Decolorization potential of reactive dyes by using galvanising industry's waste (aluminum hydroxide sludge) depending on dye chromophore

Abstract

The galvanising industry's wastewater treatment facilities generate waste metal hydroxide. These sludges have the potential to be used to remove textile dyes from effluents. In this study, three reactive dyes, which are frequently used in cellulosic textile materials' dyeing, Remazol Turquoise Blue G 133% (CI RB21), Remazol Red 3B (CI RR23), and Remazol Red 3BS 133% (CI RR239) were used to investigate the color removal efficiency of aluminum hydroxide sludge (AHS) depending on dye chromophore. Adsorption studies were conducted under varying conditions of pH, initial dye concentrations, and AHS doses. The characteristics of the AHS were examined by SEM (EDX and DX-Mapping), BET, XRD, and FTIR. The maximum dye removal was achieved at pH 3 for CI RB21, and at pH 5 for CI RR239 and CI RR23. Over 90% of dye removal was obtained for CI RR239 and CI RB21, when the adsorbent dosages were 8 g/l and 5 g/l, respectively. For CI RR23, the highest color removal percentage was only 72.7%, when the dosage of adsorbent was 10 g/l. It was also determined that at 500 mg/l initial CI RB21 dye concentration, the removal percentage of CI RB21 reached 95%, while the maximum removal percentages (95% for CI RR239 and 68.3% for CI RR23) were achieved at the 200 mg/l and 100 mg/l initial dye concentrations for CI RR239 and CI RR23, respectively. In the study, it was observed that the number of sulfo groups affecting the ionic charge of dye molecules and molecular weights of the dyes have a significant effect on the dye removal efficiency.