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Pembuatan Grafena dengan Metode Reduksi Graphene Oxide Menggunakan Bahan Baku Grafit dan Reduktor Natrium Hipopospit Ratna Sari; Cut Dina Mastura; Teuku Rihayat; Ratni Dewi; Lukman Hakim
Jurnal Serambi Engineering Vol 7, No 2 (2022): April 2022
Publisher : Fakultas Teknik

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32672/jse.v7i2.4211

One of the new materials that has developed recently is graphene. Graphene is a new closed, strongest, and superior material in the world today which is formed from a single layer of carbon atoms which has a hexagonal structure resembling a honeycomb. This study aims to determine the effect of graphite size on the quality of graphene produced using the graphene oxide reduction method. This method uses sodium hypophosphite reductor and oxidizing agent KMnO4, sulfuric acid and hydrogen peroxide. The quality of graphene is observed by looking at the electrical conductivity produced. This study varied the size of the graphite (106 µm, 125 µm, 150 µm, 180 µm dan 250 µm) and the reductor volume variation (3 ml, 5 ml, 7 ml, 9 ml dan 11 ml). The graphene oxide solution was heated in hot water and then filtered, ultrasonically for 3 hours, and in the oven for 6 hours at 80oC. From the results of the electrical conductivity test, the best results were obtained at a graphite size of 106 µm while for the volume of the reductor the best results were at 11 ml. Graphene was characterized using FTIR (Fourier transform infrared) and SEM (scanning electron microscope). The results of the characterization of the powder samples show that there has been a change in the structure of graphite to graphene. The size of the graphite and the volume reducing agent has a significant effect on the graphene’s electrical conductivity.

Produksi Gas Hidrogen dari Air Laut Menggunakan Proses Photovoltaic-Electrolysis dengan Katalis H2SO4 Lukman Hakim; Elma Agustina Berutu; Ratna Sari; Ratni Dewi
Jurnal Serambi Engineering Vol 8, No 1 (2023): Januari 2023
Publisher : Fakultas Teknik

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32672/jse.v8i1.5575

AbstractHydrogen is a new and renewable energy that has advantages over other energies. Among the hydrogen gas production methods that have the potential to be developed is seawater electrolysis, which is an abundant source. The electrolysis method uses a Direct Current (DC) electric current source. In this study, DC electric current was used from the results of solar panels (photovoltaic) with a volume of seawater as an electrolyte solution of 3500 ml. The electrolysis process times were 15, 30, 45, and 60 minutes using graphite electrodes with variations in voltages of 5, 10, 15 and 20 volts and H2SO4 catalyst concentrations of 0.1M, 0.25M, 0.5M and 0.75M at ambient conditions and 1 atm. The study results showed that the voltage and catalyst concentration of H2SO4 showed the effect of the formation of hydrogen gas. Where the effect of the loading voltage is reversed with the catalyst concentration of H2SO4. The higher voltage, the flow rate of the hydrogen gas produced also increases and the higher the concentration of H2SO4 catalyst used, lower the flow rate of the hydrogen gas produced. Based on the research results, the highest hydrogen gas flow rate was obtained at a catalyst concentration of 0.1M H2SO4, at a voltage of 20 volts with a flow time of 60 minutes, a flow rate of 20.5 ml/minute and in seawater electrolysis using H2SO4 catalyst did not produce NaOCl as a byproduct.Keywords: electrolysis, energy, graphite, hydrogen, catalyst

Analisa Pemanfaatan Kompresor BOG K-6801 A/B pada Fasilitas LNG Hub Fadhel Muhammad; Syafruddin Syafruddin; Ratna Sari
Jurnal Teknologi Vol 23, No 1 (2023): April 2023
Publisher : Politeknik Negeri Lhokseumawe

