Study on electrochemical oxidation of 4-Chlorophenol on a vitreous carbon electrode using cyclic voltammetry

Degradation and metagenomic analysis of 4-chlorophenol utilizing multiple metal tolerant bacterial consortium

Chlorophenols are persistent environmental pollutants used in synthesizing dyes, drugs, pesticides, and other industrial products. The chlorophenols released from these processes seriously threaten the environment and human health. The present study describes 4-chlorophenol (4-CP) degradation activity and metagenome structure of a bacterial consortium enriched in a 4-CP-containing medium. The consortium utilized 4-CP as a single carbon source at a wide pH range, temperature, and in the presence of heavy metals. The immobilized consortium retained its degradation capacity for an extended period. The 4-aminoantipyrine colorimetric analysis revealed complete mineralization of 4-CP up to 200 mg/L concentration and followed the zero-order kinetics. The addition of glycerol and yeast extract enhanced the degradation efficiency. The consortium showed both ortho- and meta-cleavage activity of catechol dioxygenase. Whole genome sequence (WGS) analysis revealed the microbial compositions and functional genes related to xenobiotic degradation pathways. The identified genes were mapped on the KEGG database to construct the 4-CP degradation pathway. The results exhibited the high potential of the consortium for bioremediation of 4-CP contaminated sites. To our knowledge, this is the first report on WGS analysis of a 4-CP degrading bacterial consortium.

Exploring the mechanism of the Fe(iii)-activated Fenton-like reaction based on a quantitative study

The Fenton method is an important water treatment process.

Acclimation of 2-chlorophenol-biodegrading activated sludge and microbial community analysis

Using glucose as cosubstrate, activated sludge that could effectively biodegrade 40 mg/L 2-chlorophenol was successfully domesticated in sequencing batch reactors. To acclimate the sludge, 2-chlorophenol was increased stepwise from 0 to 40 mg/L. High-throughput sequencing revealed that the microbial community richness increased during the first 5 days of acclimation to 5 mg/L 2-chlorophenol and then decreased after another 20 days as 2-chlorophenol was increased. The original sludge obtained from a water resource recovery facility had the highest microbial diversity. As the acclimation continued further, community richness and diversity both increased, but they decreased again, significantly, when 2-chlorophenol reached 40 mg/L. Saccharibacteria_norank, Bacillus, Saprospiraceae_uncultured, and Lactococcus were the dominant bacteria. Bacillus and Pseudomonas were the main known chlorophenol-degrading bacteria. WCHB1-60_norank, Tetrasphaera, Comamonadaceae_unclassified, and Haliangium showed poor tolerance to 2-chlorophenol. Higher bacterial tolerance to chlorophenols does not mean higher degrading capability. The degradation of chlorophenols was not positively correlated with the detected abundance of known 2-chlorophenol-degrading bacteria. PRACTITIONER POINTS: Activated sludge that could effectively biodegrade 40 mg/L 2-chlorophenol was successfully domesticated using glucose as cosubstrate in sequencing batch reactors. Saccharibacteria_norank, Bacillus, Saprospiraceae_uncultured, and Lactococcus were the dominant bacteria. Bacillus and Pseudomonas were the main known chlorophenol-degrading bacteria detected in this study. The degrading capability and tolerance of bacteria to chlorophenols were relatively independent and the degradation of chlorophenols may be the synergistic effect of various bacteria.

Recent electrochemical methods in electrochemical degradation of halogenated organics: a review

Halogenated organics are widely used in modern industry, agriculture, and medicine, and their large-scale emissions have led to soil and water pollution. Electrochemical methods are attractive and promising techniques for wastewater treatment and have been developed for degradation of halogenated organic pollutants under mild conditions. Electrochemical techniques are classified according to main reaction pathways: (i) electrochemical reduction, in which cleavage of C-X (X = F, Cl, Br, I) bonds to release halide ions and produce non-halogenated and non-toxic organics and (ii) electrochemical oxidation, in which halogenated organics are degraded by electrogenerated oxidants. The electrode material is crucial to the degradation efficiency of an electrochemical process. Much research has therefore been devoted to developing appropriate electrode materials for practical applications. This paper reviews recent developments in electrode materials for electrochemical degradation of halogenated organics. And at the end of this paper, the characteristics of new combination methods, such as photocatalysis, nanofiltration, and the use of biochemical method, are discussed.

