Experimental, quantum chemical and molecular dynamic simulations studies on the corrosion inhibition of mild steel by some carbazole derivatives

Abstract

Five selected carbazole derivatives, namely carbazole, 3,6-dibromocarbazole, 2-hydroxycarbazole, 1,2,3,4-tetrahydrocarbazole and 9-(2-ethylhexyl)carbazole-3,6-dicarboxaldehyde were investigated for their inhibitive effects on Desulfovibrio vulgaris (D. vulgaris) induced corrosion of mild steel and in 1 M HCl medium using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The carbazole derivatives were found to be mixed type inhibitors with predominantly cathodic inhibitive effects for mild steel in 1 M HCl. Surface morphology results showed the compounds formed adsorbed film on mild steel surface in both aqueous acid and sulphate reducing bacteria (SRB) media. Quantum chemical calculations were used to provide molecular based explanations for the inhibitive effects of the compounds. The interactions of the molecules with mild steel surface was simulated based on molecular dynamic simulations approach using Fe(110) crystal surface as representative metallic surface.

Corrosion inhibition of carboxylate inhibitors with different alkylene chain lengths on carbon steel in an alkaline solution

“…Generally, molecules which have higher E HOMO are more easily to donate electrons to the unlled molecular orbital of suitable acceptor molecules with low energy. 21 Previous studies showed that the inhibition efficiency increases with the increasing E HOMO values. 23,26 In contrast, the E LUMO value is related to the capability of a molecule to accept electrons.…”

“…Quantum chemical calculation was performed using Materials Studio 7.0 soware. [19][20][21] The Density Functional Theory (DFT) method, B3LYP, combined with the 6-311G(d,p) basis [22][23][24] set was used in this study. Full geometry optimizations were carried out on carboxylate ions due to the alkaline environment.…”

“…Quantum chemical parameters were computed including the energy of the highest occupied molecular orbital (E HOMO ), the energy of the lowest unoccupied molecular orbital (E LUMO ), energy band gap (DE), chemical potential (m), electronegativity (X), chemical hardness (h), electrophilicity (u) and nucleophilicity (3). [19][20][21][22][23][24][25][26] The quantum chemical reactivity indices were derived from the frontier molecular orbital energies (E HOMO and E LUMO ) using appropriate relations (eqn (1)-(5)) as previously reported in literature. [18][19][20][21][22][23][24] DE ¼ E LUMO À E HOMO (1)…”

“…[19][20][21][22][23][24][25][26] The quantum chemical reactivity indices were derived from the frontier molecular orbital energies (E HOMO and E LUMO ) using appropriate relations (eqn (1)-(5)) as previously reported in literature. [18][19][20][21][22][23][24] DE ¼ E LUMO À E HOMO (1)…”

Mixed community biofilms and microbially influenced corrosion

“…Thus, removal of these mediators might help in mitigating MIC. Other MIC control strategies use surfactants 29 and mixed-type inhibitors carbazole derivatives to inhibit SRB biofilm formation 30 . Ideally, biofilm inhibitors should be applied at the metal surface, and engineered to allow slow release over long periods of time.…”