Highly adsorptive removal of Congo red from aqueous solution using TiO2 doped with Fe3+ nanoparticles

Fe3+-doped TiO2 nanoparticles (NPs) were synthesized via the solvothermal method to develop a cost-effective adsorbent for Congo red (CR) removal from aqueous solutions. The synthesized NPs were characterized by XRD, FTIR, FE-SEM, EDXS, and nitrogen adsorption isotherms. Results confirmed that the incorporation of Fe3+ into the TiO2 lattice effectively decreased the particle size, increased the Brunauer-Emmett-Teller (BET) surface area, and therefore improved the adsorption capacity of TiO2 doped with Fe3+. The anatase nanocrystalline phase with spherical-shaped particles of a mean diameter of 14.8 nm was produced for Fe3+-doped TiO2. The analysis of nitrogen adsorption isotherms revealed that the BET surface area of TiO2 doped with Fe3+ was as high as 194.82 m(2).g(-1), which was larger than that of pure TiO2 (161.36 m(2).g(-1)). The equilibrium adsorption data were compatible with the Langmuir isotherm model; the maximum adsorption capacity of CR by TiO2 doped with Fe3+ reached 400 mg.g(-1) at 30 C, which was considerably higher than that of pure TiO2 (238 mg.g(-1)). Moreover, the equilibrium adsorption time of as-synthesized Fe3+-doped TiO2 NPs was significantly shorter than that of other metal oxides nanostructures in previous works, making them excellent candidates for wastewater treatment. Further studies demonstrated that the adsorption of CR onto the TiO2 doped with Fe3+ followed a pseudo-second-order kinetic model; the negative values of delta G and positive values delta H indicated that the adsorption of CR by TiO2 doped with Fe3+ was spontaneous and endothermic in nature.

Automated summary

Fe3+-doped TiO2 nanoparticles were synthesized as a cost-effective adsorbent for the removal of Congo red from aqueous solutions. The Fe3+ incorporation effectively decreased particle size and increased the BET surface area of TiO2, improving its adsorption capacity. The as-synthesized Fe3+-doped TiO2 NPs showed a shorter equilibrium adsorption time and higher adsorption capacity compared to pure TiO2, making them excellent candidates for wastewater treatment.