Use of nano-magnetic materials for removal of Congo red dye from aqueous solutions

Abstract Sol–gel auto-combustion was used to create ferrite nanoparticles with the structure Co 0.5 Cr 0.5 Fe 2 O 4 using lemon juice as a fuel agent and surfactant. It was investigated whether the generated nanomaterials could absorb Congo red dye. Different techniques were used to characterize the prepared nanocomposite x-ray diffraction (XRD), FE-SEM, EDX, FT-IR and Zeta Potential. The XRD characterization proved the phase purity of the prepared material, the particle size was 28.34 nm. The study dealt with the use of the prepared compound as an adsorbent surface for Congo red dye from its aqueous solutions. Freundlich and Langmuir equations were applied to the adsorption process data for different temperatures. The results showed that the Langmuir equation is more linear than the Freundlich equation. In addition, the thermodynamic results showed that the adsorption of Congo red dye was spontaneous, as the value of (Δ G ) was negative at low concentrations before turning to a positive value with increasing concentrations. Also, the adsorption process was endothermic and increased in randomness through the positive value of (Δ S ). The adsorption results showed that equilibrium was reached in 300 min and that the removal of Congo red dye constituted 84.24% of the total. The possibility of reusing the prepared compound several times was studied, and the results showed the possibility of activating the surface while maintaining its properties as a good adsorbent surface.