Efficient biodechlorination at the Fe3O4-based silicone powder modified chlorobenzene-affinity anode

Static magnetic field-enhanced cathodic electrocatalysis of Fe3O4-based nitrogen-doped carbon for improving the performance of microbial fuel cells

Enhancing oxygen reduction reaction (ORR) electrocatalysis through an external static magnetic field to improve the performance of microbial fuel cells (MFCs) is technically feasible, but its application in MFCs remains largely unexplored. Herein, we present a Fe3O4-based nitrogen-doped carbon (Fe3O4@NC2) magnetic catalyst that significantly boosts ORR catalytic activity, increasing the half-wave potential (E1/2) of the ORR by approximately 20 mV with a magnetic field strength of 140 mT. When the Fe3O4@NC2 cathode is combined with an external magnetic field into the MFCs, the maximum power density of the MFC can reach 553.17 ± 7.16 mW m-2. This performance notably exceeds that of the same MFCs operated without a magnetic field (522.26 ± 4.25 m-2) and that of MFCs equipped with a Pt/C cathode (447.29 ± 2.16 mW m-2). This study introduces an effective and straightforward cathodic magnetic enhancement approach, offering promising avenues for advancing MFCs technology.

Enhancing biodegradation of gaseous chlorobenzene by introducing micro-nano bubbles (MNBs): Performance and mechanisms

Chlorobenzene (CB) biodegradation is challenging due to its hydrophobic characteristics. Addition of silicone oil and surfactants are commonly used methods to enhance biodegradation efficiency by improve CB gas-liquid mass transfer efficiency. However, both approaches introduced new chemicals into the reactor, either as carbon sources for microorganisms or requiring regeneration. This study established a synergistic reactor by applying micro-nano bubbles (MNBs) with biodegradation process in a stirred tank bioreactor (STB) to purify CB waste gas. Experimental results demonstrate a reduction in start-up time by 2 days and a 13.5 % increase in overall degradation rate in synergistic reactor. The mass transfer fraction of CB (β*s) was increased by 13.33 %. Additionally, the synergistic reactor showed improved system stability and microbial activity, evidenced by the increased Zeta potential, extracellular polymer substances (EPS) secretion, and protein content. Notably, MNBs upregulate genes involved in aromatic ring hydroxylation and dehalogenation processes and promoted the enzyme SCACT (EC2.8.3.18) within the genus Acidovorax, which enhanced intracellular coenzyme A activity and facilitated chlorobenzene degradation in this genus, thereby enhancing CB degradation efficiency. These results indicate that MNBs can significantly improve the biodegradation performance of CB waste gas, offering a promising strategy for industrial applications.

Bioelectronic and photogenerated electron synergistic catalyzed removal of chlorhexidine: Degradation and mechanism

The extensive use of the antimicrobial compound chlorhexidine (CHD) has emerged as a significant threat to both the ecological environment and human health. To address this concern, a photo-electrochemical cell-microbial fuel cell (PMFC) system was studied for CHD removal by incorporating, for the first time, the photocatalysts black phosphorus/carbon nitride (BPCN) and Cu2O into the bioanode and air cathode of an MFC, respectively. By combining electrochemical, macro-genomic, and intermediate product analyses, the underlying mechanisms of bioelectronic and photoelectronic synergies were elucidated. Specifically, the bioanode and the energy band difference between BPCN and Cu2O accelerated the bioelectronic and photoelectronic transfer, reduced the reaction barrier, and enhanced the cathodic dechlorination pathway. Consequently, the PMFC showed a 31.4-fold and 8.0-fold increase in CHD removal rate compared to the MFC and PEC, respectively. The photogenerated electrons, on the other hand, acted as key cofactors, replacing cytochrome c and facilitating electron transfer at the microbial-electrode interface, which improved the system's energy yield by 53.9 %. Additionally, illumination selectively enhanced the abundance of anode functional species, carbon metabolism, and interspecific cooperation, resulting in a 4.03-fold increase in the removal of CHD and its intermediates. These findings offer new perspectives on biochemically sustainable environmental remediation for recalcitrant pollutants.

Electrode functional microorganisms in bioelectrochemical systems and its regulation: A review

Bioelectrochemical systems (BES) as environmental remediation biotechnologies have boomed in the last two decades. Although BESs combined technologies with electro-chemistry, -biology, and -physics, microorganisms and biofilms remain at their core. In this review, various functional microorganisms in BESs for CO2 reduction, dehalogenation, nitrate, phosphate, and sulfate reduction, metal removal, and volatile organic compound oxidation are summarized and compared in detail. Moreover, interrelationship regulation approaches for functional microorganisms and methods for electroactive biofilm development, such as targeted electrode surface modification, chemical treatment, physical revealing, biological optimization, and genetic programming are pointed out. This review provides promising guidance and suggestions for the selection of microbial inoculants and provides an analysis of the role of individual microorganisms in mixed microbial communities and its metabolisms.

Simultaneous removal of chlorobenzene and Cr(VI) from groundwater using microbial fuel cell with low-cost Si modified ferrihydrite electrodes

Aromatic chlorinated compounds and Cr(VI) in groundwater pose significant challenges due to their resistance. This study explores microbial fuel cells using low-cost Si-modified ferrihydrite (SiFh) electrodes for simultaneous chlorobenzene and Cr(VI) removal. The voltage output of MFC assembled with SiFh modified electrode was approximately 1.63 times higher than the bare electrode, achieving 1.23 times higher in chlorobenzene degradation efficiency. CF-SiFh loaded MFC had the highest power generation and best EET efficiency, which was positive to greatest and fastest chlorobenzene removal. Microbial community analysis identified the dominance of Cupriavidus and Pandoraea in chlorobenzene oxidation, while Lentimicrobiaceae and Rhodobacteraceae were key genera that may facilitate direct and indirect electron transfer within the biofilms. Cr species analysis in solution and solids confirmed it was reduced to Cr(OH)3 or CrxFe1-x(OH)3 coprecipitates at cathode. MFCs with SiFh-modified electrodes thus offer a promising technology for simultaneous chlorinated compound and Cr(VI) removal, promising in contaminated groundwater remediation.