Analisis Efektivitas Ekstrak Kulit Semangka (Citrullus lanatus) sebagai Inhibitor Organik pada Baja Astm A36 dengan Variasi Imersion Time pada Lingkungan Nacl 3,5%

Salim, Triani Rosita (2026) Analisis Efektivitas Ekstrak Kulit Semangka (Citrullus lanatus) sebagai Inhibitor Organik pada Baja Astm A36 dengan Variasi Imersion Time pada Lingkungan Nacl 3,5%. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penelitian ini mengkaji efektivitas ekstrak kulit semangka (Watermelon Skin Extract/WSE) sebagai inhibitor organik terhadap laju korosi dalam media korosif. Pengujian dilakukan menggunakan metode gravimetri dan polarisasi potensiodinamik elektrokimia guna mengevaluasi efisiensi inhibisi secara komprehensif. Hasil pengujian weightloss menunjukkan efisiensi inhibisi tertinggi sebesar 82,49% pada konsentrasi WSE 10%, yang kemudian dikonfirmasi oleh metode polarisasi potensiodinamik dengan nilai efisiensi sebesar 81,66% dan inhibisi mencapai 60,27% untuk pengujian Electrochemical Impedance Specstroscopy pada konsentrasi yang sama. Konvergensi hasil dari berbagai metode tersebut memberikan validasi yang kuat terhadap kemampuan WSE dalam menghambat laju korosi secara signifikan dan terukur. Analisis Atomic Force Microscopy (AFM) membuktikan terbentuknya lapisan pelindung pada permukaan logam, yang ditandai dengan penurunan nilai kekasaran rata-rata permukaan (Sa) secara signifikan dari 109 nm menjadi 40,6 nm setelah penambahan inhibitor. Penurunan tersebut mengindikasikan bahwa molekul aktif WSE berhasil teradsorpsi secara merata pada permukaan logam, membentuk lapisan pelindung yang mereduksi area aktif yang rentan terhadap serangan korosi. Mekanisme adsorpsi dikaji melalui analisis isoterm adsorpsi, di mana model isoterm Langmuir terbukti paling representatif dengan nilai koefisien determinasi (R²) sebesar 0,87879, mengindikasikan adsorpsi berlangsung secara monolayer dengan energi adsorpsi yang seragam pada setiap situs aktif permukaan. Kajian komputasional menggunakan metode Density Functional Theory (DFT) menghasilkan nilai celah energi (ΔE) dengan urutan DHMP (2,71 eV) < LA (3,68 eV) < DBP (4,09 eV), mengindikasikan bahwa DHMP memiliki reaktivitas tertinggi dan diprediksi berinteraksi paling kuat dengan permukaan Fe.
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This study investigates the effectiveness of Watermelon Skin Extract (WSE) as an organic inhibitor against corrosion rate in corrosive media. Testing was conducted using gravimetric and electrochemical potentiodynamic polarization methods to comprehensively evaluate inhibition efficiency. Gravimetric test results demonstrated the highest inhibition efficiency of 82.49% at a WSE concentration of 10%, which was subsequently confirmed by the potentiodynamic polarization method yielding an efficiency value of 81.66% at the same concentration. The convergence of results from both methods provides strong validation of WSE's capability to inhibit corrosion rates significantly and measurably. Atomic Force Microscopy (AFM) analysis confirmed the formation of a protective layer on the metal surface, evidenced by a significant reduction in the average surface roughness value (Sa) from 109 nm to 40.6 nm following inhibitor addition. This reduction indicates that WSE active molecules successfully adsorbed uniformly onto the metal surface, forming a protective layer that reduces active areas susceptible to corrosive attack. The adsorption mechanism was further examined through adsorption isotherm analysis, wherein the Langmuir adsorption isotherm model proved most representative with a coefficient of determination (R²) of 0.87879, indicating that adsorption proceeds as a monolayer with uniform adsorption energy at each active surface site. Computational studies employing the Density Functional Theory (DFT) method yielded energy gap values (ΔE) in the order of DHMP (2.71 eV) < LA (3.68 eV) < DBP (4.09 eV), indicating that DHMP possesses the highest reactivity and is predicted to interact most strongly with the Fe surface.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Korosi, Inhibitor Organik, Ekstrak kulit Semangka, Gravimetri, Polarisasi Potensiodinamik, EIS, AFM, Isoterm Langmuir, DFT, corrosion, organic inhibitor, watermelon skin extract, Gravimetric, Potentiodynamic Polarization, EIS, AFM, Langmuir Isotherm, DFT
Subjects:	Q Science > QD Chemistry > QD115 Electrochemical analysis T Technology > TA Engineering (General). Civil engineering (General) > TA418.16 Materials--Testing. T Technology > TA Engineering (General). Civil engineering (General) > TA418.74 Corrosion and anti-corrosives T Technology > TA Engineering (General). Civil engineering (General) > TA418.9.C57 Coatings
Divisions:	Faculty of Vocational > Mechanical Industrial Engineering (D4)
Depositing User:	Triani Rosita Salim
Date Deposited:	27 Jul 2026 01:50
Last Modified:	27 Jul 2026 01:52
URI:	http://repository.its.ac.id/id/eprint/137454

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