Electrochemical Study on FXL-I4 Collecting Wolframite without Pb^(2+) Flotation

In this paper,FXL-14 (tetradecyl iminobimetyl phosphonic acid) as a collector for floating wolframite without Pb^(2+) and its adsorption mechanism were studied by electrochemical method.Flotation experiment results showed that in the wide range of pH value activation of FXL-14 collecting wolframite with Pb^(2+) was not needed.Wolframite—carbon paste electrode and small-amplitude triangular potential sweep were used to measure the electro-double-layer capacitance of wolframite in the FXL-14 solution (with and without of the presence of 1×10^(-4)MPb^(2+)).It is showed that in spite of concentration of Pb^(2+) in the flotation processing,with FXL-14 (800mg/l) the electro-double-layer capacitance was bigger than with FXL-14 (800mg/l) and Pb^(2+).

An Electrochemical Study on the Corrosion Inhibition of Stainless Steel by Polyaniline Film

Polyaniline (PANI) film was electrosynthesized on 304 stainless steel by cyclic voltammetry using aqueous oxalic acid as supporting electrolyte. The potential sweep rates were changed to achieve the PANI film with different thickness and structures. Protective properties of the PANI film for corrosion of stainless steel in 3% NaCl aqueous solution were investigated by monitoring potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that the PANI film which was formed with lower sweep rate led to more positive shift of corrosion potential and greater charge transfer resistance, reflecting higher inhibition for corrosion of the stainless steel.

Electrochemical Study on the Change in Valency of Niobium Oxide in the MnO-SiO_2-Nb_2O_5 System

Change in valency of Nb-oxide in MnO-SiO_2-Nb_2O_5 system was studied with the electrochemical method using ZrO_2 as the solid electrolyte.Thermodynamic analysis has shown that the only possible reaction that could take place at the working elec- trode is:2(Nb_2O_5)=2(Nb_2O_4)+O_2 with the a_0 values experimentally evaluated,values of a Nb_2O:/a Nb_2O:were calculated and isoactivity-ratio curves drawn in MnO-SiO_2-Nb_2O_5 triangles at 1418 and 1585K.The simultaneous existence of tetra-and penta-valent Nb mineral constituents in industrial Nb-bearing slags was thus verified experimentally.

An electrochemical study on the effects of marine fouling organisms on steel used in the sea

-Study on the effects of microorganism secretive membrane and covering layer of macrofouling organisms-Balanus reticulatus, Ostrea plicatula, Membranipora, Corophium and Algae on the corrosion of carbon steel and low-alloy steel by the determination of natural corrosive potentials, linear polarization and the polarization curver of dynamic potential scanning through an electrochemical equipment.The results show that the microorganism secretion membrane formed on sample surface has some protective role, during the initial period of exposure (about ten days). Then protective role decreases and corrosive rate increases with the lapse of immersion time. The protective role of some macrofouling organisms is shown in order as follows: Corophium> Balanus reticulatus>Algae>Membranipora>Ostrea plicatula.

Study on Electrochemical Properties of MnO2/MoS2 composites

1 Introduction Supercapacitor also called electrochemical capacitor,has become one of the most promising energy storage devices due to its long service life,great power density,high energy density,green environmental protection(Simon et al,2008;Ma et al,2013).Based on the charge storage mechanisms,Supercapacitors can be divided into

ELECTROCHEMICAL AND OPTICAL STUDY ON C_(60) FILM IN LiClO_4 POLYPROPYENE CARBONATE (PC) SOLUTION

For the first time we observed the electrochromism of C_(60) film intercalated by lithium and obtained some amount of intercalate Li_3C_(60) with cyclic voltammetry. The optical absorption properties of this intercalate have been studied.

STUDY ON THE ELECTROCHEMICAL BEHAVIOR OF ION EXCHANGE MEMBRANE IN PREPARING POTASSIUM CARBONATE

This investigation describes the one step preparation of potassium carbonate by electrolysis of potas-sium chloride solution in electrolyzers with various Nation membranes.Potassium bicarbonate solution wasfed to the cathode compartment,where it was converted into carbonate by reaction with the hydroxideformed at cathode.Because of the low OH^- concentration in the cathode compartment,the back migrationof OH^- through the membrane was almost negligible,resulting in a higher current efficiency,say 90% or more.In this study,electroconductivity,mass transfer,current efficiency and cell voltage were measured.Thefeasibility of the process was discussed and the optimal conditions examined.

Electrochemical Studies of Lithium Intercalation into Graphite Film Electrode for Li^+-ion Batteries

To study the electrochemical kinetic properties of the Li/Graphite system, cycle voltammerty (CV), ac-impedance and chro- noamperometry (CA) techniques have been used. The results showed that the diffusion of lithium ions in Li_xC_6 is the rate-determining step. The chemical diffusion coefficients of lithium (D_Li) have been estimated for different x values. As for the same material, the value of D_Li was calculated in order to compare the differences among the three techniques.

