Preparation of the CNTs/AG/ITO electrode with high electro-catalytic activity for 2-chlorophenol degradation and the potential risks from intermediates.

A novel carbon nanotubes (CNTs)/agarose (AG)/ITO electrode with high electro-catalytic activity was prepared using a simple sol-gel method. Characterization results showed that the prepared CNTs/AG membrane, coated on the ITO conductive glass, was consisted of C and O. The electro-catalytic degradation for 2-chlorophenol (2-CP) and the influence factors were investigated. The results meant that electro-catalytic degradation for 2-CP was highly dependent on pH, bias voltage, and catalyst dosage. At pH 2, 4 V bias voltage, and 5 wt% CNTs dosage, the electro-catalytic efficiency of CNTs/AG/ITO electrode for 2-CP (20 mg/L) achieved 98% within 180 min. Afterwards, the electro-catalytic properties of recycling electrode, roles of the generated reactive oxygen species, and the reaction pathways were also investigated and proposed. In addition, the toxicities of the generated intermediates from the electro-catalytic degradation were calculated by easy methods. The results indicated that the toxicities of some intermediates were higher than the parent pollutant, especially the formation of 2-CP dimer which was seldom reported in the advanced oxidation process. The findings of using AG as the carrier and conductive adhesive for catalytic material and the assessment methods for the possible increasing risks from the intermediates were reported firstly in this paper.