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Rakhmawati Farma
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Aerospace Engineering Agriculture, Biological Sciences & Forestry Astronomy Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Control & Systems Engineering Earth & Planetary Sciences Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mathematics Physics Social Sciences

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Cyclic Voltammetry Sel Superkapasitor Dengan Variasi Konsentrasi Aktivator Kalium Hidroksida Rakhmawati Farma; Melinda Vivi; Sugiyanto Sugiyanto; Awitdrus Awitdrus; Erman Taer; Hamzah Yanuar
Jurnal Fisika Indonesia Vol 21, No 2 (2017)
Publisher : Department of Physics Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jfi.42203

Abstract

Aktivasi kimia sangat berpengaruh terhadap kualitas elektroda sel superkapasitor. Pada penelitian ini elektroda karbon berasal dari serabut tandan kosong kelapa sawit melalui proses pra karbonisasi dan aktivasi kimia dengan menggunakan aktivator kalium hidroksida (KOH) dengan variasi konsentrasi 0.3 M, 0.6 M dan 0.9 M dengan lama waktu aktivasi 20 jam. Proses selanjutnya adalah proses karbonisasi menggunakan gas N2 dan proses aktivasi fisika menggunakan gas CO2. Nilai densitas elektroda karbon menunjukkan peningkatan setelah proses aktivasi fisika. Hasil analisa energi dispersif sinar-X menunjukkan bahwa elektroda karbon dengan konsentrasi 0.9 M mempunyai persentase atomik  unsur karbon tertinggi sebesar 92,48%. Karakterisasi struktur mikro menunjukkan bahwa elektroda karbon bersifat semikristalin  yang ditandai kehadiran puncak landai (002) dan (100) pada sudut 2θ sekitar 24° dan 45°. Elektroda karbon dengan konsentrasi 0,9 M mempunyai nilai dimensi mikrokristalin Lc  tertinggi yaitu sebesar 7,27 Å dan nilai La terendah yaitu sebesar 6.97 Å dibandingkan dengan elektroda sel superkapasitor dengan konsentrasi 0.3 M dan 0.6 M. Karakterisasi sifat elektrokimia sel superkapasitor dengan menggunakan Cyclic Voltammetry (CV) menunjukkan bahwa sel superkapasitor pada konsentrasi KOH 0.9 M menunjukkan niai tertinggi yaitu sebesar 110, 724 F/g.
Pengaktifan Kimia Berbantuan Gelombang Mikro Karbon Aktif dari Kulit Kacang dengan Waktu Pra-karbonisasi yang Berbeda Awitdrus Awitdrus; Dewi Mulfida; Rakhmawati Farma; Saktioto Saktioto; Iwantono Iwantono
Jurnal Fisika Vol 8, No 2 (2018)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jf.v8i2.16974

Abstract

Karbon aktif berbahan dasar kulit kacang (Arachis hypogaea L) disintesis menggunakan metode pengaktifan kimia berbantuan gelombang mikro. Kulit kacang dipra-karbonisasi selama 2 jam, 3 jam dan 4 jam pada temperatur 200 oC. Pengaktifan kimia dilakukan menggunakan kalium hidroksida dengan rasio massa pra-karbonisasi dan kalium hidroksida adalah 2:1 selama 24 jam. Iradiasi gelombang mikro dilakukan pada daya keluaran 630 watt selama 20 menit. Sifat fisika karbon aktif dikarakterisasi menggunakan difraksi sinar-X untuk mengetahui struktur mikro, isoterma adsorpsi/desorpsi N2 untuk mengetahui parameter porositas, serta infra merah transformasi Fourier untuk mengetahui struktur rantai karbon aktif. Pola difraksi sinar-X menunjukkan bahwa semua karbon aktif memiliki struktur turbostratik yang ditandai dengan adanya puncak (002) dan (100). Luas permukaan dan volume pori karbon aktif tertinggi adalah 153 m2/g dan 0,064 cm3/g untuk karbon aktif dengan waktu pra-karbonisasi selama 2 jam. Struktur rantai karbon menunjukkan adanya  gugus fungsi P=O, C-O, C-C, C-H pada bilangan gelombang 1031 cm-1, 1609,67 cm-1, 2363,87 cm-1, dan 2867,31 cm-1.
SINTESIS FISIKOKIMIA DARI KARBON AKTIF BERBASIS BIOMASSA SABUT NIPAH (Nypa fruticans) UNTUK PERFORMANSI KINERJA SUPERKAPASITOR Irma Apriyani; Rakhmawati Farma; Awitdrus Awitdrus; Aria Yunita
Komunikasi Fisika Indonesia Vol 20, No 2 (2023)
Publisher : Universitas Riau

