Decolourisation of Direct Orange S dye by ultra sonication using iron oxide nanoparticles

Biosynthesised iron oxide nanoparticles (INPs) less than 100 nm were used to decolourise the textile dye, Direct Orange S by the process of ultra sonication. The parameters tested for the decolourisation of the Direct Orange S dye were the INP concentration (0.2–1g/l), pH (3–11) and H2O2 concentration (2–8 ml/l). The rate of decolourisation process was performed by both stirrer and ultra sonicator method using the first-order kinetics ln(c/c0). The percentage of dye removal for the optimum conditions such as INP, 1g/l (87.2%); pH, 9 (85.5%) and H2O2 concentration 8 ml/l (86.5%) were observed. The Direct Orange S dye was degraded efficiently by sonolysis (60 min) than by the magnetic stirrer method (120 min). High-performance liquid chromatography results showed that the peak for Direct Orange S dye was not present when the dye sample was treated by either H2O2 + INP or INP alone. Use of biosynthesised iron NPs in Direct Orange S dye (azo dye) decolourisation by a simple non-toxic Fenton reaction is a safe and novel approach. Industrialisation of this technique will be an economical way to decolorise the textile dyes present in water systems.