Kinetic and isotherm modelling of the adsorption of congo red dye onto NiFe2O4 and NiFe2O4 decorated exfoliated graphite

Abstract

Adsorption using novel materials is a common and highly applicable process in remediation of hazardous dyes in wastewater. Herein, we attempted the synthesis of NiFe2O4 decorated-exfoliated graphite (EG@NiFe2O4), an inexpensive and environmental benign material, and analyzed the adsorption process of the as-synthesized adsorbent against Congo red dye. Kinetic of the adsorption was investigated using various models including first-pseudo kinetic, second-pseudo kinetic, Bangham model and Elovich model. Isotherm of the process was evaluated by Langmuir, Freundlich, Temkin and Dubinin − Radushkevich model. Lastly, thermodynamic parameters of the adsorption towards Congo red dye was calculated. Our findings indicated that kinetic and isotherm of the adsorption process of both adsorbents (EG@NiFe2O4 and NiFe2O4) could be well explained by the pseudo-second-order model (R2 > 0.99) and Langmuir isotherm (R2 =) respectively. In addition, kinetic parameters showed that EG@NiFe2O4 possesses greater adsorption capacity in comparison with NiFe2O4. Estimated thermodynamic parameters also indicated the spontaneous and endothermic adsorption (∆G=) of the EG@NiFe2O4 composite against Congo red dye.