Affinity Augmentation of ZnFe2O4 Nanoparticles Toward Hexavalent Chromium Through a Facile Bi3+ Doping Process

A facile method to prepare activated ZnFe₂O₄ nanoparticles through novel metal ion doping using Bi³⁺ is demonstrated. The enhanced activity of the Bi³⁺-doped ZnFe₂O₄ nanoparticle was evaluated through Cr(VI) ions adsorption capability analysis from aqueous samples since industrial effluents have the metal ion as a major source of concern. ZnFe_2-xBi_xO₄ (x = 0.0, 0.05, 0.10, 0.15, 0.2) were synthesized using sol gel method, and a comparative adsorption efficiency study of Bi³⁺-doped and undoped ZnFe₂O₄ was performed. To understand the variation in adsorption efficiency and mechanism of adsorption on the Bi³⁺-doped ZnFe₂O₄, the adsorption study was conducted under varying adsorption conditions including pH, adsorbent dosage, contact time, initial ion concentration, and temperature. All the quantification studies regarding the adsorption were done using atomic adsorption spectroscopy (AAS). The studies suggested enhanced adsorption capability via Bi³⁺ doping as it can enhance the effective surface area and electrostatic charge density on the surface. Adsorption equilibrium information from this study was modeled using prominent adsorption kinetics and isotherm models, for extracting information regarding the performance of the adsorbent, rate of the adsorption and adsorption mechanism, which are imperative in the design and operation of adsorption systems. Scope of regeneration and reusability of the spent adsorbents in water treatment, which is also investigated in this work, addresses the ecological and economic demands for sustainability and also makes the wastewater treatment process cost effective.