Simultaneous Heavy-Metal Ion Adsorption and Electricity Generation From Wastewater via "Heavy-Metal Removal Batteries".

Abstract

The heavy-metal ion in wastewater is a great threat to the health of both humans and ecosystems. The common heavy-metal ion removal strategies usually suffer from energy consumption and poor recyclability. Herein, a heavy-metal removal battery is designed by constructing a two-chamber configuration. Such battery displays the capacity of simultaneous heavy-metal ion adsorption and electricity output, where heavy-metal ion adsorption is driven by the potential difference between adsorption electrodes and metal electrodes, and electricity is generated continuously during the adsorption process. Significantly, various heavy-metal ions (e.g., Mn²⁺, Co²⁺, Ni²⁺, Zn²⁺, Cr³⁺ and Pb²⁺ ions) can be removed due to the large lattice spacing of active materials in adsorption electrodes, displaying the universality of adsorbing heavy-metal ions from wastewater. In addition, an environmental-friendly chemical oxidation strategy is developed to desorb heavy-metal ions from adsorption electrodes, which not only produces high-quality metal salts, but also reduces the toxicity of sludge in the case of secondary pollution. Impressively, these heavy-metal removal batteries can be easily scaled up and integrated to extend the heavy-metal ion adsorption ability and voltage/current output. This work proves a creative approach for simultaneous heavy-metal ion removal and electricity generation from wastewater.