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30811/teknologi.v23i1.3750

Boil Off Gas (BOG) is formed as a result of the evaporation of liquefied gas at atmospheric pressure as a result of the expansion of the cargo space such as a tank which can endanger the condition of the tank if it exceeds the pressure design on the tank. So, to maintain pressure in safe conditions, the BOG usually has to be burned and directed to the flare. In another word, the factory has been wasting clean gas for free. So there is a better option to use a compressor for fuel-to-plant operation. Compressor K-6801 is a centrifugal type compressor with a single casing multi-stage compressor, with a prime mover or drive in the form of an electric motor. The BOG compressor functions to compress/drain the evaporation gases (Boil Off Gas) from the LNG tank to the PLTMG and the fuel system, while the excess output from the compressor BOG will be flowed to the booster compressor to flow along with the output from the ORV to the ARBEL (Arun-Belawan) gas network. The output BOG from the LNG tank will enter the compressor suction with a temperature of -145.5 °C and a pressure of 0.00054 kg/cm2G, where it will then come out of the discharge of the BOG compressor with ambient temperature conditions of 51.6 °C and a pressure of 15.4 kg/cm2G. After manual calculations, there was a decrease in efficiency by 13% from 98% of the design data to 85%, and a decrease in efficiency through Hysys by 21% to 77%.

Aplikasi Adsorben Nanopartikel Magnetit (Fe3O4) untuk Penyisihan Metilen Biru dari Ferric Nitrate Nonahydrate dengan Metode Sol-Gel Mauli Faulina; Ratna Sari; Nahar Nahar
Jurnal Teknologi Vol 23, No 2 (2023): Oktober 2023
Publisher : Politeknik Negeri Lhokseumawe

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30811/teknologi.v23i2.4473

The application of magnetite (Fe3O4) nanoparticle adsorbent for the removal of methylene blue from ferric nitrate nonahydrate by sol-gel method. This study was conducted to determine the effect of variations in calcination temperature and stirring time on density, and adsorption power of magnetite (Fe3O4) nanoparticles on methylene blue with variations in stirring time of 2 hours; 3 hours; 4 hours; 5 hours, and 6 hours, as well as variations in calcination temperature of 200°C; 250°C; 300°C; 350°C and 400°C. Characterization of magnetite (Fe3O4) nanoparticles was carried out using XRD, and SEM instruments. Methylene blue concentration after adsorption was measured using Uv-Vis Spectrophotometer. Determination of adsorbent surface area was done by iodine absorption test. The results showed a decrease in density along with the increase in calcination temperature and the longer the stirring, the density value will increase. Magnetite (Fe3O4) nanoparticles effectively increase the adsorption capacity of methylene blue, with the best results at a stirring time of 6 hours and a calcination temperature of 400°C the concentration after adsorption drops to 1.7316 ppm. The best iodine adsorption capacity is found in the sample of 6 hours stirring time and 200°C calcination temperature, which is 1027.89 mg/gr. The crystal size obtained based on calculations from the Scherrer equation at a variation of 3 hours stirring time and 200°C calcination temperature is 0.2 nm and the surface morphological structure of magnetite (Fe3O4) nanoparticles at the same stirring time and calcination temperature looks clustered with sizes ranging from 0.4 nm to 0.9 nm.

Penggunaan Susu Kambing dan Putih Telur serta Koagulan Ie Asam Sunti pada Pembuatan Tahu Sutera (Tofu) Anisa Putri; Salmyah Salmyah; Ratna Sari
Jurnal Teknologi Vol 23, No 2 (2023): Oktober 2023
Publisher : Politeknik Negeri Lhokseumawe

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30811/teknologi.v23i2.4472

Silken tofu is a type of tofu that has a soft and compact texture. Ie sunti acid is a by-product of the process of making sunti acid which can be used as a coagulant. The disadvantage of the coagulant, namely sunti acid, is that it produces a silken tofu texture that is not compact. Therefore, cornstarch is added to the production of silken tofu to improve the texture quality of the silken tofu produced. This research aims to determine the effect of increasing coagulant concentration and adding goat's milk and egg white on the characteristics of silken tofu. This research method uses Central Composite Design (CCD) which is included in the Response Surface Method (RSM) and organoleptic methods. With coagulant concentration (2%, 4%, 6%, 8%, 10%) and goat milk volume (100 mL, 200 mL, 300 mL, 400 mL, 500 mL), as well as egg white weight (50 g, 55 g, 60 g, 65 g, 70 g). The results obtained optimal values, namely a goat's milk volume of 300 mL, an egg white weight of 60 g, and a coagulant concentration, namely sunti acid, of 6%, producing a silken tofu texture of 23.5 mm/sec, a pH level of 5 and a fat content of 3.25%. The volume of goat's milk, the weight of egg whites, and the concentration of sunti acid did not affect the color and taste of silken tofu but did affect the aroma of silken tofu

