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"Solid sorbents based on graphite electrode waste and cerium oxide (ceria, CeO2) have been studied with regard to CO2 capture. The acid-base properties of cerium oxide produce a sorbent for the capture of CO2. The aim of the study is to evaluate the performance of CO2 capture using graphite/CeO2 composites at different weights of Ce(NO3)3.6H2O (0.5, 1 and 2 g), namely G0.5, G1 and G2, respectively. Volumetric adsorption studies of CO2 on graphite/CeO2 composites and ceria were conducted at various pressures (P) of 3, 5, 8, 15 and 20 bar, and temperatures (T) of 303, 308, 318 K. Graphite waste before modification (GBM), activated graphite waste (GA), and CeO2 for capturing CO2 were also investigated. By varying the two parameters (P and T), we found that the maximum adsorption capacities of CO2 at 303 K and 20 bar were 0.0713, 0.0316, 0.1574, 0.0987, 0.1137, and 0.0964 kg/kg respectively, for GBM, GA, G0.5, G1, G2 and CeO2. The highest adsorption capacity of CO2 was found in the G0.5 composite. The adsorption performance of CO2 using ceria was almost similar to the G1 composite. We found that CO2 adsorption capacity decreases with an increasing temperature from 303 to 318 K. It was concluded that ceria and composite graphite waste/CeO2 are stable and selective CO2 sorbents. The work allows us to synthesize a new sorbent which can be effectively applied for CO2 capture. The adsorption capacity of CO2 depends significantly on the active site and chemical modifier of the sorbents."

"Meningkatnya permintaan global akan logam tanah jarang (LTJ) dan masalah lingkungan yang terkait dengan penambangan tradisional telah mendorong eksplorasi sumber alternatif. Penelitian ini menyelidiki kelayakan pemulihan serium oksida (CeO2), sebuah LTJ berharga, dari limbah terak timah di Indonesia. Penelitian ini berfokus pada penilaian kelayakan teknis ekstraksi CeO2, evaluasi kelayakan ekonomi proses pemulihan, dan analisis dampak lingkungan, terutama terkait mitigasi radon. Proses ekstraksi skala laboratorium dilakukan, menunjukkan keberhasilan pemulihan CeO2 dengan tingkat ekstraksi maksimum 75,16% (Tarigan 2023) dalam kondisi optimal. Kelayakan ekonomi dinilai menggunakan kerangka analisis biaya-manfaat (CBA), menggabungkan analisis arus kas diskon (DCF). Hasil penelitian menunjukkan bahwa proyek ini layak secara finansial, dengan nilai kini bersih (NPV) positif sebesar Rp 100.536.458.975,00, tingkat pengembalian internal (IRR) sebesar 24%, dan periode pengembalian modal selama 6 tahun. Rasio manfaat-biaya (BCR) sebesar 1,49 semakin mendukung daya tarik ekonomi proyek ini. Penilaian dampak lingkungan mengungkapkan potensi risiko yang terkait dengan paparan radon dari terak timah, tetapi juga mengukur potensi penghematan biaya kesehatan akibat berkurangnya paparan radon. Temuan penelitian ini memiliki implikasi signifikan bagi industri pertambangan Indonesia dan pasar LTJ global, menyoroti potensi terak timah sebagai sumber sekunder LTJ dan menekankan pentingnya mengintegrasikan pertimbangan lingkungan dan kesehatan ke dalam proses industri.

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The increasing global demand for rare earth metals (REMs) and the environmental concerns associated with their traditional mining have led to the exploration of alternative sources. This study investigates the feasibility of recovering cerium oxide (CeO2), a valuable REM, from tin slag waste in Indonesia. The research focuses on assessing the technical feasibility of CeO2 extraction, evaluating the economic viability of the recovery process, and analyzing the environmental impact, particularly concerning radon mitigation. A laboratory-scale extraction process was conducted, demonstrating the successful recovery of CeO2 with a maximum extraction rate of 75.16% (Tarigan 2023) under optimized conditions. The economic viability was assessed using a cost-benefit analysis (CBA) framework, incorporating a discounted cash flow (DCF) analysis. The results indicate that the project is financially viable, with a positive net present value (NPV) of Rp100,536,458,975.00, an internal rate of return (IRR) of 24%, and a payback period of 6 years. The benefit-cost ratio (BCR) of 1.49 further supports the project's economic attractiveness. The environmental impact assessment revealed potential risks associated with radon exposure from tin slag, but also quantified the potential health cost savings resulting from reduced radon exposure. The findings of this study have significant implications for the Indonesian mining industry and the global REM market, highlighting the potential of tin slag as a secondary source of REMs and emphasizing the importance of integrating environmental and health considerations into industrial processes."