ELECTROCHEMICAL STUDIES OF TITANIUM(IV)IN 1-METHYL-3-ETHYLIMIDAZOLIUM CHLORIDE

A Titanium tetrachloride-1-methyl-3-ethytimidazolium chloride melt has been prepared.The reduction process of Ti(IV)appears to be diffusion controlled in the composition of 0.4:1 mole ralio of TiCl_4-1-methyl-3-ethylimidazolium chloride and the electrochemical behavior of Ti(IV)shows remarkable compositon dependence.

PREPARATION,CHARACTERIZATION AND ELECTROCHEMICAL PROPERTIES OF POLYPYRROLE-POLYSTYRENE SULFONIC ACID COMPOSITE FILM

Polypyrrole-polystyrene sulfonic acid(PPy-PSSA)composite films have been electrosynthesized in an aqueoussolution of PSSA.The electro-active films exhibit cation exchange during the redox process.Infrared,Raman and energy-dispersive spectroscopic results demonstrated that the polyanion of PSS^- is co-deposited into the PPy matrix and couldn't bestripped fiom the film extensively by dedoping.The doping level together with dipolaron content of the PPy-PSSAcomposite film increases during electrochemical polymerization process.SEM images revealed that the composite film hassmooth and compact morphology and AFM pictures suggested that PPy chains are possibly grown perpendicular to theelectrode surface.TGA tests indicated that the composite films has much better thermal stability than that of pure PPy.Furthermore,electrochemical studies showed that the relaxation process at certain holding potential has great effect on theshape of the cyclic voltammetric curves of PPy-PSSA composite film.The composite film exhibits cation and anionexchange during the redox process after undergoing the relaxation step.It is more difficult for divalent anion to enter thepolymer matrix than a univalent ion,and a large cation such as(CH_3CH_2CH_2CH_2)_4N^+ cannot be involved in the ionexchange process.

Electrochemical and Spectroelectrochemical studies of Mixed-Valence Heteropolyanion VMo_(12)O_(40)^(n-)(n=4,5,6) in Aprotic Media

The mixed-valence heteropolyanion VMo12O40 n-(where n=4,5,6) in aprotic media wasinvestigated by cyclic voltammatry and in-situ FTIR and UV-visible-near-lRspectroelectrochemical methods. The results indicate that the heteropolyanion VMo12O403-undergoes three reversible one electron transfer reductions and the mixed-valenceheteropolyanion VMo12O40n-(where n=4,5,6) was formed after electroreduction. The spectraof the aforementioned mixed-valence compounds were characterized by in-situspectroelectrochemical mathods

Electrochemical Studies on the Deposition of Neodymium in DMSO

The electrodeposition of neodymium on Pt and Cu electrodes was investigated in DMSO containing NdCl3 and a small mount of water at room temperature. Cyclic voltammetry indicated that the reduction process of Nd(III) on the Pt cathode was complicated. The one-step reduction wave showed two steps by adding 0.3 mol/L ethylenediamine(EN). A delicate yellow, lustrous, strongly adhering film on the Cu electrode was obtained using potentiostatic electrolysis at -1.80 V (vs. aq SCE).

Poly caprolactone/titanium dioxide nanofiber coating on AM50 alloy for biomedical application

Poly caprolactone(PCL)and Poly caprolactone/TiO_(2)(PCL/TiO_(2))composite nanofiber with different weight percentage compositions(2 wt%,4 wt%and 6 wt%)of TiO_(2)were prepared and coated over AM50 alloy using electrospinning technique.The surface morphology and elemental composition result confirms that the PCL/TiO_(2)composite nanofiber fiber were successfully electrospun on the surface of AM50 alloy.The degradation behavior of PCL and PCL/6 wt%TiO_(2)coated AM50 alloy was studied by immersing in Simulated Body Fluid(SBF)solution.The electrochemical and cell proliferation studies reveals that the cellular behavior of PCL and PCL/6 wt%TiO_(2)composite nanofiber exhibited good support for cell proliferation with enhanced corrosion resistance of AM50 alloy in SBF solution.

