Magnetic biochar derived from Juglans regia for the adsorption of Cu2+ and Ni2+: Characterization, modelling, optimization, and cost analysis

Abstract

Objectives: Indian agricultural wastes such as Juglans regia shells get attention frequently because they can be used as adsorbents. This study aimed to prepare magnetically modified iron oxide immobilized biochar adsorbent using Juglans regia shells and investigate its adsorption capacity for Cu2+ and Ni2+ removal from synthetic wastewater contaminated with metals. Methods: As part of the investigation of the properties of the prepared material and its role in the adsorption process, it was characterized with FTIR, FESEM, EDX, XRD, BET, and VSM techniques. A batch adsorption method was examined by varying pH (2–12), adsorbate concentration (10–100 mg/L), contact time (5–240 min), and temperature (288–308 K). Results: A pH of 6 and an initial concentration of 50 mg/L, as well as equilibrium times of 120 and 150 min, resulted in 98.30 % copper removal and 98.10 % nickel removal, respectively. It was found that both Cu2+ and Ni2+ adsorption was governed by Langmuir's isotherm and obeyed the pseudo-second-order kinetic model. In terms of thermodynamic parameters, it appears that the adsorption of Cu2+ and Ni2+ took place in an endothermic and physical manner. The thermodynamic study determined that the activation energy (KJ/Mol) for Cu was 117.27 and for nickel was 100.24. Using Box-Behnken response surface methodology, the experiments were statistically optimized. Based on the cost estimation study, the prepared adsorbent can be used in metal-contaminated water at a cost-effective rate. Conclusion: Therefore, the prepared magnetic biochar will be useful for the adsorptive removal of Cu2+ and Ni2+ from electroplating wastewater.