"The abundance of graphite waste can be processed into valuable materials; one alternative is by making it into an adsorbent. Graphite-based adsorbent modification can be accomplished by adding magnetite nanoparticles Fe3O4. The addition of magnetite nanoparticles has been reported to improve the adsorption ability of the graphite waste. In this study, we have developed a new carbon dioxide (CO2) adsorbent based on graphite waste modified with magnetite nanoparticle Fe3O4. The Fe3O4 were prepared using an impregnation technique. The graphite/Fe3O4 composites were characterized by scanning electron microscopy with an energy-dispersive X-ray system (SEM-EDX) and Brunauer, Emmett, and Teller (BET). The CO2 adsorption performance was evaluated using an isothermal adsorption method at various temperatures (30, 35, and 45oC) and pressures (3, 5, 8, 15, and 20 bar). This resulted in graphite with different magnetite modification levels, namely non-modified graphite (GNM), a graphite/Fe3O4 20% (w/w) composite (G/Fe3O4 20%), and a graphite/Fe3O4 35% (w/w) (G/Fe3O4 35%), which indicated that the largest adsorption capacity is 10.305 mmol.g-1 at 30oC and 20 bar pressure for the G/Fe3O4 20% composite. This finding further revealed that modifying graphite waste with magnetite nanoparticles Fe3O4 has been proved to increase the capacity for adsorbing CO2 gas."

"ABSTRAKSenyawa metal alloy (LaNi5) biasa digunakan untuk anode baterai Nickel-Metal Hydride (NiMH) karena mampu mengabsorpsi hidrogen dan dapatberoperasi pada kondisi tekanan dan temperatur ruang. Ketika oksida logam tanahjarang ditambahkan ke dalam anode sel baterai NiMH, tidak hanya chargeefficiency dan capacity-retention yang akan meningkat, tetapi juga menjadi rapidcharge dan high power cycling. Penelitian dilakukan untuk melihat karakteristikbahan anode LaNi5 setelah penambahan CeO2 dan proses anil. Metode yangdigunakan adalah mechanical alloying dengan mencampur serbuk LaNi5 denganserbuk CeO2 sebanyak 1%, 2%, dan 3% berat di dalam ball mill selama 120 menitpada putaran 240 rpm. Setelah itu, dilakukan proses anil pada temperatur 300°C,600°C, dan 900°C selama 6 jam di lingkungan gas argon. Kemudian, serbukdikarakterisasi dengan menggunakan XRD, SEM-EDX, dan BET. Pengujianelektrokimia dilakukan dengan menggunakan Electrochemical ImpedanceSpectroscopy (EIS) pada frekuensi 5 mHz ? 100 kHz. Penambahan konsentrasiCeO2 diatas 2%, akan memperkecil volume cell dan mengecilkan diameter pori.Konduktivitas tertinggi yang dicapai pada penelitian ini adalah sebesar 1.5332S/cm dengan diameter pori 0.0082 cc/g. Walaupun penambahan konsentrasi CeO2ke dalam material anode meningkatkan tahanan material, tetapi penambahan 1%CeO2 dapat meningkatkan ketahanan korosi material anode dengan Ecorr sebesar -0.6432 V. Peningkatan temperatur anil menyebabkan perubahan difraksi fasamenjadi fasa NiO dan La2O3 yang menyebabkan konduktivitas menurun dan nilaitahanan semakin besar.

