Optimasi Teknik Electrowinning pada Ekstraksi Nikel dan Kobalt dari Larutan Sulfat

Lestari, Diah Trisna Rahayu (2024) Optimasi Teknik Electrowinning pada Ekstraksi Nikel dan Kobalt dari Larutan Sulfat. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Salah satu sumber nikel yaitu bijih nikel laterit. Dalam bijih laterit kobalt sering hadir sebagai logam yang terkandung dalam nikel. Electrowinning merupakan proses elektrometalurgi yang yang digunakan untuk mengekstraksi nikel dan kobalt dari larutan bijihnya. Pada penelitian ini, electrowinning nikel dan kobalt dilakukan menggunakan larutan NiSO4 0,1 M dan CoSO4 0,1 M guna menghindari ion-ion pengotor serta dapat memberikan hasil yang lebih akurat. Beberapa parameter uji meliputi potensial (overpotential), pH larutan, serta durasi electrowinning diatur secara presisi (fine tunning) untuk mendapatkan deposit nikel maupun kobalt dengan kualitas yang baik. Deposit nikel dikarakterisasi menggunakan X-Ray Diffraction (XRD) dan Fourier Transform Infra Red (FTIR). Produk yang dihasilkan berupa bubuk hitam dan bubuk hijau masing-masing pada tegangan 2,8 V dan 3,8 V. Semakin lama durasi, maka pH larutan elektrolit menjadi asam yang membuat reaksi evousi hidrogen sehingga kualitas deposit nikel menjadi buruk. Selain itu, pH larutan elektrolit mempengaruhi deposit nikel yang didapat. Pada pH 3 tidak terdapat deposit nikel melainkan hanya gas H2 yang ditandai bercak lingkaran hitam dan lapisan putih di katoda. Sebaliknya, pada pH 4 dan 5 didapatkan deposit nikel berupa bubuk hitam (durasi 15 dan 30 menit) dan berubah menjadi bubuk hijau pada durasi 45 menit. Hasil karakterisasi XRD dan FTIR menunjukkan bahwa produk nikel bubuk hitam memiliki puncak karakteristik Ni dan kristalinitas yang tinggi sedangkan produk nikel bubuk hijau memiliki kristalinitas yang rendah dah merupakan senyawa β-Ni(OH)2 amorf. Pada electrowinning kobalt didapatkan deposit berupa Co pada tegangan 2,4 V pH 5. Kemudian, pH larutan menjadi lebih asam (3-4) seiring bertambahnya tegangan. pH asam ini membuat evolusi hidrogen pada katoda sehingga deposit yang didapat berkualitas buruk.
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One source of nickel is laterite nickel ore. In laterite ores cobalt is often present as a metal contained in nickel. Electrowinning is one electrometallurgical process to extract nickel and cobalt from its ore solution. In this research, electrowinning of nickel and cobalt was carried
out using 0,1 M NiSO4 and CoSO4 solutions to avoid other impurity ions and to provide more accurate results. Several test parameters including overpotential, pH solution, and
electrowinning duration are precisely regulated (fine tunning) to obtain good nickel and cobalt deposits. Nickel deposits were characterized using X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) and Fourier Transform Infra Red (FTIR). The result obtained were that there were two types of nickel deposits, namely black powder nickel and green powder nickel at voltage 2,8 V and 3,8 V respectively. The loger duration, the more acidic the electrolyte solution became, leading to hydrogen evolution reaction which degraded the quality of the nickel deposite. Additionally, the pH of electrolyte solution affects the nickel deposits obtained. At pH 3 there are no nickel deposits but only a H2 gas as indicated by black spots and a white layer on the cathode. On the other hand, at pH 4 and 5, nickel deposits were found in the form of black powder (duration of 15 and 30 minutes) and changed to green powder at duration of 45 minutes. The results of XRD and FTIR characterization show that the black powdered nickel produkct has a characteristic peak of Ni and high crystallinity, while the green powdered nickel product has low crystallinity and is an amorphous β-Ni(OH)2 compound. In cobalt electrowinning, a deposit in the form of Co obtained at voltage of 2,4 V pH 5. Then, the pH of the solution become more acidic (3 – 4) as the voltage increases. The acidic pH causes the evolution of hydrogen at the cathode so that the deposit obtained is of poor quality.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	electrowinning, kobalt, nikel, potensial, pH
Subjects:	Q Science Q Science > QD Chemistry Q Science > QD Chemistry > QD553 Electrochemistry. Electrolysis
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Chemistry > 47201-(S1) Undergraduate Thesis
Depositing User:	Diah Trisna Rahayu Lestari
Date Deposited:	14 Aug 2024 09:03
Last Modified:	14 Aug 2024 09:03
URI:	http://repository.its.ac.id/id/eprint/114833

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