Synthesis and characterization of antibacterial chromium iron oxide nanoparticle-loaded activated carbon for ultrasound-assisted wastewater treatment

The aim of this study was to evaluate the surface adsorption capacity of CrFeO3 nanoparticle-loaded activated carbon (CrFeO3-NPs-AC) for the removal of a cationic dye (methyl violet, MV). CrFeO3-NPs were hydrothermally synthesized and loaded on AC followed by characterization using X-ray diffraction, field-emission scanning electron microscopy and energy-dispersive and Fourier transform infrared spectroscopies. The CrFeO3-NPs were tested for in vitro antibacterial activities against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria. Minimum inhibitory and minimum bactericidal concentrations of CrFeO3-NPs-AC were obtained to be 50 and 100 g ml(-1), respectively, against S. aureus and 25 and 50 g ml(-1) against P. aeruginosa. These results indicated the antibacterial properties of CrFeO3-NPs-AC. To investigate the adsorption process, several systematic experiments were designed by varying parameters such as adsorbent mass, pH, initial MV concentration and sonication time. The adsorption process was modelled and the optimal conditions were determined to be 0.013g, 7.4, 15mg l(-1) and 8min for adsorbent mass, pH, MV concentration and sonication time, respectively. The real experimental data were found to be efficiently explained by response surface methodology and genetic algorithm model. Kinetic studies for MV adsorption showed rapid sorption dynamics described by a second-order kinetic model, suggesting a chemisorption mechanism. Then, the experimental equilibrium data obtained at various concentrations of MV and adsorbent masses were fitted to conventional Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. Dye adsorption equilibrium data were fitted well to the Langmuir isotherm. From the Langmuir model, the maximum monolayer capacity was calculated to be 65.67mg g(-1) at optimum adsorbent mass.