CuFe2O4/EB and PPY/GO/EB materials for the removal of basic fuchsin from wastewater: kinetic, equilibrium and thermodynamic studies

Abstract

In the present investigation, Eucalyptus bark (EB)-based magnetic (CuFe₂O₄/EB) and polypyrrole–graphene oxide (PPY/GO/EB) composites were designed to eliminate BF from aqueous medium. The physicochemical properties of the adsorbents were analyzed via FTIR spectroscopy, SEM, EDX spectroscopy, and TGA. According to the batch adsorption studies, the optimum adsorption parameters were determined to be pH = 5 (EB), 9 (CuFe₂O₄/EB), and 10 (PPY/GO/EB), adsorbent dosage = 0.05 g/50 mL, basic fuchsin (BF) dye initial concentration = 10 mg L⁻¹, contact time = 90 min, temperature = 303 K, agitation speed = 120 rpm, and adsorbent particle size ≤300 μm. The BF adsorption capacity of EB, CuFe₂O₄/EB and PPY/GO/EB was found to be 6.71 ± 0.24, 9.64 ± 0.33 and 9.29 ± 0.31 mg g⁻¹, respectively, with CuFe₂O₄/EB showing the best results. According to isothermal and kinetic studies, the Langmuir and pseudo-second-order models best described the experimental results. According to the thermodynamic study, it was concluded that the adsorption process is spontaneous and exothermic in nature, with ΔG° and ΔH° values of −3.32 ± 0.21 and −75.18 ± 1.8, respectively. Desorption tests revealed that high levels of dye desorption were caused by 0.1 N eluting reagent concentration. To check the functionality of CuFe₂O₄/EB on the pilot scale, a column study was conducted, and the maximum BF uptake attained was 8.93 ± 0.28 mg g⁻¹ at a 3 cm bed height. The Thomas and BDST models fitted the experimental data well. Thus, this study demonstrated that CuFe₂O₄/EB and PPY/GO/EB composites have promising adsorption potential, and this class of adsorbents can be used for the eco-friendly remediation of wastewater containing complex organic pollutants.