doi:10.1038/nindia.2013.52 Published online 11 April 2013
Researchers have found that polysaccharides and glucose can inhibit acid-induced corrosion of cast iron by binding to iron surfaces1. These organic compounds will be useful for protecting iron against such corrosion in various industries.
Acid solutions used in industry corrode iron materials. Among the current corrosion inhibitors, sulphur, phosphorous, nitrogen and oxygen have shown excellent properties. Although both synthetic and natural polymers are good corrosion inhibitors, very few studies have investigated the roles of natural polymers such as carbohydrates, which have great affinity to metal surfaces.
To determine the corrosion-inhibition efficiency of carbohydrates, the researchers cut a sample of cast iron into pieces, washed them with acetone and distilled water and then dried them at room temperature. They dissolved varying concentrations of inhibitor compounds, including hydroxypropyl cellulose, gellan gum, a complex sugar and glucose, in hydrochloric acid solutions. The washed and dried pieces of cast iron were then dipped into these acid solutions.
The iron pieces had relatively smooth surfaces, which is attributed to the inhibitors retarding the corrosion rate. The inhibitors suppressed the corrosion rate more efficiently at higher concentrations.
Hydroxypropyl cellulose exhibited a higher corrosion-inhibition efficiency than gellan gum and glucose. The researchers say that hydroxypropyl cellulose can inhibit corrosion of cast iron in acidic solutions through both physical and chemical interactions with iron surfaces.
The authors of this work are from: Department of Chemistry, Periyar University, Salem, Department of Chemistry, National Institute of Technology, Tiruchirappalli, Tamil Nadu, India.