Kaolin-based magnetic zeolites A and P as water softeners

In this work, we report an experimental investigation on the synthesis of zeolites A and P, using kaolin as the main SiO2 and Al2O3 sources, by hydrothermal route, as well as on the structural, spectroscopic and magnetic properties of the produced zeolite composites with magnetite nanoparticles. The zeolites were successfully synthesized and the characterization of the obtained materials was carried out considering different techniques, including X-ray diffraction (XRD), infrared vibrational spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), as well as measurements of the magnetization as a function of the temperature and applied magnetic field. XRD analysis confirmed zeolites A and P as main crystalline phases, with a low intensity peak regarding the presence of small quantities of quartz remaining from the unreacted clay. SEM showed the well-defined morphologies of zeolites and, in the composites, magnetite nanoparticles dispersed over their surface. The average size of the magnetite nanoparticles was ca. 50 nth as determined by TEM analyses. The magnetic characterization confirmed the ferrimagnetic behavior of the magnetite nanoparticles and of the composites, as well as verified that the magnetic properties of the nanoparticles are not affected by the zeolites in the composite formation. Thus, the results evidenced that high quality zeolite composites with magnetite nanoparticles can be reached by considering the employed low cost method, placing this route as an attractive alternative for water softening reaching removal levels of about 97% in the first application times. (C) 2017 Elsevier Inc. All rights reserved.