ISSN-L: 2223-9553, ISSN: 2223-9944 Vol. 4 No. 2 March 2013 Academic Research International         CHRYSOPHYLLUM ALBIDUM (AFRICAN STAR APPLE) FRUIT EXTRACT AS ENVIRONMENTALLY FRIENDLY INHIBITOR ON THE CORROSION OF ALUMINIUM IN ACIDIC MEDIUM I. C. Madufor 1 , U. E. Itodoh 2 , M. U. Obidiegwu 3 , M. S. Nwakaudu 4 1, 2, 3 Department of Polymer and Textile Engineering, Federal University of Technology, 4 Department of Chemical Engineering, Federal University of Technology, Owerri, NIGERIA. 1 icmadufor@yahoo.com , 2 uchennaitodoh@yahoo.com ABSTRACT Inhibition of aluminium corrosion in 0.1M H 2 SO 4 in the absence and presence of Chrysophyllum albidum fruit extract (CAFE) at temperature range of 30 ‒ 60 o C was studied using weight loss and thermometric techniques. The fruit extract acts as an inhibitor in the acid environment. The inhibition efficiency increased with increase in inhibitor concentration but decreased with increase in temperature. The inhibiting effect of the CAFE could be attributed to the presence of some phytochemical constituents in the fruit extract which is adsorbed on the surface of the aluminium. The CAFE was found to obey Temkin adsorption isotherm at all the concentrations and temperatures studied. Thermodynamic parameters reveal that the adsorption process is spontaneous. Keywords: Aluminium; Chrysophyllum albidum; Inhibition; Corrosion; Sulfuric acid. INTRODUCTION Aluminium is a metal with a high electronegative potential (-1.67 V). It is also highly resistant to most acidic and neutral solutions due to the formation of a protective oxide film on its surface. This film is responsible for the corrosion resistance of aluminium in most environments (Umoren, et al., 2008). Nevertheless, in some cases, aluminium may be exposed to high concentrations of acids or bases. These solutions dissolve the passive film. Under these circumstances, corrosion inhibitors should be used. The use of chemical inhibitors for aluminium alloy has been established to be the most practical and cost effective means of preventing corrosion (Umoren, et al., 2008; Umoren & Obot, 2006; Umoren, et al., 2008). Most of the well known acid inhibitors are organic compounds containing nitrogen, sulphur and/or oxygen atoms. Moreover, many N- heterocyclic compounds have been proven to be effective inhibitors for corrosion of metals and alloys in aqueous media (Umoren & Obot, 2008; Ergun, et al., 2008; Ozcan, et al., 2008; Saliyan & Adhikari, 2008). The influence of organic compounds containing nitrogen on aluminium corrosion in acidic solutions has been investigated by several authors (Fiala, et al., 2007; Hasanov, et al., 2007; Al-Juaid, 2007; Allam, 2007; Ali, et al., 2008). These organic compounds can absorb on the metal surface, block the active corrosion sites on the surface and thereby reduce the corrosion rate. In this paper, weight loss and thermometric techniques were employed to study inhibition capability of CAFE on aluminium corrosion in 0.1M H 2 SO 4 . The effect of temperature is also reported.