Sihotang, Jolo Putra (2026) Pengaruh Asam Sitrat 0,25-0,75 g/L Sebagai Aditif Alternatif Eugenol Pada Elektrorefining Timah Terhadap Efisiensi Arus, Stabilitas Sn2+, Morfologi Endapan, dan Kemurnian Timah. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Timah merupakan salah satu komoditas penting bagi Indonesia, dan kualitas akhirnya salah satunya ditentukan oleh proses electrorefining.Proses electrorefining timah berbasis elektrolit sulfat (SnSO4–H2SO4–H2SiF6) bertujuan menghasilkan timah dengan kemurnian tinggi, namun hasilnya sering dibatasi morfologi endapan katoda yang kasar/dendritik. Pada PT Timah, aditif gelatin–eugenol digunakan untuk mengendalikan pertumbuhan dendrit, tetapi eugenol dinilai kurang ekonomis karena harganya relatif mahal sehingga diperlukan aditif alternatif yang lebih
murah. Asam sitrat dipilih sebagai penggantinya karena mampu menurunkan aktivitas ion logam bebas sehingga laju deposisi lebih terkendali dan kristal tumbuh lebih merata. Penelitian ini bertujuan menganalisis pengaruh penambahan asam sitrat dengan variasi konsentrasi 0,25; 0,50; dan 0,75 g/L terhadap efisiensi arus, kestabilan ion Sn2+, morfologi endapan, dan kemurnian timah, serta menentukan konsentrasi paling efektif. Larutan dibuat mengacu pada kondisi eksisting PT Timah (Sn2+ ±21,93 g/L; H2SO4 ±158,25 g/L; H2SiF6 ±44,82 g/L; pH ≤ 1) dengan gelatin–eugenol 0,25 g/L sebagai pembanding, diuji selama dua siklus. Efisiensi arus dihitung berbasis Hukum Faraday; morfologi dianalisis melalui SEM-EDX dan ImageJ; kemurnian dibaca dengan Spark ARL; data divalidasi menggunakan One-Way ANOVA dan uji Tukey HSD. Hasil menunjukkan variasi aditif berpengaruh signifikan terhadap efisiensi arus dan penambahan massa katoda. Asam sitrat 0,50 g/L memberikan hasil terbaik dengan efisiensi arus tertinggi 73,71%, penambahan massa katoda paling konsisten 85,75 gram, penurunan ion Sn2+ paling stabil, serta pengotor Pb dan Cu terendah. Sebaliknya, konsentrasi 0,75 g/L menurunkan efisiensi arus menjadi 54,53% dan memperbanyak dendrit. Seluruh variasi menghasilkan kemurnian di atas 99,99% sehingga memenuhi standar Banka 4N. Dengan demikian, asam sitrat berpotensi menjadi aditif alternatif yang lebih ekonomis dibandingkan eugenol tanpa penurunan
kemurnian timah yang signifikan, dengan konsentrasi 0,50 g/L sebagai kondisi optimum dalam penelitian ini.
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Tin is one of Indonesia’s important commodities, and its final quality is largely determined by the electrorefining process. The tin electrorefining process based on a sulfate electrolyte (SnSO4–H2SO4–H2SiF6) aims to produce high-purity tin, yet its results are often limited by coarse or dendritic cathode deposit morphology. At PT Timah, a gelatin–eugenol additive is used to control dendrite growth; however, eugenol is considered less economical due to its
relatively high price, creating a need for a cheaper alternative additive. Citric acid was chosen as its replacement because it can lower the activity of free metal ions, allowing a more controlled deposition rate and more uniform crystal growth. This study aims to analyze the effect of citric acid addition at varying concentrations of 0.25, 0.50, and 0.75 g/L on current efficiency, Sn2+
ion stability, deposit morphology, and tin purity, as well as to determine the most effective concentration. The electrolyte was prepared based on PT Timah’s existing conditions (Sn2+ ±21.93g/L;H2SO4 ±158.25g/L;H2SiF6 ±44.82g/L;pH≤1),with gelatin–eugenol0.25g/L as a comparison, and tested over two cycles. Current efficiency was calculated based on Faraday’s Law; morphology was analyzed through SEM-EDX and ImageJ; purity was measured using
Spark ARL; and the data were validated using One-Way ANOVA and the Tukey HSD test. The results show that the additive variation had a significant effect on current efficiency and cathode mass gain. Citric acid at 0.50 g/L gave the best results, with the highest current efficiency of 73.71%, the most consistent cathode mass gain of 85.75 grams, the most stable decrease in Sn2+ ion concentration, and the lowest Pb and Cu impurities. Conversely, a concentration of 0.75 g/L lowered the current efficiency to 54.53% and increased dendrite formation. All variations produced tin purity above 99.99%, thus meeting the Banka 4Nstandard. These results
suggest that citric acid could serve as a cheaper additive alternative to eugenol while maintaining relatively stable tin purity, with 0.50 g/L giving the best result within the tested range.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Asam sitrat, Electrorefining Timah, Efisiensi arus, Morfologi endapan, Kemurnian timah, Citric acid, Tin electrorefining, Current efficiency, Deposit morphology, Tin purity. |
| Subjects: | Q Science > QD Chemistry > QD553 Electrochemistry. Electrolysis T Technology > TN Mining engineering. Metallurgy > TN688 Hydrometallurgy |
| Divisions: | Faculty of Industrial Technology > Material & Metallurgical Engineering > 28201-(S1) Undergraduate Thesis |
| Depositing User: | Jolo Putra Sihotang |
| Date Deposited: | 28 Jul 2026 06:51 |
| Last Modified: | 28 Jul 2026 06:51 |
| URI: | http://repository.its.ac.id/id/eprint/138487 |
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