The corrosion inhibition of Al and its alloys is the subject of tremendous technological importance due to the increased industrial applications of these materials. This study reports the corrosion inhibition of AA8011 aluminium alloy in acidic solutions using Newbouldia leavis leaf extract by way of gravimetric measurements. It was shown that the presence of Newbouldia leavis leaf extract inhibited the corrosion of aluminium in the test solutions and the inhibition efficiency depended on the concentration of the plant extract as well as on the time of exposure of the aluminium samples in H 2 SO 4 solutions containing the extract. The experimental data complied to the Langmuir adsorption isotherm and the value and sign of the Gibb's free energy of adsorption obtained suggested that inhibitor molecules have been spontaneously adsorbed onto the aluminium surface through a physical adsorption mechanism.

Complexes of Ba(II), Sr(II) and Zn(II) with 1-phenyl-3-methyl-4-(p-nitrobenzoyl) pyrazolone-5(HNPz) have been synthesized and characterized. The HNPz was prepared from high grade p-nitrobenzoyl chloride and 1-phenyl-3-methyl-5-pyrazolone. The process involved benzoylation of 17.60 g (0.10 M) 1-phenyl-3-methyl-5-pyrazolone (HPMP) with 14.55 g (0.103 M) nitrobenzoylchloride. The complexes of Ba (II), Sr (II) and Zn (II) were prepared by dissolving 5 mmol of BaCl 2 .2H 2 O,SrCl 2 .6H 2 O and ZnSO 4 .7H 2 O respectively in 10 mmol of HNPz. The complexing agent and the metal complexes were characterized by elemental analysis, UV-visible and infrared spectroscopies. The results show the complexes to be dihydrated bischelates conforming to a general molecular formula, MLn.2H 2 O, where L is the 4-acylpyrazolonato ion and n is the ligand number or oxidation state of metal,M (Ba, Sr, Zn). The study also indicates the formation of octahedral complexes which are presumed to have been formed through the enolic and carbonyl oxygen atoms of the coordination reagent; in which water molecules complete the expected coordination numbers of Ba(II), Sr(II) and Zn(II).

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