From agricultural wastes to advanced materials for environmental applications: Rice husk-derived adsorbents for heavy metals removal from wastewater

Agroindustry annually generates enormous amounts of residues, and their re-utilization is a convenient approach to mitigate environmental pollution and increase energy savings. Rice husk (RH) is one of the most widely available agricultural wastes in many countries of the world. RH and its ashes are often used directly for manufacturing and synthesizing new materials with added-value features. In this work, the preparation of composite materials for wastewater treatment has been explored by producing and testing mesoporous ironoxide/ RH composites for heavy metal adsorption. The composites were fully characterized and their application to the removal of Pb2+ and Cu2+ ions from model aqueous solutions at different pH values was tested to evaluate their adsorption performances and select those materials more suited for realistic applications. Our results indicated that the composite materials exhibited higher metal adsorption capacities than the pristine carbonized RH and the iron components, highlighting a synergism between the carbonized RH and iron-oxide phases.