title: Synthesis, inhibition effects and quantum chemical studies of a novel coumarin derivative on the corrosion of mild steel in a hydrochloric acid solution.
abstract: BACKGROUND
  The acid corrosion inhibition process of mild steel in 1 M HCl by 4-[(2-amino-1, 3, 4-thiadiazol-5-yl)methoxy]coumarin (ATC), has been investigated using weight loss technique and scanning electron microscopy (SEM). ATC was synthesized, and its chemical structure was elucidated and confirmed using spectroscopic techniques (infrared and nuclear magnetic resonance spectroscopy).
  
  
  RESULTS
  The results indicated that inhibition efficiencies were enhanced with an increase in concentration of inhibitor and decreased with a rise in temperature. The adsorption equilibrium constant (K) and standard free energy of adsorption (ΔGads) were calculated. Quantum chemical parameters such as highest occupied molecular orbital energy, lowest unoccupied molecular orbital energy (EHOMO and ELUMO, respectively) and dipole moment (μ) were calculated and discussed. The results showed that the corrosion inhibition efficiency increased with an increase in both the EHOMO and μ values but with a decrease in the ELUMO value.
  
  
  CONCLUSIONS
  Our research show that the synthesized macromolecule represents an excellent inhibitor for materials in acidic solutions. The efficiency of this macromolecule had maximum inhibition efficiency up to 96 % at 0.5 mM and diminishes with a higher temperature degree, which is revealing of chemical adsorption. An inhibitor molecule were absorbed by metal surface and follow Langmuir isotherms low and establishes an efficient macromolecule inhibitor having excellent inhibitive properties due to entity of S (sulfur) atom, N (nitrogen) atom and O (oxygen) atom.
authors.affiliation: University of Technology (UOT), Baghdad, 10001 Iraq.
authors.forename: Khalida F
authors.initials: KF
authors.lastname: Al-Azawi
authors.affiliation: University of Technology (UOT), Baghdad, 10001 Iraq.
authors.forename: Shaimaa B
authors.initials: SB
authors.lastname: Al-Baghdadi
authors.affiliation: University of Technology (UOT), Baghdad, 10001 Iraq.
authors.forename: Ayad Z
authors.initials: AZ
authors.lastname: Mohamed
authors.affiliation: University of Technology (UOT), Baghdad, 10001 Iraq ; Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia (UKM), 43000 Bangi, Selangor Malaysia.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Al-Amiery
authors.affiliation: University of Technology (UOT), Baghdad, 10001 Iraq.
authors.forename: Talib K
authors.initials: TK
authors.lastname: Abed
authors.affiliation: Faculty of Engineering, University of Nizwa, 616 Nazwa, Sultanate of Oman.
authors.forename: Salam A
authors.initials: SA
authors.lastname: Mohammed
authors.affiliation: Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia (UKM), 43000 Bangi, Selangor Malaysia.
authors.forename: Abdul Amir H
authors.initials: AA
authors.lastname: Kadhum
authors.affiliation: Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia (UKM), 43000 Bangi, Selangor Malaysia.
authors.forename: Abu Bakar
authors.initials: AB
authors.lastname: Mohamad
keywords: (thiadiazol-5-yl)methoxy)coumarin; Corrosion inhibitor; Isotherm; Weight loss