Synthesis of Mg-Decorated Carbon Nanocomposites from MesoCarbon MicroBeads (MCMB) Graphite: Application for Wastewater Treatment

The potential application of a carbon nanocomposite from battery anode materials modified with magnesium (Mg) was explored to remove phosphate from aqueous solutions. Thermogravimetric analysis (TGA) shows that the Mg content of the prepared Mg/C composite is around 23.5%. Laboratory batch adsorption kinetics and equilibrium isotherm experiments demonstrate that the composite has an extremely high phosphate adsorption capacity of 406.3 mg PO 4 /g, which is among the highest phosphate removal abilities reported so far. Results from XRD, SEM-EDX, and XPS analyses of the postsorption Mg/C composite indicate that phosphate adsorption is mainly controlled by the precipitation of P to form Mg 3 (PO 4 ) 2 ·8H 2 O and MgHPO 4 ·1.2H 2 O nanocrystals on the surface of the adsorbent. The approach of synthesizing Mg-enriched carbon-based adsorbent described in this work provides new opportunities for disposing spent batteries and developing a low-cost and high-efficiency adsorbent to mitigate eutrophication.