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Abstrak :
ABSTRAK
Pemberian doping Ce pada CaMnO3 akan membentuk sampel CexCa1-xMnO3. Sampel ini dibuat dengan metode zat padat dari bahan dasar CeO2, CaO dan MnO2 berdasarkan perhitungan stoikiometri untuk nilai x = 0,1 ; x = 0,5 dan x = 0,9. Preparasi sampel dimulai dengan mencampur semua bahan dasar dengan menggunakan ball mill selama 1 jam. Proses dilanjutkan dengan pemanasan menggunakan furnace dengan suhu 800 C selama 8 jam, kemudian proses ball mill kembali selama 1 jam, lalu sampel dipanaskan lagi pada suhu 1100 C selama 10 jam, kemudian sampel dikompaksi untuk uji XRD dan SEM. Hasil karakterisasi sampel dengan XRD direfinement menggunakan program GSAS. Berdasarkan analisis tersebut diperoleh informasi mengenai hal-hal sebagai berikut; untuk x = 0,1 ; x = 0,5 dan x = 0,9 pada sampel CexCa1-xMnO3 memiliki struktur kristal orthorombic; space group Pnma 62 , dan peningkatan komposisi Ce tidak menyebabkan perubahan space group dan struktur kristal. Meningkatnya komposisi Ce menyebabkan penurunan nilai parameter kisi dan volume unit sel.

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ABSTRACT
ce doping addition into CaMnO3 will form new material CexCa1 xMnO3. This material are made with solid method using raw materials such as CeO2, CaO and MnO2 based on stoichiometric analysis for x 0,1 x 0,5 and x 0,9. To get to this material we conduct some steps that consist of raw material mixing in a ball mill for 1 hour, 800 C heating for 8 hours, back to ball mill process for 1 hour, continued with 1100 C heating process for 10 hours, and pressed in a coin shape for XRD and SEM testing purpose. XRD test results will be refined using GSAS. Based on that analysis, we gained some information. The results showed that for any x, the CexCa1 xMnO3 crystal structure were orthorhombic with Pnma 62 space group. The increase of Ce did not influence the space group and crystal structure, but it caused the decrease of lattice parameter and unit cell volume.

Abstrak :
Penelitian Penelitian kali ini berfokus pada pengaruh unsur logam tanah jarang Cerium Ce terhadap fasa intermetalik yang terbentuk pada saat proses solidifikasi, unsur Cerium yang ditambahkan sebesar 0.1; 0.3 dan 0.5 wt pada matriks Al-5Zn-0.5Cu.Dengan penambahan unsur Cerium Ce semakin banyak, sesuai dengan urutannya, maka anoda korban akan semakin turun efisiensinya. Penambahan unsur Cerium pada proses mempengaruhi Icorr sebagai efisiensi dari anoda korban, yaitu 6.2 x 10-5 , 5 x 10-5 dan 4.57 x 10-5 Volt. Selain itu penambahan Cerium semakin banyak akan membuat ukuran butir semakin kecil, yaitu 167, 133, dan 118 ?m. Fasa intermetalik yang terbentuk dapat dilihat pada grafik grafik hasil pengujian DSC Differential Scanning Calometry dimana grafik tersebut menjelaskan terdapatnya fasa Al11Ce3 Al8Cu4 Ce Al dan Al2Zn2Ce yang dapat mempengaruhi efisiensi anoda korban.

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The research is focused on the effect of Rare Earth Cerium Ce element on the microstructure morphology during the solidification proccess. The concentration of Cerium Ce addition are 0.1 0.3 0.5 wt on Al 5Zn 0.5Cu matrix and corelated to the characteristic and mechanism of corrosion proccess in Al 5Zn 0.5Cu sacrificial anode. In this research, Aluminium alloy will get the optimum addition if it seen from the microstructure at 0.5 wt addition, but it reverse to the corrosion mechanism on the sacrificial anode. The more and more addition of Cerium, the morphology of microstructure is finer and equixed, but the corrosion rate of the sacrificial anode decrease. The effect of Differential Scanning Calorimetry DSC on the microstructure can be seen on the morphology of the presipitate. With the addition of the element Cerium on the sacrificial anode Al 5Zn 0.5Cu produce phase formed are Al2Zn2Ce , Al8Cu4Ce which may affect the efficiency of the sacrificial anode.

