Decolorization of Reactive Orange 16 and Reactive Black 5 in aqueous solution by ozonation

Abstract

Textile industry is one of the most chemically intensive industries on Earth and the major polluter of potable water.There are many methods for dye removal in the textile industry. One of the most effective methods is colour removalby ozonation. The application of ozonation has increased in recent years. Preference of the ozonation method is theefficiency of colour removal and the short application time. In ozonation process, not only colour but also the toxicitycaused by products of treated wastewater is important. So, suitable ozonation period must be obtained. The aim ofthis study is the removal of Reactive Black 5 (RB-5) and Reactive Orange 16 (RO-16) from the synthetic aqueoussolution by ozonation. In this study, dye removal (%) and chemical oxygen demand (COD) removal (%) weredetermined and carried out by kinetic analyzing. The maximum dye removals were 99.9 % and 99 % at all pH valuesin initial dye concentration of 100 mg $L^{-1}$ for RB-5 (40 min) and RO-16 (70 min), respectively. It was found that CODremoval is 100 % for both dyes. Ozonation kinetics were studied and it was found that it agreed with the pseudo firstorder kinetics for two dyes. The highest pseudo first order kinetic constants are 0.1918 $min^{-1}$ ($R^2$: 0.9978, pH:2) and0.0794 $min^{-1}$ ($R^2$: 0.9918, pH:6) for RB-5 and RO-16, respectively. The results obtained in this study showed thatozonation of reactive dyes at acidic or neutral pH was more suitable than that of alkaline pH.