Optimasi Sifat Inhibitor Korosi Senyawa Thiaamida-Pirazolindol Berdasarkan Teori Fungsional Kerapatan

Abstract

Abstrak. Sifat inhibitor korosi senyawa turunan thiaamida-pirazolindol (TP) telah dikaji menggunakan teori fungsional kerapatan pada tingkatan teori B3LYP/6-31G(d). Pengaruh gugus substitusi pendonor dan penarik elektron (NH2, SH, CHCH2, CH3, OH, CHO, COOH, F, NO2) terhadap efisiensi anti korosi senyawa thiaamidapirazolindol juga dihitung. Parameter kuantum untuk senyawa anti korosi seperti energi orbital (EHOMO dan ELUMO), potensial ionisasi (I), afinitas elektron (A) dan elektronegativitas (χ) memiliki hubungan yang linier dengan efisiensi anti korosi (IE%) senyawa turunan thiaamida-pirazolindol. Gugus pendonor elektron meningkatkan nilai IE%. Urutan kenaikan IE% adalah NO2 < CHO < COOH < F < CHCH2 < OH < CH3 < NH2. Penambahan gugus pendonor elektron amina (NH2) meningkatkan IE% hingga 98,76 % dibandingkan IE% thiaamida-pirazolindol murni 90,80 %. Penambahan gugus penarik elektron menurunkan IE% hingga mencapai 82,82 %. Kajian teoritis ini akan berkontribusi besar dalam mendesain dan sintesis senyawa inhibitor organik dengan efisiensi inhibitor tinggi.Kata kunci: inhibitor korosi, teori fungsional kerapatan, thiaamida-pirazolindol Abstract. Corrosion inhibitor properties of thiamide pyrazolindole and its derivatives has been elucidated by means of density functional theory (DFT) at B3LYP/6-31G(d) level of theory. Effect of electron donating and withdrawing groups such as NH2, SH, CHCH2, CH3, OH, CHO, COOH, F and NO2 on the corrosion inhibitor of thiamide pyrazolindole derivatives also have been studied. The quantum chemical parameters such as the frontier orbital energies (EHOMO), ionization potential (I), electron affinity (A) and electronegativity (χ) are closely related to the corrosion inhibition efficiency (IE%) of thiamide pyrazolindole derivatives. The presence of electron donating groups increases IE% values meanwhile electron withdrawing groups reduce IE% values. The enhancement of IE% follows NO2 < CHO < COOH < SH < F < CH3 < CHCH2 < OH < NH2. Electron donating NH2 group gives 98,76 % of IE%, pure thiamide pyrazolindol IE% = 90,80 %. In contrast, electron withdrawing NO2 group gives IE% only 82,82 %. This theoretical study would have a significant contribution in designing high-efficiency organic corrosion inhibitors.

The effect of sambiloto leaf (Andrographis paniculata Nees) extract inhibitor concentration on the corrosion rate of iron in the corrosive HCl medium and well water

“…This test was carried out to determine the efficiency of the Sambiloto leaf extract inhibitor against the corrosion rate of nails by adding the Sambiloto leaf extract, which has varied concentrations of 1%, 5%, 10%, and 15% in the corrosive medium that has been provided, as shown in Figure 3. The inhibitor's ability to determine the corrosion rate of nails in the corrosive medium can be determined quantitatively using the following equation [8].…”

“…Note : r : Corrosion rate t : time (days) Wo : initial weight (gr) Wf : final weight (gr) A : surface area (cm 2 ) Furthermore, the efficiency value of the inhibitor can be determined quantitatively using the following equation [8]. Data analysis was conducted to determine the correlation between the concentration of Sambiloto leaf inhibitors on the corrosion rate in different media.…”

“…Akbar's research utilizes guava fruit as a natural inhibitor because it is believed to have important content in the form of tannins [8]. This study aimed to determine the efficiency of guava fruit extract inhibitors in inhibiting the rate of iron corrosion in the corrosive medium of well water and seawater.…”