S. Rajendran, S. S. Syed Abuthahir,  S.SyedZahirullah, C.Vignesh, K.J.Vikrant, R.Vignesh,

ABSTRACT

The main oxidation states of iron are Fe2+ (ferrous) and Fe3+ (ferric). When these ions interact with a base ferrous hydroxide (Green –Fe (OH)2 and ferric hydroxide (brown- Fe(OH)3 will be produced. Conversion of Fe2+ into Fe3+ is very easy and it can take place even by oxygen present in air or water (Aerial Oxidation). Iron hydroxides have been produced by electrochemical method. An aqueous alkaline sodium chloride solution as electrolyzed using graphite cathode and mild steel anode at room temperature. During this process a green precipitate of ferrous hydroxide was produced. During electrolysis iron is converted into Fe2+ which reacts with OH- ion (NaOH) present in the solution. After sometime the solution turned brown due to formation of ferric hydroxide. This oxidation is possible by the presence of dissolved oxygen present in the solution. Moreover during electrolysis of sodium chloride solution, Cl+ is produced which oxidizes ferrous into ferric. This ferric hydroxide has been converted into other forms of iron oxide namely ?-FeO(OH), ?-FeO(OH) and finally magnetic oxide of iron (Fe3O4). These iron oxides have been analyzed by FTIR and SEM. The particle size of this iron oxide is in the range of Nano particles. These iron oxides will be useful in agriculture. They will increase the soil fertility various microorganisms which increase the soil fertility (Iron reducing bacteria) namely Geobacter bemidjiensis, Geobacter metallireducens, Geobacter sulfurreducens, Shewanella oneidensisMR-1 and Shewanella putrefaciens, etc., live on this iron oxides. The electron released by these bacteria is accepted by ferric iron, whereby it is reduced to ferrous. Thus this ferrous ferric iron equilibrium is very helpful for the metabolism of various microorganisms such as iron reducing bacteria. These ferrous-ferric electron transfer equilibrium can be used to convert harmful Cr6+ into harmless Cr3+. This concept will bring revolution in tannery effluent treatment industry. This process is an electrochemical process and it can be started and stopped at any time. Hazardous chemicals are not used. The products are environmental friendly. Hence this process is considered as green approach. Keywords: Green Synthesis, Iron oxides, Nanoparticles, Soil fertility, environmental friendly process.