Chemical Engineering Commons^™

Research On Molten Carbnate Fuel Cell, Naichao Li, Baolian Yi, Lianying Kong, Enjun Zhang, Huaxin Lin, Tianxi Qu, Yingcai Cheng

Journal of Electrochemistry

Cold-roll-milling has been evaluated as a technique for preparing porous LiAlO₂ matrices for use as a molten carbonate fuel cell electrolyte matrix. This technique produces reliable electrolyte structures with the following characteristics and advantages: ease of handling, uniform thickness, using nontoxic inorganic solvents, controlled pore size distribution, and ability to be impregnated with the alkali carbonate without fracrure.

The Molren Carbnatod Fuel Cell (MCFC) was assembled from sintered Ni electrodes and LiAlO₂ electrolyte matrix, the electrode area is 28 cm², the effect of operating conditions on cell performance was tested, it was found that the cell …

Catalytic Oxidation Of Methanol On Pt/C-Spe And Ptru/C-Spe Electodes, Aihua Su, Changzhi Li, Gongquan Sun, Ying Zhang, Tianhong Lu

Journal of Electrochemistry

Anode catalysts of methanol oxidation for direct methanol fuel cell, Pt/C and PtRu/C, ere prepared by chemical reduction in this work. The results indicated that the PtRu/C showed higher electrocatalytic activity than that of Pt/C. It was explained by XRD and XPS analyses that the existence of Ru enhanced the catalytic activity for electrochemical oxidation of methanol.

Study Of The Modified Electrolytic Manganese Dioxide, Guohui Yuan, Dewei Chu, Rihui Shen, Hongwei Pan, Cuifen Zhang

Journal of Electrochemistry

A modified electrolytic manganese dioside doped with Bi (Bi-EMD)wasprepared and examined by XRD and XPS. It is predominantly γ-mnO₂ and the Bi exists as Bi₂O₃ in the modified material. The content of Bi in Bi-EMDs increased with the increasement of Bi³⁺ concentration in electrolyte, and reached 14.3(wt)% from the bath of 0.008 mol·L^-1 Bi³⁺ used. Some Zn/Bi-EMD prototype batteries of AA size were assembled, and which cycle life tests showedthat the Bi-EMD has better reversibility.

Influence Of O-Phenylenediamine On The Catalysis At Hrp Enzyme Electrode In 1,4-Dioxane, Hong Chen, Hui-Huang Wu

Journal of Electrochemistry

Horseradish peroxidase (HRP) was immobilized by crosslinkage on the glassycarbon electrode to prepare the enzyme electrode, where the reduction of H₂O₂ was studied in 1,4-dioxane media. It was shown that HRP electrode can catalyze the reduction of H₂O₂ without anymedintor, however, as an activator, o-phenylenediamine can promote the bio-catalysis. In thepresence of the activator, the parallel reactions occurred on the enzyme electrode. The workingcondition of the HRP electrode was investigated as the sensors for H₂O₂ and o-phenylenediamine, also the influence of water content in organic phase was discussed on the performance …

The Oxidation Of Hydrogen Absotbing Alloys And Its Inhibition, Suqin Wang, Baojia Xia, Geping Yin, Pengfei Shi

Journal of Electrochemistry

This paper introduces the method to judge: 1)the possibility of oxidation of themetal hydride electrode in an anode process by cyclic voltammetric curves, 2)the oxidation pattern ofmetal hydride electrode in oxygen atmosphere in various charged states, and 3)the inhibition ofoxidation of hydrogen absorbing alloys by certain surface treatment.

Studies On The Structure Of Licoo2 Synthesized With Tartaric Acid And The Behaviorof Its Rechargeable Lithium Battery, Fuping Zhang

Journal of Electrochemistry

The structure of LiCoO₂ synthesized with tartaric acid and the behavior of itsrechargeable Lithium battery have been studied by XRD, XPS, CV, CT. It has been shown that LiCoO₂ has a space group R3m with hexagonal parameters a=0.2810 nm, c=1.4088 nm. Low-spin state Co³⁺ configuration in LiCoO₂ has been suggested. Also, Li₂O, was identified onits surface. Furthermore, the capacity and the middle working voltage of its Lithium battery are about 120 mA·h·g^-1 and 3.8 V, respectively. The EMF of the cell changes with the Lithium composition of itscathode following E=4.318-0.450 X^2/3 in …

