Synthesis of iron nanoparticles using iron recovered from rust: An application for the catalytic degradation of phenols.

Iron nanoparticles are reported to be synthesised by green route to reduce adverse environmental impacts as well as to reduce the synthesis cost. The present study explores a secondary source of iron, i.e. waste iron rust to prepare iron nanoparticles via green route. The iron nanoparticles synthesised this way were amorphous. The synthesised nanoparticles were used as a heterogeneous catalyst for the purpose of phenol and p-nitrophenol (PNP) degradation in their aqueous solutions by Fenton degradation. More than 95% of phenol and PNP was removed within 120 min using 0.25 g/L amount of catalyst. The degradative removal of both the pollutants was found effective up to pH 6. Pseudo-second-order kinetic was fitted best the degradation data of the pollutants. The dissolution of catalyst iron by corrosion was analysed by testing the amount of iron leached and dissolved into the aqueous solution of phenol and PNP; maximum concentration of total iron was found 11.10 mg/L in phenol and 13.53 mg/L in PNP. The chemical oxygen demand (COD) was decreased to 40 mg/L from 336 mg/L for phenol and COD of PNP solution was decreased up to 56 mg/L from 384 mg/L.