A high surface area superparamagnetic mesoporous spinel ferrite synthesized by a template-free approach and its adsorptive property

Magnetic mesoporous spinel NiFe₂O₄ of high surface area (up to 301.6 m² g^-1) and well-defined pore size distribution maximized at 2.5-16.2 nm has been synthesized by a facile oxalate decomposition process from corresponding single-phase multi-component precursor without using any pore-generating template. XRD, DSC-TG, SEM, EDS, TEM, VSM and N₂ sorption isotherm techniques were employed to characterize the precursor and resulting composites. The mesoporous material showed good adsorptive property for acid orange 7 (AO7) and can be used as a magnetically separatable adsorbent to treat AO7 contained wastewater. AO7 adsorbed on the adsorbent can be facilely removed by thermal decomposition and the synthesized mesoporous NiFe₂O₄ can be easily recycled with maintained adsorption property.