Available online www.jocpr.com Journal of Chemical and Pharmaceutical Research, 2014, 6(7):1417-1425 Research Article ISSN : 0975-7384 CODEN(USA) : JCPRC5 1417 Corrosion inhibition by naturally occurring substance containing Opuntia- Ficus Indica extract on the corrosion of steel in hydrochloric acid Z. Ghazi 1 , H. ELmssellem 1 , M. Ramdani 1 , A.Chetouani 1,2 , R. Rmil 1 , A. Aouniti 1 , C. Jama 3 and B. Hammouti 1* 1 Laboratoire de Chimie Appliquée et environnement (LCAE-URAC18), Faculté des Sciences, Oujda, Morocco 2 Laboratoire de chimie physique, Centre Régionale des Métiers de l'Education et de Formation ''CRMEF'', Région de l'Orientale, Oujda, Morocco 3 UMET-ISP, CNRS UMR 8207, ENSCL, Université Lille Nord de France, F-59652 Villeneuve d'Ascq Cedex, France _____________________________________________________________________________________________ ABSTRACT Corrosion is an unavoidable but a controllable process. Due to the issues of toxicity of substances, there is an increasing interest in exploration and utilization of eco-friendly inhibitors, which are also known as green inhibitors. The inhibitive effects of aqueous extracts of Opuntia ficus indica (OFI) on the corrosion of mild steel, in hydrochloric acid have been investigated by weight loss and polarisation measurements. Weight loss measurements gave an inhibition efficiency of about 91 % in the presence of 5g/l at 308K. EIS results revealed that green inhibitor effects excellently as a corrosion inhibitor for C38 steel in 1 M hydrochloric acid media with retarded the dissolution reactions to an extent dependent on the metal used. Polarisation measurements indicate that all the extracts increase the polarisation of the cathodic reaction of all the steel tested and the anodic polarisation, have no effect on the anodic reaction. The above results showed that OFI acted as a mixed-type corrosion inhibitor and the mechanism of inhibition has been discussed. The changes in impedance parameters (charge transfer resistance, R ct , and double layer capacitance, C dl ) were indicative of adsorption of OFI on the steel surface, leading to the formation of protective films. The adsorption of used compound on the steel surface obeys Langmuir’s isotherm. The apparent activation energy, enthalpy of the dissolution process and the free energy were determined and discussed. Key words: steel, inhibition, corrosion, hydrochloric acid, Green inhibitors, Plant extracts, Opuntia ficus indica _____________________________________________________________________________________________ INTRODUCTION The prickly pear, Opuntia ficus-indica: (OFI), is a species of plant of the family Cactaceae, is widely distributed in Morocco, native to Mexico, and cultivated in dry regions as an important nutrient and food source. It’s a highly p r od uctive cactus, which is cultivated as a food source for both human and animals. Also, it plays an important ecological part in combating erosion, and it is adapted and integrates in the agricultural production system of arid and semi –arid zones in Morocco. This is an interesting vegetable due the environmental conditions in which it grows and its resistance to climatic extremes; however, little is known about its nutritional properties, especially in the later stages of maturity. The Opuntia ficus-indica (OFI) fruit is an important and abundant potential raw material for the Moroccan industry where they play a strategic role in subsistence agriculture and the cactus cladodes, fruits, and flowers ere traditionally used as medicines in several Countries, The Opuntia Ficus Indica: 58.79%. Linoleic acid was the dominating fatty acid with an exceptional level, up to 58.79% for OFI oil. OFI contained a higher amount of sterols: 27.32% in total lipid oil. These results bring attention to the possible use of cactus seed oil as a natural source of PUFA for nutritional, industrial or pharmaceutical purpose [1, 3]. Opuntia prickly pads are an important source of several nutritional elements like pectin, mucilage and minerals. Currently there is only information related to young stage pads and precious little relating to the nutritional value of