Abstract
The adsorption behavior of anionic dye congo red (CR) from aqueous solutions using an anion exchange membrane (EBTAC) has been investigated at room temperature. The effect of several factors including contact time, membrane dosage, ionic strength and temperature were studied. Kinetic models, namely pseudo-first-order and pseudo-second-order, liquid film diffusion and Elovich models as well as Bangham and modified freundlich Equations, were employed to evaluate the experimental results. Parameters such as adsorption capacities, rate constant and related correlation coefficients for every model were calculated and discussed. The adsorption of CR on anion exchange membranes followed pseudo-second-order Kinetics. Thermodynamic parameters, namely changes in Gibbs free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) were calculated for the adsorption of congo red, indicating an exothermic process.
Highlights
Improper treatment and disposal of dye-contaminated wastewaters from textile, dyeing, printing, ink and related industries have originated serious environmental concerns worldwide [1,2,3,4,5,6,7,8]
Such behavior is typical from the presence of several adsorption sites on the membrane surface in the initial stage of reaction, which gradually gets saturated with the dye at increasing contact times
21.13 mg/g, with increasing initial dye concentrations from 25 to 50 mg/L. These results indicated dye removal from aqueous solution based on the initial dye concentration, with high values of correlation coefficient (R2 > 0.99), confirming a good fit of experimental data with a pseudo-second-order kinetic model
Summary
Improper treatment and disposal of dye-contaminated wastewaters from textile, dyeing, printing, ink and related industries have originated serious environmental concerns worldwide [1,2,3,4,5,6,7,8]. Fundamental studies are still required to better understand the adsorption mechanisms of some complex dye systems onto membranes (Kinetics, thermodynamics, etc.) in order to implement the use of such technologies at industrial scale. This contribution has been aimed to provide a fundamental study of the use of commercial anion exchange membranes (EBTAC) to remove anionic dyes (congo red (CR) (Figure 1)) from aqueous solutions to mimic wastewater treatment experiments/conditions. It is worth pointing out that congo red, based on benzidine, is banned in several countries because of health concerns and its commercial use is limited
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