Abstract
Color removal of an aqueous solution containing water-based inks, a mixture of resins, pigments, and dyes, was investigated by using metal hydroxide sludge, which is a waste from the electroplating industry. High color removal (>93%) was shown within 5 min from 30 mg/L ink solution using 0.3 g of metal hydroxide sludge/50 mL of ink solution, and an agitation rate of 90 rpm for a wide range of initial solution pH values (4–10). Color removal efficiency was lower at a higher temperature (40–50°C) and larger particle sizes of metal hydroxide sludge. The maximum adsorption capacity for the red ink was 34.48 mg/g of metal hydroxide sludge. Comparison with conventional flocculants shows that metal hydroxide sludge was most effective in removal of color. Trends for color removal for red, blue, and yellow inks were similar. Treatment of water-based ink wastewater from a real flexographic printer was achieved by coagulation of the highly turbid wastewater with 0.05% (v/v) of sulfuric acid and using 3% (w/v) of metal hydroxide sludge to remove the residual color. This resulted in the optimum color, pH, and COD values of treated water with heavy metals below the standard limitations.
Get full access to this article
View all access options for this article.