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ABSTRACTA Lanthanum Nickel compound (LaNi5) is widely used for an anode ofNickel-Metal Hydride (NiMH) battery due to excellence on hydrogen absorptionand good capability to be operated at room temperature and pressure condition.Addition of rare earth oxide to the NiMH has increase charge-retention efficiencyand capacity also has both rapid charge and high power cycling. The experimenthas been conducted to observe the characteristic of the anode LaNi5 materialsafter addition of CeO2 and annealing. As method of this experiment, mechanicalalloying was done by mixed LaNi5 and CeO2 powder which had 1%, 2% and 3%weight mass in ball mill for 120 minutes at 240 rpm. After that, the annealing wascarried out at varied temperature, 300°C, 600°C and 900°C for 6 hours in argongas exposure. Then the powders were characterized with XRD, SEM-EDX, andBET. Electrochemical Impedance Spectroscopy (EIS) was used forelectrochemical testing on the frequency between 5 mHz - 100 kHz. The results ofthis experiment show that increasing CeO2 more than 2% concentration lead todecrease the volume of cells and the pore diameter. Furthermore, this is affect thevalue of ionic conductivity with the highest conductivity is 1.5332 S / cm and0.0082 cc / g in diameter pore. Although the addition of CeO2 concentration intothe anode material increases the resistance, the addition of 1% CeO2 can improvethe corrosion resistance of the anode material with Ecorr of -0.6432 V. Inconclusions, annealing temperature increasing will changes diffraction phase withthe dominant phase NiO and La2O3, thus the conductivity was decreasing and theresistance was increasing."

"Indonesia memiliki potensi yang besar dalam memproduksi enzim untuk industri bioteknologi. Sayangnya, dengan sumber daya alam yang melimpah, enzim untuk industri bioteknologi masih diimpor. Perkembangan produksi enzim di Indonesia harus didukung untuk menurunkan tingkat impor enzim. Industri biodiesel merupakan salah satu industri bioteknologi yang memanfaatkan enzim untuk produknya. Lipase adalah enzim utama dan berperan sebagai biokatalis untuk produksi biodiesel. Produksi enzim lipase dari Rhizopus oryzae dikembangkan dengan menggunakan metode fermentasi solid state dan submerged untuk menghasilkan enzim lipase dalam jumlah tinggi dengan limbah pertanian yang dimanfaatkan sebagai substrat untuk produksi lipase. Kondisi optimum untuk produksi lipase ditemukan dengan berbagai waktu, konsentrasi substrat dan konsentrasi induser dari fermentasi. Waktu fermentasi divariasikan menjadi 1, 3, 5, dan 7 hari dengan variasi konsentrasi substrat 0.5, 1, 1.5, 2, and 2.5, substrat yang digunakan adalah dedak gandum. Dan variasi induser adalah 2, 4, 6, dan 8. Ekstraksi akan dilakukan melalui kain muslin, sentrifugasi dan disaring dengan kertas saring. Lipase yang dihasilkan adalah enzim lipase basah dan kering. Titrasi digunakan sebagai uji enzimatik untuk aktivitas lipase. Dengan kondisi optimum dari konsentrasi inducer 6,9, konsentrasi substrat 1,9 dan 3,5 hari periode fermentasi. Aktivitas unit yang dihasilkan dari lipase 62,67 U/ml dan 50 U/ml untuk Submerged Fermentasi dan Solid-State Fermentation masing-masing. Dengan hasil sintesis biodiesel sebesar 38,11 melalui rute non-alkohol.

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Indonesia has huge potentials on producing enzymes for biotechnology industries. Unfortunately, with abundant natural resources, the enzymes for biotechnology industries were still imported. The development of enzyme production in Indonesia should be supported in order to reduce the import level of enzymes. Biodiesel industry is one of the biotechnology industries that utilizes enzyme for their product. Lipase is the main enzyme and act as the biocatalyst for the production of biodiesel. The production of lipase enzyme from Rhizopus oryzae are developed using the Solid State fermentation and Submerged fermentation method in order to yield high amount of lipase enzyme with the agricultural waste is utilize as the substrate for the lipase production.

The optimum condition for the production of lipase is discovered by varying time, substrate concentration and inducer concentration of the fermentation. The time of fermentation is 1, 3, 5, and 7 days with substrate concentration variation of 0.5, 1, 1.5, 2, and 2.5, the substrate used is Wheat Bran. And the variation of the inducer is 2, 4, 6, and 8. The extraction will be done by squeezing the suspension through muslin cloth, centrifugation and filtered by filter paper. Titration is used as the enzymatic assay for the lipase activity. Under optimum condition of 6.9 inducer concentration, 1.9 substrate concentration and 3.5 day of fermentation period. Resulting unit activity of lipase of 62.67 U ml and 50 U ml for Submerged Fermentation and Solid State Fermentation respectively. With biodiesel synthesis yield of 38.11 through non alcohol route. "

