SOLID WASTE AS ENVIRONMENTAL BENIGN CORROSION INHIBITORS IN ACID MEDIUM Mohammad Ismail Faculty of Civil Engineering Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia A. S. Abdulrahman Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM/ Mechanical Engineering Department, Federal University of Technology Minna, Nigeria Mohammad Sakhawat Hussain Faculty of Mechanical Engineering Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia ABSTRACT The inhibitive properties of solid waste (Genus Musa, Genus Saccharum and Citrullus Lanatus) on the corrosion of mild steel strip in 1M HCl were investigated using weight loss technique. These materials are considered as waste and constitute nuisance to the environment as there is no meaningful uses of them. Inhibition efficiency of 69.60%, 68.41%, and 58.15% at 10% v/v of extracts concentration for 72 hours exposed time for Genus saccharum, Citrullus lanatus and Genus musa, respectively, were achieved. Adsorptions of the inhibitors molecules on mild steel strip surfaces were consistent with Langmuir adsorption isotherm. Keywords: Corrosion; Metals and alloys; Inhibition; Weight loss techniques; Plant extracts. 1. Introduction Considerable efforts are being deployed to find suitable compounds to be used as corrosion inhibitors in various corrosive media to stop or delay to the maximum the attack of a metal. Many metals and alloys which are used in different human activities are susceptible to different mechanisms of corrosion due to their exposure to different corrosive media. The study of mild steel corrosion phenomena has become important particularly in acidic media because of the increased industrial applications of acid solutions. For instance, refining of crude oil usually results in a variety of strong acid attacking the equipment surface and industrial cleaning processes such as pickling and acid de-scaling(Ostovari 2009). Among the acid solutions used for industrial cleaning, hydrochloric acid is one of the most widely used agents (Ostovari 2009). Due to the viability of mild steel, its high cost of production and installations, most industries have adopted various steps aimed at prolonging the life span of this valuable metal. The cost of corrosion has been reported from many studies to be in the order of 1–5% of GNP for any country (Mohammed A. Amin 2010). However, one of the most practicable and preferred method used to remedies this problem is the inhibitors (Eddy 2009). The principle of corrosion inhibitor is to prevent the chloride ions from reacting with the steel surface. Thus, corrosion inhibitors are chemical substance which decreases the corrosion rate when present in the corrosion system at a suitable concentration without significantly changing the concentration of any other corrosive agent. Corrosion inhibitors are of great practical importance, being extensively employed in minimising metallic waste in engineering materials. Inhibitors when compared to other corrosion protection methods have some advantages such as versatility and cost (So¨ylev T.A. 2008). Although many synthetic compounds show good anticorrosive action, most of them are highly toxic to both human beings and environment (Satapathy 2009). These inhibitors may cause temporary or permanent damage to human organ such as kidney or liver (Raja and Sethuraman 2008). The known hazardous effects of most synthetic organic inhibitors and restrictive environmental regulations have now made researchers to focus on the need to develop Mohammad Ismail et al. / International Journal of Engineering Science and Technology (IJEST) ISSN : 0975-5462 Vol. 3 No. 2 Feb 2011 1742