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"Studi pada pengujian ini dilakukan untuk menginvestigasi pengaruh konsentrasi dari inhibitor ekstrak daun pegagan (Centella asiatica) pada baja 3% krom di lingkungan air formasi. Ketahanan korosi dan kemampuan inhibisi korosi diuji dengan metode polarisasi elektrokimia, electrochemical impedance spectroscopy, dan uji rendam di dalam larutan air formasi. Senyawa-senyawa yang menghambat korosi dari ektrak inhibitor ini diidentifikasi melalui pengujian FTIR dan karakteristik produk korosi yang terbentuk diinvestigasi dengan Scanning Electron Microscopy (SEM). Konsentrasi inhibitor yang digunakan dalam pengujian ini adalah 0 ppm, 100 ppm, 250 ppm, 500 ppm, dan 1000 ppm. Hasil yang didapatkan mengindikasikan ekstrak daun Centella asiatica dapat digunakan untuk menghambat korosi pada baja 3% krom di lingkungan air formasi.

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The present study was carried out to investigate the effect of concentration of Centella asiatica leaves extract inhibitor for 3% Cr steel in produce water environment. The corrosion resistance and corrosion inhibition ability was tested by electrochemical polarization measurements, electrochemical impedance spectroscopy, and immersion tests in a produced water solution. The compounds that inhibit corrosion in this inhibitor extract is identified by FTIR test and the characteristic of corrosion scales are investigated by Scanning Electron Microscopy (SEM). The concentration of inhibitor extract which was used in this study is 0 ppm, 100 ppm, 250 ppm, 500 ppm, and 1000 ppm. The results indicate that Centella asiatica extract can be used to inhibit corrosion for 3% Cr steel in produced water environment.

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"Kemampuan ekstrak daun pegagan (Centella asiatica) sebagai inhibitor ramah lingkungan untuk baja J55 di lingkungan air formasi diinvestigasi dengan pengujian polarisasi tafel, weight loss, dan Electrochemical Impedance Spectroscopy (EIS). Senyawa fenolik dan antioksidan yang berperan untuk menginhibisi korosi diinvestigasi melalui pengujian FTIR. Selain itu, lapisan yang terbentuk di permukaan logam juga dipelajari dengan menggunakan Scanning Electron Micsroscope. Variabel yang digunakan adalah konsentrasi inhibitor, yaitu 0 ppm, 100 ppm, 250 ppm, 500 ppm, dan 1000 ppm. Ekstrak daun pegagan yang mempunyai gugus fenolik merupakan inhibitor jenis campuran, dan dominan anodik. Efisiensi inhibisi paling tinggi didapatkan dengan konsentrasi 250 ppm. Inhibitor ekstrak daun pegagan dapat digunakan sebagai alternatif inhibitor ramah lingkungan untuk baja J55 pada lingkungan air formasi.

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This study aimed to investigate the ability of Centella asiatica leaves extract as an environment friendly inhibitor for J55 steel in produce water environment. Corrosion inhibition ability of this extract was tested using tafel polarization, weight loss and electrochemical impedance spectroscopy methods. FTIR test was used to investigate phenolic and antioxidant compound that plays an important role to inhibit corrosion. In addition, formed layer on the metal surface was also studied using scanning electron microscope. In this study the concentration of Centella asiatica extract used was 0 ppm, 100 ppm, 250 ppm, 500 ppm, and 1000 ppm. It can be concluded that Centella asiatica extract could be used as an alternative and environmental friendly inhibitor for J55 steel in produce water environment."

