INVESTIGASI EKSTRAK BAHAN ALAM SEBAGAI INHIBITOR KOROSI HIJAU PADA BAJA MENGGUNAKAN TEORI FUNGSIONAL KERAPATAN

Salah satu material yang ketahanannya terhadap korosi rendah adalah baja ketika berinteraksi dengan lingkungan korosif. Penggunaan green inhibitor mampu memberikan kinerja penghambatan korosi yang baik dengan efisiensi inhibisi yang tinggi pada baja. Green inhibitor yang dalam struktur senyawanya mengandung gugus heteroatom (seperti O, N, S, P) dan cincin aromatik efisien digunakan sebagai inhibitor korosi pada baja. Makalah ini memberikan tinjauan komparatif penting bagi pengembangan green inhibitor ekstrak bahan alam pada baja. Kajian DFT pada level atomik berdasarkan orbital molekuler, parameter kuantum kimia, dan karakteristik adsorpsi menunjukkan hasil yang sesuai dengan hasil eksperimen. Distribusi kerapatan elektron melalui plot Frontier Molecular Orbitals (FMO) menggambarkan prediksi situs aktif melalui distribusi daerah HOMO-LUMO molekul inhibitor yang berinteraksi dengan permukaan baja. Untuk mendapatkan korelasi antara sifat elektronik molekul inhibitor dengan potensi penghambatan (inhibisi) korosi, kalkulasi parameter kimia kuantum seperti potensial ionisasi (I), afinitas elektron (A), kekerasan global (η), elektronegativitas absolut (χ), kelembutan global (σ), fraksi elektron yang ditransfer (ΔN), elektrofilisitas global (ɷ) dan donasi balik elektron (ΔEback-donation) menunjukkan reaktivitas molekul inhibitor yang berpotensi sangat baik untuk dapat berinteraksi dan berikatan kuat dengan permukaan logam, sehingga berpotensi menghasilkan efisiensi inhibisi yang tinggi. Mekanisme inhibisi korosi dapat melalui adsorpsi kimia dan/atau adsorpsi fisika dengan membentuk senyawa kompleks antara molekul inhibitor dengan permukaan baja untuk melindungi dari lingkungan korosif. Pengembangan kajian ke depan harus dapat menampilkan mekanisme interaksi dan inhibisi dari molekul inhibitor secara lebih detail dan sistematis pada level atomik pada beberapa permukaan logam seperti Fe, Al, Cu, dan lainnya.

The Study of Mixing Purple Sweet Potato and Turmeric Extract as Green Corrosion Inhibitor for API-5L in NaCl 3,5% Environment

Green inhibitors have become a major option for corrosion prevention since people are more aware of environmental damage. It is true that chemical inhibitors are more powerful at preventing corrosion, but its side effects are very harmful to the environment. Purple sweet potato (Ipomoea batatas L) in single use has been proven as an active inhibitor for certain applications. To improve this property, purple sweet potato is used as a mixed with other plants that contain antioxidant agents, such as ginger, melinjo, turmeric, jeera, etc. This paper discussed the effect of applying mixed extract of purple sweet potato with turmeric (Curcuma longa) as a green inhibitor to corrosion rate of API 5L steel in a 3.5% NaCl environment. Turmeric extract contains curcumin and kaempferol antioxidants while purple sweet potato extract contains antocyanin antioxidants. Corrosion rates were analyzed based on weight loss and polarization methods. The results showed the highest inhibitor efficiency was 82.54% achieved by 16 ml of turmeric mixed with 2 ml of purple sweet potato, and the optimum inhibitor efficiency was 74.2% achieved by 8 ml of turmeric mixed with 6 ml of purple sweet potato.

The Effectivity of Oil Palm Inhibitor Processed by Aminolysis to Control Corrosion on Steel in Sodium Chloride Environment

A green inhibitor based on Palm kernel oil (PKO) was prepared to investigate its corrosion inhibition behaviour against steel ASTM A36 in sodium chloride solution. The aminolysis method was used to synthesize the green inhibitor and produced fatty acid diethanolamine. Afterwards, the mixture of PKO and diethanolamine of 1:6 and 1:20 were prepared. These mixtures were added into sodium chloride solution with concentration 50, 100, 500, and 1,000 ppm and they were used as working solution in corrosion testing. Corrosion testing was conducted using anodic polarization. The confirmation of microstructure of steels surfaces were done by optical microscope. The results obtained from corrosion testing showed that inhibitors of palm oil, especially palm kernel oil (PKO), provided a good corrosion protection effect. The present work provided very promising results in the preparation of green corrosion inhibitors.

Trachyspermum Leaves Extract as a Green Inhibitor for Corrosion Inhibition of Mild Steel in 0.1m HCl: Experimental and Computational Study

The present study aims at investigating the impacts of the extract of Trachyspermum leaves on the mild steel corrosion in 0.1M hydrochloric acid (HCl), while highlighting its inhibitory mechanisms. The effects of mild steel corrosion in solutions of HCl were examined using the gravimetric and galvanostatic polarization techniques, along with EIS analyses. According to the results, the maximum inhibitory effectiveness corresponding to the minimum corrosion rate could be observed at the highest desirable level of inhibitor concentration equal to 100 ppm, while the corrosion rate decreases with an increase in the extract concentration. The absorption examinations indicated the best description of the metal surface interaction by Langmuir isotherm, while obtaining the best exposure time for the Trachyspermum leaves extract adsorption into the surface of the metal in different concentration. Based on the results of polarization, the inhibitors can play the role of a mixed inhibitor, also confirmed by the computational data.

Sage Extract as a Natural Source of Corrosion Inhibitor for Tinplate in 3.0 % NaCl

Research background. Due to the growing interest and attention of the world towards environmental problems and protection of environment, the worldwide demand for biodegradable and effective corrosion inhibitors for tinplate has grown. Considering the diversity of the structures of polyphenols that are present in sage extract, it represents a promising potential source of low-cost and biodegradable effective green corrosion inhibitors for tinplate in 3.0 % sodium chloride solution which is evaluated in this study. Experimental approach. Tafel polarization and electrochemical impedance spectroscopy (EIS) at 25 °C has been used to evaluate the inhibition action of sage (Salvia officinalis, L.) extract as a green inhibitor for the corrosion protection for tinplate in 3.0 % sodium chloride solution. Results and conclusions. Electrochemical impedance spectroscopy has been used to show that sage extract could serve as an effective inhibitor (90.2 %) for the corrosion of tinplate in 3.0 % NaCl at a concentration of 0.2 mg/L, and temperature of 25 °C. The results obtained from potentiodynamic polarization have revealed that the sage extract inhibitor acts as a mixed type, with inhibition efficiency up to 82.5% and the inhibition efficiencies calculated from EIS are in close agreement with those results. FTIR results indicated that the inhibitory effect of the sage extract is due to the presence of a passivation layer on the tinplate surface, which consists of organic compounds such as polyphenols. It has been confirmed by these results that the sage extract is more efficient at inhibiting the corrosion of tinplate at a concentration of 0.2 mg/L than in higher concentrations. Also, it exhibits good inhibitive performance for tinplate in 3 % sodium chloride solution. Novelty and scientific contributions. The exceptional corrosion potential of sage extract opens a door for its use and revalorization as a green corrosion inhibitor in the food industry.