Introduction
Recently, water shortage problem becomes more and more serious in the world [1]. The desire to make a drinking water by treating a ground water, a surface water, a sea water and so on has been increasing. An electrodialysis (ED) is one of the useful methods and has applied to make the drinking water as well as RO and NF membranes [2~5].
ED is an electrical system utilizing ion exchange membranes. Ion exchange membranes have permselectivity similar to RO and NF membranes [6]. It is very important to understand the mechanism of permselectivity of ion exchange membranes to design ED system. The transport number ratio between target ion and standard ion has been treated to discuss the permselectivity of ion exchange membrane in ED system [7]. Recently, it was found that the ratio of transport number of several anions to chloride ion changed with the progress of electrodialysis. In this paper, a mechanism of permselectivity of ions in the electrodialysis system is theoretically discussed to make clear the reason why the transport number ratio changes with the progress of deionization in electodialysis process. In addition, the simple way to simulate ED system is proposed.
2. Theoretical
2.1 Model of electrodialysis system
The ratio of transport number of anion a and chloride ion, PaCl is defined by eq.(1) [7].
Here, ta and tCl denotes the transport number of anion a and Cl ion, respectively. [a]B and [Cl]B are the concentration (eq/m3) of anion a and Cl in the diluted compartment, respectively. [Ja] (eq/m2s) denotes the flux of anion a and[Js] the sum of all ion fluxes through the anion exchange membrane. Thus, PaCl defined by eq.(1) shows the transport number ratio of anion a and Cl at ...
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... the transport number ratio depends on only the total electrolyte concentration in the diluted compartment, CB. PaCl is determined by the membrane resistances of ions transport in the system where CB is sufficiently high. On the other hand, in the system where CB is sufficiently low, PaCl is determined by the equivalent conductance of electrolytes in the diluted compartment. Thus, PaCl changes with the progress of electrodialysis, since the electrolyte concentration in the diluted compartment decreases with time. The transport number ratio was analyzed with this model and it was shown that the model explained the experimental results very well.
It was also possible to simulate ED system after the electric resistances of the equivalent circuit were obtained from the analysis of the time course of PaCl. The simulation results agreed with ED data very well.
The experiment is aimed at giving a better understanding of the osmosis process and the different conditions in which osmosis occurs. INTRODUCTION When a cell membrane is said to be selectively permeable, it means that the cell membrane controls what substances pass in and out through the membrane. This characteristic of cell membranes plays a great role in passive transport. Passive transport is the movement of substances across the cell membrane without any input of energy by the cell.
In life, it is critical to understand what substances can permeate the cell membrane. This is important because the substances that are able to permeate the cell membrane can be necessary for the cell to function. Likewise, it is important to have a semi-permeable membrane in the cell due to the fact that it can help guard against harmful items that want to enter the cell. In addition, it is critical to understand how water moves through the cell through osmosis because if solute concentration is unregulated, net osmosis can occur outside or inside the cell, causing issues such as plasmolysis and cytolysis. The plasma membrane of a cell can be modeled various ways, but dialysis tubing is especially helpful to model what substances will diffuse or be transported out of a cell membrane. The experiment seeks to expose what substances would be permeable to the cell membrane through the use of dialysis tubing, starch, glucose, salt, and various solute indicators. However, before analyzing which of the solutes (starch, glucose, and salt) is likely to pass through the membrane, it is critical to understand how the dialysis tubing compares to the cell membrane.
1. Due to their charged nature, sodium ions cannot diffuse passively through the plasma membrane, which is a lipid bilayer. The sodium ion and its cloud of polarized water are capable of interacting with the polar hydrophilic heads of the phospholipids but not with the hydrophobic tails, so they could only cross the plasma membrane though ions channels, integral membrane proteins that form ion-conducting pores in the lipid bilayer, or pumps. The size of the pore and they way it interacts with ions, gives the channel its ion selectivity, so they allow only one ion to pass through. The sodium ion channels are voltage gated channels, meaning they response to voltage changes across the membrane. The ion channel detects an electric stimulus, it opens to the extracellular space allowing sodium ions to pass though the membrane by simple diffusion. Ion channels allow ions to move passively, no ATP is needed for their transport; however ATP is used to open and close the channels.