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31258/jkfi.20.2.127-134

Abstract

Biomass-based activated carbon materials provide a new approach for the development of high-performance electrode materials for supercapacitor cells. In addition, the carbon materials are low cost and sustainable for large-scale production of electrode materials. In this study, carbon electrodes made from nipa palm (Nypa fruticans) coir were synthesized physicochemically. The pore size distribution of the carbon electrodes can be adjusted with the increased CO2 activation temperature (700°C, 800°C, and 900°C). The results showed that the SN-800 carbon electrode had the lowest density shrinkage and showed excellent electrochemical performance. The highest specific capacitance was obtained at 247 F/g at a current density of 1 A/g in a symmetrical two-electrode system. This work provides an efficient strategy for the preparation of high performance carbon electrodes based on nipa coir biomass.
PEMODELAN GENERATOR PLASMA HIDROGEN FREKUENSI GELOMBANG MIKRO TEKANAN ATMOSFIR Reeky Fardinata; Saktioto Saktioto; Rakhmawati Farma
Indonesian Physics Communication Vol 20, No 3 (2023)
Publisher : Universitas Riau

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31258/jkfi.20.3.205-214

Abstract

The model used in this work is a two-dimensional fluid plasma model coupled with Maxwell equations at atmospheric pressure. The model was created by applying different plasma torch parameters using the finite element approach. Three separate stages of the numerical modeling were used to show how the increase in electron density increases with time. It may be inferred from the molecular ion distribution features that the torch's quartz tube's port, which is larger than the tube's center, is where the molecular ions are primarily disseminated. Reduced pressure and the calculated distance from the port to the center of the quartz tube result in a drop in the density ratio of molecular ions to electrons. The research on microwave plasma properties revealed that atmospheric pressure is important for modeling and developing plasma sources, particularly for the conversion of carbon dioxide.
SINTESIS KARBON AKTIF BERBASIS BIOMASSA SERAT BINTARO SEBAGAI BAHAN ELEKTRODA UNTUK APLIKASI SEL SUPERKAPASITOR Aria Yunita; Rakhmawati Farma; Awitdrus Awitdrus; Irma Apriyani
Indonesian Physics Communication Vol 20, No 3 (2023)
Publisher : Universitas Riau

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31258/jkfi.20.3.223-230

Abstract

Biomass-based activated carbon has been widely developed due to its environmental friendliness, abundant availability, porous structure, high specific surface area and good electrical conductivity. One of the ways to improve the performance of supercapacitor cells is to increase the carbonization temperature, so that in this study various carbonization temperatures were carried out at 500°C, 600°C and 700°C. The results showed that the carbonization temperature of 600°C was the optimum temperature for making SB-based activated carbon. This is indicated by the results of measuring the physical properties of SB-600 in the form of the lowest density shrinkage value which can increase porosity thereby increasing the performance of supercapacitor cells. From this study, the highest capacitance value of 213 F.g-1 was found on the SB-600. The results obtained indicate that the selection of the optimum carbonization temperature is important and can improve the performance of supercapacitor cells.
Potential of palm frond waste as a basic material for making porous activated carbon Novi Yanti; Pharada Kresna; Muhammad Nasir; Rakhmawati Farma; Lilik Tri Hardanto; Rika Taslim; Erman Taer
Indonesian Physics Communication Vol 21, No 1 (2024)
Publisher : Universitas Riau

