STUDY OF NICKEL POWDER SYNTHESIS USING CONSTANT CURRENT ELECTROLYSIS METHOD
Nickel powder is one of the nickel derivative products that has various applications such as in high-strength low alloy steel and superalloys, and heterogeneous catalysts in the petrochemical industry. Nickel powder can be synthesized using electrolysis methods, either in acidic or alkaline elect...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/85459 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Nickel powder is one of the nickel derivative products that has various applications
such as in high-strength low alloy steel and superalloys, and heterogeneous
catalysts in the petrochemical industry. Nickel powder can be synthesized using
electrolysis methods, either in acidic or alkaline electrolytes. Electrolysis in alkaline
electrolytes can be an alternative to avoid extensive hydrogen evolution in
electrolysis with low nickel concentrations. Solutions containing NH4+/NH3 were
selected because it can produce high current efficiency and at the same time can
maintain the pH of the electrolyte in a certain range. In this study, a study was
conducted on the synthesis of nickel powder using the electrolysis method in
alkaline electrolytes NH4Cl/NH3 to produce nickel powder with a morphology
approaching spherical.
A series of electrolysis experiments were carried out in two stages. Phase I
experiments were conducted to determine the optimum electrolysis conditions that
produce nickel powder with the smallest size and the significance of the influence
of electrolysis parameters on the average grain size of the nickel powder produced.
The variables varied were the concentration of Ni2+ 2.5 gpl, 5 gpl, and 10 gpl;
current density of 5 A/dm2, 10 A/dm2, and 15 A/dm2; electrolyte temperature of 25,
40, and 60 oC; and electrolysis time of 10, 15, and 20 minutes. Phase II experiments
were conducted to determine the effect of thiourea additive addition on nickel
powder morphology and the effect of nickel concentration on nickel powder
morphology and current efficiency. The electrolyte solution was prepared by
dissolving NiSO4.6H2O, and AgNO3 (0.5% mol of nickel) into 500 mL of
NH4Cl/NH3 buffer solution. The electrolysis experiment was conducted using
nickel anode and 316L stainless steel cathode with a fixed current supply. The
resulting Ni powder was characterized using particle size analysis (PSA) to
determine the average grain size, scanning electron microscope and energydispersive
X-ray spectroscopy (SEM-EDS) to determine the morphology of the
nickel powder formed.
The optimum condition was achieved at an initial Ni2+ concentration of 10 gpl, a
current density of 10 A/dm2, a temperature of 40 oC, and an electrolysis time of 15
minutes, which produced nickel powder having an average size of 13.07 ????m. The
Ni2+ concentration significantly affected the average grain size of nickel powder
(68.21% contribution). Current density, temperature, and time have a significant
effect (9.57%, 4.74%, and 14.29% contributions). The addition of thiourea
produced nickel powder with a spheroidal/spherical-agglomerated blood cell-like
morphology based on ASTM F1877-05. Decreasing the Ni2+ concentration from 12
gpl to 8 gpl caused a decrease in average grain size of nickel powder with the
smallest average size being 7.38 ????m. Increasing the Ni2+ concentration from 6 gpl
to 10 gpl caused an increase in current efficiency with the highest level of 64.59%. |
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