Abstrak :
The anodizing process was conducted in an Al7xxx aluminum alloy with silicon carbide which yielded a non-uniform thickness of anodic film with cavities, micro-pores and micro-cracks within it. This phenomenon occurred due to the presence of Silicon Carbide (SiC) particles within the Aluminum Matrix Composite (AMC), which impedes the initiation and growth of the protective anodic alumina oxide layer. Therefore, cerium sealing has been considered as the cheapest and simplest post treatment to remedy the poor anodic alumina oxide film in order to further enhance the corrosion resistance in aggressive circumstances. This paper examined the protection effect of an integrated layer which was composed of an anodized oxide layer and cerium deposits on an Al7075/SiC composite. Electrochemical Impedance Spectroscopy (EIS) was used to examine the corrosion protection effect and the corrosion behavior of an integrated layer in 3.5% sodium chloride (NaCl) solution at room temperature. In this study, anodizing of Al7075/SiC was carried out in a sulfuric acid H2SO4 solution at current density values of 15, 20, and 25 mA/cm2, respectively at room temperature, 0oC and -25oC for 30 minutes. Subsequently, cerium sealing was conducted in a cerium choloride plus hydrogen peroxide (CeCl3.6H2O + H2O2) solution at room temperature and pH 9 for 30 minutes. The best protection effect was found for Al7075/SiC, anodized at 0oC. Field Emission-Scanning Electron Microscope (FE-SEM) examination confirmed that the enhancement of corrosion resistance was due to the cerium deposit formed on the entire surface of the oxide anodized layer.

Abstrak :
Proses anodisasi pada aluminium menghasilkan struktur fenomenal berupa oksida logam yang terkenal dengan istilah Anodic Aluminum Oxide (AAO). AAO sangat diperlukan untuk meningkatkan daya adhesi pada proses pelapisan selanjutnya baik pada aluminium dan paduannya maupun komposit aluminium. Hal tersebut terjadi akibat adanya ikatan saling kunci antara lapisan oksida hasil anodisasi (AAO) dengan pelapis berikutnya. Morfologi pori pada AAO dapat dengan mudah dimodifikasi melalui perubahan parameter anodisasi. Namun, sayangnya penelitian-penelitian sebelumnya belum menyediakan informasi apapun mengenai pengontrolan diameter pori. Sedangkan seperti yang kita ketahui bahwa perbedaan aplikasi yang diinginkan membutuhkan diameter pori yang berbeda pula. Oleh karena itu guna mendapatkan diameter pori dengan ukuran tertentu maka pemilihan parameter proses anodisasi yang tepat sangatlah penting. Untuk memenuhi kebutuhan tersebut, dalam penelitian ini akan dihasilkan persamaan empiris yang dapat memprediksi ukuran diameter dan densitas pori AAO yang terbentuk hasil anodisasi dengan berbagai parameter tertentu agar dapat digunakan dalam aplikasi yang sesuai. Tujuan utama penelitian ini adalah pengembangan persamaan empiris yang menggambarkan hubungan konsentrasi oksalat, tegangan dan waktu anodisasi terhadap diameter pori. Namun penelitian ini juga menganalisis mekanisme pembentukan, karakteristik, dan ketahanan korosi lapisan terintegrasi pada Al7075/SiC. Serta menganalisis pengaruh konsentrasi, temperatur, dan resistivitas larutan elektrolit, dan tegangan anodisasi terhadap diameter dan densitas pori AAO pada aluminium foil. Proses anodisasi Al7075/SiC dilakukan dalam larutan asam sulfat 16% H2SO4 dengan rapat arus 15, 20, 25 mA/cm2 pada 25, 0, -25oC selama 30 menit. Selanjutnya dilakukan proses sealing dalam larutan CeCl3.6H2O + H2O2 pada temperatur ruang dengan pH 9 selama 30 menit. Proses anodisasi pada aluminium foil dilakukan dalam larutan 3 M H2SO4 + 0,5 M; 0,7 M; dan 0,9 M