Filiz Nuran Acar

Sonocatalytic degradation of Direct Blue 71 azo dye at the presence Zero-Valent Iron (ZVI)

AbstractThe sonocatalytic degradation of Direct Blue 71 (DB71) azo dye has been studied in the presence of low-frequency ultrasound (20 kHz). An initial concentration of 50 mg L−1 of dye, within the range of typical concentration in textile wastewaters, was used. Batch sorption studies were conducted to study the effects of various parameters such as Zero-Valent Iron (ZVI) dose, pH, and effect of different power levels (20, 55, and 95 W), on DB71 oxidation. Oxidation of DB71 with the assistance of ultrasound was enhanced with the increase in ZVI initial concentration and ultrasonic power, and with the decrease in pH. It was observed that the color removal efficiency was influenced by the solution H2O2 amount. Accordingly, removal of 91.2% color and 97.2% total organic carbon (TOC) of dye was achieved by applying the optimal operational parameters with 0.3 g L−1 of catalyst, 2.5 pH and 25°C, during 20 min. In hybrid study, the color removal yield of 100% was obtained by combination of US/ZVI/H2O2 at dyestu...

Degradation of Textile Dyes, Dyebaths and Dyeing Wastewater by Homogeneous and Heterogeneous Sonophotolysis

Abstract The degradability of an azo dye (C.I. Acid Black 2), synthetic and real dyebaths, and actual textile dyeing wastewater were investigated using a homogeneous and heterogeneous Advanced Oxidation Processes (AOPs) in combination with power ultrasound (US). The components of the homogeneous process were US, short wave UV-C and ferrous ions, and those of the heterogeneous were US, short wave UV-C, ZnO and H2O2. It was found that decolorization of all solutions followed a kinetic pattern similar to that of pseudo-first order profile with, however, stabilization of the visible absorbance at a non-zero plateau. The estimated color decay rate constants of the dye and the synthetic dyebath in homogeneous and heterogeneous processes were 0.479 min-1, 8.52 min-1 and 0.0799 min-1, 0.0193 min-1, respectively. More rapid degradation of the dye solution than the dyebath in heterogenous processes is a consequence of the presence of auxiliary chemicals in the latter that may scavenge OH radicals and absorb UV light. It was also found that real dyebath solutions were more recalcitrant than dyeing wastewater due to the intense color of the former. The COD removal efficiencies of the dyebath and wastewater were 1-3% and 40%, respectively after 2 h treatment with US/UV/Fe2+ homogeneous hybrid process. The heterogeneous hybrid process US/UV/ZnO/H2O2 provided 10-12% COD elimination in both the dyebath and the wastewater within the same time period.

Color and COD Removal of Azo Dye ‘Basic Blue 9’ by Fenton Oxidation Process: Determined of Optimal Parameters and Kinetic Study

Abstract Advanced oxidation of an azo dye, Basic Blue 9 (BB9) by Fenton oxidation was investigated in batch experiments. The UV-vis spectral changes of in aqueous solution during Fenton process were studied. It was easier to destruct the azo linkage group than to destruct the aromatic rings of (BB9) by Fenton process. The effects of different reaction parameters such as initial ferrous concentration, initial hydrogen peroxide (H2O2) concentration, initial pH, the initial (BB9) concentration and the temperature on the oxidative degradation of (BB9) have been assessed. The optimal reacting conditions for the color and COD removal were determined and it was found to be initial pH = 3.0, H2O2 = 100 mgL-1, Fe2+ = 3 mgL-1 at 20 °C temperature for 100 mgL-1 initial dye concentration. pH is highly effective parameter of color and COD removal in this work. Under optimal conditions, 100% color and 91% COD efficiencies of dye in aqueous solution were achieved within 20 min reaction time. The color removal kinetic of azo dye, (BB9), has also been investigated in the different H2O2 concentration. Kinetic data were studied using Behnajady-Modirshahla-Ghanbery model for color removal. It has been found that experimental kinetic data are represented well by Behnajady-Modirshahla-Ghanbery kinetic.