Synthesis and phosphorus adsorption of coal-fly-ash magnetic adsorbents
Magnetic phosphorus adsorbent coal-fly-ash magnetic sphere@La2O3(CMS@La2O3) was synthesized by a chemical precipitation method, using CMS as magnetic core. Structural and magnetic characterization shows that Lanthanum oxide is uniformly coated on the surface of CMSs. The magnetism of the prepared CMS@La2O3is measured as 20.35 emu • g-1, which is strong enough for effective magnetic separation. The F adsorption performance of the CMS@La2O3was investigated by the ammonium molybdate spectrophotometric method. It is found that the P adsorption of CMS@La2O3is closely related to the adsorption time, pH value, and coexisting anions in the wastewater. The highest P adsorption was measured as 19.50 mg•g-1. CO32-and SO42-in the waste water could sharply reduce the P adsorption even in a very low concentration by occupying the P-adsorption site; on the La2O3surface, while the existing of Cl-ions has very little effect on the P adsorption. The P adsorption of CMS@La2O3is well accordant with the pseudo-second order kinetics equation, indicating that it is dominated by the chemical adsorption. The adsorption reaction could be explained by the "surface hydmxylation-ion exchange" model on the La2O3surface. The used CMS@La2O3adsorbent could be recycled for several times after appropriate treatment.