"[ABSTRAKKorosi pada tubing baja karbon merupakan masalah serius bagi eksplorasi dan produksi minyak dan gas. Perilaku korosi baja paduan rendah 3%Cr (3Cr) dan baja karbon J55 dalam lingkungan air formasi diinvesitigasi dengan menggunakan pengujian tafel polarisasi potensiodinamik, electrochemical impedance spectroscopy (EIS) dan pengamatan metalografi. Komposisi dan morfologi dari produk korosi kedua baja dianalisa dengan energy dispersive spectroscopy (EDS) dan scanning electron microscopy (SEM). Hasil pengujian memperlihatkan adanya korosi lokal pada baja J55 dengan struktur mikro pro-eutektoit ferit dan perlit, dan tidak terlihat pada baja 3Cr dengan struktur mikro martensit temper dikarenakan terbentuknya lapisan produk korosi kaya-Cr yang padat, kontinyu dan melekat dengan baik ke permukaan baja. Lapisan produk korosi yang bercelah dan tidak kontinyu pada baja J55 menyediakan jalan bagi ion-ion agresif untuk masuk dan menimbulkan korosi lokal pada permukaan baja.ABSTRACTCorrosion of carbon steel tubings is a serious problem for oil and gas wet exploration and production. Corrosion behaviour of low bearing 3%Cr (3Cr) alloy steel and J55 carbon steel in produced water were investigated by polarisation potentiodynamic tafel, electrochemical impedance spectroscopy (EIS) and metallography observation. The composition and morphology of corrosion products were analyzed by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The results show that there was localized corrosion was observed in J55 carbon steel with pro-eutectoid ferrite and pearlite microstructure, which did not exist in 3Cr steel with tempered martensite microstructure due to formation of a dense, continuous and adherent Cr-rich scale on surface steel. Many pits in the less adherent corrosion scale of J55 carbon steel could build up ion-diffusion channels which would degrade the protective capabilities of the product films and aggravate localized corrosion.;Corrosion of carbon steel tubings is a serious problem for oil and gas wet exploration and production. Corrosion behaviour of low bearing 3%Cr (3Cr) alloy steel and J55 carbon steel in produced water were investigated by polarisation potentiodynamic tafel, electrochemical impedance spectroscopy (EIS) and metallography observation. The composition and morphology of corrosion products were analyzed by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The results show that there was localized corrosion was observed in J55 carbon steel with pro-eutectoid ferrite and pearlite microstructure, which did not exist in 3Cr steel with tempered martensite microstructure due to formation of a dense, continuous and adherent Cr-rich scale on surface steel. Many pits in the less adherent corrosion scale of J55 carbon steel could build up ion-diffusion channels which would degrade the protective capabilities of the product films and aggravate localized corrosion.;Corrosion of carbon steel tubings is a serious problem for oil and gas wet exploration and production. Corrosion behaviour of low bearing 3%Cr (3Cr) alloy steel and J55 carbon steel in produced water were investigated by polarisation potentiodynamic tafel, electrochemical impedance spectroscopy (EIS) and metallography observation. The composition and morphology of corrosion products were analyzed by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The results show that there was localized corrosion was observed in J55 carbon steel with pro-eutectoid ferrite and pearlite microstructure, which did not exist in 3Cr steel with tempered martensite microstructure due to formation of a dense, continuous and adherent Cr-rich scale on surface steel. Many pits in the less adherent corrosion scale of J55 carbon steel could build up ion-diffusion channels which would degrade the protective capabilities of the product films and aggravate localized corrosion., Corrosion of carbon steel tubings is a serious problem for oil and gas wet exploration and production. Corrosion behaviour of low bearing 3%Cr (3Cr) alloy steel and J55 carbon steel in produced water were investigated by polarisation potentiodynamic tafel, electrochemical impedance spectroscopy (EIS) and metallography observation. The composition and morphology of corrosion products were analyzed by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The results show that there was localized corrosion was observed in J55 carbon steel with pro-eutectoid ferrite and pearlite microstructure, which did not exist in 3Cr steel with tempered martensite microstructure due to formation of a dense, continuous and adherent Cr-rich scale on surface steel. Many pits in the less adherent corrosion scale of J55 carbon steel could build up ion-diffusion channels which would degrade the protective capabilities of the product films and aggravate localized corrosion.]"

"Dalam limbah elektronik, bagian yang paling banyak dan tinggi kandungan logam berharga terdapat pada bagian printed circuit board PCB , antara lain emas dan tembaga. Penelitian ini bertujuan untuk melihat pengaruh penambahan zat H2O2 dan MnO2 sebagai oksidator terhadap nilai recovery logam emas dan tembaga menggunakan media asam klorida pada printed circuit board. Ukuran PCB direduksi menjadi 1,0 ndash; 2,0 cm2. Pelindian dilakukan menggunakan aquaregia sebagai larutan kontrol untuk mengetahui kadar awal logam emas dan tembaga, kemudian analisa AAS. Setelah itu dilakukan pelindian dengan menggunakan media asam klorida dengan variasi penambahan oksidator H2O2 serta MnO2 sebanyak 3 dan 5 dan kemudian dilakukan analisa AAS. Sehingga akan didapatkan nilai recovery dari logam emas dan tembaga dari penelitian ini. Nilai recovery logam emas dan tembaga paling tinggi ada pada larutan HCl 0,5 M dengan penambahan oksidator H2O2 sebanyak 5 , nilai recovery yang didapat yaitu 59 untuk logam emas dan tembaga.