Photoelectrochemical And Spectroelectrochemical Studies Oniron Oxide Ultrafine Particles, Maizhi Yang, Yongjun Ji, Wen Zhang, Shengmin Cai, Xiaojiang Lu, Zhongqun Tian, Jin Luo

Journal of Electrochemistry

In this paper, Raman spectra, photocurrent and the UV-VIS reflectance aremeasured for studying the α-Fe₂O₃ ultrafine particles adsorbed on Pt electrode. The blue shifts of Raman peaks demonstrate the size quantization effect for the particles of 50 nm in diameter ascompared with the bulk material. With the changing of the potential, the photocurrent decrcases as the UV-VIS reflectance increases, and vice-versa. Therefore, the potential not only affects the hargetransfer direcdtion in the interface of electrode/redox couple, but also influences the light absortion onthe surface of particles. According to the results of photoelectrochemistry, we suggest that the cathodic …

The Electrochemical Reduction Of 2-Ethylanthraquinone (2eaq), Yaobin Zhu

Journal of Electrochemistry

The process of electrochemical reduction of 2EAQ in DMSO is studied using CVand ESR methods in this work, Pt, Pd and some implanted materials are used as electrodes. The quasi-rever-sible property of two electron transfer steps and their following homogeneous chemical reactions are illustrated. The mechanism of the electrochemical red uction of 2EAQ and the kinetic parameters of the related steps are obtained. Having measured the influence of water content in the system, the effect of the proton donor is discussed. After comparising the experimental results with each other these experiments gives us the idea that the replacement of metal …

Horseradish Peroxidase/Poly-O-Phen Ylenediamine Mem Brane Electrode: Preparation And Properties, Dong Wei, Huihuang Wu

Journal of Electrochemistry

A horseradish peroxidase (HRP)/poly-o-phenylenediamine (PPD) membrane electrode was prepared by electropolymerization of o-phenylenediamine on glassy carbon in pH 7.0 phosphate buffer, the process of the enzyme immobilization was studied. The enzyme electrode obtained exhibits the activity to catalyze the electroreduction of hydrogen peroxide in the absence of any electron transfer mediator. The red uction reaction occurs in the potential range of PPD redoxprocess, it was believed that the polymer participates in electron transfer of the enzyme. The enzyme reaction kinetics at rotating HRP/PPD electrode was analysed, and the factors influencing kinetic parameters were discussed.

An Indirect Electrochemical Oxidation Of Toluene──Anodic Oxidation Of Mn(Ⅱ) On The Lead Electrode, Zhonghua Wang, Qingmin Hua, Guacai Chen, Zhongquan Wang, Yunan Qiu, Xingguo Yan

Journal of Electrochemistry

The electrochemical oxidation of Mn(Ⅱ) to Mn(Ⅱ) in concentrated H₂SO₄ (2 ~ 8 mol⋅L^-1) at lead electrode has been studied. It is found that the electrode surface is oxidized to PbO₂ in a direct electrochemical reaction, then PbO₂ formed reacts with Mn(Ⅱ) in a chemical reaction. Some effects involves current density, concentration of H₂SO₄, temperature and conversionwere evaluated. The rule of electrogenerated Mn(Ⅲ) in flow electrolysis cell were determined at several conditions. The current efficiency at greater than 90% is obtained in general.

The Reduction Of Oxygen To Hydrogen Peroxide At The Poly(O-Phenylenediamine)-Filmed Electrode, Zhaoe Lu, Tiangeng Zhong, Guanyong Zhang

Journal of Electrochemistry

The poly(o-phenylenediamine) (PPD) filmed graphite electrode was formed by electro-polymerization of o-phenylenediamine in acidified (pH=1) 0.2 mol·L^-1 Na₂SO₄ solution using the cyclic voltammetric methed. The catalytic effect of the electrcareduction of oxygen in acid olution was demonstrated by the voltammogram of the electrode in the oxygen saturated acid solutionof Na₂SO₄. The current efficiency of the reduction of oxygen to hydrogen peroxide was determined by the electrolysis in a divided cell under the condition of constant current. The various effectsinfluencing the accmulation of H₂O₂ in the catholyte were discussed.

