This study evaluated the feasibility of Rhodamine-B dye (Rh B) removal from aqueous solution, using Lead-Iron Oxide nanoparticles Loaded Activated Carbon (FePbO@AC). The parameters like pH, contact time, adsorbent/adsorbate dosage and temperature on adsorption was studied. Optimized conditions are pH of 7.0, 25 min contact time, 50 ppm of dye concentration and 200 mg of adsorbent concentration. The kinetics of adsorption was calculated using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The calculations revealed that the pseudo-second-order kinetic equation best-fit the adsorption data. The Langmuir isotherm model best fit the equilibrium data. The maximum sorption capacity (Q_max) for dye is 1000 mg Rh B/g FePbO@AC. Change in entropy (ΔS), Gibb’s free energy change (ΔG), and enthalpy (ΔH) were calculated for the adsorption of Rh B dye. Graphical Abstract

Zn_0.3Fe_0.45O₃ bimetallic oxide nanoparticle (ZnFeBONp) was synthesized and characterized by FESEM, EDS, XRD, BET, TEM and FT-IR techniques with the aim of exploring its application for removing of Congo red dye from waste samples. The effects of pH, contact time, adsorbent dosage and dye concentration on the removal of dye were investigated and optimized as pH 6.5, 40 min contact time, 0.2 g adsorbent dose for 20 ppm dye. Results indicated that the synthesized adsorbent could effectively remove high concentrations of dye in a short contact time. Isotherm modeling revealed that the Langmuir isotherm could better describe the adsorption of the dye on the ZnFeBONp as compared to other models. The q_max up to 333.33 mg g⁻¹. The results showed that the adsorption system followed the Ho and McKay equations for the entire adsorption. Kinetics of Congo red adsorption on ZnFeBONp best fit with the pseudo-second-order model. Because of the high-specific surface area and nano-scale particle size, ZnFeBONp indicated favorable adsorption behavior for dye.