H2C2O4, dan 0,3; 0,5; 0,7 M H2C2O4 selama 40-60 menit. Proses anodisasi dilakukan pada tegangan konstan 35, 40, dan 45 V untuk larutan asam oksalat dan 15 V untuk larutan campuran. Pengamatan dan evaluasi morfologi lapisan pori hasil anodisasi dilakukan menggunakan alat FE-SEM (Field Emission Scanning Electron Microscope), ketahanan korosi material diinvestigasi menggunakan pengujian polarisasi dan EIS, sedangkan analisa kualitatif terhadap morfologi pori (diameter dan densitas) pada AAO menggunakan perangkat lunak ImagePro. Pengembangan persamaan empiris menggunakan metode derajat terkecil dan permukaan respon. Proses terintegrasi yang diaplikasikan pada komposit Al7075/SiC pada temperatur anodisasi 0 oC menghasilkan terbentuknya deposit bulat kaya cerium dengan diameter 64 nm ( 3 nm) yang menutupi seluruh permukaan lapisan oksida dan rongga secara efektif. Proteksi terintegrasi anodisasi dan pelapisan cerium meningkatkan ketahanan korosi hingga 4 order perbesaran dibandingkan tanpa perlindungan akibat terjadinya ikatan saling kunci antara kedua lapisan tersebut. Peningkatan konsentrasi larutan elektrolit asam oksalat, temperatur, tegangan dan waktu celup anodisasi dalam larutan 0,3; 0,5; dan 0,7 M mengakibatkan peningkatan diameter pori permukaan pada AAO. Sedangkan, penambahan asam sulfat dalam asam oksalat menghasilkan pori dengan morfologi diameter pori yang jauh lebih halus dan densitas pori yang jauh lebih besar. Secara umum, densitas pori hanya tergantung pada diameter pori hasil anodisasi, dimana peningkatan diameter pori menghasilkan densitas pori yang semakin menurun. Persamaan empiris hubungan antara tiga faktor anodisasi (konsentrasi asam oksalat, tegangan, dan waktu anodisasi) dengan diameter pori hasil dari penelitian ini adalah : Dp = 0,140625 MVt + 0,33125 MV ? 523542 Mt + 35,64583 M ? 0,04006 Vt + 0,685764 V +1,792431 t ? 42,5053 (derajat terkecil) dan Dp = 33,3 ? 236,3 M ? 1,453 V + 0,3942 t + 7,60 MV (metode derajat satu) ......Anodizing process in aluminum produces a phenomenal structure in form of metal oxide which is known as Anodic Aluminum Oxide (AAO). AAOis a very useful morfology to improve the adhesion properties for further coating in aluminum alloy and composite aluminum. This phenomenon is related to the presence of interlock bond between AAO and the next layer. The AAO morphology can be modified simply by varying anodizing parameters. Therefore, selecting appropriate parameters plays an important role in order to obtain the desired pore size. Unfortunately, the preliminary studies did not provide any information on controlling the pore size and density (through increasing/decreasing the concentration of sulfuric acids, voltage, and duration of anodizing to determine pore diameter and density). For that purpose, in this research some empirical models were built to predict the pore size produced by anodizing process in various parameters. The grand design if this research aims to develop empirical equations which predict the relationship between oxalic acid concentration, anodizing voltage and time to the pore diameter. However, this research also aims to analyze the formation mechanism and of the integrated layer on Al7075/SiC, as well as the enhancement of corrosion resistance resulted from the integrated layer. Moreover, the influence of various anodizing parameters, i.e. resistivity, concentration, temperature, and type of electrolyte on pore characteristics of AAOis also conducted in this study. Anodizing process of Al7075/SiC was conducted in 16% H2SO4 solution in current densities 15, 20, 25 mA/cm2 at25, 0, -25oC for 30 minutes. Subsequently, cerium sealing process