Putri, Zahra Andini (2026) Pengambangan Green Inhibitor Berbeasis Kulit Bawang Merah (ALLIUM CEPA L.) Untuk Mitigasi Korosi Baja Api 5L Grade B Dalam Lingkungan NACL. Diploma thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Baja API 5L Grade B merupakan material utama yang banyak digunakan dalam sistem perpipaan industri petrokimia, perminyakan, dan kelautan. Pada lingkungan laut atau pesisir dengan media netral seperti larutan NaCl 3.5% material ini rentan mengalami degradasi akibat proses korosi. Penelitian ini bertujuan untuk mengkaji potensi dari ekstrak kulit bawang merah (Allium cepa L.) sebagai green corrosion inhibitor dalam memperlambat laju kosoi baja API 5L Grade B pada media korosif 3.5% NaCl. Ekstrak diperoleh melalui metode maserasi menggunakan etanol 70% dan analisis GC-MS mengidentifikasi tiga senyawa aktif dominan, yaitu Benzoic acid, 3,4-dihydroxy- (14,08%), Ethyl α-D-glucopyranoside (12,45%), dan 3(2H)-furanone, 2-hexyl-5-methyl- (11,95%). Analisis DFT menunjukkan bahwa Benzoic acid, 3,4-dihydroxy- memiliki karakteristik inhibitor terbaik dengan nilai energi gap (ΔE) terkecil sebesar 1,33 eV. Pengujian wightloss menunjukukkan efisiensi inhibisi meningkat seiring penambahan konsentrasi inhibitor, dengan efisiensi tertinggi sebesar 91% pada konsentrasi 400 mg/L pada waktu perendaman 20 hari. Pengujian elektrokimia PDP mengategorikan inhibitor sebagai mixed-type inhibitor, didukung oleh nilai energi bebas adsorpsi Gibbs (ΔG°ads) sebesar -24kJ/mol yang mengindikasikan mekanisme terjadinya perlindungan secara katodik dan anodik. Hasil EIS menunjukkan kenaikan nilai resistansi polarisasi (Rp) dari 44,514 Ω (blanko) menjadi 1227,8 Ω pada 400 mg/L. Model adsorpsi isoterm langmuir terbukti paling sesuai dengan nilai R² sebesar 0,9984 mengindikasikan terjadinya mekanisme adsorpsi monolayer. Analisis AFM menunjukkan penurusan kekasaran permukaan yang signifikan setelah penambahan 400 mg/L inhibitor, dengan nilai Sa menurun dari 77,1 nm menjadi 33,0 nm dan Sq dari 93,3 nm menjadi 48,0 nm. Hasil penelitian ini menunjukkan bahawa ekstrak kulit bawang merah berpotensi sebagai solusi pengendali korosi yang ramah lingkungan untuk aplikasi pipa maritim.
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API 5L Grade B steel is a primary material widely used in piping system for the petrochemical, oil and gas, and marine industries. In marine or coastal environments with neutral media such as 3.5% NaCl solutions, this material is susceptible to degradation due to corrosion processes. This study aims to investigate the potential of shallot (red onion) peel extract (Allium cepa.L) as a green corrosion inhibitor for retarding the corrosion rate of API 5L Grade B Steel in a corrosive medium of 3.5% NaCl. The extract was obtained through a maceration method using 70% ethanol, GC-MS analysis identified three dominan active compounds, namely enzoic acid, 3,4-dihydroxy- (14.08%), ethyl α-D-glucopyranoside (12.45%), and 3(2H)-furanone, 2-hexyl-5-methyl- (11.95%). DFT analysis revealed that benzoic acid, 3,4-dihydroxy- exhibited the best inhibitor characteristics, with the smallest energy gap (ΔE) value of 1.33 eV. Weightloss testing showed that inhibiton effiency increased with increasing inhibitor concetration, reaching a maximum efficiency of 91% at a concentration of 400 mg/L after 20 days of immersio. Electrochemical PDP testing classified the inhibitor as a mixed type inhibitor, supported by a Gibbs free energy of adsorption (ΔG°ads) value of –24 kJ/mol, indicating a protection mechanism involving both cathodic and anodic processes. EIS result showed and increase in polarization resistance (Rp) from 44,514 Ω (blank) to 1,227.8 Ω at 400 mg/L. The langmuir adsorption isothrem model was found to provide the best fit, with R² value of 0.9984, indicating in surface roughness following the addiction of 400 mg/L inhibitor, with the Sa value decreasing from 77.1 nm and 33. nm and Sq from 93.3 nm to 48.0 nm. The results of this study indicate that shallot peel extract has an environmentally friendly corrosion control solution for maritime piping applications.
| Item Type: | Thesis (Diploma) |
|---|---|
| Uncontrolled Keywords: | Kata Kunci: Baja API 5L, Inhibitor Organik, Korosi, Kulit Bawang Merah, GCMS, Weightloss, PDP, EIS, AFM. Keywords: API 5L Steel, Green Inhibitor, Corrosion, Red Onion Skin, GCMS, Weightloss, PDP, EIS, AFM. |
| Subjects: | T Technology > TA Engineering (General). Civil engineering (General) > TA418.74 Corrosion and anti-corrosives T Technology > TA Engineering (General). Civil engineering (General) > TA418.75 Corrosion-resistant materials |
| Divisions: | Faculty of Vocational > Mechanical Industrial Engineering (D4) |
| Depositing User: | Zahra Andini Putri |
| Date Deposited: | 20 Jul 2026 03:16 |
| Last Modified: | 20 Jul 2026 03:16 |
| URI: | http://repository.its.ac.id/id/eprint/135543 |
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