(332i) Facile Ball Milling Method for Developing Surface Functional Groups on Carbon-Based Adsorbents and Their Roles in the Removal of Heavy Metals in Aqueous Solution

Water pollution by heavy metals poses a serious threat to both human health and the environment due to their toxic properties and tend to accumulate in living organisms. Carbon-based adsorbents such as graphene and its derivatives, carbon nanotubes, activated carbon, and biochar are often used to remove heavy metals from aqueous solutions. This work provides a comprehensive review of recent research on various carbon adsorbents in terms of the governing removal mechanisms of their surface functional groups and the associated removal behaviors and performances to heavy metals in aqueous solutions. It then categorizes various synthesis methods that are commonly used to functionalized carbon adsorbent for enhanced heavy metals removal. Facile ball milling method is successfully developed in this study to introduce additional heteroatoms, primarily oxygen and nitrogen onto biochar surfaces for enhanced material and sorptive properties to heavy metals in aqueous solutions. Ball milled biochar had greater internal and external specific surface area, larger pore volume, nano-size properties, stronger negative zeta potential for both O and N functionalizing methods. Faster adsorption kinetics and 6 -10 times enhanced Ni (II) adsorption were displayed. Ball milling thus has great potential to increase the efficiency of environmentally friendly biochar for various environmental applications.