Plant extracts as corrosion inhibitors for mild steel in H2SO4 and H3PO4 media – Review II

Abstract

One of the most important methods combating corrosion is the use of substances or chemical compounds called corrosion inhibitors. However, many of these compounds used as inhibitors are toxic; therefore the usage of them is harmful for human health and the environment. Chemical compounds containing aromatic rings and π bonds are highly effective as corrosion inhibitors, but besides being toxic, the synthesis of these compounds is very difficult and time consuming. Therefore, scientists have focused on a new class of inhibitors such as plant extracts, fruit, vegetable extracts and essential oils in recent years. In addition to being environmentally friendly in preventing corrosion plant extracts have some superior properties such as cheap, less toxic and easy to obtain. Mild steel has been widely used alloy due to the importance of industrial applications such as mining, cleaning of boilers, oil well tubes and metal processing equipment. Sulphuric acid is an important industrial chemical which is used in pulp and paper industry for chlorine dioxide generation tall of splitting and pH-adjustment. However, it is an important drawback that it is a corrosive substance. Phosphoric acid is also one of the important chemicals which has used in several industries such as agriculture, pharma, in food and beverage, and controlling the pH level of some products. In this review, studies carried out for mild steel corrosion in sulphuric acid and phosphoric acid environments with plant extracts, which are widely used in recent years as corrosion inhibitors are summarized.