Pandian Bothi Raja

Reviews on Corrosion Inhibitors: A Short View

A range of numerous corrosion inhibitors, viz. organic molecules with hetero atoms and π-electron clouds, inorganic salts and plant excerpts likewise their corresponding phytoconstituents were reported with success for metals in different corrosive media. Various literature reviews related to corrosion inhibitors have been reported by many authors based on their application, classification, and inhibition mechanism. A short view of all these reviews is summarized in this manuscript. Various aspects of corrosion inhibitors as well as their recent trends and advancement are also discussed.

NATURAL CORROSION INHIBITORS FOR STEEL REINFORCEMENT IN CONCRETE — A REVIEW

Reinforced concrete is one of the widely used construction materials for bridges, buildings, platforms and tunnels. Though reinforced concrete is capable of withstanding a large range of severe environments including marine, industrial and alpine conditions, there are still a large number of failures in concrete structures for many reasons. Either carbonation or chloride attack is the main culprit which is due to depassivation of reinforced steel and subsequently leads to rapid steel corrosion. Among many corrosion prevention measures, application of corrosion inhibitors play a vital role in metal protection. Numerous range of corrosion inhibitors were reported for concrete protection that were also used commercially in industries. This review summarizes the application of natural products as corrosion inhibitors for concrete protection and also scrutinizes various factors influencing its applicability.

QUINAZOLINONE COMPOUNDS AS CORROSION INHIBITORS FOR MILD STEEL IN SULFURIC ACID MEDIUM

Three quinazolinone compounds, namely 6-chloroquinazolin-4(3H)-one (Q1A), 3-phenethyl-2-thioxo-2,3-dihydropyrido[2,3-d]pyrimidin-4(1H)-one (Q1B), and 6-chloro-3-phenethyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-one (Q1C), have been synthesized, and the inhibition effect of these compounds on the corrosion of mild steel (MS) in 0.5 M H2SO4 has been studied via weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) techniques. These studies revealed that the inhibition efficiency (IE) increased with the concentrations of all the inhibitors studied. The IE of polarization studies is in good agreement with EIS and weight loss measurements and also showed the mixed mode of inhibition by all the quinazolinone compounds. The inhibition was accomplished by adsorption of quinazolinone compounds on the mild steel surface, which was found to obey the Langmuir isotherm. Thermodynamic parameters proved that Q1B and Q1C followed the chemisorption mode, while Q1A followed the physisorption mode of inhibition. SEM studies supported the adsorption of quinazolinone compounds over the metal surface, and the inhibition efficiency follow the order Q1C > Q1B > Q1A.

Green synthesis of silver nanoparticles using tannins

Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.