Highly effective removal of 4-chloroaniline in water by nano zero-valent iron cooperated with microbial degradation

The misuse of aromatic amines like 4-chloroaniline (4-CA) has led to severe environmental and health issues. However, it's difficult to be utilized by microorganisms for degradation. Nano-zero-valent iron (nZVI) is a promising material for the remediation of chloroaniline pollution, however, the synergistic effect and mechanism of nZVI with microorganisms for the degradation of 4-CA are still unclear. This study investigated the potential of 4-CA removal by the synergistic system involving nZVI and 4-CA degrading microbial flora. The results indicate that the addition of nZVI significantly enhanced the bio-degradation rate of 4-CA from 43.13% to 62.26%. Under conditions involving 0.1% nZVI addition at a 24-hour interval, pH maintained at 7, and glucose as an external carbon source, the microbial biomass, antioxidant enzymes, and dehydrogenase were significantly increased, and the optimal 4-CA degradation rate achieved 68.79%. Additionally, gas chromatography-mass spectrometry (GC-MS) analysis of intermediates indicated that the addition of nZVI reduced compounds containing benzene rings and enhanced the dechlorination efficiency. The microbial community remained stable during the 4-CA degradation process. This study illustrates the potential of nZVI in co-microbial remediation of 4-CA compounds in the environment. The extensive occurrence of 4-chloroaniline (4-CA) in the environment as a persistent organic pollutant with teratogenic, carcinogenic, and genotoxic characteristics has garnered significant attention. The accumulation of 4-CA in living beings and its resistance to disintegration through biological processes have prompted extensive research in environmental science to find effective techniques for its removal. This study proposes a novel approach to improve the microbial degradation of 4-CA using nano zero-valent iron. By investigating the degradation pathway and mechanisms under this combined effect, it offers a new perspective and theoretical foundation for the biodegradation of persistent organic pollutant.