was carried out in CeCl3.6H2O+H2O2 at room temperature and pH 9 for 30 minutes. Anodizing of aluminum foil were carried out in 0,3; 0,5; 0,7M H2C2O4 solution and a mixture solution of 0.5M, 0.7M, and 0.9M H2C2O4 and 3M H2SO4 for 40-60 minutes. Anodizing processes were performed under potentiostatic conditions with constant potentials of 35, 40, and 45V for oxalic solution and 15 V for a mixture solution. Morphology of AAO layer observations were performed using field emission scanning electron microscopy (FE-SEM) FEI Inspect F50, while the corrosion resistance of materials were investigated by means of polarization and EIS, and qualitative analysis of pore characteristics (pore diameters and densities) accomplised by ImagePro software. The development of empirical equations using least square and response surface methods Integrated protection by conducting anodization at 0oC prior to cerium sealing in Al7075/SiC leads tothe formation of cerium spherical deposit in the diameter of 64 nm ( 3nm) which effectively covered most of the surface of oxide film as well as cavity. Moreover, this integrated protection enhanced four orders magnification of corrosion resistance than that of bare composite due to interlock bonding between the layers. The increasing of electrolyte concentration and temperature, as well as voltage and duration of anodizing in 0.3; 0.5; dan 0.7 M oxalic acid leads to the increasing of pore diameter in AAO surface. While, the addition of sulfuric acid in oxalic acid provides much smaller pore diameters and higher pore densities at lower voltages than single electrolyte of oxalic acid. In general, pore density is only dependent on pore diameter, which decreases with the increases of pore diameter. The empirical equations built in this research are : Dp = 0,140625 MVt + 0,33125 MV ? 523542 Mt + 35,64583 M ? 0,04006 Vt + 0,685764 V +1,792431 t ? 42,5053 (least square) and Dp = 33,3 ? 236,3 M ? 1,453 V + 0,3942 t + 7,60 MV (first order model)

Abstrak :
Pada studi ini, tiga persentase massa dari perak ditambahkan ke nanokomposit oksida nikel dan oksida cerium dengan tiga rasio molar berbeda dari kedua oksida. Nanokomposit telah disintesis menggunakan metode ultrasonic-assisted. Lima teknik karakterisasi digunakan untuk mengevaluasi bahan, X-ray diffraction (XRD), X-ray fluorescence (XRF), UV-Vis diffuse reflectance, Raman Spectroscopy, dan Adsorpsi/Desorpsi Nitrogen. Dua sumber radiasi, cahaya tampak UV digunakan untuk mendegradasi metilen biru sebagai objek polutan untuk aktivitas fotokatalitik. Katalis nanokomposit dengan persentase massa Ag sebanyak 20 wt.% menunjukkan aktivitas fotokatalitik tertinggi. Dalam proses degradasi metilen biru dengan katalis nanokomposit elektron scavenger merupakan spesies aktif utama pada proses degradasi ......In this study, three different weight percentages of silver were added to the nickel oxide and cerium oxide nanocomposites with three different molar ratios of the two oxides. These nanocomposites were synthesized using ultrasonic-assisted techniques. Five characterization techniques were carried out to evaluate the materials, X-ray diffraction (XRD), X-ray fluorescence (XRF), UV-Vis diffuse reflectance, Raman Spectroscopy, and Nitrogen Adsorption/Desorption. Two radiation sources, visible and ultraviolet, were used to degrade methylene blue as a pollutant object for photocatalytic activities. The nanocomposite catalyst with twenty weight percentages of silver showed the highest photocatalytic activity. In the degradation process of methylene blue with these nanocomposite catalyst that electrons becomes the main active species in the process.