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Baterai Lithium-Ion merupakan salah satu media yang efektif untuk meyimpan energi. Baterai ini pun terus diteliti lebih lanjut untuk meningkatkan efisiensi dan kekuatan baterai. Pada saat ini. Anoda LTO merupakan material yang sedang dikembangkan sebagai pengganti anoda grafit. LTO atau litium titanat memiliki beberapa kelebihan seperti sifat zero strain yaitu tidak terjadi perubahan volume atau perubahan volume yang sangat rendah saat charge dan discharge. Sintesis LTO dilakukan dengan menggunakan metode solid state dengan proses mekanokimia dan sintering pada suhu 850^o C selama 6 jam. Kadar Zn yang ditambahkan sebesar 3 wt%, 7wt% dan 11 wt%. dan grafit sebesar 3 wt%. Penambahan doping Zn pada LTO meningkatkan konduktifitas elektronik dan kapasitas spesifik dari baterai. Komposit LTO-Grafit/Zn dilakukan karakterisasi menggunakan XRD dan SEM-EDS. Uji performa baterai dilakukan menggunakan pengujian EIS, CV dan CD. Hasil pengujian EIS didapatkan nilai konduktifitas tertinggi pada komposit LTO-grafit/Zn 3%. Kapasitas spesifik tertinggi hasil uji CV didapatkan LTO-grafit/Zn 11% sebesar 154.3 mAH/g. Kapasitas chage discharge tertinggi didapatkan LTO-grafit/Zn 11% pada current rates 0.5 C sampai 15C

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Lithium-Ion batteries are one of the effective media for storing energy. This battery continues to be investigated further to increase the efficiency and power of the battery. At this time. LTO anode is a material that is being developed as a substitute for graphite anode. LTO or lithium titanate has several advantages, such as the zero strain characteristic, that is, there is no change in volume or volume changes that are very low during charge and discharge. The LTO synthesis was carried out using a solid state method with a mechanochemical process and sintering at a temperature of 850^o C for 6 hours. Zn content added is 3 wt%, 7wt% and 11 wt%. and graphite at 3 wt%. Addition of Zn doping to LTO increases the electronic conductivity and specific capacity of the battery. LTO-Graphite/Zn composites were characterized using XRD and SEM-EDS. Battery performance test is carried out using EIS, CV and CD testing. The EIS test results obtained the highest conductivity value on 3% LTO-graphite / Zn composites. The highest specific capacity CV test results obtained LTO-graphite/Zn 11% of 154.3 mAH / g. The highest chage discharge capacity is obtained by LTO-graphite/Zn 11% in the current rates of 0.5 C to 15C.

 

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"Studi komputasi adalah studi yang ditentukan dari perhitungan struktur elektronik berupa material, seperti Fe, Ni, dan Co. Struktur kristal berupa material Fe, Ni, dan Co yang dikomputasikan adalah Fe3Ni2 dan Fe6Ni3Co. Struktur Fe6Ni3Co yang didapatkan dengan mengganti Ni pada Fe3Ni2 dengan Co. Studi ini telah dilakukan dengan menggunakan Density Functional Theory (DFT) melalui metode atomistik, optimasi geometri, dan analisis konstanta elastis. Metode atomistik menunjukkan bahwa struktur kristal yang berbentuk tetragonal dan kelompok ruang P4/mmm. Optimasi geometri dilakukan dengan menggunakan energy cutoff sebesar 300 eV terhadap struktur kristal yang berbentuk tetragonal dengan parameter kisi (a, b, c) adalah (10, 10, 1) dalam satuan Å. Analisis konstanta elastis menghasilkan besaran Cij terdiri dari i adalah pola regangan secara masing-masing sebanyak 6 dan j adalah amplitudo sebanyak 6. Cij berguna untuk menentukan konstanta elastis beserta jenisnya, antara lain modulus elastisitas, modulus bulk, modulus geser, kompresibilitas, dan rasio poisson serta berguna untuk menentukan kondisi stabilitas dari Fe3Ni2 dan Fe6Ni3Co.

