Removal of heavy metals by BEA zeolite/Fe3O4 composite prepared via dry-gel conversion method using agrowaste-derived raw material

Using agrochemicals are considered as an anthropogenic source of heavy metal contamination in water, and ecofriendly remediation tools for removal is desired. Here, we demonstrate material circulation by converting SiO2 extracted from agrowaste: rice husk ash, into an easily collectable adsorbent: BEA zeolite/Fe3O4 composite, through dry-gel conversion technique. In addition, the synthesized BEA zeolite/Fe3O4 composite was tested for removal of heavy metals for the first time. Instrumental analyses confirmed that incorporated Fe3O4 particles inside BEA zeolites showed no severe effects on its morphologies. Pseudo-second order kinetic and Langmuir isotherm models were found best described the adsorption of three typical toxic heavy metals: Pb(II), Cu(II), Zn(II). Moderate adsorption capacities of 0.675, 0.310, and 0.308 mmol/g for Pb(II), Cu(II), and Zn(II), respectively, following the selectivity order: Pb(II) > Cu(II) ≈ Zn(II) were obtained. The composite adsorbent exhibits magnetic collectability, reusability and stability, indicating its practicality for removal of heavy metals from water.