DECOMPOSITION OF AZO DYE DIRECT RED 23 IN THE FENTON PROCESS IN THE PRESENCE OF IRON OXIDE NANOPOWDER

Decoloration problems are important both in the wastewater treatment technology and in water conditioning. Actually, nearly all branches of industry discharge dyestuff to sewage. The type and quantities of the dyestuff vary with the type of industrial plant, production volume and assortment, and applied technologies. Most dyestuff is discharged into sewage by companies that produce it and these which use it. A significant source of colored wastewater is textile industry. The Fenton process is one of the methods to significantly reduce the concentration of pollutants in textile wastewater. It involves not selective and highly efficient oxidation of organic compounds with hydroxyl radicals produced in the chain decomposition of hydrogen peroxide with the participation of divalent iron salt. The process is a radical reaction which generates big quantities of HO center dot hydroxyl radicals that are capable of oxidizing even the most resistant pollutants present in the wastewater. Main advantages of the method include high oxidation efficiency, inexpensive and easily available substrates and simple procedure. Novelty in the oxidation of pollutants by the Fenton method is running it with the participation of iron nanocompounds. The presence of nanoparticles has an influence on the oxidation of many compounds present in water. With the use of iron nanocompounds, the removal of trichlorethylene, phenol, olefin, humic acids, antibiotics and chlorophenols was investigated. The presence of nanoparticles affects also the oxidation of dyestuff in water solutions and industrial wastewater. However, there are relatively few references in the literature on this subject. The aim of our investigations was to determine the decomposition efficiency of azo dye Direct Red 23 by the Fenton method with the use of iron nanocom pounds and to compare it with the classical Fenton method. The azo dyes belong to the group of hardly biodegradable xenobiotics whose efficient removal from wastewater is a necessity. The subject of our studies was azo dye Direct Red 23 used in textile industry. Water solutions of the dye were subjected to treatment by the classical Fenton method and to treatment in the presence of iron(I I, Ill) oxide nanopowder. In wastewater samples before and after the treatment, color was determined by DFZ parameter as well as COD and TOO. The Fenton process was optimized due to studies on the effect of compound used in the treatment, doses of iron and iron(II, Ill) oxide nanopowder, hydrogen peroxide and pH of the solution on decoloration efficiency. It was found that the efficiency of dye decomposition in the processes of treatment in which iron nanocompounds were applied, was higher than in the classical method.