Removal of anionic dye eosin Y from aqueous solution using ethylenediamine modified chitosan

In this study, chitosan was cross-linked with ethylenediamine (EDA) to prepare an outstanding sorbent for the removal of anionic dye eosin Y from aqueous solution. FTIR, DTG, XPS and zeta potential analysis were used to characterize the sorbent. The effect of particle size, solution pH, agitation rate, temperature, adsorbent dosage (50–500 mg/L), contact time (10 min–24 h) and initial concentration of dye (50–300 mg/L) on the adsorption process was investigated. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants, and the data fitted well with Langmuir model with a maximum adsorption capacity of 294.12 mg/g at 25 °C. Kinetic studies followed the pseudo second-order rate model, which indicated that the chemisorption is the rate-limiting step. Thermodynamic parameters such as enthalpy change (ΔH° = −5.004 kJ/mol), free energy change (ΔG° < 0) and entropy change (ΔS° = −11.656 J/(mol K)) indicate the exothermic and spontaneous nature of adsorption.