A green, porous and eco-friendly magnetic geopolymer adsorbent for heavy metals removal from aqueous solutions

Geopolymers are a class of synthesized amorphous aluminosilicate materials that can be used as an adsorbent for the removal of heavy metals. In this paper, the bentonite clay was employed to synthesize geopolymer that can remove heavy metals such as Cu(II), Pb(II), Ni(II), Cd(II), and Hg(II) from industrial wastewaters. The Fe3O4 nanoparticles were applied to modify the geopolymer and the use of a geopolymer/Fe3O4 nanocomposite as an efficient and magnetic adsorbent for heavy metals removal from aqueous solution was investigated in this work, for the first time. The influence of different contact time and initial concentrations of metal ions on sorption was examined and the best result was achieved in 2 min contact time in the presence of 0.05 g nanocomposite. The prepared geopolymer and nanocomposite samples were characterized by Fourier transform infrared spectroscopy spectra, field-emission scanning electron micrograph images, thermogravimetric analysis, energy dispersive X-ray analysis, X-ray diffraction pattern and Brunauer-Emmett-Teller analysis. The prepared magnetic geopolymer base on bentonite clay showed 99%, 99%, 92%, 96% and 92% removal efficiency for the sorption of copper, lead, nickel, cadmium, and mercury ions from industrial wastewaters. The present work includes diverse advantageous such as environmentally-friendly protocol, magnetic separation, inexpensive raw materials, easy and simple conditions and high yields as same as short adsorption times.