Abstrak :
Aluminum alloy is one of the materials found in many applications, especially for electrical conductor materials. AlZrCe alloy reinforced by Al2O3 nanoparticles with Mg addition is proposed as one of the alternative materials to replace Aluminum Conductor Steel Reinforced (ACSR) as an aluminum conductor. Aluminum alloy Al-0.12%Zr-0.15%Ce as a master alloy was added with various weights of magnesium (Mg) from 2 to 5 wt% and was reinforced with 1.2% volume fraction of Al2O3 nanoparticles with particle sizes less than 80 nm. The molten metal matrix was blended with the reinforcement by a stirrer with a rotational speed of 500 rpm at a temperature of 750oC in an argon gas environment and casted by gravity casting. The objective of this research was to investigate the effect of magnesium on microstructural changes, electrical conductivity, and mechanical properties, such as tensile strength and hardness of the composites. The microstructure observation results showed that the greater the Mg content in composites up to 5%, the smaller the grain size of the composite matrix, wherein the grain size of the composite without Mg is 28 ?m, while the grain size of the composite with Mg of 2%, 3% and 5% are 27 ?m, 17 ?m and 9 ?m respectively. Similarly, tensile strength and hardness increased with increasing levels of Mg to 5% where the addition of 5% Mg, the tensile strength increased from 106 to 204 MPa and hardness increased from 30 to 68 BHN. In contrast, the electrical conductivity sharply decreased, due to the addition of Mg in the composite with a gradient of reduction, to 2.74% IACS (International Annealed Copper Standard) for every increasing 1% Mg. In which the electrical conductivity of the composite without Mg is 55.1% IACS and after adding 5 wt% Mg, it decreased to 41.3% IACS.

Abstrak :
Terak Feronikel (TFN) merupakan produk sampingan yang dihasilkan dari proses peleburan nikel dengan metode pirometalurgi. Potensi TFN yang dimanfaatkan saat ini yaitu untuk konstruksi jalan, bahan campuran dalam industri semen dan aplikasi lain seperti pupuk, geopolimer dan teknik hidraulik. Namun demikian, proses keberlanjutan pemanfaatan TFN diperlukan karena produksi TFN meningkat sejalan dengan peningkatan permintaan nikel. Apalagi TFN merupakan bahan berbahaya dan beracun yang mampu mencemari tanah dan air tanah bila disimpan dalam waktu lama. Oleh karena itu, upaya peningkatan nilai tambah TFN perlu dilakukan untuk menekan akumulasi produk TFN. TFN mengandung sekitar 30% silika, 20% magnesium, 12% besi, 1-2% aluminium, dan serta nikel (Ni), kobalt (Co), kromium (Cr), dan unsur logam tanah jarang (LTJ) . Berdasarkan kandungan yang ada di dalam TFN tersebut, proses ekstraksi unsur berharga menarik untuk dilakukan guna meningkatkan nilai tambah TFN. Tujuan umum dari penelitian ini adalah memanfaatkan terak feronikel sebagai upaya peningkatan nilai tambah dengan mengekstraksi logam berharga dan logam tanah jarang terutama untuk lanthanum dan cerium dengan proses piro-hidrometalurgi. Tujuan khusus yang ingin dicapai dalam penelitian ini adalah untuk mengetahui analisis karakteristik TFN, studi pengaruh proses redusksi, studi pengaruh kalsinasi dan pelindian NaOH , studi pengaruh proses fusi alkali, pelindian air dan pelindian HCl, serta studi pengembangan proses ekstraksi logam berharga dari TFN. Penelitian dilakukan dengan beberapa tahapan, bahan baku berupa TFN dikeringkan dalam oven, kemudian dilakukan reduksi ukuran menggunakan crusher dan disc mill. Bahan baku TFN dengan ukuran -200 mesh dicampur aditif Na2CO3 menggunakan mixer. Proses reduksi dilakukan dengan penambahan karbon dari batubara (BB) dan arang cangkang kelapa sawit (CKS) ditambah dengan zat aditif Na2CO3. Reduksi dilakukan dengan variasi temperature, rasio batubara atau arang cangkang kelapa sawit dan rasio Na2CO3. Proses kalsinasi dilakukan pada temperature 700°C selama 1 jam dilanjutkan dengan proses pelindian NaOH dengan variasi konsentrasi NaOH, temperatur dan waktu pelindian. Pelindian dengan NaOH ini silakukan untuk memisahkan silica dengan magnesium. Silika yang terpisah dijadikan produk samping sebagai silica presipitat. Proses fusi alkali dengan penambahan aditif dilakukan dengan variasi temperatur. Pemanggangan