Magnetic geopolymer based on rice husk ash for the removal of metals from aqueous solutions

Abstract

In this work, a study of the removal efficiency for lead(II), copper(II), zinc(II), niquel(II), and cadmium(II) from aqueous solutions using modified geopolymer with magnetite, through an adsorption process is presented. Various pretreatments and calcination steps at different temperatures were applied to rice husks to obtain a silica-rich ash, which is the raw material in the synthesis of geopolymers. Their mineralogical composition and microstructural property were determined by XRF and XRD, respectively. The major functional groups on the surface were identified by spectrometry FT-IR. The major functional groups on the surface were also identified as well. SEM micrographs were taken to acknowledge the ashes morphology. The results indicate that the geopolymer modified with magnetite and obtained from rice husk ash with a Si/Al ratio of 0.5, solid/liquid ratio of 1.5 and 10% of magnetite showed the best metals adsorption capacity than same metals taken by the iron-free geopolymer and the rice husks. These results indicate that the magnetic geopolymer from rice husk ash is an efficient and low-cost alternative adsorbent to remove Pb, Cu, and Zn from aqueous solutions.