Simulasi Numerik Prarancangan Perpipaan LNG Circulation Line di Aliran Masuk Air Ambient Vaporizer (AAV) Muhammad Ikhsan; Ratna Sari; Reza Fauzan
Jurnal Teknologi Vol 23, No 2 (2023): Oktober 2023
Publisher : Politeknik Negeri Lhokseumawe

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30811/teknologi.v23i2.4138

The circulation process is a process to make pipes in the LNG industry always in LNG operational cryogenic temperature condition -160° C. The LNG circulation line facility on the AAV inlet pipe is expected to flow LNG continuously as a solution to keep the pipe always in a state of cryogenic temperature. The pressure drop from one point to another with lower pressure is referred to as a "pressure drop. Loss of pressure in the process at the AAV piping system is caused by several parameters including pipe size, flow rate, and pressure also because of a change in pipe size and friction along the pipeline. The purpose of this research is to analyze the effect of pipe size on pressure drop and compare it with theoretical calculations and simulation programming. Hysys is engineering software designed to simulate processes in industry to design process calculations related to engineering. Based on the results of the manual calculation, the 3-inch pipe size has the lowest pressure drop value of 0.314 kg/cm2 and the results using aspen hysys is 0.053 kg/cm2. Using a double pipe piping system, the 4-inch annulus has a pressure drop value of 0.445 kg/cm2, and the result from Aspen Hysys is 0.059 kg/cm2. Pressure drop is significantly influenced by pipe size; the smaller the pressure drop that happens, the greater the pipe size must match the pipe connection size. The pressure drop that occurs in variations in pipe size has a great influence on the LNG flow back into the storage tank.

Produksi Gas Hidrogen dari Air Laut Menggunakan Proses Photovoltaic-Electrolysis dengan Katalis H2SO4 Lukman Hakim; Elma Agustina Berutu; Ratna Sari; Ratni Dewi
Jurnal Serambi Engineering Vol 8, No 1 (2023): Januari 2023
Publisher : Fakultas Teknik

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32672/jse.v8i1.5575

AbstractHydrogen is a new and renewable energy that has advantages over other energies. Among the hydrogen gas production methods that have the potential to be developed is seawater electrolysis, which is an abundant source. The electrolysis method uses a Direct Current (DC) electric current source. In this study, DC electric current was used from the results of solar panels (photovoltaic) with a volume of seawater as an electrolyte solution of 3500 ml. The electrolysis process times were 15, 30, 45, and 60 minutes using graphite electrodes with variations in voltages of 5, 10, 15 and 20 volts and H2SO4 catalyst concentrations of 0.1M, 0.25M, 0.5M and 0.75M at ambient conditions and 1 atm. The study results showed that the voltage and catalyst concentration of H2SO4 showed the effect of the formation of hydrogen gas. Where the effect of the loading voltage is reversed with the catalyst concentration of H2SO4. The higher voltage, the flow rate of the hydrogen gas produced also increases and the higher the concentration of H2SO4 catalyst used, lower the flow rate of the hydrogen gas produced. Based on the research results, the highest hydrogen gas flow rate was obtained at a catalyst concentration of 0.1M H2SO4, at a voltage of 20 volts with a flow time of 60 minutes, a flow rate of 20.5 ml/minute and in seawater electrolysis using H2SO4 catalyst did not produce NaOCl as a byproduct.Keywords: electrolysis, energy, graphite, hydrogen, catalyst

UTILIZATION OF CORN (Zea mays) AS A COMBINATION INGREDIENT IN TOFU PRODUCTION WITH THE ADDITION OF IE ASAM SUNTI EXTRACT AND IE KULOH SIRA EXTRACT AS NATURAL COAGULANTS Radhia Ulfa Rahmi; S Salmyah; Ratna Sari
Jurnal Sains dan Teknologi Reaksi Vol 24, No 01 (2026): JURNAL SAINS DAN TEKNOLOGI REAKSI
Publisher : Politeknik Negeri Lhokseumawe

