Comparative Study on the Adsorption of Tartrazine and Indigo Carmine onto Maize Cob Carbon

The similarities and differences in the removal of two acid dyes tartrazine (TA) and indigo carmine (IC) from aqueous solutions by active carbon prepared from maize cob was investigated in the study. The effects of initial concentration, contact time, and temperature were discussed. The maize cob carbon (MCC) showed better adsorption performance for IC than TA. The adsorption equilibrium was reached within 80 min for IC and 270 min for TA with an initial concentration of 400 mg/L. The maximum adsorption capacity was 68.78 mg/g for TA and 118.48 mg/g for IC at 25 degrees C on the basis of Langmuir isotherm. The formation of hydrogen bonds was considered to be the predominant influence in enhancing the interaction between IC and MCC. The kinetic studies showed that the adsorption of both dyes onto MCC exactly followed the pseudo-second order kinetic model for all studied concentrations. Thermodynamic studies revealed that the adsorption was a spontaneous and physical adsorption process for both dyes.