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Dilution Equation

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Dilution (equation)

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Dilution is a reduction in the concentration of a chemical (gas, vapor, solution). It is the process of reducing the concentration of a solute in solution, usually simply by mixing with more solvent. To dilute a solution means to add more solvent without the addition of more solute. The resulting solution is thoroughly mixed so as to ensure that all parts of the solution are identical.

The same direct relationship applies to gases and vapors diluted in air for example. Although, thorough mixing of gases and vapors may not be as easily accomplished.

For example, if there are 10 grams of salt (the solute) dissolved in 1 liter of water (the solvent), this solution has a certain salt concentration/molarity. If one adds 1 liter of water to this solution the salt concentration is reduced. The diluted solution still contains 10 grams of salt/(0.171 moles of NaCl).

Mathematically this relationship can be shown in the equation:

 C1\times V1 = C2\times V2

Where:

C1 = Concentration/molarity 1

V1 = Volume 1

C2 = Concentration/molarity 2

V2 = Volume 2

Contents

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[edit] Basic Room Purge Equation

The Basic Room Purge Equation, is used in industrial hygiene. It determines the time required to reduce a known vapor concentration existing in a closed space to a lower vapor concentration. The equation can only be applied when the purged volume of vapor or gas is replaced with “clean” air or gas. For example, the equation can be used to calculate the time required at a certain ventilation rate to reduce a high carbon monoxide concentration in a room.

\ D_t=\left [ \frac{V}{Q} \right ]\quad \cdot ln\left [ \frac{C_{initial}}{C_{ending}}\right ] \quad

Sometimes the equation is also written as:

\ ln\left [ \frac{C_{ending}}{C_{initial}}\right ] \quad={-}\frac{Q}{V} \cdot (t_{ending}-t_{initial})\quad  where tinitial = 0

Dt = Time required; the unit of time used is the same as is used for Q.

V = Air or gas volume of the closed space or room in cubic feet, cubic meters or liters

Q = Ventilation rate into or out of the room in cubic feet per minute, cubic meters per hour or liters per second

Cinitial = Initial concentration of a vapor inside the room measured in ppm

Cending = Final reduced concentration of the vapor inside the room in ppm

[edit] Dilution Ventilation Equation

The Basic Room Purge Equation can be used only for purge scenarios. In a scenario where a liquid continuously evaporates from a container in a ventilated room, a differential equation has to be used.

 {dC \over dt} - \frac{G - Q' C}{V}

Where the ventilation rate has been adjusted by a mixing factor K.

 Q' = \frac{Q}{K}

C = concentration of a gas

G = generation rate

V = room volume

Q’ = adjusted ventilation rate of the volume

Titanium Dioxide as a Photocatalyst

from Wikipedia

As a photocatalyst

TiO fibers and spirals.

Titanium dioxide, particularly in the anatase form, is a photocatalyst under ultraviolet light. Recently it has been found that titanium dioxide, when spiked with nitrogen ions or doped with metal oxide like tungsten trioxide, is also a photocatalyst under visible and UV light. The strong oxidative potential of the positive holes oxidizes water to create hydroxyl radicals. It can also oxidize oxygen or organic materials directly. Titanium dioxide is thus added to paints, cements, windows, tiles, or other products for its sterilizing, deodorizing and anti-fouling properties and is used as a hydrolysis catalyst. It is also used in the Graetzel cell, a type of chemical solar cell.

The photocatalytic properties of titanium dioxide were discovered by Akira Fujishima in 1967[18] and published in 1972.[19] The process on the surface of the titanium dioxide was called the Honda-Fujishima effect.[18] Titanium dioxide has potential for use in energy production: as a photocatalyst, it can

  • carry out hydrolysis; i.e., break water into hydrogen and oxygen. Were the hydrogen collected, it could be used as a fuel. The efficiency of this process can be greatly improved by doping the oxide with carbon.[20].
  • Titanium dioxide can also produce electricity when in nanoparticle form. Research suggests that by using these nanoparticles to form the pixels of a screen, they generate electricity when transparent and under the influence of light. If subjected to electricity on the other hand, the nanoparticles blacken, forming the basic characteristics of a LCD screen. According to creator Zoran Radivojevic, Nokia has already built a functional 200-by-200-pixel monochromatic screen which is energetically self-sufficient.

