ABSTRACT
With the rapid increase in global industrial activities, biologically toxic and carcinogenic compounds and metal ions are being constantly released into the water environment. On the other hand, toxic metal concentration in drinking water sources also affects human health. For instance, arsenic (As) is one of the most toxic and carcinogenic chemical elements, and is regarded as the first priority issue of toxic substances by the World Health Organization (WHO). Its practical and effective removal from groundwater remains an important and intractable challenge in water treatment. Adsorption has always been the choice of treatment for the recovery/reuse of heavy metals in industrial effluents. Though zeolites, activated carbon, and magnetic (Fe2O3) nanoparticles (MNPs) are known to be more versatile, there is a growing need for more efficient, economical, and specific adsorbents. For instance, MNPs are widely used as adsorbents in the removal of heavy metals from industrial effluents, but one disadvantage is their aggregation (Tollefson 2007), which can be overcome in two main ways: one method is by loading functional nanoparticles (NPs) on common porous adsorbents such as activated carbon, porous alumina, zeolite, diatomite, and so on, which can partly resolve these problems by sacrificing adsorption capacities. The other method is to design and synthesize micro-nanohierarchically structured adsorbents, such as metal organic frameworks (MOFs), which make a compromise between high adsorption capacity and NP stability.
