Name: ammonia synthesis at low pressure
Uploaded: 2017-08-23T13:00:00
Description: Watch this Scientific Journal Video about Ammonia Synthesis at Low Pressure at JoVE.com

This work was primarily supported by ARPA-E, a part of the US Department of Energy, by the Minnesota Environment and Natural Resources Trust Fund, as recommended the Legislative-Citizen Commission on Minnesota Resources, and by MNDRIVE, an initiative of the University of Minnesota. Additional support came from the Dreyfus Foundation.

1. Pilot Plant Start-up
<ol>
	<li>Nitrogen production system
	<ol>
		<li>Turn on the air dryer, the air compressor, and the nitrogen generator. Verify that there is at least 800 kPa of air in the air compressor tank. This keeps sending nitrogen to the buffer tank until there is no more than 0.004% (40 ppm) oxygen in the nitrogen.</li>
		<li>Turn on the nitrogen gas booster. The gas booster starts to fill the nitrogen supply tanks, at pressures as high as 17 MPa.</li>
	</ol>
	</li>
	<li>Hydrogen...

<ol>
	<li>Erisman, J. W., Sutton, M. A., Galloway, J., Klimont, Z., Winiwarter, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+a+century+of+ammonia+synthesis+changed+the+world.">How a century of ammonia synthesis changed the world.</a> Nat Geosci. 1 (10), 636-639 (2008).</li><li>Vojvodic, A., Medford, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+the+limits:+A+low-pressure,+low-temperature+Haber-Bosch+process.">Exploring the limits: A low-pressure, low-temperature Haber-Bosch process.</a> Chem Phys Lett. 598, 108-112 (2014).</li><li>Jennings, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Catalytic Ammonia Synthesis. , (1991).</li><li>. Nitrogen (Fixed) - Ammonia Available from: <a target="_blank" href="https://minerals.usgs.gov/minerals/pubs/commodity/nitrogen/mcs-2016-nitro.pdf">https://minerals.usgs.gov/minerals/pubs/commodity/nitrogen/mcs-2016-nitro.pdf</a> (2016)</li><li>Wojcik, A., Middleton, H., Damopoulos, I., Van herle, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+as+a+fuel+in+solid+oxide+fuel+cells.">Ammonia as a fuel in solid oxide fuel cells.</a> J Power Sources. 118 (1-2), 342-348 (2003).</li><li>Zamfirescu, C., Dincer, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+ammonia+as+a+sustainable+fuel.">Using ammonia as a sustainable fuel.</a> J Power Sources. 185 (1), 459-465 (2008).</li><li>Christensen, C. H., Johannessen, T., S&#248;rensen, R. Z., N&#248;rskov, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+an+ammonia-mediated+hydrogen+economy?.">Towards an ammonia-mediated hydrogen economy?.</a> Catalysis Today. 111 (1-2), 140-144 (2006).</li><li>Hummelsh&#248;j, J. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=reversible+high-density+hydrogen+storage+in+compact+metal+ammine+salts.">reversible high-density hydrogen storage in compact metal ammine salts.</a> J Am Chem Soc. 130 (27), 8660-8668 (2008).</li><li>Ni, M., Leung, M. K. H., Leung, D. Y. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia-fed+solid+oxide+fuel+cells+for+power+generation-A+review.">Ammonia-fed solid oxide fuel cells for power generation-A review.</a> Int J Energy Res. 33 (11), 943-959 (2009).</li><li>Zamfirescu, C., Dincer, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+as+a+green+fuel+and+hydrogen+source+for+vehicular+applications.">Ammonia as a green fuel and hydrogen source for vehicular applications.</a> Fuel Process Technol. 90 (5), 729-737 (2009).</li><li>Ertl, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+Science+and+Catalysis-Studies+on+the+Mechanism+of+Ammonia+Synthesis:+The+P.+H.+Emmett+Award+Address.">Surface Science and Catalysis-Studies on the Mechanism of Ammonia Synthesis: The P. H. Emmett Award Address.</a> Catal Rev. 21 (2), 201-223 (2006).</li><li>Nielsen, A., Kjaer, J., Bennie, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rate+equation+and+mechanism+of+ammonia+synthesis+at+industrial+conditions.">Rate equation and mechanism of ammonia synthesis at industrial conditions.</a> J Catal. 3 (1), 68-79 (1964).</li><li>. DE-FOA-0001569 Sustainable Ammonia Synthesis Available from: <a target="_blank" href="https://science.energy.gov/~/media/grants/pdf/foas/2016/SC_FOA_0001569.pdf">https://science.energy.gov/~/media/grants/pdf/foas/2016/SC_FOA_0001569.pdf</a> (2016)</li><li>Sustainable Ammonia Synthesis - Exploring the scientific challenges associated with discovering alternative, sustainable processes for ammonia production. DOE Roundtable Report Available from: <a target="_blank" href="https://science.energy.gov/~/media/bes/pdf/reports/2016/SustainableAmmoniaReport.pdf">https://science.energy.gov/~/media/bes/pdf/reports/2016/SustainableAmmoniaReport.pdf</a> (2016)</li><li>Reese, M., Marquart, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+of+a+Small-Scale+Haber+Process.">Performance of a Small-Scale Haber Process.</a> Ind Eng Chem Res. 55 (13), 3742-3750 (2016).</li><li>Schl&#246;gl, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catalytic+Synthesis+of+Ammonia-A+"Never-Ending+Story".">Catalytic Synthesis of Ammonia-A "Never-Ending Story".</a> Ange Chemie Int Ed. 42 (18), 2004-2008 (2003).</li><li>Dyson, D. C., Simon, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetic+Expression+with+Diffusion+Correction+for+Ammonia+Synthesis+on+Industrial+Catalyst.">Kinetic Expression with Diffusion Correction for Ammonia Synthesis on Industrial Catalyst.</a> Ind Eng Chem Fund. 7 (4), 605-610 (1968).</li><li>Temkin, M., Pyzhev, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetics+of+ammonia+synthesis+on+promoted+catalysts.">Kinetics of ammonia synthesis on promoted catalysts.</a> Acta Physiochim USSR. 12, 327-356 (1940).</li><li>Annable, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+the+Temkin+kinetic+equation+to+ammonia+synthesis+in+large-scale+reactors.">Application of the Temkin kinetic equation to ammonia synthesis in large-scale reactors.</a> Chem Eng Sci. 1 (4), 145-154 (1952).</li><li>Guacci, U., Traina, F., Ferraris, G. B., Barisone, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+Application+of+the+Temkin+Equation+in+the+Evaluation+of+Catalysts+for+the+Ammonia+Synthesis.">On the Application of the Temkin Equation in the Evaluation of Catalysts for the Ammonia Synthesis.</a> Ind Eng Chem Prod DD. 16 (2), 166-176 (1977).</li><li>Hummelsh&#248;j, J. S., S&#248;rensen, R. Z., Kustova, M. Y., Johannessen, T., N&#248;rskov, J. K., Christensen, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+nanopores+during+desorption+of+NH3+from+Mg(NH3)6Cl2.">Generation of nanopores during desorption of NH3 from Mg(NH3)6Cl2.</a> J Am Chem Soc. 128 (1), 16-17 (2006).</li><li>Huberty, M. S., Wagner, A. L., McCormick, A., Cussler, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+absorption+at+haber+process+conditions.">Ammonia absorption at haber process conditions.</a> AIChE Journal. 58 (11), 3526-3532 (2012).</li><li>Himstedt, H. H., Huberty, M. S., McCormick, A. V., Schmidt, L. D., Cussler, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+synthesis+enhanced+by+magnesium+chloride+absorption.">Ammonia synthesis enhanced by magnesium chloride absorption.</a> AIChE Journal. 61 (4), 1364-1371 (2015).</li><li>Malmali, M., Wei, Y., McCormick, A., Cussler, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+Synthesis+at+Reduced+Pressure+via+Reactive+Separation.">Ammonia Synthesis at Reduced Pressure via Reactive Separation.</a> Ind Eng Chem Res. 55 (33), 8922-8932 (2016).</li><li>Wagner, K., Malmali, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Column+absorption+for+reproducible+cyclic+separation+in+small+scale+ammonia+synthesis.">Column absorption for reproducible cyclic separation in small scale ammonia synthesis.</a> AIChE Journal. , (2017).</li></ol>

