Polymeric ion exchanger supported ferric oxide nanoparticles as adsorbents for toxic metal ions from aqueous solutions and acid mine drainage

Background Acid mine drainage (AMD) is a worldwide industrial pollution of grave concern. AMD pollutes both water sources and the environment at large with dissolved toxic metals which are detrimental to human health. This paper reports on the preparation of polymeric ion exchange resins decorated with hydrated iron oxides and their application for the ecological removal of toxic metals ions from AMD. Methods The hydrated iron oxide particles were incorporated within commercial chelating ion exchange resins using the precipitation method. The synthesised hybrid resins were then characterized using appropriate spectroscopic and solid-state techniques. The metal ion levels were measured using the inductively coupled plasma-optical emission spectrometer (ICP-OES). The optimization of contact time, pH, and adsorbent dosage were conducted to enhance the efficiency of adsorption of toxic metals onto the hybrid organic/inorganic nanosorbents. Kinetics and adsorption isotherms were constructed to study the adsorption mechanisms of the adsorbents. Results The results showed that the dispersed Fe-O is hydrated and amorphous within the hybrid materials. The adsorption kinetics followed the pseudo-second-order shown by the high R-2 values. The hybrid adsorbents were finally tested on environmental AMD samples and were able to remove toxic metals Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn at various removal degrees. Conclusion Solution pH played a crucial role in the adsorption of toxic metals on hybrid iron oxide adsorbents. The hybrid TP-260 HFO had higher affinity for toxic metals than other prepared adsorbents thus has a potential for acidic mine water pollution remediation. The adsorbed Al(III) can be recovered using NaCl-NaOH binary solution from the loaded resins.