Enhanced dechlorination and biodegradation of 2-chloroaniline by a 2-aminoanthraquinone-graphene oxide composite under anaerobic conditions

Abstract

The effect of a 2-aminoanthraquinone-graphene oxide (AQ-GO) composite on the anaerobic dechlorination and degradation of chloroanilines by an enriched bacterial consortium was investigated. The results showed that the maximal degradation efficiency of 20 mg/L 2-chloroaniline (2-CA) reached 91.4% at a dose of 20 mg/L AQ-GO in 30 d. Moreover, the pseudo-first-order rate constant of 2-CA degradation in the AQ-GO-mediated system was 2.9-fold higher than those in AQ- and GO-mediated systems alone. During this process, a synergetic effect between AQ and GO was observed, which was attributed to the increased intracellular and extracellular electron transfer pathways. GC-MS analysis showed that 2-CA could be degraded to hexanoic acid and ultimately mineralized to CO2. Illumina MiSeq sequencing revealed that additional AQ-GO significantly increased the relative abundance of Firmicutes. Further analysis showed that the populations of the genera Oscillospira, unclassified Lactobacillales, unclassified Veillonellaceae and Ruminococcus exhibited positive correlations with the rate constant of 2-CA degradation and the dehydrogenase activity of bacterial consortium. These findings indicated that AQ-GO promoted the enrichment of functional bacteria and increased the bacterial activity, resulting in the enhanced dechlorination and degradation of 2-chloroaniline.