Preparation of MnO₂-Modified Graphite Sorbents from Spent Li-Ion Batteries for the Treatment of Water Contaminated by Lead, Cadmium, and Silver

Herein, a novel adsorbent was prepared via grafting MnO₂ particles on graphite recovered from spent lithium-ion batteries to treat water contaminated by lead, cadmium, and silver. This is the first study reporting the recovery of spent LIB anode material and its application to heavy-metal-contaminated wastewater treatment. Characterizations using scanning electron microscopy, energy-dispersive X-ray analysis, and Fourier transform infrared showed that the adsorbent surface was coated with MnO₂ ultrafine particles that served as the sorption mechanism to remove heavy-metal ions. In comparison to the raw artificial graphite (AG) powder, the MnO₂-modified AG (MnO₂-AG) exhibited a markedly improved removal capacity toward Pb(II), Cd(II), and Ag(I), whose removal rates reached as high as 99.9, 79.7, and 99.8%, respectively. The removal of the heavy metals by MnO₂-AG was mainly through the ion exchange of hydroxyl groups. This study provides the possibility of synthesis of an efficient adsorbent by reusing the "waste", such as spent Li-ion batteries. It is an economic and environmentally friendly approach for both heavy-metal-contaminated water treatment and waste recycling.