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In electronic waste, part containing most and high content of valuable metals is located in printed circuit board PCB part, such as gold and cooper. This research aim to observe the effect of adding H2O2 and MnO2 as oxidizing agent on the value of gold and cooper recovery using chloric acid leaching media on printed circuit board. The size of PCB is reduced to 1.0 ndash 2.0 cm2. The leaching is done using aquaregia as lixiviant control in order to determine the gold and cooper content, and later be analyzed by AAS. Afterwards, leaching is done using chloric acid media with the variation addition of H2O2 and MnO2 as oxidizing agent with the amount of 3 and 5, and later be analyzed by AAS. The result of the research is the value of gold and cooper recovery. The highest gold and cooper metals recovery contained on HCl 0.5 M lixiviant with the addition of H2O2 5, with the value of recovery 59 for gold and cooper metals."

"Dengan kemajuan teknologi, maka pemakaian produk elektronik akan terus meningkat. Sehingga peluang untuk mengolah limbah elektronik sangatlah besar untuk era yang sekarang sedang berjalan. Salah satu limbah elektronik yang menjadi target proses pengolahan limbah adalah, Printed Circuit Board. Limbah PCB direduksi ukurannya menjadi sekitar 1,0 cm x 1,0 cm, dan kemudian limbah PCB yang telah dilakukan reduksi ukuran kemudian di leaching dengan menggunakan larutan asam klorida, asam klorida ditambahkan hydrogen peroxide, serta larutan aqua regia, masing ndash; masing dengan konsentrasi 4M dan 6M.Hasil dari proses leaching tersebut kemudian dilakukan pengujian secara visual dan dengan Optical Microscope untuk mengetahui transformasi fisik setelah proses leaching dan juga pengujian dengan Atomic Absorption Spectrophotometery untuk mendapatkan nilai recovery logam emas dan tembaga. Hasil dari proses leaching menunjukkan recovery logam emas dan tembaga dapat mencapai sebesar 64.50 dan 90.24.

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With the advancement of technology, the usage of electronic products will continue to increase. And because of this, it is an immense opportunity to recycle electronic wastes. One of the known types of electronic waste to be targeted for the recycling process of electronic wastes is, the Printed Circuit Board. In which, PCB waste is reduced in size about 1.0 cm x 1.0 cm, and after it is reduced in size, it is then leached by using hydrochloric acid solution, hydrochloric acid mixed with hydrogen peroxide, and aqua regia solution, each with concentration of 4M and 6M.

The result of the leaching process is then tested visually and by using Optical Microscope to understand the physical transformation after the leaching process. And then it is tested by using the Atomic Absorption Spectrophotometery in order to get the recovery value of gold and copper metals. The results of the leaching process shows that recovery of gold and copper metals could reach up to 64.50 and 90.24."

"Limbah elektronik memiliki nilai ekonomis yang cukup baik karena mengandung logam yang berharga,sehingga dibutuhkan pengembangan teknologi untuk pengolahannya,salah satu teknologinya yaitu dengan metode pelindian dan stripping.Limbah elektronik yang berasal dari PCB printed circuit board dilindi dengan menggunakan larutan HCl 0,5 M dan H2O2 0,4 M,lalu ditambahkan dengan karbon aktif,yang kemudian di stripping dengan NaOH dengan konsentrasi 0,5 M, 1,0 M, 1,5M , dan 2,0 M. Kemudian hasil percobaan diuji dengan menggunakan metode AAS Atomic absorption spectroscopy dan metode SEM Scanning Electron Microscopy -EDX energy dispersive X-ray.Hasil penelitian menunjukkan terdapat hubungan antara konsentrasi NaOH dengan recovery emas, yaitu dengan meningkatkan konsentrasi NaOH maka nilai recovery dari emas akan ikut meningkat,dengan menggunakan larutaan NaOH 2,0 M,recovery yang didapat sebesar 9 ,yang disebabkan karena kurang hadirnya ligan dalam pembentukan ion emas yang stabil dalam larutan.

