Self-powered sodium borohydride alkaline fuel cell for efficient removal of lead(II) and copper(II)

Abstract

Heavy metals in industrial wastewater cause serious environmental pollution and they are easy to accumulate and difficult to degrade. Copper and lead are two typical heavy metals, and it is of great significance to remove them at the same time. This work shows a strategy of reducing and removing Pb(II) and Cu(II) by self-powered non-biological fuel cell (SP-nBFC) with dual-chamber reactor. Therein, sodium borohydride in alkaline solution as fuel (electron donor) was electrooxidized on nicke1 foam (NF) at anode and Pb(II) and Cu(II) ions (electron acceptors) in strong acidic solution were electro-reduced at Bi/MXene/GP cathode (bismuth nanoparticles and MXene modified graphite paper (GP)).Additionally, a proton exchange membrane, Nafion, was introduced into form complete circuit by offering ions channel. The results showed that Cu(II) and Pb(II) were reduced to Cu and Pb, and the SP-nBFC could produce electricity in this process without external energy consumption. The Bi/MXene/GP cathode could increase significantly removal efficiencies of Cu(II) and Pb(II), which were higher than about 37.0 %, 22.5 % for Cu(II) and 25.7 %, 16.3 % for Pb(II) than those of GP and MXene/GP cathode. This system could obtain a high Cu(II) removal efficiency (RE, 99.3 %) and moderate Pb(II) RE of 56.8 %, and acquire Cu and Pb sediments in cathode chamber. Furthermore, the proposed system could generate 923 mV of maximum potential and 1420 mW/m2 of maximum power density in 48 h. Thus, this SP-nBFC system provides a viable method for treatment of Cu(II) and Pb(II) pollution and generating electricity simultaneously, and also has prospective approach for other heavy metals remediation.