Studies On Coordination Behavior Of Dimethyl Sulfoxide In Complex Of Rare Earth With Cryptand, Shichang Liu, Tianpei Zhu

Journal of Electrochemistry

Electrochemical reduction reaction in the course of the titration of Eu(2.2.2) and Eu(2.2) using strong bonding solvent, DMSO, in C₂H₄Cl₂ has been investigated by cyclic voltammetry. The greater the concentration of strong bonding solvent, the more negative the half-wave potentials for the reduction reaction are. The coordination number of Eu(2.2.2) and Eu(2.2) which are 2 and 3 respectively, with DMSO can be calculated, according to the relations between half-wave potentials and the variety of concentration of DMSO.

The Study Of The Growth Processes Of The Oxides On Lead Electrodes In Sulfuric Acid Solution, Hesheng Zhai, Xuguang Chen, Jinkua You, Yong Yang, Zugeng Lin

Journal of Electrochemistry

The growth processes of PbO and PbO₂ on lead electrodes have been investigatedby using in-situ methods that are combined with temporary AC resistance measurment technique and in-situ laser scanning photoelectrochemical microscopy. It is found that a linear relationship existsbetween the electrode resistance(R) and^1/2 after the electrode is oxidized at +0.6 V(vs.Hg/H₂SO₄/35% H₂SO₄) for more than 5 min. This result suggests that the growth of PbO is well distributed during the early stage of oxidation. The study by using laser scanning photoelectrochemical microscopy has further proved this point. The results also …

A Photoelectrochemical Investigation Of Zirconium Oxide Film, Maizhi Yang, Ping Wei, Di Quarto F., Piazza S., Sunseri C.

Journal of Electrochemistry

A photoelectrochemical investigation has been carried out on zirconium initialoxide film and its oxide film grownanodically at constant rate up to different thickness. Both anodicand cathedic photocurrents on the photocurrent spectrum depended on the potential, but had littlerelation with the forming anedic films or measuring solutions. Photocurrent spectrum and photocurrenttransients suggested that the oxide films on zirconium were duplex layers structure. The internal layerwas ZrO₂ and the external layer ZrO₂·(H₂O)_n. The photocurrent included photogenerated carrier ininternal and external oxide films, as well as internal photoinjection process for electrons from thesubstrate metal into the …

Electroreduction Of The Nittobenzene On Titanium Electrode Implanted With Palladium, Zhongda Wu, Xianjun Zhu, Hongsen Wang

Journal of Electrochemistry

The titanium substrates were bombarded with 1×10¹⁷～5×10¹⁷ ions·cm^-2 ofpalladium at the room temperature. The surface composition of implanted electrode and concentration-depth profiles of various elements were measured by AES. The electrored uction processes ofnitrobenzene (NB) in 0.1 mol/L NaOH solution at Pd/Ti electrodes have been investigated by cyclicvoltaivimetry. The results show that the palladium implanted titanium electrodes exhibit a high catalyticactivity in the electroreduction of NB. The NB radical anion, which is the product of one-electronelectroreduction of NB, was detected by ESR in-situ in conjunction with electrochemical methods. Aniline was also detected as a product of …

Electroreduction Of Holmium Ion On Iron Electrde In Molten Cholorides, Qiqin Yang, Guankun Liu, Yuzhi Su

Journal of Electrochemistry

The cyclic voltammetry, open circuit potential-time curve after poteritiostatic electrolysis, current-time curve at potential step, X-ray diffraction and electron probe microanalysiswere used to investigate the electrode process of Ho(Ⅲ) reduced on iron electrode in molten chloridesand the phases of surface alloy layer. The Ho-Fe alloys are formed at first, and then the metallic holmium is deposited when Ho(Ⅲ) is reduced on iron electrode. The charge transfer is reversible. The free energies of formation for the four inter metallic compounds of Ho-Fe system, the diffusion coefficients and diffusion activation energy of Ho in alloyed cathode are determined.

