以零價鐵脫色Acid Black 24偶氮染料廢水之研究

Abstract

The wastewater from textile dyeing industry is difficult to be treated successfully according to both high variability of composition, color intensity and biological toxicity. Traditionally, textile industries employ chemical coagulation with biological treatment to deal with this refractory wastewater. Unfortunately, the effluents form this type of wastewater treatment processes can not meet the effluent discharge standards. In this study, we observed the successful decolorization and TOC removal of the diazo dye, C.I. Acid Black 24 (AB24) by zero-valent iron (ZVI) addition while evaluating the experimental variables such as iron dosage, initial dye concentration, pH, and reaction time. From the results, the decolorization of AB24 was observed sharply at first 25 minutes. After 25 minutes of reaction, the color removal was insignificant for longer reaction time. The higher the iron dosage, the higher the color removal efficiency was achieved. The color removal efficiency was dependent on iron dosage and various initial dye concentrations simultaneously, though the color and TOC removal efficiencies linearly increased by elevating iron dosage till 100.0 g l^(-1), they reached the maximum equilibrium in spite of sequential iron increase. Because of better dissolution of zero valent iron, the decolorization was more efficient at lower pH. For higher pH of 10.2, the decolorization was less efficient than lower pH. For reaction time of 60 minutes, the TOC removal of AB24 was very effective to reach about 50 % TOC removal for initial dye concentration of 25.0 mg l^(-1). The best removal efficiencies of color of 96.9 % and total organic carbon (TOC) of 45.0 % were obtained with initial dye concentration of 50.0 mg l^(-1)and iron dosage of 200.0 g l^(-1).