Modeling sorption of select basic dyes onto alternative materials

Abstract

This study aims to identify and analyze potential alternative sorbents for basic dye removal from effluents. The textile industry releases large volumes of dye containing effluent every year. These dyes are designed to be highly stable and resist degradation, creating a removal challenge. Basic, or cationic, dyes are one of the most toxic classes of dye. One of the most popular methods of dye removal is sorption. Due to the high cost of common sorbents, such as activated carbon, it is necessary to analyze alternative sorbents. The sorption of three different basic dyes (basic blue 9, basic yellow 1, basic red 2) were studied on four sorbents (tea, coffee, banana peel, and AC) in 8-day experiments. AC had the greatest sorption affinity of all three dyes, but reached its sorption capacity at 5,000 mg/L for basic blue 9, 440 mg/L for basic yellow 1, and 480 mg/L for basic red 2. The other sorbents were not found to reach sorption capacity for the concentration levels investigated in this study. The Freundlich isotherm model best represented the obtained experimental data. This model was then used to compare sorption affinity, KF, to various physical chemical characteristics to create predictive models for other basic dyes. These models were also used to determine the most likely primary sorption mechanism for each sorbent; physisorption for AC, ion exchange sorption for tea, coffee, and banana peel.