Silanation of nanostructured mesoporous magnetic particles for heavy metal recovery

Nanostructured mesoporous magnetic (m-Fe3O4) particles are promising candidate materials for separation, detoxification, and precious metal recovery. The silanation of m-Fe3O4 particles using 3-aminopropyltriethoxysilane is described. The silanized films were characterized using XPS, diffuse-reflectance FTIR spectroscopy, and electrokinetic techniques. The loading capacity of the silanized m-Fe3O4 particles was found to be superior to that of m-Fe3O4 or directly silanized Fe3O4 particles. Extraction and separation of transition metals (II) were investigated using the silanized m-Fe3O4 particles. The effectiveness of metal (II) extraction was found to increase with increasing solution pH, but was less effective at pH below 2. Satisfactory separation with loading efficiency in the order of Cu2+ > Ni2+ > Zn2+ was obtained. The adsorbed metals were successfully desorbed with 1 M aqueous HCI solutions. As a result, the recovered m-Fe3O4 particles can be recycled in industrial applications.