Research On The Preparation Of Nickel Ferrite Composite And Its Adsorption Performance

In recent years, water pollution is getting worse and dye wastewater has become a major source of water pollution. Adsorption is the most common kind of dye wastewater treatment technology because of its high efficiency, low cost and ease of operation, but the traditional adsorbent suffers from high cost of regeneration, difficult recovery and low adsorption selectivity. Therefore, the use of novel functional magnetic materials with the advantage of high efficiency, high selectivity and easy recovery in dye wastewater treatment has become increasingly concerned by researchers.The activated carbon（AC）/NiFe₂O₄, NiFe₂O₄/polyaniline（PANI） and NiFe₂O₄/PANI/Ag composite were synthesized via hydrothermal method, situ chemical oxidation polymerization and chemical reduction method, respectively. The as-prepared composites were characterized and analyzed by vibrating sample magnetometer（VSM）, X-ray diffraction（XRD）, pore structure and specific surface area analysis and Fourier transform infrared spectroscopy（FT-IR）. The absorption property of the composites for azo dyes removal was studied.Results indicate that ionic strength nearly has no influence on the adsorption of methyl orange by AC/NiFe₂O₄. The removal efficiency of methyl orange can be achieved above 99 % with the initial pH of 3 and the adsorbent dosage of 0.3 g, while the time of equilibrium adsorption is only 20 min. The adsorption of methyl orange by AC/NiFe₂O₄ conforms to the Langmuir adsorption model, which suggested that the adsorption is monolayer coverage. 0<R_L<1 and 0.1<1/n<0.5 indicate that the adsorption is favorable and belongs to preferential adsorption. The thermodynamic behavior analysis indicates that the adsorption of methyl orange is a spontaneous and endothermic process. The adsorption process of AC/NiFe₂O₄ for methyl orange presented an ideal fit to the pseudo-second-order model and controlled by both intraparticle diffusion procedure and film diffusion procedure. AC/NiFe₂O₄ still remains good magnetic properties and ability of adsorption of methyl orange after regenerated six times by 0.1 mol/L NaOH solution, the removal efficiency can reach 85.10 %.When the adsorbent dosage is 0.3 g, the removal percentage of methyl orange can be achieved above 96 % at 308 K and the adsorption equilibration time is 30 min. The adsorption of methyl orange on NiFe₂O₄/PANI conforms to the Langmuir adsorption model, which suggests that the adsorption is monolayer coverage. 0<R_L<1 and 0<1/n<0.5 indicate that the adsorption is favorable. The thermodynamic behavior analysis indicates that the adsorption of methyl orange is a spontaneous and endothermic process. The adsorption process of NiFe₂O₄/PANI for methyl orange fits to the pseudo-second-order model and mainly controlled by intraparticle diffusion procedure. NiFe₂O₄/PANI still remains good removal efficiency of methyl orange after regenerated by 0.1 mol/L HCl solution.The increasing of ionic strength promotes the adsorption of congo red by NiFe₂O₄/PANI/Ag. And the lower the temperature is, the better the adsorption efficiency is. Congo red adsorbed on NiFe₂O₄/PANI/Ag conforms to both the Langmuir adsorption model and the Freundlich adsorption model. The adsorption capacity at 288 K is 207.47 mg/g. 0<R_L<1 and 0.1<1/n<0.5 indicate that the adsorption is favorable. The thermodynamic behavior analysis indicated that the adsorption of congo red is a spontaneous and exothermic process and belongs to the physisorption. The adsorption process of NiFe₂O₄/PANI/Ag for congo red shows a greater fit to the pseudo-second-order model and controlled by both intraparticle diffusion procedure and film diffusion procedure. NiFe₂O₄/PANI/Ag still has certain adsorption capacity of congo red after regenerated by 0.1 mol/L HCl solution.