Removal of textile dyes applying oxidative photochemical processes (UV/H2O2/commercial steel wool)

摘要

The discoloration/degradation of aqueous solutions of synthetic textile dyes for cold dyeing (Dark Blue, Orange and Strong Red) was accomplished by an oxidative photochemical process in heterogeneous phase using UV light or direct sunlight, hydrogen peroxide and commercial steel wool for domestic use as a Fe source. Solutions (1 g L-1) were conveniently characterized by its Color index. The effect of the concentration of the oxidant added and the mass of steel wool in the system were evaluated, and the optimal conditions for each dye discoloration/degradation were determined. Discoloration percentages higher than 85% were achieved both when the reaction was assisted by radiation UV (germicidal lamps) as when the system was exposed to direct sunlight. The final degradation of the discolored samples was determined by measuring the decrease in the absorption band at 254 nm as an indicator of the rupture of aromatic rings. The photodegradation processes presented in this work, carried out in the presence of zero-valent iron (commercial steel wool), constitutes an example of an environmentally benign technology.