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Electronic waste has good economic value because it contains valuable metal, so it needs technology development for its processing, one of the technology for processing electronic waste is by leaching and stripping method. Electronic waste from PCB printed circuit board is leached by using HCl 0,5 M and H2O2 0,4 M solution, then added with activated carbon, stripping process using NaOH solution with concentration of 0,5 M, 1,0 M, 1,5M, and 2,0 M was conducted in this research. The experimental results were tested by AAS atomic absorption spectroscopy method and SEM Scanning Electron Microscopy EDX energy dispersive X ray.

The results showed that there was a correlation between NaOH concentration with gold recovery.By increasing NaOH concentration, the recovery value of gold would increase too.The best recovery of gold was used 2,0 M NaOH,that resulted 9 recovery of gold.it cause by the lack of presence of ligands in the formation of stable gold ions in solution."

"Terak akhir timah merupakan produk samping hasil peleburan terak-1 yang mengandung jenis oksida serupa dengan semen Portland OPC , yaitu SiO2, CaO, Al2O3, dan Fe2O3 sehingga terdapat potensi untuk diutilisiasi sebagai beton. Penelitian ini bertujuan untuk mengetahui karakteristik OPC dan semen campuran terak-2 terhadap korosivitas material semen dan baja berdasarkan metode Electrochemical Impedance Spectroscopy EIS dan Cyclic Polarization. Penelitian ini menggunakan terak akhir timah Bangka yang dicampurkan dengan OPC masing-masing sebanyak 10 , 20 , dan 30 . Beton yang dicetak memiliki rasio 0.5 w/c dengan proses curing selama 28 hari lalu direndam di dalam larutan NaCl 3.5 selama 6 hari. Hasil analisa menunjukkan baja di dalam campuran 20 terak memiliki ketahanan korosi yang paling kompetitif dan stabil terhadap beton OPC murni, diikuti campuran 10 , dan 30 terak secara berturut-turut.

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Final tin slag is a byproduct of slag 1 smelting process that contains similar oxides compared to Portland cement OPC , which is SiO2, CaO, Al2O3, and Fe2O3 so that there is potential to be initiated as a concrete. The aim of this research is to know the characteristics of OPC and cement of slag 2 mixture against corrosivity of cement and steel material based on Electrochemical Impedance Spectroscopy EIS and Cyclic Polarization methods. This study uses final tin slag from Bangka mixed with OPC each of 10 , 20 , and 30 . The molded concrete has a ratio of 0.5 w c with 28 days curing process then immersed in a 3.5 NaCl solution for 6 days. The analysis shows that the steel in 20 slag 2 concrete mixture has the most competitive and stable corrosion resistance compared to original OPC concrete, followed by 10 , and 30 slag mixture respectively."

"ABSTRAKAnoda korban Al-Zn-In adalah paduan yang paling umum digunakan untuk memproteksi struktur terutama baja di lingkungan air laut dari korosi. Akan tetapi, paduan ini memiliki potensial yang sangat negatif sehingga bisa memicu terjadinya hydrogen embrittlement atau stress corrosion cracking (SCC) pada struktur baja. Dengan menurunkan potensial yang diaplikasikan pada struktur dalam range sekitar -0.80V sampai -0.85V vs SCE akan menurunkan jumlah hidrogen bebas yang bisa memicu terjadinya SCC. Dua macam unsur paduan ditambahkan untuk mengurangi keelektronegativan potensial dari paduan Al-5Zn. Unsur-unsur tersebut adalah tembaga dan silikon dengan variasi komposisi 0.5wt% dan 1wt%. Penelitian bertujuan untuk memilih unsur paduan yang lebih baik yang mendekati kriteria anoda korban aluminium bertegangan rendah yang dibutuhkan. Electrochemical Impedance Spectroscoy (EIS), Cyclic Polarization, dan pengukuran potensial sistem digunakan untuk mengkarakterisasi paduan baru dari anoda korban aluminium bertegangan rendah. Berdasarkan pengujian-pengujian diatas, paduan Al-5Zn-1Cu adalah paduan yang paling efektif untuk memproteksi baja dengan nilai potensial baja setelah di coupling dengan paduan tersebut adalah -0.81V vs SCE dan nilai Rctnya terkecil dari semua paduan yaitu 1,12 kΩ yang menandakan transfer muatan antar logam dan elektrolit lebih mudah terjadi.

