Enhanced photoelectrocatalytic degradation of ammonia by in situ photoelectrogenerated active chlorine on TiO_2 nanotube electrodes

TiO2 nanotube （TINT） electrodes anodized in fluorinated organic solutions were successfully prepared on Ti sheets. Field-emission scanning electron microscopy （FE-SEM） and X-ray diffraction （XRD） were performed to characterize the TiNT electrodes. The linear voltammetry results under irradiation showed that the TiNT electrode annealed at 450℃ presented the highest photoelectrochemical activity. By combining photocatalytic with electrochemical process, a significantly synergetic effect on ammonia degradation was observed with Na2SO4 as supporting electrolyte at pH 10.7. Furthermore, the photoelectrocatalytic efficiency on the ammonia degradation was greatly enhanced in presence of chloride ions without the limitation ofpH. The degradation rate was improved by 14.8 times reaching 4.98 × 10^-2 min^-1 at pH 10.7 and a faster degradation rate of 6.34 × 10^-2 min^-1 was obtained at pH 3.01. The in situ photoelectrocatalytic generated active chlorine was proposed to be responsible for the improved efficiency. On the other hand, an enhanced degradation of ammonia using TiNT electrode fabricated in fluorinated organic solution was also confirmed compared to TiNT electrode anodized in fluorinated water solution and TiO2 film electrode fabricated by sol-gel method. Finally, the effect of chloride concentration was also discussed.

Electro-catalytic degradation properties of Ti/SnO_2–Sb electrodes doped with different rare earths

Ti/SnO2–Sb electrode has a good effect on the removal of organic pollutants. But its short service life limits its large-scale application in industry. Electro-catalytic degradation performances and service life of the electrode can be significantly improved by doping rare earth（RE） ions into the oxide coating of Ti/SnO2–Sb electrode. Ti/SnO2–Sb electrodes doped with different RE elements（Ce, Dy, La, and Eu） were prepared by the thermal decomposition method at 550 ℃. Electro-catalytic degradation performances of electrodes doped with different RE elements were evaluated by linear sweep voltammetry（LSV） and Tafel curves. During the electrolysis,the conversion of p-nitrophenol was performed with these electrodes as anodes under galvanostatic control. The structures and morphologies of the surface coating of the electrodes were characterized by scanning electron microscope（SEM）. The results demonstrate that the electro-catalytic degradation performances of Ti/SnO2–Sb electrodes are improved to different levels by doping different RE ions. Improved Ti/SnO2–Sb electrodes by the introduction of different RE have higher oxygen evolution potential, better electro-catalysis ability, better coverage,and longer electrode life.

A comparative study of liquid and solid inner contact roxatidine acetate ion-selective electrode membranes

A comparative study was conducted using two designs of a roxatidine acetate （ROX）-selective electrode; a conventional liquid inner contact called electrode A and a graphite-coated solid contact called electrode 13. The fabrication of electrodes was based on roxatidine-tetraphenylborate （ROX-TPB） as an ion-association complex in a PVC matrix using different plasticizers. Electrode A has a linear dynamic range of 2.2 ×10^-5 mol/L to 1.0 ×10^-2 mol/L, with a Nernstian slope of 54.7 mV/decade and a detection limit of 1.4 ×10^-6 mol/L. Electrode B shows linearity over the concentration range of 1.0×10^-6 mol/L to 1.0×10^-2 tool/L, with a Nernstian slope of 51.2 mV/decade and a limit of detection of 1.1×10^7 mol/L which is remarkably improved as a result of diminishing ion fluxes in this solid contact, ion-selective electrode. The proposed sensors display useful analytical characteristics for the determination of ROX in bulk powder and its pharmaceutical formulation. The present electrodes show clear discrimination of ROX from several inorganic, organic ions, sugars, some common drug excipients and the degradation product （3-[3-（1-piperidinyl methyl） phenoxy] propyl amine） of ROX. Furthermore, the proposed electrodes were utilized for the determination of ROX in human plasma, where electrode B covers drug Cmax which indicated its applicability to pharmacokinetic, bioavailability and bioequivalent studies. The results obtained by the proposed electrodes were statistically analyzed and compared with those obtained by a reported HPLC method. No significant difference for either accuracy or precision was observed.

Pd-MnO_2 nanoparticles/TiO_2 nanotube arrays(NTAs) photo-electrodes photo-catalytic properties and their ability of degrading Rhodamine B under visible light

Pd-MnO2/TiO2 nanotube arrays（NTAs） photo-electrodes were successfully fabricated via anodization and electro deposition subsequently; the obtained Pd-MnO2/TiO2 NTAs photo electrodes were analyzed by scanning electron microscopy（SEM）, X-ray diffraction（XRD） and characterized accordingly. Moreover, the light harvesting and absorption properties were investigated via ultraviolet–visible diffuse reflectance spectrum（DRS）; photo degradation efficiency was investigated via analyzing the photo catalytic degradation of Rhodamine B under visible illumination（xenon light）. The performed analyses illustrated that Pd-MnO2 codoped particles were successfully deposited onto the surface of the TiO2 nanotube arrays;DRS results showed significant improvement in visible light absorption which was between400 and 700 nm. Finally, the photo catalytic degradation efficiency results of the designated organic pollutant（Rhodamine B） illustrated a superior photocatalytic（PC） efficiency of approximately 95% compared to the bare TiO2 NTAs, which only exhibited a photo catalytic degradation efficiency of approximately 61%, thus it indicated the significant enhancement of the light absorption properties of fabricated photo electrodes and their yield of UOH radicals.