Preparation and performance of magnetic zirconium-iron oxide nanoparticles loaded on palygorskite in the adsorption of phosphate from water

Magnetic zirconium-iron oxide nanoparticles loaded on palygorskite as a low-cost adsorbent was produced by one-step co-precipitation technique and its properties for phosphate adsorption were overall investigated. The Brunauer Emmett Teller (BET) specific surface area analysis, scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the adsorbent and evaluate the adsorption interactions. The influences of pH, ionic strength and coexisting ions on phosphate adsorption were measured with a discussion of the adsorption mechanism. Results indicated that no very noticeable changes on the surface properties, structure and phosphate adsorption capacity be found for the magnetic zirconium-iron oxide nanoparticles loaded on palygorskite or not. The adsorption kinetics fitted to the pseudo-second-order model and adsorption isotherm followed Langmuir equation and Dubinin-Radushkevich equation. The phosphate adsorption was slightly affected by ionic strength and highly dependent on pH, i.e. increasing pH sharply restrained adsorption under neutral and alkaline conditions. The surface OH groups in the adsorbent processed an important role in adsorption and the adsorption mechanism conformed to ion exchange and complex. The adsorbent could be conveniently regenerated and effectively reused. (author)