strong van der Waals interaction affecting the CNT bundles. A good dispersion degree can be achieved, for instance, by lowering the van der Waals interaction with the strategy of non-covalent interaction between polyanionic surfactant and the CNT surface. Herein, a simple and quick technique to disperse multiwall CNT (MWCNT) by using a polyanionic dispersant, carboxymethyl cellulose (CMC), is reported. The dispersion degree of MWCNT in aqueous solution during the sonication process was studied using UV-Vis analysis. Transmission electron microscope (TEM) was also applied to further investigate the interaction between CMC and MWCNT. The result shows that the maximum dispersion of MWCNT was achieved with a maximum absorbance in the UV-Vis spectra. Higher CMC concentration resulted in a higher viscosity of the solution, thus it increased the sonication duration in obtaining the maximum dispersion. By varying the MWCNT concentration at a constant CMC concentration of 0.25 wt.%, a homogenous MWCNT dispersion was obtained up to 0.2 wt.%. The encapsulation of a thin CMC layer on the MWCNT surface with a thickness of 1.5?3 nm was evidenced by TEM micrograph analysis.