Sol-Gel Derived Carbon Ceramic Electrode Bulk-Modified with Tris(1,10-phenanthroline-5,6-dione)iron(II) Hexafluorophos-phate and Its Use as an Amperometric Iodate Sensor

A surface-renewable tris(1, 10-phenanthroline-5,6-dione)iron (Ⅱ)hexafluorophosphate (FePD) modified carbon ceramic electrode was constructed by dispersing FePD andgraphite powder in methyltrimethoxysilane (MTMOS) based gels. The FePD-modified electrode presentedpH-dependent voltammetric behavior, and its peak currents were diffusion-controlled in 0.1 mol/LNa_2SO_4 + H_2SO_4 solution (pH = 0.4). In the presence of iodate, clear electrocatalytic reductionwaves were observed and thus the chemically modified electrode was used as an amperometric sensorfor iodate in common salt. The linear range, sensitivity, detection limit and response time of theiodate sensor were 5 x 10^(-6)―1 x 10~2 mol/L, 7.448 μA·L/mmol, 1.2 x 10^(-6) mol/L and 5 s,respectively. A distinct advantage of this sensor is its good reproducibility of surface-renewal bysimple mechanical polishing.

Cupric Hexacyanoferrate Nanoparticle Modified Carbon Ceramic Composite Electrodes

Graphite powder-supported cupric hexacyanoferrate (CuHCF) nanoparticles weredispersed into methyltrimethoxysilane-based gels to produce a conducting carbon ceramic composite,which was used as electrode material to fabricate surface-renewable CuHCF-modified electrodes.Electrochemical behavior of the CuHCF-modified carbon ceramic composite electrodes was characterizedusing cyclic and square-wave voltammetry. Cych'c voltammograms at various scan rates indicated thatpeak currents were surface-confined at low scan rates. In the presence of glutathione, a clearelectrocatalytic response was observed at the CuHCF-modified composite electrodes. In addition, theelectrodes exhibited a distinct advantage of reproducible surface-renewal by simple mechanicalpolishing on e-mery paper, as well as ease of preparation, and good chemical and mechanicalstability in a flowing stream.

Ceramic Carbon/Polypyrrole Materials for the Construction of Bienzymatic Amperometric Biosensor for Glucose

A novel amperometric glucose biosensor was constructed by electrochemical formation of a polypyrrole (PPy) membrane in the presence of glucose oxidase (GOD) on the surface of a horseradish peroxidase (HRP) modified ferrocenecarboxylic acid (FCA) mediated sol-gel derived ceramic carbon electrode. The amperometric detection of glucose was carried out at +0.16 V (vs. SCE) in 0.1 mol/L phosphate buffer solution (pH 6.9) with a linear response range between 8.0x10(-5) and 1.3x10(-3) mol/L of glucose. The biosensor showed a good suppression of interference and a negligible deviation in the amperometric detection.

High CO_(2)permeation using a new Ce_(0.85)Gd_(0.15)O_(2-δ)-LaNiO_(3)composite ceramic–carbonate dual-phase membrane

This work shows the synthesis,characterization and evaluation of dense-ceramic membranes made of Ce_(0.85)Gd_(0.15)O_(2-δ)-LaNiO_(3)(CG-LN)composites,where the fluorite-perovskite ratio(CG:LN)was varied as follows:75:25,80:20 and 85:15 wt.%.Supports were initially characterized by XRD,SEM and electrical conductivity(using vacuum and oxygen atmospheres),to determine the composition,microstructural and ionic-electronic conductivity properties.Later,supports were infiltrated with an eutectic carbonates mixture,producing the corresponding dense dual-phase membranes,in which CO_(2)permeation tests were conducted.Here,CO_(2)permeation experiments were performed from 900 to 700℃,in the presence and absence of oxygen(flowed in the sweep membrane side).Results showed that these composites possess high CO_(2)permeation properties,where the O_(2)addition significantly improves the ionic conduction on the sweep membrane side.Specifically,the GC80-LN20 composition presented the best results due to the following physicochemical characteristics:high electronic and ionic conductivity,appropriate porosity,interconnected porous channels,as well as thermal and chemical stabilities between the composite support and carbonate phases.

