Thermodynamic study of some basic dyes adsorption from aqueous solutions on activated carbon and new correlations

Highlights: • Adsorption isotherm data are presented for safranine O and malachite green oxalate dyes. • Thermodynamic parameter (ΔH^o, ΔG^o and ΔS^o) are reported. • A new model based on the principle of phase equilibrium and solution thermodynamics is presented. • New model is giving better correlations than existing A.R. Khan et al., model. - Abstract: The adsorption behaviour of safranine O and malachite green oxalate dyes on activated carbon as a function of temperature for a fixed initial concentration was investigated at T = (303, 313 and 323) K and p = 0.1 MPa through adsorption isotherms and their thermodynamic parameters ΔG^o, ΔH^o and ΔS^o. The isotherms were correlated with a new model based on the principle of phase equilibrium. The new model equation comprising of 4 adjustable parameters correlates the isotherms as a function of temperature, sorbate melting temperature. The overall deviation between the experimental and the correlated results was less than 6.85% in averaged absolute relative deviation (AARD).