Adding carbon quantum dots to enhance microbial extracellular electron transfer for accelerating aniline degradation in simulated wetlands

Microbial extracellular respiration is relatively weak in natural water systems because of the low electroactivity of environmental media, which limits the production of extracellular respiration-based reactive oxygen species (ROS) and the removal of pollutant. In this study, carbon quantum dots (CDs) were added to a simulated wetland to enhance extracellular respiration and accelerate the microbial oxidation of aniline under intermittent aeration conditions. The results indicated that CDs promoted extracellular electron transfer to increase the production of Fe²⁺ and ROS, and led to a 23.5 % higher aniline removal rate than that of the control group without CD addition. Multiple lines of evidence indicated that CDs bind to microorganisms in wetlands to induce the polarization of respiratory enzymes, thereby enhancing microbial electroactivity and the activity of respiratory chain enzymes. In addition, CDs enhanced proton efflux to form a higher membrane potential for adenosine triphosphate (ATP) production, which facilitated ROS generation. This study demonstrated a simple and efficient approach to enhance microbial extracellular electron transfer for ROS production and remediation of polluted wetlands.