An ecofriendly approach for corrosion control of 6061 Al-15%(v)SiC(P)composite and its base alloy

Corrosion inhibition characteristics of bio polymer dextran was studied for the corrosion control of 6061 Al-15%_((v)) SiC_((P)) composite and its base alloy in 1 mol·L^(-1) HCl. Standard electrochemical techniques such as potentiodynamic polarization(PDP) measurements and electrochemical impedance spectroscopy(EIS) method were adopted for corrosion rate measurement. Surface morphology was studied by scanning electron microscopy(SEM) and elemental mapping was done by energy dispersive X-ray(EDX) analysis. Suitable mechanism was proposed for corrosion and inhibition process. Results indicated that dextran acts as an excellent anticorrosive agent for the corrosion control of 6061 Al-15%_((v)) SiC_((P)) composite, with maximum inhibition efficiency of 91% for the concentration of 0.4 g·L^(-1) at 303 K. Dextran acted as a mixed type of inhibitor, and got physically adsorbed both on composite and base alloy by obeying Langmuir adsorption isotherm. Dextran is proved to be a green inhibitor with environmental and economic benefits.

Study of antigen and antibody reaction in electrochemical reactions with ellipsometric spectroscopy

IN the study of antigen and antibody reaction with ellipsometric spectroscopy, most researchers calculated the thickness of antibody film, absorbance and film constant by mathematic models.But by using simple mathematic models, it is very hard to describe accurately the real state of the system. Huang and Ord proposed a new physical measurement (optical tracking rate,Vop), indicating the total change of △, Ψ in study of oxidation and reduction reaction of the iron electrode in alkaline solution. Many experimental results showed that the spectral peaks in Vop～t figure correspond to the turning points on the polarization curve. This work

THE EXPERIMENTAL STUDY FOR NATURAL CONVECTIVE HEAT AND MASS TRANSFER IN POROUS MEDIA

An electrochemical method is employed to study experimentally natural convection driven by combined thermal and solutal buoyant forces in a fluid-saturated porous enclosure. The horizontal temperature and concentration gradients are imposed in such a way that their effects on the flow are either opposing or augmenting. The inside temperature profiles and heat and mass transfer characteristics on the vertical walls are experimentally determined. The effects of dimensionless parameter Ra, Le, N on flow, heat and mass transfer are discussed in details.

Effect of Hydrodynamic Conditions on Corrosion Inhibition of Cu-Ni(90/10)Alloy in Seawater and Sulphide Containing Seawater Using 1,2,3-Benzotriazole

Electrochemical studies of the effect of hydrodynamic conditions on corrosion inhibition of Cu-Ni （90/10） alloy in synthetic seawater and sulphide containing synthetic seawater by 1,2,3-benzotriazole （BTAH） are presented. Impedance, potentiodynamic polarization and cyclic voltammetric （CV） studies are employed in the present investigation. The studies are carried out by using Cu-Ni （90/10） alloy rotating disc electrode at different rotation speeds and at different immersion periods. Reynolds numbers at each rotation speed infer that the flow of seawater is laminar. With increasing rotation speed of the electrode immersed in seawater without sulphide and BTAH, both the charge transfer resistance （Rot） and film resistance （Rf^lm） are increased. However, in the presence of sulphide ions and without BTAH, both the Rot and Rf,m are found to decrease with increasing rotation speed at identical immersion periods. Interestingly, when BTAH is added to seawater or seawater containing sulphide, both the Rot and Rf,m are increased to such a great extent that an inhibition efficiency of 99.99% is obtained. In the presence of BTAH, the phase angle Bode plots are more broadened and the maximum values of phase angle are increased to a value close to 90~ as the rotation speed is increased. The BTAH film is highly protective even under hydrodynamic condition also. Potentiodynamic polarization studies infer that BTAH functions as a mixed inhibitor under hydrodynamic conditions also. CV studies reveal that the protective BTAH film is stable even at anodic potentials of ＋850 mV vs Ag/AgCI.

Sol-Gel Coating with 3-Mercaptopropyltrimethoxysilane as Precursor for Corrosion Protection of Aluminium Metal

Sol—gel coatings offer a number of advantages over other methods of protection for metallic materials.In the present work,3-mercaptopropyltrimethoxysilane（MPTS） was used as the precursor for sol—gel coating on aluminium metal.The gelation of MPTS sol—gel was characterized by Fourier transform infrared spectroscopy（FT-IR） studies.The formed film was found to be stable up to 350 ℃ as evident from thermogravimetric analysis.X-ray diffraction study and scanning electron microscopy supported the formation of MPTS coating on aluminium surface while the characterization of the coating was done by FT-IR studies.The corrosion inhibition potential of the sol—gel coatings on metal in 3.5%（w/v） of NaCI solution was assessed as a function of different concentrations of MPTS using electrochemical polarization and impedance measurements.The corrosion inhibition efficiency was found to increase with increasing MPTS concentration.The results of the study unravel the use of MPTS as a precursor in the formation of sol—gel coating over aluminium surface so as to protect the metallic surface from corrosion in neutral environment.