An experimental comparison of a graphite electrode and a gas diffusion electrode for the cathodic production of hydrogen peroxide

Development of a trickle bed reactor of electro-Fenton process for wastewater treatment

To avoid electrolyte leakage and gas bubbles in the electro-Fenton (E-Fenton) reactors using a gas diffusion cathode, we developed a trickle bed cathode by coating a layer composed of carbon black and polytetrafluoroethylene (C-PTFE) onto graphite chips instead of carbon cloth. The trickle bed cathode was optimized by single-factor and orthogonal experiments, in which carbon black, PTFE, and a surfactant were considered as the determinant of the performance of graphite chips. In the reactor assembled by the trickle bed cathode, H2O2 was generated with a current of 0.3A and a current efficiency of 60%. This performance was attributed to the fine distribution of electrolyte and air, as well as the effective oxygen transfer from the gas phase to the electrolyte-cathode interface. In terms of H2O2 generation and current efficiency, the developed trickle bed reactor had a performance comparable to that of the conventional E-Fenton reactor using a gas diffusion cathode. Further, 123 mg L(-1) of reactive brilliant red X-3B in aqueous solution was decomposed in the optimized trickle bed reactor as E-Fenton reactor. The decolorization ratio reached 97% within 20 min, and the mineralization reached 87% within 3h.

Degradation of organics in reverse osmosis concentrate by electro-Fenton process

The present work studied, for the first time, the removal of organic pollutants from a high-salinity reverse osmosis (RO) concentrate by electro-Fenton approach using a graphite-felt as cathode. To gain insights into the process, the in situ generation of hydrogen peroxide was also investigated. The COD removal efficiency and energy consumption were optimized by investigating the effects of some important operating parameters such as ferric ion concentration, initial pH and cathodic potential. Under the conditions of cathodic potential at -0.72V and Fe(3+) concentration 0.2mM, more than 62% COD could be removed in 3h treatment, meeting the local wastewater discharge requirement (COD <50mg/L). It confirmed the feasibility of electro-Fenton process for the treatment of RO concentrate accounting for its cost-effectiveness in wide pH ranges.

Influence of operational parameters on electro-Fenton degradation of organic pollutants from soil

The combination of the Fenton's reagent with electrochemistry (the electro-Fenton process) represents an efficient method for wastewater treatment. This study describes the use of this process to clean soil or clay contaminated by organic compounds. Model soil of kaolinite clay polluted with the dye Lissamine Green B (LGB) was used to evaluate the capability of the electro-Fenton process. The effects of operating parameters such as electrode material and dye concentration were investigated. Operating in an electrochemical cell under optimized conditions while using electrodes of graphite, a constant potential difference of 5 V, pH 3, 0.2 mM FeSO(4). 7H(2)O, and electrolyte 0.1 M Na(2)SO(4), around 80% of the LGB dye on kaolinite clay was decolorized after 3 hours with an electric power consumption around 0.15 W h g(-1). Furthermore, the efficiency of this process for the remediation of a real soil polluted with phenanthrene, a typical polycyclic aromatic hydrocarbon, has been demonstrated.