Electrocatalytic Oxidation Of Formaidehyde And Formic Acid On A Pt/SbAd Electrode, Hong Li, Lincai Jiang, Xiong Jiang

Journal of Electrochemistry

The electrocatalytic activity for the oxidation of formaldehyde and formic acid ona Sb-modified platinum (Pt/Sb_ad) was investigated. Results showed that the Pt/Sb_ad electrode was electrocatalytically more active than a Pt electrode in the anodic oxidation of formaldehyde and formicacid. In the case of formaldehyde, an oxidation peak appeared at a potential of ca. 0.7V. During the oxidation of formic acid, a 4-fold increase in the 1st peak current was observed. The Sb-modified platinum electrode was found to be most electrocatalytically active at a coverage of 0.75±0.05. The electrocatalytic activity of the Pt/Sb_ad electrode can be best …

Synthesis Of LiXCoo2 And Its Behaviour In Rechargeable Lithium Battery, Mingfeng Guo, Ruimin Yang, Zebo Zhang, Jincao Ye

Journal of Electrochemistry

The Variations of crystal lattice parameters of Li_xCoO₂ during charge anddischarge have been st ud ied by XRD and AAR spectroscopy. It was found that the Li_xCoO₂ crystalvolume expanded during charge and contracted during discharge. The crystal lattice structure was broken because of the formation of Co₃O₄ when deeply charge.The variation of lattice parameter C₀ value in cycling process was similar to that in charge process.The variation of 006 peak was the mostsensitive in every case. In case of preheating for 20 hours at 700℃ before operating high temperature, the …

Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde

Tanzania Journal of Engineering and Technology (TJET)

One of the major steps in the design of a process plant is development of an appiopriate flowsheet. At this step, the technical solutions may be con- sidered in relation to the social and economic factors. In this paper, guide- lines for developing a flowsheet for continuous, steady State process in a developing country environment have been proposed. To illustrate the pro- posed guidelines, a case study involving design of an ethanol distillation plant has been used.

Polymer Supported Z-N Catalysts For C2h4-Polymerization,I: Development Catalyst Preparation Method, S Mteza

Tanzania Journal of Engineering and Technology (TJET)

Substantial improvement of low sensitivity pressure transducers aiming at obtaining a more realistic output signal is discussed. The output signal direct from these transducers has deficiencies of amplitude attenuation and phase lag, thus the measured values are not necessarily the true in- stantaneous values. In order to correct for such shortcomings the unit step response of these transducers is also studied experimentally. A math- ematical model is established based on the experimental results to build up a compensation circuit which is then included in the instrumentation setup to eliminate these deficiencies. The effectiveness of the compensated transducer is demonstrated by …

Influence Of Arc Discharge Duration On Turbulent Mass Burning Rate, E Mushi

Tanzania Journal of Engineering and Technology (TJET)

The influence of arc discharge duration on turbulent mass burning rate was investigated for turbulent r.m.s vglocities of u '=1.73 m/s and u'=4.5 nfs. Methane air mixtures were used at equivalence ratios ranging from 0.83 to / .25. Flame size was obtained through schiieren photography while the intensity Of CH chemiluminescence emissions was used to measure mass burning rate. A variable spark duration unit was used for ignition sparks and all the experiments were done in a fan stirred bomb. Discharge duration has no effect when the equivalence ratio is I. For higher values longer duration inoeases the burning rate …

Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde

Tanzania Journal of Engineering and Technology (TJET)

When designing a heat exchanger; one aims at attaining high heat transfer rates SO as to minimise heat transfer area and therefore the overall cost. This paper presents a method of improving the overall heat travsfer coef- ficient of a conventional shell and tube heal exchanger. The method in- volves injecting steam into the process fluid as it enters the heat exchanger thus effecting mixing of fluid as it travels along the exchanger Tests car- • ried out using this technique showed a significant increase in the overall heat transfer coefficient values.

Experimental Investigation On The Use Of Native Biomass As Biosorbents For Metal Pollutant Removal, R Litto

Tanzania Journal of Engineering and Technology (TJET)

Waste water treatment is a perrnunent task. Many novel techniques have emerge in recent years and one of them is using biomass in removing heavy- metals. In this research screening and preliminary optimization experi- ments have identified different types of abundant biomass which can accu- mulate heavy metals such as Fe3*, C03•, Cu2+ and ftvm effluent. Cystoseira Myrica has a high uptake ofCr3+ while Sargassum Polycystum has been found to have a high uptake 0fFe3+. Observed biosorption kinet- ics shows rapid initial stage, followed by slower second stage and the amount of material adsorbed increases linearly as its concentration in …

Pulping Of Sisal Fibres: Effects Of Chemical Concentration, Na-Zs03/Na2c03 Ratio And Fibre To Chemical Ratio, J Katima