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30811/jstr.v24i01.9407

This study aims to examine the effect of coagulant volume and the addition of corn on the characteristics of tofu. The method used is Central Composite Design (CCD), which is part of the Response Surface Methodology (RSM), along with organoleptic testing to assess consumer acceptance. The raw material variations consist of combinations of soybean and corn in the ratios of 900 g:100 g, 800 g:200 g, 700 g:300 g, 600 g:400 g, and 500 g:500 g, as well as coagulant volumes of ie asam sunti and ie kuloh sira ranging from 100 to 300 ml. The results showed that the best combination was 700 grams of soybean and 300 grams of corn with 250 ml of ie asam sunti, producing a texture of 200 mm/second, pH 5.6, protein content of 5.6%, and a yield of 75%. Meanwhile, 250 ml of ie kuloh sira produced a texture of 240 mm/second, pH 5.8, protein content of 5.8%, and a yield of 75%. Organoleptic testing was conducted using a hedonic scale to determine consumer preference for the resulting tofu. The evaluation covered aroma, taste, and color, which are important indicators of the acceptability of corn tofu products..Keywords: ie asam sunti, ie kuloh sira, soybean, corn tofu

Utilization of Bidara Leaf Extract (Ziziphus mauritiana Lamk) as a Body Scrub For Skin Care Agna Safira Yulia; Ratni Dewi; Nahar Nahar; Ratna Sari
Jurnal Teknologi Vol 26, No 1 (2026): April 2026
Publisher : Politeknik Negeri Lhokseumawe

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30811/teknologi.v26i1.8683

Body scrub is a skincare product designed to exfoliate dead skin cells. Bidara leaf extract (Ziziphus mauritiana Lamk) was selected for its flavonoid, saponin, and tannin content, which contribute to antibacterial and antioxidant properties, while Epsom salt functions as an exfoliating agent that aids in dead skin removal and enhance skin regeneration. This study involved variations in bidara leaf extract concentration (0–5%) and Epsom salt concentration (10–50%). The formulations were evaluated through physical quality tests, including pH, homogeneity, adhesion, spreadability, organoleptic properties, antibacterial activity, and antioxidant activity. Results indicated that the formulation with 1% bidara leaf extract and 20% Epsom salt yielded the best outcomes, with a pH of 5.2 (compliant with SNI standards for topical preparations), good homogeneity, soft texture, and high panelist acceptance, particularly for sensitive skin. Antibacterial testing revealed the highest activity at 1% extract concentration, with an inhibition zone of 23 mm against Staphylococcus aureus. Antioxidant activity demonstrated free radical inhibition with an IC50 value of 18.94 µg/mL. These findings suggest that body scrub formulations incorporating bidara leaf extract and Epsom salt hold potential as natural, effective, and environmentally friendly skincare products.

Pengaruh Resirkulasi Fraksi Cair Selama Karbonisasi Hidrotermal terhadap Karakteristik Arang Hidro Kulit Tanduk Kopi T. M. Abrar Farhan Yazid; Sariadi Sariadi; Ratna Sari; Raudah Raudah
Jurnal Teknologi Vol 26, No 1 (2026): April 2026
Publisher : Politeknik Negeri Lhokseumawe

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30811/teknologi.v26i1.8513

This research investigates the optimization of hydrochar production from coffee husks through a microwave-assisted Hydrothermal Carbonization (HTC) process, focusing on the influence of reaction time and liquid fraction recirculation. The main objective is to evaluate how these two variables affect the characteristics of the hydrochar and the chemical composition of the liquid fraction. Hydrochar characteristics were analyzed through iodine adsorption tests and acid group density measurements, while the liquid fraction from the optimal cycle was analyzed using High-Performance Liquid Chromatography (HPLC). The results indicated that the optimal operating time was 120 minutes, which produced the highest iodine adsorption capacity of 31,034.39 mg/g. Recirculating the liquid fraction for one cycle significantly increased the iodine adsorption capacity, reaching a peak of 34,309.18 mg/g. This improvement was driven by the acid-catalytic effect of the liquid fraction, which was shown to accumulate acetic acid (0.153% v/v). However, excessive recirculation led to a decrease in hydrochar quality due to pore blocking. In conclusion, the combination of a 120-minute carbonization process with a single recirculation cycle represents the optimal condition for producing high-quality hydrochar, effectively balancing pore development with the catalytic effects of liquid fraction recirculation

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