dengan penambahan aditif diharapkan dapat mengikat silika yang merupakan unsur paling melimpah di TFN. Hasil pemanggangan fusi alkali kemudian dilindi dengan air. Residu yang dihasilkan dari pelindian air ini, kemudian dilindi menggunakan HCl. Sedangkan filtrat hasil pelindian air diendapkan dengan asam HCl encer secara titrasi untuk mendapatkan endapan silica presipitat. Analisis dilakukan dengan menggunakan X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM) dan Inductively Coupled Plasma OES (ICP-OES). Hasil penelitian ini menunjukkan bahwa proses reduksi menghasilkan fasa dominan yang terbentuk yaitu sodium magnesiosilikat. Proses kalsinasi dilanjutkan NaOH menghasilkan persentase perolehan magnesium tertinggi adalah 73,10%, yang dihasilkan dari proses pelindian pada temperatur 100°C selama 240 menit dengan menggunakan NaOH 10M. Proses fusi alkali dengan penambahan zat aditif dapat mengikat silika yang merupakan unsur utama di TFN. Pelindian dengan air dari hasil fusi alkali dapat melarutkan silika dalam bentuk senyawa sodium silikat. Silika yang terlarut selanjutnya diendapkan dengan proses presipitasi untuk mendapatkan silika presipitat. Sedangkan residu hasil pelindian yang sudah mempunyai konsentrasi magnesium dan LTJ (lantanum dan cerium) dilakukan pelindian asam. Pelindian asam menggunakan larutan HCl dilakukan untuk mengekstrak kandungan magnesium dan LTJ (lanthanum dan cerium) yang terlarut dalam larutan filtrat. Hasil optimum ekstraksi magnesium dari pelindian asam menggunakan larutan HCl adalah 82,67 %. Kondisi optimum dicapai pada temperatur pelindian 80 °C, waktu pelindian 30 menit, konsentrasi HCl 2M, kecepatan pengadukan 300 rpm dan rasio S/L 1:10. Pada kondisi tersebut, studi kinetika magnesium menunjukkan bahwa proses pelindian magnesium pada TFN dipengaruhi oleh difusi. Kondisi pelindian optimum ekstraksi cerium dan lanthanum dicapai pada temperatur pelindian 80 °C, waktu pelindian 30 menit dan konsentrasi HCl 8 M dengan persentase ekstraksi optimum 92,63 % dan 86,82 %. Hasil studi kinetika menunjukkan nilai energi aktivasi ≤ 40 kJ/mol, sehingga difusi melalui lapisan abu akan mengontrol proses pelindian tersebut. Nilai energi aktivasi membuktikan bahwa pelindian cerium dan lanthanum dikendalikan oleh difusi melalui lapisan abu dari partikel padat dibandingkan dengan reaksi di permukaan partikel. ......Ferronickel slag (FNS) is a by-product which was resulted from a nickel smelting process with a pyro-metallurgical method. The potential of TFN currently being utilized is for road construction, mixed materials in the cement industry, and other applications such as fertilizers, geopolymers, and hydraulic engineering. However, the sustainability process for FNS utilization is required due to increasing FNS production which is in line with increasing nickel demand. Moreover, FNS is a hazardous and toxic material that capable to pollute the soil and groundwater when it has been stored for long period. Therefore, attempts to upgrade the added value of FNS needs to be carried out to inhibit FNS accumulation. FNS contains 30% of silica, 20% of magnesium, 12% of iron, 1-2% of aluminum, and a small amount of nickel (Ni), cobalt (Co), chromium (Cr), and rare earth elements (REE). Based on the FNS content, the extraction process of valuable content is attractive to perform to upgrade the added value of FNS. The general objective of this research is to utilize the ferronickel slag as an effort to upgrade the added value by extracting the rare earth metals, especially for lanthanum and cerium, using pyro-hydrometallurgy processes. The specific objectives to be achieved in this study were to determine the analysis of FNS characteristics, study the effect of the reduction process, study the effect of calcination and NaOH leaching, study the effect of the alkaline fusion process, water leaching, and HCl leaching, and study the development of the precious metal extraction process from FNS. The research carried out in several stages, the raw material in the form of FNS was dried in an oven, then size reduction was carried out using a crusher and disc mill. FNS raw material with a size of -200 mesh is mixed with Na2CO3 additive using a mixer. The reduction