A novel electrocatalytic approach for effective degradation of Rh-B in water using carbon nanotubes and agarose

Carbon nanotubes (CNTs)/agarose (AG) membrane on the ITO (indium tin oxide) conductive glass, with high efficiency of electrocatalytic degradation for rhodamine B (Rh-B) in water, was prepared using an easy and green method. The prepared CNTs/AG membrane was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectra (EDS), infrared spectroscopy (IR), and electrochemical impedance spectroscopy (EIS). The results revealed that CNTs were dispersed in the AG membrane. Additionally, the electrocatalytic activities for Rh-B were conducted on the electrochemical workstation with a three-electrode system. Both initial pH and potential played an important role in the process of electrocatalytic degradation. At pH 3 and potential reaching 4 V, the removal rate of Rh-B (10 mg/L) in water achieved 96% within 20 min. The stability of the prepared CNTs/AG membrane was also investigated. Besides, the toxicities of the main intermediates from the electrocatalytic degradation for Rh-B were calculated using the ECOSAR program and EPIWIN software, and results indicated that the toxicities of some intermediates were higher than those of the parent pollutant (Rh-B). These findings provided a light-spot to simplify the preparation of efficient working electrode and emphasized the possible potential risks from intermediates at the same time.

Acclimation of 2-chlorophenol Biodegrading Activated Sludge and Microbial Community Analysis

Taking glucose as co-substrate, the activated sludge which could effectively biodegrade 2-chlorophenol (2-CP) of 40 mg/L　was successfully domesticated after acclimation for 49 days in sequencing batch reactors. High-throughput sequencing (HTS) analysis revealed that the community richness initially increased for 5 days and then decreased after another 20 days with the increase of 2-CP. The original sludge obtained from water resource recovery facility had the highest diversity. At the beginning of acclimation, the community diversity decreased. With the acclimation going on, both richness and diversity of community increased, but decreased significantly when the concentration of 2-CP was increased to 40 mg/L. Saccharibacteria_norank, Bacillus, Saprospiraceae_uncultured and Lactococcus were the dominant bacteria detected in this study. Bacillus and Pseudomonas were the main chlorophenol-degrading bacteria. WCHB1-60_norank, Tetrasphaera, Comamonadaceae_unclassified and Haliangium had lower tolerance to 2-CP. Higher bacterial tolerance to CPs does not mean higher degrading capability. The degradation of CPs was not positively correlated with the abundance of known 2-CP degrading bacteria detected in this study.

Reactivity of carbon black diamond electrode during the electro-oxidation of Remazol Brilliant Blue R

This article reports for the first time, the reactivity of Carbon Black Diamond (CBD) electrode using cyclic voltammetry and electrochemical impedance techniques in 0.25 M H₂SO₄ solution containing 0.5 mM K₄Fe(CN)₆.

Preparation and characterization of a novel porous Ti/SnO2–Sb2O3–CNT/PbO2 electrode for the anodic oxidation of phenol wastewater

Porous Ti/SnO₂–Sb₂O₃–CNT/PbO₂ electrodes were successfully fabricated using a thermal decomposition technique and electro-deposition technologies.

Self-enhanced electrogenerated chemiluminescence of ruthenium(ii) complexes conjugated with Schiff bases

Self-enhanced electrochemiluminescence based on ruthenium complexes conjugated with Schiff bases is studied and used for co-reactant free metal anion recognition.