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ABSTRACT

Al-Zn-In sacrificial anode is commonly used to protect structure especially steel in seawater from general corrosion or galvanic corrosion. However, this alloy is too electronegative and can induce hydrogen embrittlement or SCC in steel. Decreasing the applied potential to the structure in suitable range around -0.80 V until -0.85V vs SCE can reduce the amount of free hydrogen that can make SCC. Two kind of alloying element are added to reduce the electronegative potential of Al-5Zn alloy. Those elements are copper and silicon with the amount of addition is 0.5wt% and 1wt%. This research was trying to select the best alloying that close to the determine requirements. Electrochemical impedance spectroscopy (EIS), cyclic polarization, and system potential measurements were used to characterize new alloy aluminium sacrificial anode low voltage. Among those various alloy tested, Al-5Zn-1Cu is the most proper result of the new low voltage aluminium sacrificial anode because the Rct was smallest (1,12kΩ) and the potential of steel after coupling with Al-5Zn-1Cu was -0.811V vs SCE. These potential is the closest one with the require potential for low voltage aluminium sacrificial anode."

" ABSTRAK Paduan anoda korban konvensional untuk lingkungan operasi bawah laut adalah paduan Aluminium - Zinc - Indium Al-Zn-In . Anoda korban konvensional ini menawarkan efisiensi yang tinggi, namun pada baja berkekuatan tinggi, paduan anoda korban ini akan menimbulkan fenomena hydrogen embrittlement. Tujuan dari penelitian ini adalah untuk mengembangkan alternative paduan anoda korban aluminium untuk menghasilkan potensial proteksi ldquo;low voltage rdquo; sehingga dapat mencegah timbulnya hydrogen embrittlement pada baja berkekuatan tinggi. Unsur Si ditambahkan untuk menaikan potensial proteksi dari paduan anoda koban aluminium ini. Berdasarkan hasil polarisasi, penambahan unsur Si akan menurunkan ketahanan korosi dari paduan anoda korban aluminium dengan meningkatkan rapat arus dari paduan anoda korban ini. Pengujian metalografi juga dilakukan untuk membandingkan mikrostruktur sebelum dan setelah dicelupkan pada larutan NaCl 3.5 . Kandungan unsur Si yang tinggi akan meningkatkan laju korosi-nya. Korosi terjadi pada ?-phase Zn dan disekitar fasa eutektik Si. Unsur Zn dapat membentuk second phase yang berfungsi untuk merusak lapisan pasif dari aluminium, oleh sebab itu maka akan meningkatkan efisiensi arus dan laju korosi dari paduan anoda korban aluminium. Dengan demikian, paduan anoda korban Aluminium - Zinc - Silikon Al-Zn-Si dapat menjadi kandidat sebagai alternatif paduan anoda korban low voltage.

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ABSTRACT Conventional Aluminum Anode for seawater service is Aluminum Zinc Indium Alloy Al Zn In . Although it offers high efficiency and high potential protection, in high strength steel it can also increases possibility for hydrogen embrittlement and stress corrosion cracking. Purpose of this research is to develop new Aluminum alloy to produce a low voltage Aluminum Anode to prevent the hydrogen embrittlement in high strength steel. Silicon is added as an alloying element to reduces the potential protection of Aluminum anode. Based on polarization result, silicone addition could reduce corrosion resistance of aluminum by reducing corrosion current density of Aluminum alloy. Optical Metallography is also conducted to compare microstructure before and after immersion in NaCl 3.5 . Higher silicon content showed more severe in corrosion rate. Corrosion occurs on phase Zinc and around the eutectic Si phase. Zinc can make a second phase which can breakdown alumina passive film, thus increasing anode efficiency and corrosion rate of aluminium anode alloy. Therefore, sacrificial anode Aluminium Zinc Silicone Al Zn Si alloy could be new low voltage sacrificial anode candidates"