DC Conductivity Study
Figure 1 shows the typical impedance plot (imaginary part,Zi against real part, Zr of complex impedance, Z*) of CMC/CS doped with different NH4Br content at 303K. This impedance analysis is important in conductivity study and becomes a powerful tool in the investigation of ionically conduction behaviour in solid biopolymer electrolyte films. From the plot, it contains two-well defined regions, namely a high frequency region semicircle arc and low frequency region inclination spike. The semicircle represents the bulk effect of electrolyte which due to parallel combination of bulk resistance, R (proton migration) and bulk capacitance, C (immobile polymer chain). The inclination spike denotes the effect between two blocking electrodes which represent the formation of double layer capacitance of polymer electrolyte interface (proton migration at low frequency, f). The value of bulk resistance, Rb can be retrieved from the interception between low-frequency and high-frequency region on Zr-axis, which the value was then used to calculate ionic conductivity of the system.
Figure 1: The Cole-cole plots of the real impedance, Zr against imaginary impedance, -Zi biopolymer electrolyte system for (a) CMC/CS film, (b) CMC/CS-10 wt.% NH4Br, (c) CMC/CS-20 wt.% NH4Br and (d) CMC/CS-30 wt.% NH4Br at 303 K
Based on the plot, the value of Rb decrease with addition of NH4Br content up to 20 wt.%, and start to decrease beyond that concentration. Together with the decreasing in Rb value, the high semicircle arc seems to gradually fade away and completely disappears above 20 wt.% of NH4Br. Based on the previous study, the depressed semicircle and inclines spike (Figure 1a, 1b and 1 d) shows that the ...
... middle of paper ...
... T for CMC/CS-20 wt.% NH4Br electrolyte film
Conclusion
A yellow-ish transparent of CMC/CS-NH4Br electrolyte films were successfully prepared using solution casting technique. DC conductivity for the highest conducting electrolyte film is 2.12 x 10-5 Scm-1 at room temperature, and gradually increases with temperature. Dielectric analysis shows that εr increases as increasing in salt content. This behaviour is due to the increase in density of charge which provides more space for ion mobility. The value of εr also found to increase with temperature but tend to decrease with frequency. AC conductivity proved this system is follows the Jonscher power law. The conduction mechanism studies shown the CMC/CS-NH4Br electrolyte film is accompanied by QMT model in which the value of s is independently to temperature and tend to go constantly with increasing in temperature.
If more than one complex is formed at different pH values, their existence can be decided by this type of study. The pH, at which the absorption due to a particular complex species is far greater than that of metal ion and or the ligand alone, is selected for the study of that species. As the complex formation is the function of pH; it should be kept constant for particular system. Similarly, ionic strength is maintained constant throughout by adding an appropriate volume of sodium perchlorate. pH can be remained constant by using suitable buffer, provided the buffer does not interfere with the complex formation at wavelength where complex species show maximum
Cyclic voltammetry makes possible the elucidation of the kinetics of electrochemical reactions taking place at the electrode surface [31, 32]. In a typical voltammogram, there can be several peaks. From the sweep-rate dependence of the possible to investigate the role of adsorption, diffusion and coupled homogeneous chemical reaction mechanism. [33]
The dielectric constant found decreases monotonically in the lower frequency and it is independent at higher frequency. The high value of the dielectric constant at low frequencies can be attributed to the accumulation of charge carriers near the electrodes and at higher frequency the dipoles or polar molecules are unable to orient themselves in the direction of the applied field, hence the dielectric constant appears to decrease or is steady with increasing frequency [58]. The dielectric constants (εꞌ & εꞌꞌ) were found to increases with temperature at a fixed frequency for all electrolyte films due to the greater freedom of movement of the dipole molecular chains of polymer electrolytes at high temperatures. At lower temperatures, the dipoles are rigidly fixed or tightly bound in the dielectric material; therefore the field cannot change the condition of the dipoles. As the temperature increases, the dipoles become comparatively free and they respond to the applied electric field causes the change in the induced energy at the dipole site and consequently enhance the dipole motion
Rajagopal, Indira, and S.R. Rajangopalan. "Electrochemical Preparation of Potassium Gold Cyanide." Bull. Mater. Sci. 6.2 (1984): 165-75. Web. 14 Nov. 2013.
