Silica extraction from agricultural waste as corrosion inhibitor

Abstract

Rice husk and rice straw are found abundant as by-product of the the rice milling industry. Both of the agricultural wastes have a great potential to be used as raw material in industry. Rice husk and rice straw normally consist of high percentage of silica when they are burnt to ash. Silica extracted from the ash will undergo basic or acid treatment to increase the percentage of silica as corrosion inhibitor. Corrosion inhibitors for metals are mostly nitrogen, sulfur or oxygen containing organic compounds, such as quarternary ammonium salts, organic amine derivatives, organic phosphates, succinimides and imidazoline derivatives that offer electron transfer through physical or chemical adsorption on metal surfaces. Nano structured silica can form non-porous coating through the –Si-OSi- linkage on a metal surface, which is treoretically a good barrier for blocking air and water. Besides, silica has a very high surface area that could provide a large number of silanol groups for the film formation on various aluminium alloys. Therefore, silica has an excellent potential as corrosion inhibitor.