In 1995 Fujishima and his group discovered the superhydrophilicity phenomenon for titanium dioxide coated glass exposed to sun light.[18] This resulted in the development of self-cleaning glass and anti-fogging coatings.

TiO2 incorporated into outdoor building materials, such as paving stones in noxer blocks or paints, can substantially reduce concentrations of airborne pollutants such as volatile organic compounds and nitrogen oxides.[21]

A photocatalytic cement that uses titanium dioxide as a primary component, produced by Italcementi Group, was included in Time‘s Top 50 Inventions of 2008.[22]

TiO2 offers great potential as an industrial technology for detoxification or remediation of wastewater due to several factors.

  1. The process occurs under ambient conditions very slowly; direct UV light exposure increases the rate of reaction.
  2. The formation of photocyclized intermediate products, unlike direct photolysis techniques, is avoided.
  3. Oxidation of the substrates to CO2 is complete.
  4. The photocatalyst is inexpensive and has a high turnover.
  5. TiO2 can be supported on suitable reactor substrates.

IPurTech LightCLEAN Photocatalyst Oxidation

From IPurTech

LightCLEAN

Titanium Dioxide is the most common white pigment used in everyday life. Its use ranges from paints to toothpaste. It was discovered recently that a tiny proportion of one crystal form of caused some paint resins to deteriorate. The resin was in fact broken down by a reaction of the Titanium Dioxide and light. Researchers identified the type of Titanium Dioxide causing the breakdown and managed to isolate it and produce a coating system which uses this type of Titanium Dioxide alone.
This active form of TiO2 is now held in a special resin which is unaffected by the pigment but any other organic which lands on its surface decays rapidly in a photocatalytic reaction. Thus a simple method of destroying, on contact odours, VOC’s, and bacteria was discovered.

A Catalyst is a substance that accelerates or slows down the chemical reaction of other substances without itself being affected. Positive catalyst accelerates reaction, while negative one slows it down.
Photocatalyst causes catalytic reaction when exposed to light. Titanium dioxide is most commonly used as photocatalyst, because it is acid-resistant, alkali-resistant, and harmless to the human body. xide is the most common white pigment used in everyday life. Its use ranges from paints to toothpaste. It was discovered recently that a tiny proportion of one crystal form of caused some paint resins to deteriorate. The resin was in fact broken down by a reaction of the Titanium Dioxide and light. Researchers identified the type of Titanium Dioxide causing the breakdown and managed to isolate it and produce a coating system which uses this type of Titanium Dioxide alone.
This active form of TiO2 is now held in a special resin which is unaffected by the pigment but any other organic which lands on its surface decays rapidly in a photocatalytic reaction. Thus a simple method of destroying, on contact odours, VOC’s, and bacteria was discovered.

A Catalyst is a substance that accelerates or slows down the chemical reaction of other substances without itself being affected. Positive catalyst accelerates reaction, while negative one slows it down.
Photocatalyst causes catalytic reaction when exposed to light. Titanium dioxide is most commonly used as photocatalyst, because it is acid-resistant, alkali-resistant, and harmless to the human body.

Photocatalytic Oxidation (PCO)

Photo catalytic Oxidation

PCO has a wide variety of potential applications. The application closest to commercialization is
the destruction of VOCs in air. The PCO process can be applied directly to airborne emissions, as
well as to gaseous pollutants generated from remediation techniques, such as soil vapor
extraction and air stripping.
The goal of this project is to determine the feasibility of treating VOC emissions from
semiconductor plants. Although originally planned to look at a number of simulated waste
streams, this work focused on solvent vapor emissions from a parts cleaning sink.