process is carried out by adding carbon from coal and palm kernel shell charcoal plus the additive Na2CO3. The reduction is done by varying the temperature, the ratio of coal or oil palm charcoal, and the ratio of Na2CO3. The calcination process was carried out at a temperature of 700 ° C for 1 hour followed by a NaOH leaching process with variations in the concentration of NaOH, temperature, and leaching time. This NaOH leaching is carried out to separate the silica from magnesium. The separated silica is used as a byproduct as silica precipitates. Alkali fusion process with the addition of additives is carried out with temperature variations. Roasting with the addition of additives is expected to bind Silica which is the most abundant element in the FNS. The roasting results are then leached with water. The residue resulting from the water leaching is then leached using HCl. Meanwhile, the filtrate from the water leaching was precipitated with dilute HCl acid by titration to obtain precipitated silica precipitates. Also, leaching is carried out using alkali NaOH. Analyzes were performed using X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and Induced Coupled Plasma OES (ICP-OES). The results of this study indicate that the reduction process produces the dominant phase formed, namely sodium magnesiosilicate. The calcination process followed by NaOH resulted in the highest percentage of magnesium recovery, which was 73.10%, which was produced from the leaching process at 100 ° C for 240 minutes using 10M NaOH.The results of this study indicate that the alkali fusion process with the addition of additives can bind Silica as a major impurity element. Leaching with water can dissolve Silica in the form of sodium silicate which was resulted from alkali fusion. Dissolved silica can be used further as a material for Silica Precipitate, which can be obtained by precipitation. Meanwhile, the leaching residue is concentrated on valuable metals (magnesium) including rare earth elements (lanthanum, and cerium). Acid leaching using HCl solution was performed to calculate the upgrading content of dissolved magnesium, lanthanum, and cerium in the leached solution. The optimum result of magnesium extraction from acid leaching using HCl solution is 82.67%. The optimum condition reaches at leaching temperature of 80 °C, leaching time of 30 minutes, HCl concentration of 2 M, stirring speed of 300 rpm, and S/L ratio of 1/10. In that condition, Kinetics studies of magnesium show that the Magnesium leaching process of FNS was influenced by diffusion. The optimum leaching condition of cerium and lanthanum extractions reach at leaching temperature of 80 ⁰C, leaching time of 30 minutes, and HCl concentration of 8 M with optimum extraction percentage of 92.63% and 86, 82% respectively. The results of the kinetics study showed that the activation energy value was ≤ 40 kJ/mol, thus the diffusion through the ash layer would control the leaching process. The activation energy values prove that the release of cerium and lanthanum is controlled by diffusion through the ash layer of the solid particles compared to the reaction at the particle surface.

Abstrak :
Unsur transisi merupakan unsur yang terdapat pada golongan 3-12. Unsur transisi ini memiliki bilangan oksidasi yang bervariasi. Dengan adanya hal tersebut menyebabkan unsur transisi memiliki kemampuan sebagai katalis yang baik dan memiliki kemampuan penyerapan zat pada permukaan yang baik. Selain unsur transisi juga terdapat Logam Tanah Jarang LTJ . Unsur LTJ terdapat pada deret lanthanida dan juga Yttrium Y dan Scandium Sc .Terak timah merupakan limbah slag dari proses peleburan timah. Terak timah yang digunakan yaitu terak timah I. Terak timah dapat dimanfaatkan untuk mendapatkan mineral berharga seperti Tantalum Pentaoksida Ta2O5 dan Niobium Pentaoksida Nb2O5 dan LTJ. Proses diawali dengan pemanggangan, pencelupan pada larutan NaOH 0.5M. Kadar Ta2O5 dan Nb2O5 mengalami penurunan setelah proses pemanggangan. Setelah itu dilakukann proses pelindian menggunakan larutan pelindi HCl dengan konsentrasi 4M, 6M dan 8M. Kadar dari mineral pengikut mengalami penurunan tetapi kadar dari Ta2O5, Nb2O5, Ce2O3 serta La2O3 juga mengalami penurunan.

