Abstract
The phenomenon of corrosion of metals including Fe, Al, Cu, Zn, Mg and their alloys is controlled to a great extent by selection of highly corrosion resistant inhibitors. The associated cost factor favors the use of cheap metallic materials along with efficient corrosion prevention methods in many industrial applications. In this aspect, corrosion inhibitors have a significant role in the protection of metals from corrosion. These inhibitors are either hazardous chemicals or environmentally friendly chemicals. Many authors reported that the use of plants extracts from mango, cashew, passion-fruit, orange, khillah seeds, African bush pepper, neem leaves and papaya as corrosion inhibitors in an acid medium for protection of metals such as steel, copper, and copper alloys gave high inhibition efficiency. Some environmentally friendly chemicals namely, octanoic acid, 2-ethylhexanoic acid and their alkali salts, sodium borates, triazoles, hydrocarbyl, and benzotriazoles were used as corrosion inhibitors. Polymeric compounds such as polyacrylic, polymaleic, and polyaspartic acid and its salts were also used as corrosion inhibitors for acidic ferrous metal surfaces in contact with acidic corrosive aqueous saline environment saturated with carbon dioxide. Published patents related to the corrosion inhibition using green corrosion inhibitors are discussed.
Keywords: Corrosion inhibitor, acidic corrosion, adsorption isotherm, Langmuir, weight loss, polarization, impedance, synthetic inhibitors, environmentally friendly inhibitors, biodegradation.
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