Cu(II) and Cr(VI) Removal in Tandem with Electricity Generation via Dual-Chamber Microbial Fuel Cells

Abstract

Microbial fuel cells (MFCs) have shown great advantages in electricity production, heavy metal removal, and energy recovery. However, the impact and mechanism of conflicting effects of numerous electron acceptors on heavy metal removal remain unknown. The effects of different initial heavy metal concentrations, cathodic dissolved oxygen, and electrode materials on the electricity generation and heavy metal removal efficiencies of Cu(II) and Cr(VI) were investigated in this study. When the initial concentration of Cr(VI) increased from 10 mg/L to 150 mg/L, the maximum voltage, coulomb efficiency, and maximum power density declined from 99 to 44 mV, 28.63% to 18.97%, and 14.29 to 0.62 mW/m2, and the removal efficiencies of Cu(II) and Cr(VI) decreased dramatically from 98.34% and 99.92% to 67.09% and 37.06%, respectively. Under anaerobic cathodic conditions, the removal efficiency and removal rate of Cu(II) and Cr(VI) were lower than those under aerobic conditions. When the cathode electrode was titanium sheet and graphite plate, the coulomb efficiency and maximum power density increased to 38.18%, 50.71%, 33.95 mW/m2, and 62.23 mW/m2. The removal efficiency and removal rates of Cu(II) and Cr(VI) were significantly increased to 98.09%, 86.13%, and 0.47, 0.50 mg/(L h) with a graphite plate, respectively. The pH of the cathode varied considerably greater as the MFC current increased. Cu(II) and Cr(VI) were removed and reduced to elemental Cu, Cu2O, and its oxides as well as Cr(OH)3 and Cr2O3 precipitates on the cathode electrode by cathodic bioelectrochemical reduction.

Copper from Waste Printed Circuit Boards Was Effectively Bioleached Using Newly Isolated Microorganisms and Subsequently Recovered by Microbial Fuel Cell

“…The voltage (U, mV) was recorded using a data acquisition system (34972A, Agilent Technologies Inc., Santa Clara, CA, USA). An electrochemical workstation (CHI600D, Shanghai Chenhua Instrument Co., Ltd., Shanghai, China) was used to test cyclic voltammetry (CV) curves [19]. X-ray diffraction (XRD, X'PERT POW-DER, Panaco, Amsterdam, The Netherlands) was used to determine the material deposited on the cathode material.…”

“…Electrons reach the cathode via an external circuit, thus generating an external voltage. Protons cross the PEM membrane to the cathode, where they combine with the electrons transferred from the anode and the Cu 2+ in the cathode chamber to carry out a reduction reaction, reducing the Cu 2+ to copper [19,20].…”

“…The electrons reach the cathode through wires and then combine with an electron acceptor (i.e., oxidizing substances, such as O 2 , Cu 2+ , etc.) to produce a reduction reaction, thus generating electricity [18][19][20]. It has been proven that wastewater containing Cu 2+ was used as the cathode solution (electron acceptor) of MFC, and that the biological power generation was 0.4-0.6 V. The Cu 2+ was reduced to elemental copper and Cu 2 O [21,22].…”

The Potential Use of Pseudomonas stutzeri as a Biocatalyst for the Removal of Heavy Metals and the Generation of Bioelectricity

“…(2024) studied an MFC with synthetic wastewater, managing to reduce Cu (II), Mg (II), Mn (II), Zn (II), and Na by 93 85, 93, 88, and 36%, respectively, and mentioned that bacterial nanowires are also formed in toxic environments and are responsible for the elimination of toxic ions present in the substrate and, at the same time, allow a higher rate of electron transport, generating greater efficiency in the MFC [68]. Other metal ions (lead, cadmium, chromium, and copper) have also been reduced using MFCs, highlighting the importance of the physiological activity of biofilms and extracellular polymeric substances for the reduction of these metals, where the use of nanoparticles and anodic and cathodic biosynthesis are the most notable points [69,70]. Treatments for the improvement of electrodes in terms of porosity and electron conduction have been intensely investigated in published documents, as well as metal nanoparticles and the isolation of microorganisms for their use as biocatalysts with the aim of re-potentiating the generation of electrical energy, which are being considered with greater importance by researchers [71,72].…”