Sorption of acid dyes from effluents using activated carbon

The sorption of three acid dyes, namely, Acid Red 114, Polar Yellow and Polar Blue RAWL, onto activated carbon, has been studied. Equilibrium isotherms have been measured for three single component systems (AB, AR, AY) and one binary component system (AB+AY). The isotherms were determined by shaking 0.05 g activated carbon, particle size range 500–710 μm, with 0.05 dm 3 dye solution of initial concentrations from 10 to 250 mg/dm 3. A constant temperature agitating 400-rpm shaking water bath was used and the temperature maintained at 20±2°C. A contact time of 21 days was required to achieve equilibrium. Analysis of data has been carried out in two stages. (a) In single component analysis, the experimental isotherm data were analysed using Langmuir, Freundlich, Redlich-Peterson, Temkin and Dubinin-Radushkevich equations for each individual dye. The monolayer adsorption capacities are 101.0 mg Acid Red per g carbon, 100.9 mg Acid Blue per g carbon and 128.8 mg Acid Yellow per g carbon. (b) In multicomponent analysis, one binary system has been analysed using an extended form of the Langmuir equation. The correlation between theoretical data and experimental data only had limited success due to competitive and interactive effects between the dyes and dye-surface interactions.