Zhirong Sun

Modification of a Pd-loaded electrode with a carbon nanotubes–polypyrrole interlayer and its dechlorination performance for 2,3-dichlorophenol

A novel Pd loaded Ti electrode was prepared with a carbon nanotubes and polypyrrole interlayer modification, referred to as a Pd/CNTs–PPy/Ti electrode. Pretreated CNTs were deposited on the substrate uniformly by electrophoretic deposition technique. Modification by the CNTs–PPy interlayer made the Pd particles smaller and well-distributed. Pulsed-current electrodeposition technique led to more compact Pd particles. The hydrogen adsorption current value increased 55.3% and the electrochemical active surface area (EASA) increased 58.7% compared to the electrode without modification. The prepared Pd/CNTs–PPy/Ti electrode was employed in dechlorination of 2,3-dichlorophenol (2,3-DCP) in aqueous solution. The potential impact factors on the electrocatalytic dechlorination were studied, including dechlorination current, initial pH value of catholyte, reaction temperature and common ions in aqueous solution. Complete dechlorination could be achieved within 70 min under the selected conditions i.e., current of 5 mA, and an initial pH of 2.5 at ambient temperature. The common ions in aqueous solution, such as NO3−, CO32−, HCO3−, Mg2+, K+ and Ca2+, had no obvious effect on the electrocatalytic dechlorination within the scope of this investigation. The prepared Pd/CNTs–PPy/Ti electrode exhibited promising dechlorination potential with higher electrochemical activity.

Degradation of diuron by heterogeneous electro-Fenton using modified magnetic activated carbon as the catalyst

In this work, polytetrafluoroethylene coating was firstly conducted to make stable and effective magnetic-activated carbon as a heterogeneous electro-Fenton catalyst for diuron oxidation. The catalysts were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). In addition, the effects of operating parameters such as catalyst dosage, current intensity, substrate concentration and pH on the degradation of diuron were investigated. The removal efficiency of diuron was more than 95% within 120 min oxidation under the conditions of I = 100 mA, pH = 6.7 ± 0.2, catalyst loading 3 g L−1 and diuron concentration 10 mg L−1. Moreover, the catalyst durability test demonstrated that the modification of 5% PTFE on the catalyst indeed has a significant beneficial effect on the useful life of the catalyst. We compared the performance of catalysts with or without PTFE modification in consecutive experiments; the modified catalysts exhibited remarkable advantages in that the diuron removal efficiency was stable with relatively low iron leaching (<0.1 mg L−1) during ten consecutive degradation experiments, which proved the durability and reusability of the modified catalyst. This work demonstrates that such a heterogeneous EF using stable magnetic activated carbon catalyst with PTFE modification is promising for organic wastewater treatment in initial neutral pH conditions; at the same time, these good properties of the modified catalyst increase the possibility of practical application.