Effect of ozone on the performance of a hybrid ceramic membrane-biological activated carbon process

Two hybrid processes including ozonation-ceramic membrane-biological activated carbon （BAC） （Process A） and ceramic membrane-BAC （Process B） were compared to treat polluted raw water. The performance of hybrid processes was evaluated with the removal efficiencies of turbidity, ammonia and organic matter. The results indicated that more than 99% of particle count was removed by both hybrid processes and ozonation had no significant effect on its removal. BAC filtration greatly improved the removal of ammonia. Increasing the dissolved oxygen to 30.0 mg/L could lead to a removal of ammonia with concentrations as high as 7.80 mg/L and 8.69 mg/L for Processes A and B, respectively. The average removal efficiencies of total organic carbon and ultraviolet absorbance at 254 nm （UV254, a parameter indicating organic matter with aromatic structure） were 49% and 52% for Process A, 51% and 48% for Process B, respectively. Some organic matter was oxidized by ozone and this resulted in reduced membrane fouling and increased membrane flux by 25%-30%. However, pre-ozonation altered the components of the raw water and affected the microorganisms in the BAC, which may impact the removals of organic matter and nitrite negatively.

Mixed-conducting ceramic–carbonate membranes exhibiting high CO2/O2 permeation flux and stability at high temperatures

This investigation demonstrates the feasibility to fabricate high quality ceramic–carbonate membranes based on mixed-conducting ceramics.Specifically,it is reported the simultaneous CO2/O2 permeation and stability properties of membranes constituted by a combination of ceramic and carbonate phases,wherein the microstructure of the ceramic part is composed,in turn,of a mixture of fluorite and perovskite phases.These ceramics showed ionic and electronic conduction,and at the operation temperature,the carbonate phase of the membranes is in liquid state,which allows the transport of CO32-and O2–species via different mechanisms.To fabricate the membranes,the ceramic powders were uniaxially pressed in a disk shape.Then,an incipient sintering treatment was carried out in such a way that a highly porous ceramic was obtained.Afterwards,the piece is densified by the infiltration of molten carbonate.Characterization of the membranes was accomplished by SEM,XRD,and gas permeation techniques among others.Thermal and chemical stability under an atmosphere rich in CO2 was evaluated.CO2/O2 permeation and long-term stability measurements were conducted between 850 and 940℃.The best permeation–separation performance of membranes of about 1 mm thickness,showed a maximum permeance flux of about 4.46×10^–7 mol·m^–2·s^–1·Pa^–1 for CO2 and 2.18×10^–7 mol·m^–2·s^–1·Pa^–1 for O2 at 940℃.Membranes exhibited separation factor values of 150–991 and 49–511 for CO2/N2 and O2/N2 respectively in the studied temperature range.Despite long-term stability test showed certain microstructural changes in the membranes,no significant detriment on the permeation properties was observed along 100 h of continuous operation.

Preparation, Electrochemical Behavior and Electrocatalytic Activity of a Copper Hexacyanoferrate Modified Ceramic Carbon Electrode

A copper hexacyanoferrate modified ceramic carbon electrode （CuHCF/CCE） had been prepared by two-step sol-gel technique and characterized using electrochemical methods. The resulting modified electrode showed a pair of well-defined surface waves in the potential range of 0.40 to 1.0 V with the formal potential of 0.682 V （vs. SCE） in 0.050 mol·dm^-3 HOAc-NaOAc buffer containing 0.30 mol·dm^-3 KCl. The charge transfer coefficient （a） and charge transfer rate constant （ks） for the modified electrode were calculated. The electrocatalytic activity of this modified electrode to hydrazine was also investigated, and chronoamperometry was exploited to conveniently determine the diffusion coefficient （D） of hydrazine in solution and the catalytic rate constant （kcat）. Finally, hydrazine was determined with amperometry using the resulting modified electrode. The calibration plot for hydrazine determination was linear in 3.0 × 10^-6--7.5 × 10^-4 mol·dm^-3 with the detection limit of 8.0 × 10^-7 molodm^-3. This modified electrode had some advantages over the modified film electrodes constructed by the conventional methods, such as renewable surface, good long-term stability, excellent catalytic activity and short response time to hydrazine.