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Abstrak :
ABSTRAK
Senyawa metal alloy (LaNi5) biasa digunakan untuk anode baterai Nickel- Metal Hydride (NiMH) karena mampu mengabsorpsi hidrogen dan dapat beroperasi pada kondisi tekanan dan temperatur ruang. Ketika oksida logam tanah jarang ditambahkan ke dalam anode sel baterai NiMH, tidak hanya charge efficiency dan capacity-retention yang akan meningkat, tetapi juga menjadi rapid charge dan high power cycling. Penelitian dilakukan untuk melihat karakteristik bahan anode LaNi5 setelah penambahan CeO2 dan proses anil. Metode yang digunakan adalah mechanical alloying dengan mencampur serbuk LaNi5 dengan serbuk CeO2 sebanyak 1%, 2%, dan 3% berat di dalam ball mill selama 120 menit pada 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, serbuk dikarakterisasi dengan menggunakan XRD, SEM-EDX, dan BET. Pengujian elektrokimia dilakukan dengan menggunakan Electrochemical Impedance Spectroscopy (EIS) pada frekuensi 5 mHz ? 100 kHz. Penambahan konsentrasi CeO2 diatas 2%, akan memperkecil volume cell dan mengecilkan diameter pori. Konduktivitas tertinggi yang dicapai pada penelitian ini adalah sebesar 1.5332 S/cm dengan diameter pori 0.0082 cc/g. Walaupun penambahan konsentrasi CeO2 ke 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 fasa menjadi fasa NiO dan La2O3 yang menyebabkan konduktivitas menurun dan nilai tahanan semakin besar.

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ABSTRACT
A Lanthanum Nickel compound (LaNi5) is widely used for an anode of Nickel-Metal Hydride (NiMH) battery due to excellence on hydrogen absorption and good capability to be operated at room temperature and pressure condition. Addition of rare earth oxide to the NiMH has increase charge-retention efficiency and capacity also has both rapid charge and high power cycling. The experiment has been conducted to observe the characteristic of the anode LaNi5 materials after addition of CeO2 and annealing. As method of this experiment, mechanical alloying 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 was carried out at varied temperature, 300°C, 600°C and 900°C for 6 hours in argon gas exposure. Then the powders were characterized with XRD, SEM-EDX, and BET. Electrochemical Impedance Spectroscopy (EIS) was used for electrochemical testing on the frequency between 5 mHz - 100 kHz. The results of this experiment show that increasing CeO2 more than 2% concentration lead to decrease the volume of cells and the pore diameter. Furthermore, this is affect the value of ionic conductivity with the highest conductivity is 1.5332 S / cm and 0.0082 cc / g in diameter pore. Although the addition of CeO2 concentration into the anode material increases the resistance, the addition of 1% CeO2 can improve the corrosion resistance of the anode material with Ecorr of -0.6432 V. In conclusions, annealing temperature increasing will changes diffraction phase with the dominant phase NiO and La2O3, thus the conductivity was decreasing and the resistance was increasing.

Abstrak :
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.

Abstrak :
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. ......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.