Quantum Chemical Computation of Corrosion Inhibitors with Biocides Action

Issue 3(65) 2012
Pages 8-15

G.S. Beloglazov

Perm State Pharmaceutical Academy and University of Dodoma (UDOM), Tanzania

Keywords: biocides, corrosion inhibitors, electronic structure, molecular orbitals, quantum-chemiсаl computation

Results of quantum chemical calculations of corrosion inhibitors (Ci) molecules (particularly,
p-R-C6H4-SO2-NH2 where R= F, Cl, Br, CH3) both in free state and adsorbed on cluster modeling aluminium surface containing 20 Al atoms are compared to experimental data on efficiencies of protective action (EPA) against corrosion by Ci. Energies of boundary orbitals (HOMO, LUMO) and dipole moments of isolated molecules of Ci as well as changes of atomic charges on Ci atoms when Ci molecule adsorbed have been computed using semi-empiric MNDO quantum chemistry method. It was found that correlation coefficients between EPA and changes of electric charge on N atom [ΔQ(N)] and O atom [ΔQ(O)] due to adsorption of Ci on the metal surface are the most significant.
At adsorption and eventually the protection action of Ci, the specific role of polar groups (such as hydroxile) and specific role of heteroatoms (such as N, S etc) have been confirmed in the framework of the concepts of molecular orbitals and donor-acceptor interaction between adsorbent and adsorbate.