A study on the electrochemical disinfection with H202 generated at the gas diffusion electrode （GDE） from active carbon/poly- tetrafluoroethylene was performed in a non-membrane cell. The effects of Pt load and the ...A study on the electrochemical disinfection with H202 generated at the gas diffusion electrode （GDE） from active carbon/poly- tetrafluoroethylene was performed in a non-membrane cell. The effects of Pt load and the pore-forming agent content in GDE, and operating conditions were investigated. The experimental results showed that nearly all bacterial cultures inoculated in the secondary effluent from wastewater treatment plant could be inactivated within 30 min at a current density of 10 mA/cm^2. The disinfection improved with increasing Pt load. Addition of the pore-forming agent NH4HCO3 improved the disinfection, while a drop in the pH value resulted in a rapid rise of germicidal efficacy and the disinfection time was shortened with increasing oxygen flow rate. Adsorption was proved to be ineffective in destroying bacteria, while germicidal efficacy increased with current density. The acceleration rate was different, it initially increased with current density. Then decreased, and finally reached a maximum at a current density of 6.7 mA/cm^2. The disinfection also improved with decreasing total bacterial count. The germicidal efficacy in the cathode compartment was approximately the same as in the anode compartment, indicating that the contribution of direct oxidation and the indirect treatment of bacterial cultures by hydroxyl radical was similar to the oxidative indirect effect of the generated H2O2.展开更多
Pd/C catalyst used for the Pd/C gas diffusion cathodes was prepared by hydrogen reduction method and formaldehyde reduction method, and characterized by X-ray diffraction (XRD), transmission elec- trode microcopy (TEM...Pd/C catalyst used for the Pd/C gas diffusion cathodes was prepared by hydrogen reduction method and formaldehyde reduction method, and characterized by X-ray diffraction (XRD), transmission elec- trode microcopy (TEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) tech- niques. The electrochemical degradation of 4-chlorophenol was investigated in the diaphragm elec- trolysis system, aerating firstly with hydrogen gas then with air, using three different kinds of gas dif- fusion cathode. The results indicated that the self-made Pd/C gas diffusion cathode can not only re- ductively dechlorinate 4-chlorophenols by aerating hydrogen gas, but also accelerate the two-electron reduction of O2 to hydrogen peroxide (H2O2) by aerating air. Therefore, the removal efficiency of 4-chlorophenol by using Pd/C gas diffusion cathode is better than that of the C/PTFE gas diffusion cathode (no catalyst). The catalytic activity of Pd/C catalyst prepared by hydrogen reduction method is higher than that prepared by formaldehyde reduction method. The stability of the Pd/C gas diffusion cathodes is good. Therefore, both the removal efficiency and the dechlorination degree of 4-chlorophenol reached about 100% after 60 min, and the removal efficiency of 4-chlorophenol in terms of chemical oxygen demand (COD) in the cathodic compartment reached 87.4% after 120 min.展开更多
基金supported by the National Natural Science Foundation of China (No.20777053)
文摘A study on the electrochemical disinfection with H202 generated at the gas diffusion electrode （GDE） from active carbon/poly- tetrafluoroethylene was performed in a non-membrane cell. The effects of Pt load and the pore-forming agent content in GDE, and operating conditions were investigated. The experimental results showed that nearly all bacterial cultures inoculated in the secondary effluent from wastewater treatment plant could be inactivated within 30 min at a current density of 10 mA/cm^2. The disinfection improved with increasing Pt load. Addition of the pore-forming agent NH4HCO3 improved the disinfection, while a drop in the pH value resulted in a rapid rise of germicidal efficacy and the disinfection time was shortened with increasing oxygen flow rate. Adsorption was proved to be ineffective in destroying bacteria, while germicidal efficacy increased with current density. The acceleration rate was different, it initially increased with current density. Then decreased, and finally reached a maximum at a current density of 6.7 mA/cm^2. The disinfection also improved with decreasing total bacterial count. The germicidal efficacy in the cathode compartment was approximately the same as in the anode compartment, indicating that the contribution of direct oxidation and the indirect treatment of bacterial cultures by hydroxyl radical was similar to the oxidative indirect effect of the generated H2O2.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 50325824, 50678089)China Postdoctoral Science Foundation (Grant No. 20060390454)the Excellent Young Teacher Program of MOE, P. R. China
文摘Pd/C catalyst used for the Pd/C gas diffusion cathodes was prepared by hydrogen reduction method and formaldehyde reduction method, and characterized by X-ray diffraction (XRD), transmission elec- trode microcopy (TEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) tech- niques. The electrochemical degradation of 4-chlorophenol was investigated in the diaphragm elec- trolysis system, aerating firstly with hydrogen gas then with air, using three different kinds of gas dif- fusion cathode. The results indicated that the self-made Pd/C gas diffusion cathode can not only re- ductively dechlorinate 4-chlorophenols by aerating hydrogen gas, but also accelerate the two-electron reduction of O2 to hydrogen peroxide (H2O2) by aerating air. Therefore, the removal efficiency of 4-chlorophenol by using Pd/C gas diffusion cathode is better than that of the C/PTFE gas diffusion cathode (no catalyst). The catalytic activity of Pd/C catalyst prepared by hydrogen reduction method is higher than that prepared by formaldehyde reduction method. The stability of the Pd/C gas diffusion cathodes is good. Therefore, both the removal efficiency and the dechlorination degree of 4-chlorophenol reached about 100% after 60 min, and the removal efficiency of 4-chlorophenol in terms of chemical oxygen demand (COD) in the cathodic compartment reached 87.4% after 120 min.
文摘采用2种导流方式,即S导流型和E导流型的单室电合成反应器,制备有效面积为438 cm^2的气体扩散电极,研究不同导流方式对气体扩散阴极电合成反应器制备过氧化氢(H2O2)的影响。结果表明,S导流型反应器中,随水力停留时间(Hydraulic Retention Time,HRT)减小,H2O2质量浓度逐渐降低;在电流密度为25 m A/cm^2、HRT为5.7 min时,H2O2质量浓度可达2062 mg/L;当HRT为1.1 min时,H2O2产率可达0.150 kg/(m^2·h);在电流密度为25 m A/cm^2、HRT为1.1 min时,能耗为8.33(k W·h)/kg,电流效率达到90%~93%。E导流型反应器中,在25 m A/cm^2下、HRT=5.7 min时,产生的最大H2O2质量浓度为1693 mg/L;HRT对H2O2产率影响不明显,在25 m A/cm^2、HRT=1.1~2.9min时,H2O2产率平均约为0.125 kg/(m^2·h);HRT的减小不能显著降低能耗,在25 m A/cm^2、HRT=5.7 min时,能耗高达14.66(k W·h)/kg。E导流型反应器性能较差的主要原因在于不能促使阳极气体及时排出,造成H2O2的产率和电流效率均降低。因此,S导流型反应器性能优于E导流型反应器。最大H2O2产率优于文献报道的结果,可归因于较小的极板间距和气体扩散电极表面导流板的共同作用。