Biomimetic Membranes

BIOMIMETIC MEMBRANES – NEW SEPARATION TECHNOLOGY TOOLS WITH ANCIENT ROOTS

Nature provides an excellent palette of highly effective membranes capable of highly selective vectorial transport of a large number of molecular species. It is therefore striking that the membrane industry has developed synthetic separation membrane processes in a very different way [1].

Traditional separation membranes are mostly dense polymeric films where advanced chemistry is used to control the surface properties of the films produced [2]. A wide range of polymers and production techniques are been used resulting in a great diversity in structure and function of separation membranes tailored to a wide variety of applications. Separation is usually described in terms of pore/solute size, pore/solute charge and dielectric effects, coupled with diffusion or convective flow. Occasionally, more complex partitioning and transport mechanisms are used, however, most synthetic membranes may be broadly described as polymer sheets containing micron to nanometre sized holes.

This is in stark contrast to the bewildering complexity of biological membranes. 30 % of the human genome codes for membrane proteins [3], and a typical mammalian cell membrane hosts several hundred lipid types [4]. Despite dramatic progress over the last decades in our understanding of the molecular basis for biological membrane transport (e.g. [5-7]), this complexity remains a major obstacle in our molecular understanding of how living cells maintain their integrity and perform their function [8].

One way leading to a better understanding of membranes and membrane transport is to focus on a few of its components and features. This understanding is crucial if we want to exploit – or mimic – nature’s tremendous capability for selective membrane transport. The term Biomimetic Membranes denotes the common denominator for such endeavours [9]. Recent examples of membrane biomimetics include low noise recording devices for ion channel research [10], free-standing triblock copolymer membranes [11, 12], enzyme-immobilization [13], and gas-extraction membranes [14].

In the development of biomimetic membranes it is important to know the morphological descriptors such as the amount and intrinsic properties of amphiphiles (lipidic or block coplymeric types) forming the membrane, the equilibrium thickness, and the coverage. Also important are the properties of interaction: the stability against mechanical perturbations (e.g. viscoelastic responses to changes in hydrostatic or osmotic pressure differences) [15, 16], the rate of regeneration (self healing) [17], the ease with which functional peptides or proteins can be adsorbed/incorporated [18] and, once incorporated, how proteins interact with the amphiphilic matrix [19]; and surface (e.g. electrostatic) energetics [20].

Perhaps the most challenging part of biomimetic membrane development is to understand the interaction between the membrane and its support – in particular when this support also is porous and thus can support mass transport across the membrane [21]. In Aquaporin’s case the biomimetic membrane with embedded aquaporins must support pressures up to 10 bar and allow a water flux > 100 l /m3 h. Therefore the development of the Aquaporin membrane™ is closely linked to the simultaneous development of suitable porous support materials.

