A kinetic and thermodynamic investigation for adsorption of cadmium (ii) ions on the microwave modified sugar cane bagasse

Abstract

In the current research work, urea-treated microwave-modified sugar cane bagasse (MSCB), an agricultural waste, is employed as low-cost adsorbent for removing Cd (II) ions from reaction media. In this research work, the comparative analysis of MSCB and unmodified sugar cane bagasse (USCB) were studied at the same time and comparison was made for investigating the better adsorption performance using Cd (II) ions as model contaminant. Different parameters affecting the removal of Cd (II) ions including time, pH, and dose were studied. Results indicate that MSCB required less extreme conditions for effective working as compared to USCB. The optimal adsorbent dose was 0.4 g while the working pH was in the range of 6–7. The MSCB showed higher calculated adsorption capacity of 37.037 mg/g while lower value of 15.384 mg/g was found for USCB. Kinetic data showed that this adsorption reaction was endothermic, feasible and spontaneous. The ∆H⁰, ∆S⁰ and ∆G⁰ values for USCB was found to be − 14.998 kJ/mol, 54.68 J/kmol and − 3.255 KJ/mol whereas, the values for MSCB were − 18.789 kJ/mol, 69.94 J/kmol, and − 2.104 KJ/mol, respectively. The higher values for MSCB showed its excellent efficiency towards removal of Cd(II). However, it has been observed that both adsorbents exhibited best correlation with the Langmuir and Freundlich model of adsorption. Hence, this work provides a novel and excellent adsorbing material for adsorption of Cd (II) ions from aqueous medium.