Analisis Efektivitas L-Carnitine Kadaluwarsa Sebagai Inhibitor Korosi Pada Baja ASTM A36 Di Lingkungan HCl 1M

Endang Setyo, Rini (2030) Analisis Efektivitas L-Carnitine Kadaluwarsa Sebagai Inhibitor Korosi Pada Baja ASTM A36 Di Lingkungan HCl 1M. Diploma thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Korosi merupakan permasalahan utama pada logam, khususnya baja ASTM A36, yang menimbulkan kerugian ekonomi besar. Penelitian ini mengevaluasi efektivitas L-Carnitine kadaluwarsa sebagai inhibitor organik terhadap laju korosi baja ASTM A36 dalam media HCl 1M, dengan variasi konsentrasi 0, 20, 40, 60, 80, dan 100 ppm serta waktu perendaman 3, 6, 9, 12, dan 15 jam. Metode pengujian meliputi Weight Loss (WL), Polarisasi Potensiodinamik (PDP), Electrochemical Impedance Spectroscopy (EIS), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), dan Fourier Transform Infrared (FTIR). Hasil WL menunjukkan efisiensi inhibisi >90% pada perendaman awal (3 jam) untuk seluruh konsentrasi, dengan konsentrasi 60 ppm memberikan kestabilan efisiensi terbaik sepanjang variasi waktu perendaman. Data PDP menunjukkan penurunan arus korosi (Icorr) dari 3299,2 µA/cm² tanpa inhibitor menjadi 131,76 µA/cm² pada 100 ppm, dengan efisiensi inhibisi meningkat dari 63,58% menjadi 96,01%. Hasil EIS konsisten dengan tren tersebut tahanan polarisasi (Rp) meningkat dari 18,977 Ω menjadi 213,61 Ω, sementara CPE menurun dari 3840 µF menjadi 79,68 µF, dengan efisiensi inhibisi meningkat dari 71,29% menjadi 91,12%. FTIR mengidentifikasi gugus aktif L-Carnitine (O–H, C=O, C–O, C–N, C–H) yang mengandung atom hetero (O, N) dan mampu berinteraksi dengan permukaan baja. SEM dan AFM menunjukkan permukaan yang lebih halus dan terlindungi pada sampel dengan inhibitor dibandingkan permukaan tanpa inhibitor yang mengalami pitting dan kerusakan berat. Analisis isoterm adsorpsi sesuai dengan Isoterm Langmuir (R² = 0,99375), mengindikasikan pembentukan monolayer, dengan nilai ΔG°ads = −28,51 kJ/mol yang menunjukkan adsorpsi spontan dengan mekanisme kombinasi fisisorpsi-kemisorpsi. Berdasarkan PDP, L-Carnitine dikategorikan sebagai inhibitor tipe campuran (mixed-type) karena memengaruhi proses anodik dan katodik. Kesimpulannya, L-Carnitine kadaluwarsa efektif menghambat korosi baja ASTM A36 dalam media HCl 1 M melalui adsorpsi monolayer, menunjukkan potensi pemanfaatan limbah farmasi sebagai inhibitor korosi yang ramah lingkungan.
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Corrosion is a major issue for metals, particularly ASTM A36 steel, causing substantial economic losses. This study evaluates expired L-Carnitine as an organic inhibitor for corrosion of ASTM A36 steel in 1 M HCl, with inhibitor concentrations of 0, 20, 40, 60, 80, and 100 ppm and immersion times of 3, 6, 9, 12, and 15 hours. Testing methods included Weight Loss (WL), Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy (EIS), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR) spectroscopy. WL results showed inhibition efficiencies above 90% at the initial immersion (3 h) for all concentrations, with 60 ppm exhibiting the most consistent efficiency across immersion times. PDP data revealed a decrease in corrosion current density (Icorr) from 3299.2 μA/cm² without inhibitor to 131.76 μA/cm² at 100 ppm, with inhibition efficiency increasing from 63.58% to 96.01%. EIS results agreed: polarization resistance (Rp) rose from 18.977 Ω to 213.61 Ω, CPE decreased from 3840 μF to 79.68 μF, and inhibition efficiency increased from 71.29% to 91.12%. FTIR identified active functional groups in L-Carnitine (O–H, C=O, C–O, C–N, C–H) containing heteroatoms (O, N) that interact with the steel surface. SEM and AFM showed a smoother, better-protected surface with inhibitor compared to severe pitting and roughness without inhibitor. Adsorption isotherm analysis fitted the Langmuir model (R² = 0.99375), indicating monolayer formation, with ΔG°ads = −28.51 kJ/mol suggesting spontaneous adsorption via a combined physisorption-chemisorption mechanism. Based on PDP results, L-Carnitine is classified as a mixed-type inhibitor, affecting both anodic and cathodic reactions. In conclusion, expired L-Carnitine effectively inhibits corrosion of ASTM A36 steel in 1 M HCl via monolayer adsorption, supporting the potential reuse of pharmaceutical waste as an environmentally friendly corrosion inhibitor.

Item Type:	Thesis (Diploma)
Uncontrolled Keywords:	Kata kunci: Baja ASTM A36, HCl 1 M, Inhibitor organik, Korosi, L-Carnitine Kadaluwarsa.
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ1186 Metal-cutting tools.
Divisions:	Faculty of Vocational > Mechanical Industrial Engineering (D4)
Depositing User:	Endang Setyo Rini
Date Deposited:	21 Jul 2026 04:23
Last Modified:	21 Jul 2026 04:23
URI:	http://repository.its.ac.id/id/eprint/136022

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