Mechanism and kinetics of adsorption and removal of heavy metals from wastewater using nanomaterials

At high environmental concentration, some heavy metals display adverse health effects on living organisms and ecosystems. They bioaccumulate in the food chain and end up in wastewater, calling for advanced techniques of remediation. Here, we review recently developed nanomaterials used to remove heavy metals in wastewater, with focus on synthesis, removal mechanisms and kinetics. Nanomaterial-based adsorbents include zero-valent, carbon-based nanomaterials and nanocomposites. Nanomaterial synthesis is done by co-precipitation, sol-gel, spinning, chemical vapour deposition, pyrolysis and sputtering. Removal mechanisms include chemical precipitation, adsorption, ion exchange, coagulation and membrane filtration. We discuss factors controlling the adsorption processes, such as pH, temperature, contact period and dosage.