Adsorption of fluoride using bimetallic oxide nanoparticles supported on industrial waste prepared by a chemical reduction method

Steel slags (SSs) were used as support materials for Al-Cu oxide nanoparticles (Nps) for fluoride adsorption. The nanocomposites were prepared by a chemical reduction method and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, pH zpc, and surface area, although the surface area did not influence the deposition of nanoparticles. The interactions between the Al-Cu Nps and the waste were identified by X-ray photoelectron scanning (XPS) analysis. In SST, the Nps surrounded the grain boundary. The ferric phases in SSLP limited the deposition of Nps. Al Nps were deposited in larger amounts than Cu Nps. The characteristics of the waste were analyzed to establish the extent to which it can be applied as a support material. The nanocomposites showed better adsorption capacity than did the wastes. The kinetics of the nanocomposites was described by models that were different from those that had been fitted to the kinetic data for SST and SSLP. The equilibrium times for SSLP/Al-Cu and SST/Al-Cu were 380 and 130 min, respectively. The process was described as physisorption for SSLP/Al-Cu and chemisorption for SST/Al-Cu. The rate-controlling step was different before and after modification. The adsorption process for SST and SSLP took place on a heterogeneous surface. Removal by SST/Al-Cu was achieved through a combination of mechanisms. The adsorption efficiency of SST/Al-Cu was studied by modeling batch adsorbers. The most efficient system was the counterflow design. The material with the highest affinity for fluoride was SST/Al-Cu (5.25 mg g(-1)).