  1. Rios, G.M., M.P. Belleville, and D. Paolucci-Jeanjean, Membrane engineering in biotechnology: quo vamus? Trends Biotechnol, 2007. 25(6): p. 242-6.
  2. Byrne, W., Reverse Osmosis. 2. ed. 2002, Littleton, CO: Tall Oaks Publishing Inc. 1-636.
  3. Bernsel, A. and G. Von Heijne, Improved membrane protein topology prediction by domain assignments. Protein Sci, 2005. 14(7): p. 1723-8.
  4. Dowhan, W., Molecular basis for membrane phospholipid diversity: why are there so many lipids? Annu Rev Biochem, 1997. 66: p. 199-232.
  5. Doyle, D.A., et al., The structure of the potassium channel: molecular basis of K+ conduction and selectivity. Science, 1998. 280: p. 69-77.
  6. Preston, G.M., et al., Appearance of water channels in Xenopus oocytes expressing red cell CHIP28 protein. Science, 1992. 256(5055): p. 385-7.
  7. Tajkhorshid, E., et al., Control of the selectivity of the aquaporin water channel family by global orientational tuning. Science, 2002. 296(5567): p. 525-30.
  8. Andersen, O.S., D.B. Sawyer, and R.E. Koeppe, II, Modulation of channel function by the host bilayer. Biomembrane Structure and Function, 1992: p. 227-244.
  9. Martin, D.K.e., Nanobiotechnology of Biomimetic Membranes. 2007, New York: Springer Verlag.
  10. Mayer, M., et al., Microfabricated teflon membranes for low-noise recordings of ion channels in planar lipid bilayers. Biophys J, 2003. 85(4): p. 2684-95.
  11. Nardin, C., M. Winterhalter, and W. Meier, Giant Free-Standing ABA Triblock Copolymer Membranes, Langmuir, 2000. 16: p. 7708-7712.
  12. Meier, W., C. Nardin, and M. Winterhalter, Reconstitution of Channel Proteins in (Polymerized) ABA Triblock Copolymer Membranes, Angew Chem Int Ed Engl, 2000. 39(24): p. 4599-4602.
  13. Trau, D. and R. Renneberg, Encapsulation of glucose oxidase microparticles within a nanoscale layer-by-layer film: immobilization and biosensor applications. Biosens Bioelectron, 2003. 18(12): p. 1491-9.
  14. Romero, J., et al., New hydrophobic membranes for contactor processes – applications to isothermal concentration of solutions. Desalination, 2006. 193: p. 280-285.
  15. Sackmann, E., Physical basis of trigger processes and membrane structures, in Biological Membranes, D. Chapman, Editor. 1984, Academic Press Inc., Ltd.: London. p. 105-143.
  16. Israelachvilli, J., ed. Intermolecular & Surface Forces. 1992, Academic Press: London.
  17. Grant, L.M. and F. Tiberg, Normal and lateral forces between lipid covered solids in solution: correlation with layer packing and structure. Biophys J, 2002. 82(3): p. 1373-85.
  18. Rossi, C. and J. Chopineau, Biomimetic tethered lipid membranes designed for membrane-protein interaction studies. Eur Biophys J, 2007. 36(8): p. 955-65.
  19. Nielsen, C., M. Goulian, and O.S. Andersen, Energetics of Inclusion-Induced Bilayer Deformations. Biophys. J., 1998. 74: p. 1966-1983.
  20. Lundbæk, J.A., A.M. Maer, and O.S. Andersen, Lipid bilayer electrostatic energy, curvature stress, and assembly of gramicidin channels. Biochemistry, 1997. 36: p. 5695-5701.
  21. Reimhult, E. and K. Kumar, Membrane biosensor platforms using nano- and microporous supports. Trends Biotechnol, 2008. 26(2): p. 82-9.

Aquaporins

A MIRACLE THAT CAN CHANGE THE WORLD

An essential building block in the water membrane technology of Aquaporin A/S is the aquaporin molecule. The aquaporin molecule is described in the following.

Living cells are enclosed by a lipid bilayer membrane, separating the cells from other cells and their extra cellular medium. Lipid bilayer membranes are essentially impermeable to water, ions, and other polar molecules; yet, in many instances, such entities need to be rapidly and selectively transported across a membrane, often in response to an extra- or intracellular signal. The water-transporting task is accomplished by aquaporin water channel proteins (Preston et al., 1992).

Aquaporins are crucial for life in any form and they are found in all organisms, from bacteria via plants to man. Aquaporins facilitate rapid, highly selective water transport, thus allowing the cell to regulate its volume and internal osmotic pressure according to hydrostatic and/or osmotic pressure differences across the cell membrane. The physiological importance of the aquaporin in human is perhaps most conspicuous in the kidney, where ~150-200 litres of water need to be reabsorbed from the primary urine each day, that is, aquaporin facilitated water transport is invoked when water rapidly must be retrieved from a body fluid. In kidneys, this is made possible mainly by two aquaporins denoted AQP1 and AQP2 (11 different aquaporins are known in humans). In plants, aquaporins are also critical for water absorption in the root and for maintaining the water balance throughout the plant (Agre et al., 1998, Borgnia et al., 1999).

