Synthesis and evaluation of Mn-Sn modified Ru-Ir electrode for electrocatalytic treatment of high chloride acrylonitrile wastewater.

Acrylonitrile wastewater was an organic wastewater with strong toxicity and poor biodegradability. Therefore, electro-catalytic technology became a promising acrylonitrile wastewater treatment technology because of no secondary pollution, wide application range and low water quality requirements. The optimal Mn-Sn modified Ru-Ir electrode material was synthesized by thermal method and applied in electro-catalytic treatment of acrylonitrile wastewater. The electrode materials were characterized by SEM, TEM, XRD, XPS and electrochemical characterization. SEM, TEM, XRD and XPS indicated that Mn and Sn were capable of incorporating and replacing the part of Ru or Ir and could alter the microstructure of Ru-Ir and the types of Mn and Sn oxides, raising the oxygen evolution potential (OEP) and voltampere charge. When the molar ratio of Mn-Sn was 1:1, OEP, voltampere charge and exchange current density could reach 1.303 V, 1.51 C/cm2 and 6.29×10-4 A/cm2, respectively. The co-doping of Mn-Sn had significant influence on the electrocatalytic performance of Ru-Ir electrode materials. The optimum synthesis conditions of Mn-Sn modified Ru-Ir electrode were as follows: the molar ratio of Mn-Sn was 1:1, calcination time was 4.0 hours, calcination temperature was 450℃, and solvent was water. Under certain conditions, the removal rate of acrylonitrile with Mn-Sn modified Ru-Ir electrode was 100%. Mn-Sn modified Ru-Ir electrode had high oxygen evolution potential and good removal effect of acrylonitrile, which was higher than that of ruthenium iridium electrode and RuO2 electrode.

Application of Pd-Sn modified Ru-Ir electrode for treating high chlorine ammonia-nitrogen wastewater.

Electro-catalytic technology is a promising approach for wastewater treatment, owing to its easy operation, minimal generation of secondary pollution, small foot-print and rapid start-up. In this work, the chlorine evolution potential of the Pd-Sn modified ruthenium(Ru)-iridium(Ir) electrode was investigated for the electro-catalytic treatment of high chlorine ammonia-nitrogen wastewater. The effect of reaction conditions on the removal of ammonia-nitrogen, kinetics and apparent activation energy of ammonia-nitrogen removal were studied. The possible denitrification process of high chlorine ammonia-nitrogen wastewater was discussed. The results indicated that the chlorine evolution potential of the Pd-Sn modified Ru-Ir electrode was 1.0956 V(vs. SCE). The electro-catalytic treatment of high chlorine ammonia-nitrogen conformed to zero-order kinetic law, and the apparent activation energy of removal process was 14.089 kJ/mol. With a current was 0.5 A, the removal efficiency of ammonia-nitrogen could achieve 100% at a reaction time of 40 min. Indirect oxidation played an essential role in the electro-catalytic ammonia-nitrogen removal using the Pd-Sn modified Ru-Ir electrode. This paper demonstrated that the electro-catalytic technology was a promising approach for efficiently treating the high chlorine ammonia-nitrogen wastewater.