Cyclic Voltammetry is an electrochemical method used to study electrically active species. The basic theory behind cyclic voltammetry is that the species being studied undergoes excitation viva a potential. The potential is cycled between two points. Cyclic voltammetry can be used to study kinetics, mechanisms, synthesis, and quantitative analysis. In the following experiment, cyclic voltammetry will be used to study the concentration of acetaminophen in children’s pain reliever. The analysis of the elixir concentration was found to be 28.1 mg/L; given that the specified concentration was 32 mg/L. The percent error of the analysis was found to be 12.1 %.
While the solution is being stirred, an air condenser is attached to the vial and 12.2 mg of NaBH4 is added in 3 portions through the condenser. The condenser is capped with a drying tube containing calcium chloride and cotton. After thirty minutes a TLC analysis is taken of the reaction to see how many compounds are present. Three compounds were identified on the TLC meaning that the reaction did not go to completion and the mixture was placed back on a hot plate to react further for ten minutes longer. The TLC showed the starting product 4-tert-butylcyclohexanone and the cis-/trans- forms of 4-tert-butylcyclohexanol; the cis isomer is more polar and will appear above the trans
The first term that I noted during the movie was Conductive Polymers. Conductive polymers are almost always organic meaning a large class of chemical compounds whose molecules contain carbon. These polymers have extended delocalized bonds which are bonds found in a molecule that do not belong to a single atom or covalent bond. They are conjugated systems of double bonds and in a aromatic systems. The conjugated systems are atoms covalently bonded with alternating single and double bonds. When the electrons are removed or added into the valence bands the electrical conductivity increases. The conductive polymer has a low conductivity until the electron is removed from the valence band called (p-doping) or (n-doping) until it becomes more conductive. The movement of the charges is what is responsible for electrical conductivity. These polymers are plastic which are organic polymers and with mechanical properties such as flexibility and elasticity.
...h the help of the second buffer which increases the ionic strength of the solution. The charge of the buffer can also be modified to alter the rate of interaction between proteins and the resin. If the proteins are negatively charged at our corresponding given P.H, we should use anion exchange chromatography and if it is positively charged, we should use cation exchange chromatography.
Thin solid films were probably first obtained in 1838 by electrolysis. They were systematically prepared by Faraday in 1857.
In an “electrolytic solution”, if two electrodes, one being positive and the other negative, are placed in the solution then ions have the ability to transport free electrons to and from both of the electrodes. Acids in a solution are good electrolytes since the acids supply the solution with hydrogen ions. If a solution contains organic compound has sugar or starch, then that solution won’t conduct electricity well since organic compounds are contributing as many hydrogen ions as acids. The most familiar electrolytes would be elements such as potassium, calcium, sodium, and magnesium. Lithium-ion batteries are commonly used in many household as a source of energy, however the battery relies heavily on liquid electrolytes which are flammable and are prone to fires.Researchers at Oak Ridge National Laboratory has created a solid electrolytes that is made out of lithium triphosphate to try to overcome the safety issues presented by lithium-ion
In this recent century, there is ease into taking our technology as something for granted. After all, technology has opened up our abilities to instantly connect to the other side of the world, instantly retrieve information from the Internet, and instantly listen to digital content if desired. However, while a cell phone, laptop, and iPod has many differences from one another, all of those three devices share one item in common at the very least and that is a Lithium-Ion Battery.
This is the most common battery that people use today like Energizer or Duracle batteries. The most common form of a primary cell is the Leclanche cell, invented by a French chemist Georges Leclanche in the 1860s. The electrolyte for this battery consisted of a mixture of ammonium chloride and zinc chloride made into a paste. The negative electrode is zinc, and is the outside shell of the cell, and the positive electrode is a carbon rod that runs through the center of the cell. This rod is surrounded by a mixture of carbon and manganese dioxide. This battery produces about 1.5 volts.
From looking at the results I can conclude that when the pH was 3 and
The solid having high electric (ionic) conductive are called solid electrolyte. In general the conductivity of the electrolyte lies in between 10-6 to 10-1 s/cm range.
There are formulas to calculate electrical conductivity and resistivity. Conductivity is defined as the inverse of resistivity (a high conductivity means a low resistance), I=V/R or current equals voltage over resistance. This is known as Ohm’s Law. Electrical resistance is calculated by the formula, R=V/I or resistance equals voltage over current. Ohm’s law however does not hold true if temperature changes. Materials that obey Ohm’s law are known as ohmic or linear because the potential difference across it varies linearly with the current. In addition, whether or not a material obeys Ohm’s law its resistance can be described in bulk resistivity. Furthermore, over sizable ranges of temperature, this temperature depe...