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31258/jkfi.21.1.99-108

Abstract

Palm frond waste (Elaeis guineensis Jacq.) has been successfully processed as a raw material in the manufacture of porous activated carbon through the development of tools and methods. Preparation of raw materials, drying, pre-carbonization using an energy-efficient furnace, washing, integrated pyrolysis (N2/H2O), neutralization, and conversion of carbon powder into monolith coins are the general steps for making porous activated carbon. The focus of this research lies in increasing the production of activated carbon from a laboratory scale to an industrial scale through efficiency in all aspects of production. Precarbonization and pyrolysis are important stages in increasing the scale of activated carbon production. Currently, the conversion of biomass waste into carbon is still on a laboratory scale, namely by using an electric oven which is not time efficient, not economical and not energy efficient. Increasing the scale of pre-carbonization is carried out by replacing the use of electric ovens with modified energy-saving furnaces that can increase carbon production up to 74% in a very efficient time. Furthermore, the physical activation stage (pyrolysis) is carried out in a water vapor (H2O) environment and without the addition of chemicals as activating agents, of course it is more economical and environmentally friendly. This scale-up is the main key in the development of porous carbon which has high potential for application as a component in energy storage devices, namely electrodes in supercapacitors. Through these results it is known that the fronds of palm leaves have great potential as a basic material for making sustainable activated carbon to be forwarded to an industrial scale.
Physical Properties Analysis of Activated Carbon from Oil Palm Empty Fruit Bunch Fiber on Methylene Blue Adsorption Farma, Rakhmawati
Journal of Technomaterial Physics Vol. 1 No. 1 (2019): Journal of Technomaterial Physics
Publisher : Talenta Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/jotp.v1i1.824

Abstract

The present research was conducted to analyze the physical properties of activated carbon from oil palm empty fruit bunch fiber (OPEFBF) to be applied as methylene blue adsorbent material. The OPEFBF was pre-carbonized at 280oC for 4 hours in vacuum, milled, and sieved to obtain the self-adhesive carbon grain (SACG) with a size less than 106 µm. The chemical activation was done using potassium hydroxide (KOH) with variations of 25%, 50%, and 75% from the SACG weight, stirred at 400 rpm for 24 hours at room temperature and pyrolyzed using microwave irradiations at the output power of 720 W for 15 minutes. The physical properties of activated carbon consist of two characterizations, namely microstructure evaluated with X-ray diffraction (XRD) and surface morphology evaluated with scanning electron microscopy (SEM). The XRD pattern showed that the activated carbon had a semi-crystalline structure characterized by the presence of (002) and (100) planes at the diffraction angle of 2θ about 21o and 43o, respectively. The surface morphology of activated carbon depicted that a higher percentage of KOH resulted in more pores were formed. Thus, the higher the surface area of activated carbon, the greater the adsorption of methylene blue. The highest methylene blue adsorption was obtained in the sample of 75% KOH with 87.73 mg/g. The energy dispersive X-ray showed that the increase of KOH percentage used enhanced the percentage of carbon element produced.
Harnessing multi-doping porous carbon from Musa paradisiaca L. peel waste for solid-state supercapacitors Purba, Cenora Evelynza; Nursyafni, Nursyafni; Apriwandi, Apriwandi; Kresna, Pharada; Julnaidi, Julnaidi; Nasir, Muhammad; Farma, Rakhmawati; Dewi, Rahmi; Martin, Awaludin; Hardanto, Lilik Tri; Taslim, Rika; Taer, Erman
Indonesian Physics Communication Vol 21, No 3 (2024)
Publisher : Universitas Riau

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31258/jkfi.21.3.187-196

Abstract

The demand for low-cost carbons with multi-doping in supercapacitors has led to a significant focus on utilizing biomass waste to produce activated carbons. The research successfully utilized Musa paradisiaca L. (MPL) peel as a porous carbon for solid-state supercapacitor. The process involved collecting banana peel waste, drying the peels using sunlight, pre-carbonization using a furnace, pH neutralization, drying, crushing carbon particles, and ensuring uniform particle size. Different concentrations of the catalytic ZnCl2 solution (300, 500, and 700 mmol/g) were selected to optimize physical and electrochemical properties. The resulting chemically activated MPL carbon powder was evaluated using SEM-EDS, XRD, and BET. MPL activated carbon with a 500 mmol/g solution of ZnCl2 was found to have optimal physical properties with a carbon percentage of 81.65%, oxygen 17.39%, phosphorus 0.42%, and boron 0.52%. Electrochemical properties were evaluated using dual-electrode system was exhibited the highest specific capacitance of 67 F/g. These findings demonstrate the potential of MPL peel waste as a high quality electrode for supercapaicor next-generation.
N-doped porous activated carbon from rubber seed shells (Hevea brasiliensis) as high-energy supercapacitor material Daulay, Siti Rahma; Farma, Rakhmawati; Awitdrus, Awitdrus
Indonesian Physics Communication Vol 21, No 3 (2024)
Publisher : Universitas Riau

