Since invented by Iijima in 1991 [1], CNTs have become important materials in many aspects, due to their unique structural, mechanical, electrical and physicochemical properties [2]. Currently CNT containing materials are developed and evaluated for many different applications including sensors, electronics, actuators, drug delivery vehicles and new composites [3]. Unfortunately, CNTs typically exist as ropes or bundles of 10-30 nm in diameter because of strong van der Waals interactions that results in stacking and entangling; these phenomena have slowed down the applications of CNTs [4-5]. To overcome this problem it is beneficial to perform covalent surface modification and functionalization of CNTs to achieve homogenous dispersion of CNTs in polymer matrices for high quality nanocomposites [6]. Composite membranes containing CNTs are very promising, due to the predicted very high flux for water and gas. These exceptionally high transport rates have been attributed to the inherent molecular smoothness of the nanotubes [7]. Previous work to develop CNT membranes have been performed, Hinds et al. and Majumder et al. fabricated a well ordered CNTs membrane consisting of aligned multiwalled CNTs [8-9], Holt et al. have constructed a nanotube-Si3N4 composite membranes using CVD technique [10]. The results obtained are promising, however, the methods to prepare the CNT membranes are very tedious and time consuming; an up-scaling at competitive costs seems impossible. Herein, we report for the first time the facile preparation of thin-film-composite reverse osmosis membranes containing open SWCNTs. For membrane preparation the state-of the-art interfacial polymerization of trimesoylchloride (TMC) and phenylene diamine (PDA) first intr...
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...n of nanocomposites. JACS 2003; 125(51):16015-16024.
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[18] Meyer JC, Paillet M, Michel T, More´ac A, Neumann A, Duesberg GS, et al. aman Modes of Index-Identified Freestanding Single-Walled Carbon Nanotubes. Phys.Rev.Lett 2005; 95:217401(1)- 217401(4).
[19] Mukherjee A, Combs R, Chattopadhyay, Abmayr DW, Engel PS, Billups WE. Attachment of nitrogen and oxygen centered radicals to single-walled carbon nanotube salts. Chem.Mater 2008; 20:7339-7343.
[20] Kwak S-Y, Jung SG, Kim SH. Structure-motion-performance relationship of flux enhanced reverse osmosis membranes composed of aromatic polyamides thin films. Environ. Sci. Technol 2001; 35:4334-4340.
If the concentration of one side of the membrane is greater than the molecules will travel from the higher to lower concentration. Eventually there will be a dynamic equilibrium and there will be no net movement of molecules from one side to the other. Osmosis is the diffusion of water. Like diffusion, the water moves from a region of higher water potential to a region of lower water potential.
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.
Osmosis is the facilitated diffusion of water across the cell membrane of a cell. The inside layer of the cell membrane is hydrophilic, meaning water cannot easily pass through the membrane. The cell membrane has to have aquaporins, which are water channel proteins, that move the water across the membrane. If there is a water and salt solution outside the cell, the salt can enter the cell by diffusion, but the cell membrane is not permeable to the water. Because there is more solute solution inside the cell, there is less water. The aquaporins move the water across the membrane until equilibrium is reached.
Carbon Nanotubes could make t-shirts bulletproof. Retrieved March 11, 2014, from Nano Werk: http://nanowerk.com/spotlight/spotids1054.php. Fecht, S. (n.d.). Lighter, stronger bulletproof clothing. Retrieved April 8, 2014, from Popular Mechanics: http://popularmechanics.com/science/health/med-tech/6spidersilksuperpowers.htm.
Most cell membranes are like that, being permeable to water and some solutes only. Osmosis is therefore the diffusion of water through a partially permeable membrane. The basic principles of diffusion apply here.
Activity 3: Investigating Osmosis and Diffusion Through Nonliving Membranes. In this activity, through the use of dialysis sacs and varying concentrations of solutions, the movement of water and solutes will be observed through a semipermeable membrane. The gradients at which the solutes NaCl and glucose diffuse is unproportional to any other molecule, therefore they will proceed down their own gradients. However, the same is not true for water, whose concentration gradient is affected by solute ...
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early 1990’s, no such material was known. In 1991, carbon nanotubes were discovered. Although not
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PC-SK standard cation exchange membranes and PC-SA standard anion exchange membranes are used in the stack. Information given by the manu...
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