Modification of Adsorptive Properties of Bagasse Fly Ash for Uptaking Cadmium from Aqueous Solution

Abstract

Novel low-cost adsorbents were developed from industrial bagasse fly ash (BFA) waste using facile chemical modification. The uptaking of cadmium from wastewater using pretreated BFA adsorbents was investigated. The influence of solution pH, contact time, initial metal concentration, adsorbent dosage, and temperature on the adsorption performance of Cd (II) onto natural and modified BFA adsorbents was examined by a batch method. Surface properties of developed BFA adsorbents were characterized by the pH_PZC, C, H, N, and S elemental analysis and FTIR spectrum. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models. Results indicated that the Langmuir isotherm fitted best. Chemical modification to BFA with HCl and HNO₃ resulted in enhancing sorption capacity of BFA for Cd (II) uptake from 19.8 to 47.6 and 25.1 mg/g and then decreasing to 11.9 mg/g upon pretreatment with EDTA, respectively. Kinetic studies showed that the cadmium sorption process followed a pseudo-second-order kinetic model. Thermodynamic calculations point towards feasibility of an adsorption process with spontaneous and endothermic nature. Overall, it can be concluded that the modified BFA can be operated as an alternative material to more costly adsorbents used for cadmium (II) in wastewater treatment processes.

DOI: http://dx.doi.org/10.5755/j01.erem.64.2.3576