Biochar as an electron shuttle for reductive dechlorination of pentachlorophenol by Geobacter sulfurreducens

TLDR

Pentachlorophenol (PCP) is a persistent environmental contaminant that can be reductively dechlorinated by the metal‑reducing bacterium Geobacter sulfurreducens, but the influence of biochar additives on this bioremediation process is not fully understood. This study examined how different biochars affect the electron transfer and dechlorination efficiency of G. sulfurreducens toward PCP.

Abstract

Abstract The reductive dechlorination of pentachlorophenol (PCP) by Geobacter sulfurreducens in the presence of different biochars was investigated to understand how biochars affect the bioreduction of environmental contaminants. The results indicated that biochars significantly accelerate electron transfer from cells to PCP, thus enhancing reductive dechlorination. The promotion effects of biochar (as high as 24-fold) in this process depend on its electron exchange capacity (EEC) and electrical conductivity (EC). A kinetic model revealed that the surface redox-active moieties (RAMs) and EC of biochar (900 °C) contributed to 56% and 41% of the biodegradation rate, respectively. This work demonstrates that biochars are efficient electron mediators for the dechlorination of PCP and that both the EC and RAMs of biochars play important roles in the electron transfer process.