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on pulping of hard fibres extracted from the leaves Of agave sisalana using sodium sulphite buffered with sodium carbonate as pulping chemical. The cooking was carried Out at 1680Cfor a cooking period of 6 hours, with varying chemical concentration, sodium sulphite to sodium carbonate ratio and fibre to chemical ratio. The results show thar boll! the pulp yield and pulp viscosity decæase with increasing chemi- cal concentration, whereas Kappa number of pulp decreases to a limit of about 16.45. Brightness increases significantly with an increase in the ra- rio of Na2S03/Na2C03. The pulp yield obtained indicated the …

Thermodynamics And Transport Proper- Ties Analysis Of Natural Gas From Songosongo In Kilwa- Tanzania, G Mrema

Tanzania Journal of Engineering and Technology (TJET)

Analysis ofthermodynamics and transport properties was carried outfor six natu- ral gas samples from Songosongofield in Kilwa - Tanzania using PRO/II simula- for. Properties of most interest in gas processing (due to their influence on the sales value) such as density, specific gravity, critical parameters, bubble point and dew point, enthalpy, latent heat of vaporisation, molecular weight, boiling point and phase were investigated. In addition composition of the gas was com- pared with that from elsewhere. The gas was assumed to be at a temperature of 30C and a pressme of 150 bar before pressure let down station. Results indicated …

Improvement Of Solar Salt Works Performance, J Katima

Tanzania Journal of Engineering and Technology (TJET)

Coal, asphalt, black oil paint, naphthol green b and alkali blue 6b were testedfor improvement Of solar energy utilisation in solar salt manufacture. It was found that the use of alkali blue 6b dye dissolved in raw seawater improves efficiency by 3.6 percent. Both modifications could increase solar salt works with a coal coated surface than one employing raw seawater dyed with alkali blue 6b.

Development And Testing Of Locally Produced Natural Rubber (Nr) And Pvc Blends, B Mutagahywa

Tanzania Journal of Engineering and Technology (TJET)

The mechanical properties of natural rubber - poly(vinyl chloride) blends have been studied. Tensile and tear strengths of the vulcanizates has been shown to increase with increasing proportions of PVC up to about 20 pphr. Abrasion loss and hardness decreases slightly with increasing concentration of PVC. Increased loading Of carbon black lowers the tensile and tear strength while increasing the abrasion loss and hardness values. This may be explained by the fact that PVC exists as a discontinuous rigid phase in the polymer compound. At normal loading of black (37 pphr) PVC improves processability and acts in the same way …

Energy From Biomass: Combustion And Gasification, G John

Tanzania Journal of Engineering and Technology (TJET)

Some fundamental facts of the combustion Of BIOMAS are outlined and di scussed . It is suggested that these provide guidelines for rhe development Of successful practical combustors. Furthemore, a realisation Of energy conversion from the same in gasfier is presented.

Nn Investigation Of Nitrogen Oxide Abscwption In Packed Columns, J Katima

Tanzania Journal of Engineering and Technology (TJET)

An experimental study was carried out on the performance of a packed column to study the absorption mechanism of nitrogen oxides (NOx). Two packed columns were set up, one with wall wiper rings to reduce wall effects and one without. Both columns were packed with stainless steel lessing rings and operated at fixed gas and liquid flow rates (40 and 8 L/min, respectively), atmospheric pressure, temperature (25°C), and sodium hydroxide concentration (8% w/w). The NOx (NO₂ and N₂O₄) equilibrium concentration and feed concentrations of up to 7000 ppm were used. The results indicated improved performance in the column with wall …

Nitrogen Oxides Rbsorption Into Sodium Hydroxide Solution In A Packed Column Column: Effect Of Naoh Concentration, J Katima

Tanzania Journal of Engineering and Technology (TJET)

Experiments have been conducted to evaluate the ettect of sodium hydroxide (NaOH) concentration upon the absorption rate of nitrogen oxides (NO ) and packed column performance. The absorption process using was carried out at atmospheric pressure and 29B K, concentrations between zero and w/ w, NO/ NO ratio of 0.5 and NO concentrations between 150 and 10000 ppm in an air mixture. The performance of the calumn was enhanced by the presence of hydroxyl ions ( 0B - ) relative to the absorption into water, however, The absorption it was found to be independent of NaOH concentration. rate of NO …