Studies of water transport in various organisms and tissues suggested that aquaporins have a narrow pore preventing any large molecule, ions (salts) and even proton (H3O+) and hydroxyl ion (OH-) flow while maintaining an extremely high water permeation rate; ~ 109molecules H2O per channel per second (Agre et al., 1998, Borgnia et al., 1999).

Until 2000 and 2001 where the first high-resolution 3D structure of AQP1 and that of the related glycerol-conducting bacterial channel protein aquaglyceroporin GlpF were reported (Fu et al., 2000; Murata et al., 2000; Ren et al., 2001; Sui et al., 2001) little was known about the origin of water selectivity.

However, based on the experimental structures, detailed computer models were put forward explaining not only the high permeation rate and the strict water selectivity but also the ability of aquaporins to prevent proton leakage (de Groot and Grubmüller, 2001; Tajkhorshid et al., 2002, Jensen et al., 2003, Zhu et al. 2003, de Groot et al., 2003, Burykin and Warshel 2003, Ilan et al., 2004, Chakrabarti at al., 2004). In essence, the architecture of the aquaporin channel allows water molecules to pass only in single file while electrostatic tuning of the channel interior controls aquaporin selectivity against any charged species, that is, transport of any salt (ion) as well as protons and hydroxyl ions is abrogated (de Groot and Grubmüller, 2001; Tajkhorshid et al., 2002, Jensen et al., 2003, Zhu et al. 2003, de Groot et al., 2003, Burykin and Warshel 2003, Ilan et al., 2004, Chakrabarti at al., 2004). In short, this implies that only water molecules pass through the aquaporin water pore, nothing else.

In the short span of just over ten years from the discovery of aquaporins in 1992 (Preston et al., 1992) to now an almost complete atomic-level understanding of aquaporin water channel function has been reached as recently underscored by awarding the Nobel Prize in chemistry to Professor Peter Agre in 2003 for his discovery of the aquaporin water channel.

The physiological roles of water channels in both eukaryotic and prokaryotic organisms have been elucidated and their roles in living cells are becoming increasingly well documented. The understanding of aquaporins and their role in life has opened the possibility of using aquaporins in an industrial context. Aquaporin’s goal is to use aquaporins as cornerstones in water filtering devices to be employed in industrial and household water filtration and purification.

References:

