Synthesis by Sol-Gel and Coprecipitation of Zn1−xFexO Nanoparticles for the Adsorption of Congo Red Dye

POTILISKI, CARLA YAMILA; KRAMER, GUSTAVO RAÚL; BRUERA, FLORENCIA ALEJANDRA; ZAPATA, PEDRO DARÍO; ARES, ALICIA ESTHER

Processes

MDPI AG

Lugar: Berna; Año: 2025 vol. 13

The influence of synthesis method on the properties of Zn1−xFexO nanoparticles withdifferent Fe doping levels (x = 0, 0.01, 0.03, and 0.05) for Congo Red (CR) adsorption wasinvestigated. Nanoparticles were prepared by sol–gel and coprecipitation and characterizedby XRD, SEM-EDS, FTIR, and BET analyses. Sol–gel synthesis produced smallerparticles (~13 nm) than coprecipitation (~35 nm), and both the method and calcinationtemperature strongly affected crystallite size. Sol–gel nanoparticles showed significantlyhigher adsorption efficiency (~90%) due to their larger BET surface area, greater BJH porevolume, and smaller particle size, which increased the number of accessible active sites.In contrast, coprecipitation nanoparticles exhibited a much lower adsorption capacity(~24%). Fe incorporation further enhanced performance by introducing lattice distortionsand oxygen vacancies, as evidenced by XRD peak broadening and increased lattice strain.SEM images displayed particle growth and compaction after adsorption, particularly indoped samples. Temperature-dependent experiments indicated that undoped ZnO lostefficiency at 60C due to weak physical interactions, whereas Fe-doped nanoparticlesmaintained high adsorption, due to improved stability of the adsorbent-adsorbate bond.The combination of Fe doping and sol–gel synthesis significantly improved the propertiesof ZnO, yielding highly efficient adsorbents suitable for environmental remediation.