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Transition elements or transition metal is an element contained in group 3 to 12 on the table periodic. The transition elements have two or more oxidation numbers. Given this causes the transition elements have the ability as a good catalyst, and has the ability absorption on the surface of the well. On the otherhand there is also a Rare Earth Elements REE . Rare Earth Elements are in series lanthanida and Yttrium Y and Scandium Sc . Tin slag is a waste from the lead smelting process. Tin slag has a valuable mineral that can be used as Tantalum Pentoxide Ta2O5 , Niobium Pentoxide Nb2O5 and Rare Earth Element REE . In this research, leaching is a process used to increase grade of Ta2O, Nb2O5 and REE Cerium Ce and Lanthanum La in tin slag. This research to found effect of roasting on 900 C, effect of using sodium hydroxide NaOH as a quenching agent and effect of variation chloride acid HCl concentration as leaching agent. The roasting result was obtained highest mass distribution on 100 and use to leaching process. But grade of Ta2O5, Nb2O5 and REE after roasting process was decreased. The result of leaching in variation concentration 4M, 6M, and 8M grade of gangue minerals was decreased but Ta2O5, Nb2O5 and REE also decreased.

Abstrak :
Pada penelitian ini sintesis nanopartikel CeO2, CuO dan nanokomposit CeO2-CuO berhasil dilakukan menggunakan ekstrak rumput mutiara Oldenlandia corymbosa sebagai sumber basa -OH dan capping agent. Nanopartikel dan nanokomposit yang terbentuk selanjutnya dikarakterisasi menggunakan instrumentasi UV-Vis DRS, FTIR, Raman, XRD, PSA, TEM, dan SEM-EDX. Karakterisasi dengan XRD membuktikan bahwa nanopartikel CuO-NPs memiliki struktur kristal monoklinik, CeO2-NPs memiliki struktur kristal FCC, sedangkan nanokomposit CeO2-CuO memiliki puncak khas gabungan kristal keduanya. Berdasarkan karakterisasi TEM, diketahui bahwa nanokomposit CeO2-CuO memiliki ukuran 10-15 nm dengan bentuk spheric. Karakterisasi dengan UV-Vis DRS membuktikan band gap nanokomposit CeO2-CuO sebesar 2,6 eV. Studi aktivitas fotokatalitik nanokomposit CeO2-CuO diamati dengan degradasi metilen biru menggunakan radiasi sinar tampak. Persentase degradasi untuk nanopartikel CeO2, CuO dan nanokomposit CeO2-CuO masing-masing adalah 18,49; 35,87; dan 59,83.

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In this study, the synthesis of CeO2 NPs, CuO NPs and CeO2 CuO nanocomposites was successfully performed using rumput mutiara Oldenlandia corymbosa extract as a base source OH and capping agent. The synthesized nanoparticles and nanocomposites were characterized with UV Vis DRS, FTIR, Raman, XRD, PSA, TEM and SEM EDX instrumentation. Characterization with XRD proves that CuO NPs nanoparticles have a monoclinic crystal structure, CeO2 NPs have an FCC crystal structure, whereas CeO2 CuO nanocomposites have their own distinctive combined crystal peak. Based on TEM characterization, it is known that the CeO2 CuO nanocomposites have a size of 10 15 nm with speric shape. Characterization with UV Vis DRS has proven that the CeO2 CuO nanocomposites have band gap energy of 2.6 eV. The study of photocatalytic activity of CeO2 CuO nanocomposites were observed with methylene blue degradation using visible light radiation. Percentages of degradation for CeO2, CuO and CeO2 CuO nanocomposites were 18.49 , 35.87 and 59.83, respectively.

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.