The electrolyte (solution) contains negative and positive ions. For electrolysis to work there must be the same amount of positive ions to negative ions so that the solution is electrically balanced. A solution of metal compounds can only conduct electricity if it is balanced. The negative ions are attracted to the anode (+ve electrode) and the positive ions (protons) are attracted to the cathode (-ve electrode). The electrolyte effect the amount of atoms attracted.
An example of a device that uses electrolysis is a rechargeable battery. Electrolysis consists of an electric current passing through a liquid, causing chemical reactions to occur within the liquid. Another example of electrolysis in the real world is the process of electroplating. In electroplating, chemicals are put in water and through electrolysis he chemicals or compounds in the liquid adhere to the metal being electroplated. Electrolysis can also be used to separate compounds and purify impure substances. Purifying a substances is achieved by separating the desired parts of a substance from the impure or unwanted sections through electrolysis. The process of electrolysis can also change the pH of a solution (Wolfson,
At the electrode-tissue interface, where the electrode and actual body come into contact, a conversion occurs between the current of electrons passing through the wires and the current of ions moved
E_cell^o was determined to be 0 V since the same metal was used as the electrodes. In doing so, the differences in the standard reduction potentials was 0 V. The R value, the ideal gas constant is given in 8.314 J/(mol K), T is the temperature at standard conditions (298.15 K), n is the number of electrons transferred (2 in this case), and F is the Faraday Constant of 96485.3399 J/(V mol). The reaction quotient, Q, was determined to equal the concentration of the concentrated Copper ion divided by the diluted Copper ion concentration (Q=([Cu_diluted^(2+)])/([Cu_concentrated^(2+)])= .05 M). The average corrected Ecell was found to be .042 V, givng a 10.52% error when compared to the theoretical
Reverse osmosis has been applied for different type of industrial waste water. In these RO system we are used two type of membranes 1. Flat sheet 2. Spiral Membrane. This type of RO membrane is used to remove parameter like calcium, zinc, Sulphate, Chloride, Magnesium Ammonia and others.
Electrolysis is a chemical reaction caused by electricity in solutions. Electrolysis can separate molecules (like separating water into hydrogen and oxygen gas, which is called electrolysis of water), electroplate a metal, can be used for welding, and can even be used for hair removal. Electrolysis was discovered by Alessandro Volta. The materials to cause electrolysis are a source of direct current (like batteries), electrolyte, and two electrodes.
In the experiment there are several possible ways of changing the electric current such as changing the voltage or the position of the electrodes within the electrolysis cell. However, it was found from preliminary work that the most effective way to change the current was to change the concentration of the acid solution. The preliminary work showed that the greater the concentration of the acid, the greater the current. Ohm's law states that R(resistance) =
where D Hg2+ and DMn+ are the distribution coefficient of the Hg2+ ions and the other interfering metal ions, respectively, which can be calculated according to Eq. (4).
This filtration system serves the same purpose, and had the ability to remove chemical components like lead and arsenic from the raw water. This is shaping up to be a cheap and effective filtration system to help the process of purifying water. Researchers in Mumbai, India discussed how here are several approaches to the purification of water with the use of nanotechnology that are currently being investigated and have the potential to be ready for use very soon, and some that are already being implemented into the
For this laboratory experiment, the objectives are to describe the seats of electromotive force or EMF, and to know the difference between the EMF and terminal voltage. Also, one of the objectives of this experiment is to know the significance of internal resistance and how this internal resistance differentiate a real battery from an ideal battery. These objectives can be accomplished by knowing how to measure the EMF of a battery and by calculating the internal resistance of the battery.
In this assignment an overview of water purification in pharmaceutical manufacturing will be briefly explored. The system(S)/equipment used in that process will be identified and installation qualification and operational qualification of this equipment will be discussed.
In this experiment three different equations were used and they are the Stoichiometry of Titration Reaction, Converting mL to L, and Calculating the Molarity of NaOH and HCl (Lab Guide pg. 142 and 143).