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Computational studies are studies that are determined from the calculation of the electronic structure of materials, such as Fe, Ni, and Co. The crystal structures in the form of Fe, Ni, and Co materials which are computed are Fe3Ni2 and Fe6Ni3Co. The Fe6Ni3Co structure obtained by replacing Ni in Fe3Ni2 with Co. This study was carried out using Density Functional Theory (DFT) through atomistic method, geometry optimization, and elastic constant analysis. Atomistic method shows that the crystal structure is tetragonal and the space group is P4/mmm. Geometry optimization was carried out using a cutoff energy of 300 eV for a tetragonal crystal structure with lattice parameters (a, b, c) of (10, 10, 1) in Å units. Analysis of the elastic constant produces the amount Cij consist of i is the pattern of strain as many as 6 each and j is the amplitude of 6. Cij is useful for determine the elastic constants and their types, including modulus of elasticity, bulk modulus, shear modulus, compressibility, and poisson’s ratio as well useful to determine the stability conditions of Fe3Ni2 and Fe6Ni3Co."

"Bekatul merupakan salah satu produk sampingan sebanyak 10% dari seluruh hasil penggilingan padi. Bekatul mengandung sekitar 12-18,5% minyak bekatul yang menjadi sumber senyawa-senyawa bioaktif yang bermanfaat. Kandungan-kandungan bioaktif dan asam lemak di dalam minyak bekatul dapat dimanfaatkan pada bidang kesehatan. Peningkatan hasil rendemen minyak bekatul dapat dilakukan dengan melakukan proses fermentasi padat menggunakan kapang Aspergillus terreus. Faktor yang dapat mempengaruhi proses fermentasi bekatul diantaranya adalah rasio massa penambahan sumber nutrisi dan jenis sumber nitrogen tambahan. Penelitian ini memvariasikan rasio massa penambahan karbon dan nitrogen sebagai sumber nutrisi sebesar 25:1, 30:1, 35:1, 40:1, dan 45:1. Kedua faktor tersebut dapat mempengaruhi hasil metabolisme kapang dalam peningkatan asam lemak. Bekatul yang telah difermentasi, akan diekstraksi menggunakan metode sonikasi secara bertingkat dengan pelarut n-heksana dan etanol. Analisis kandungan yang terdapat di dalam minyak bekatul akan dilakukan dengan menggunakan instrumen Liquid Chromatography-Mass Spectrometry (LC-MS). Hasil penelitian ini menunjukkan bahwa jenis nitrogen tambahan yang cocok untuk sumber nutrisi Aspergillus terreus pada fermentasi padat dengan medium bekatul adalah jenis nitrogen organik (pepton) dengan rendemen minyak bekatul sebesar 10,46% dan rasio massa penambahan sumber nutrisi karbon dan nitrogen adalah rasio 45:1 dengan rendemen minyak bekatul sebesar 10,40%. Proses ekstraksi dari sampel hasil fermentasi padat bekatul dengan kapang Aspergillus terreus untuk menghasilkan minyak bekatul terbanyak adalah dengan menggunakan pelarut polar (etanol). Senyawa antioksidan yang teridentifikasi pada ekstrak minyak bekatul yaitu asam linoleat dan asam a-linolenat

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Rice bran is one of the by-products, accounting for about 10% of the total rice milling yield. Rice bran contains approximately 12-18.5% rice bran oil, which serves as a source of beneficial bioactive compounds. The bioactive contents and fatty acids in rice bran oil is beneficial for health. To increase the rice bran oil yield, solid-state fermentation processes can be conducted using Aspergillus terreus. Factors affecting the rice bran fermentation process include the mass ratio of nutrient sources addition in fermentation medium and the addition of nitrogen sources. This study varied the mass ratio of carbon and nitrogen addition as a nutrient source in fermentation medium at 25:1, 30:1, 35:1, 40:1, and 45:1. Both factors can affect fungal metabolism and the increase in fatty acids during rice bran fermentation. After that, the result of rice bran fermentation process will undergo an extraction process using a multi-step sonication method with n-hexane and ethanol as solvents. The content of rice bran oil will be analyze using Liquid Chromatography-Mass Spectrometry (LC-MS). The results of this study indicate that the suitable type of additional nitrogen for Aspergillus terreus nutrition in solid-state fermentation with rice bran medium is organic nitrogen (peptone), yielding rice bran oil at 10,46%. The optimal mass ratio of added carbon and nitrogen nutrients is 45:1, resulting in a rice bran oil yield of 10.40%. The extraction process of rice bran oil from the solid-state fermentation sample with Aspergillus terreus is most effective using a polar solvent (ethanol). The identified antioxidant compounds in the rice bran oil extract include linoleic acid and a-linolenic acid."