  • Agre, P., M. Bonhivers, and M. J. Borgnia. (1998).The aquaporins, blueprints for cellular plumbing systems. Journal of Biolgical Chemistry, 273, 14659–14662
  • Borgnia, M., S. Nielsen, A. Engel, and P. Agre. (1999). Cellular and molecular biology of the aquaporin water channels. Annual Review of Biochemistry, 68, 425–458
  • Burykin and A. Warshel (2003). What really prevents proton transport through aquaporin? Charge self-energy vs. proton wire proposals, Biophysical Journal 85, 3696-3706
  • Chakrabarti, N., Tajkhorshid, E., Roux, B. and Pommes, R. (2004). Molecular basis of proton blockage in aquaporins, Structure 12, 65-74
  • de Groot, B. L., and Grubmüller, H. (2001). Water permeation across biological membranes: mechanism and dynamics of aquaporin-1 and GlpF, Science 294, 2353-2357
  • de Groot, B. L., Frigato, T., Helms, V. and Grubmüller, H. (2003). The mechanism of proton exclusion in the aquaporin-1 channel, Journal of Molecular Biology 333, 279-293
  • Fu, D., Libson, A., Miercke, L. J., Weitzman, C., Nollert, P., Krucinski, J., and Stroud, R. M. (2000). Structure of a glycerol-conducting channel and the basis for its selectivity, Science 290, 481-6
  • Ilan, B., Tajkhorshid, E., Schulten, K. and Voth, G. (2004). The mechanism of proton exclusion in aquaporin water channels. PROTEINS: Structure, Function, and Bioinformatics, 55, 223-228
  • Jensen, M. O., Tajkhorshid, E., and Schulten, K. (2003). Electrostatic tuning of permeation and selectivity in aquaporin water channels, Biophysical Journal 85, 2884-2899
  • Murata, K., Mitsuoka, K., Hirai, T., Walz, T., Agre, P., Heymann, J. B., Engel, A., and Fujiyoshi, Y. (2000). Structural determinants of water permeation through aquaporin-1, Nature 407, 599-605
  • Preston, G. M., P. Piazza-Carroll, W. B. Guggino, and P. Agre. (1992). Appearance of water channels in Xenopus oocytes expressing red cell CHIP28 water channel. Science, 256, 385–387
  • Ren, G., Reddy, V. S., Cheng, A., Melnyk, P., and Mitra, A. K. (2001).Visualization of a water-selective pore by electron crystallography in vitreous ice, Proc Natl Acad Sci U S A 98, 1398-1403
  • Sui, H., Han, B. G., Lee, J. K., Walian, P., and Jap, B. K. (2001). Structural basis of water-specific transport through the AQP1 water channel, Nature 414, 872-8
  • Tajkhorshid, E., Nollert, P., Jensen, M. O., Miercke, L. J., O’Connell, J., Stroud, R. M., and Schulten, K. (2002). Control of the selectivity of the aquaporin water channel family by global orientational tuning, Science 296, 525-530
  • Zhu, F., Tajkhorshid, E. and Schulten, K. (2003). Theory and simulation of water permeation in aquaporin-1. Biophysical Journal, 86, 50-57

fluidized bed reactor that recovers ammonia and phosphate from nutrient rich fluids

Ostara.com

Ostara’s lead technology platform is based on a proprietary fluidized bed reactor that recovers ammonia and phosphate from nutrient rich fluids, in the form of a high-value slow-release fertilizer known as struvite. Wastewater treatment plants are an ideal source of nutrient rich fluids.
Ostara’s struvite recovery technology was developed by the University of British Columbia. The research team arrived at a proprietary fluidized bed reactor design which not only removed in excess of 85% of the influent phosphorus, but also resulted in the formation of a fertilizer in granular form consistent with that used in the fertilizer industry.
The implementation of this technology at a wastewater treatment plant not only provides good fertilizer yields (P-Recovery > 85%), but also helps reduce effluent phosphate and ammonia levels, regardless of the wastewater treatment process employed, and reduces or eliminates costly and maintenance intensive struvite scaling problems that often occur in sludge dewatering liquor conveying equipment (pumps, valves and pipes).
Ostara’s process is ideally suited to wastewater treatment plants that employ biological phosphorus removal and anaerobic sludge digestion. These facilities concentrate phosphorus in their sludge dewatering liquor stream, which left untreated results in struvite scaling problems and excessive effluent phosphate levels. By implementing the Ostara struvite recovery technology, the phosphate load returned to the liquid treatment train from sludge treatment is dramatically reduced. This reduction has been shown to stabilize the biological phosphorus removal process, eliminate the struvite scaling problems, and reduce effluent phosphate levels.
The first commercial-scale Ostara nutrient removal reactor has been
operating since May 2007 as part of the City of Edmonton’s Gold Bar
wastewater treatment plant. Pilot scale reactors have been successfully operated at the Greater Vancouver Regional District’s Lulu Island wastewater treatment plant; the Penticton, British Columbia, advanced wastewater treatment plant; the City of Edmonton Gold Bar wastewater treatment plant, the Hampton Roads Sanitation District’s Nansemond wastewater treatment plant in Suffolk, Virginia, and the Durham Advanced Wastewater Treatment Facility in Tigard (Portland), Oregon operated by Clean Water Services.