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31258/jkfi.21.3.211-218

Abstract

Biomass is an environmentally safe and cost-effective source of activated carbon (AC) for supercapacitors (SC). In this study, AC was generated using precarbonisation and activation with KOH using rubber seed shell (RSS) as a precursor. The electrochemical performance was investigated by cyclic voltammetry and galvanostatic charge-discharge determination and the ACs were characterised using FTIR analysis technique. RSS materials were prepared by varying calcination temperatures of 700°C, 800°C, and 900°C without doping. RSS800 shows a maximum specific capacitance of 190 F/g and has an energy density of 26.2 Wh/kg and a power density of 695.4 kW/kg at 1 A/g. Furthermore, melamine was used as an external dopant source for the N-doping process. The doped AC sample (RSS800-90) had a specific capacitance of 288 F/g and has an energy density of 40.9 Wh/kg and a power density of 515.4 kW/kg at 1 A/g in H2SO4 electrolyte. N-doped with melamine as nitrogen source was successfully incorporated into AC to produce high-performance electrodes for SC.
Developing Carbon Nanofibers from Gnetum Gnemon Linn Pericarp Using Dual Activators KOH And Melamine as Innovative Electrode Materials for Supercapacitors Farma, Rakhmawati; Putri, Hardini Chania; Apriyani, Irma; Azwat, Luqyana Adha; Awitdrus, Awitdrus; Deraman, Mohamad; Rini, Ari Sulistyo; Setiadi, Rahmondia Nanda; Taer, Erman
Journal of Engineering and Technological Sciences Vol. 57 No. 6 (2025): Vol. 57 No. 6 (2025): December
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2025.57.6.2

Abstract

Synthesis of carbon nanofibers from Gnetum gnemon Linn (GP) biomass with dual activators, KOH and melamine, offers a potential approach for high-performance supercapacitor electrodes. This study evaluated the preparation of GP-based carbon nanofibers through single and double activation, with varying melamine masses of 0.1, 0.3, and 0.5 g at 0.3 M KOH. The pyrolysis (integrated carbonization and physical activation) occurred at 600°C in N₂ and 800°C in CO₂ atmospheres. The material was activated using 0.3 g of melamine in 0.3 M KOH to produce abundant and highly amorphous nanofiber structures. These characteristics contributed to the high specific capacitance of 400 F/g at a scan rate of 1 mV/s and an energy density of 17 Wh/kg at a power of 465 W/kg. These results demonstrated the synergistic effect of melamine and KOH in increasing the active surface area and structural conductivity. This finding confirms the potential of GP biomass that has not been optimally utilized as a sustainable precursor for energy storage applications, especially supercapacitors.
Co-Authors Ade Nur Indah Lestari Agustino Agustino Agustino Agustino Agustino Agustino Aldes Lesbani Alexander Nasution Amalia Apriliani Putri Amiruddin Supu Apriwandi Apriyani, Irma Aria Yunita Aria Yunita Awaludin Martin Awitdrus Awitdrus, Awitdrus Azwat, Luqyana Adha Balada Soerya Beta Riana Liasari Daulay, Siti Rahma Decha Apriliany Suwandi Dedi Setiabudidaya Desmagrini Desmagrini Desy Veyka Rukmana Dewi Mulfida Eko Nur Arif Erin Mazelly Hutapea Erman Taer Fitri Suryani Arsyad Fitri Wahyuni Haliza Putri Hardanto, Lilik Tri Idha Royani Ikhsan Rahman Husein Inrizky Domy Muchammadsam Irma Apriyani Irma Apriyani Iwantono Iwan Barnawi Julnaidi, Julnaidi Karina Silviani Kresna, Pharada Lilik Tri Hardanto Melda Oktaviandari Melinda Vivi Menik Ariani Miftah Ainul Mardiah Minarni Minarni Mohamad Deraman, Mohamad Muhammad Nasir Muhammad Nasir Mulfida, Dewi Novi Yanti Nurlisa Kartikasari Nursyafni, Nursyafni Nurul Tania Pharada Kresna Purba, Cenora Evelynza Putri, Hardini Chania Rahmi Dewi Rahmondia N. Setiadi Raysa Fadillah Reeky Fardinata Rika Taslim Rika Taslim Rini, Ari Sulistyo Rinti Rahimah Hasibuan Risfidian Mohadi Saktioto Saktioto Sinta Afria Ningsih Siti Nur’aini Sugiyanto Sugiyanto Vepy Asyana Vepy Asyana Widarti ' Yanuar Hamzah Yurike Asra Zurya Hanifa