Acid-Base Properties of the Adsorption of Synthetic Dyes from Solutions

Abstract

The presence of synthetic dyes is often underestimated in environmental protection. However, it has been demonstrated the impact of colored compounds in ecology and human health. Green tea (GT) and peppermint (PM) tea bag wastes were used as potential adsorbents of dyes from aqueous solutions to evaluate the effect of pH on the adsorption. Basic yellow 57, basic blue 99 and crystal violet were chosen as model dyes due to their widespread use in the industry. Dye solutions at different pH values were placed in contact with the adsorbents in batch experiments at room temperature. Results indicate that crystal violet is totally removed from the solution by the adsorbents (100% removal), followed basic blue 99 and basic yellow. PM reports the highest dye removal. Our data was compared to recently published reports, indicating their potential applicability to real wastewaters, as it is optimum at neutral pH values. These results demonstrate that these materials are excellent and cost-effective candidates for the removal of dye pollutants from contaminated solutions.