Effective utilization of drugs as green corrosion inhibitor – A review

Abstract

Corrosion is a serious problem, often difficult to eliminate completely. Corrosion process undergoes a number of reactions that change the compositions and properties of both the metal surface and the local environment. Several inhibitors like organic and inorganic inhibitors were found to be expensive, toxic and cause negative effect on the environment which restricts the use of these inhibitors against corrosion. In past years, researchers were using drugs as corrosion inhibitors. Use of drugs as corrosion inhibitors were found to be nontoxic, cheap and show a negligible negative effect on the environment. Several research studies were conducted by using different types of drugs (melatonin, cephapirin, tramadol etc) as corrosion inhibitors for various metals like mild steel, carbon steel, and aluminium steel. Studies reveal that inhibition action of these drugs was found to form insoluble complex on the metal surface thereby protecting it from corrosion. Corrosion inhibition efficiency of different drugs were studied by using methodologies like weight loss technique (WL), potentiodynamic polarization (PDP) measurements, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) and linear polarization resistance. Surface morphology of metals before and after the addition of drugs was studied through Scanning Electron Microscopy, X-Ray Diffraction, and Atomic Force Microscopy. Recently research works were conducted by using expired Dapsone drug as corrosion inhibitor against mild steel. Studies reveal that the formation of adsorbed film of modified Dapsone drug over the mild steel surface creates an obstruction against mass and charge transfer, further leading to the inhibition of corrosion. Corrosion rate was found to be decreasing as the concentration of inhibitor increases. Influence of cephapirin drugs on the corrosion of carbon steel (CS) has been examined by weight loss and electrochemical methods. EIS studies reveal the process of inhibition is through charge transfer. The quantum chemical calculation of the drug molecule were done using density functional theory (DFT) method and was found that cephapirin is a good corrosion inhibitor against carbon steel. Overall, the research studies divulge that the use of drugs as corrosion inhibitor is not only the best option for protecting metals from corrosion but also lead to the waste management of expired drug. This review focuses on the utilization of drugs as corrosion inhibitor against various metals in recent years.