Critical Steps of the Reaction-absorption Experimental Apparatus:
Make sure that there is no impurity in the nitrogen and hydrogen system. The absorbent materials will change after each cycle. In most cases, at high temperature and in the presence of ammonia, the absorbent materials fuse and form a large solid concrete. According to the thermodynamic properties of each metal halide and ammine complex, the appropriate temperatures for absorption and desorption should be employed. Before each test,...

Ammonia is a key industrial chemical. It is produced through the Haber-Bosch process, which is known as one of the most important innovations of the 20th century1,2. Ammonia synthesis is carried out in the presence of a heterogeneous catalyst at elevated temperatures (&#62; 375 &#176;C) and pressures (&#62;100 bar)3. Such high temperature and pressure requirements make ammonia synthesis very energy- and capital-intensive. Approximately, 150 million tons of ammonia are produced each year4, which accounts for 1-3% of the world&#39;s energy consumption, 5% of the natural gas consumption, and up to 3% of the climate-changing gas emissions5,6,7.
Ammonia has two major potential uses. First, ammonia is a synthetic nitrogen fertilizer1. Without this fertilizer, half of the current population would not have access to sufficient food. Second, ammonia can serve as an energy vector, either as a carbon-neutral liquid fuel or as an indirect hydrogen carrier8,9,10,11. Typically, renewable resources (e.g. wind) are available in underpopulated rural areas, where it can be captured; this type of isolated wind and solar energy is called &#34;stranded&#34;. In this scenario, the electrical and thermal energies from the renewable energy source are converted to energy-dense carbon-neutral liquid ammonia. The liquid ammonia produced can then be shipped to urban centers, where it can be directly used in ammonia-based fuel cells12 and internal combustion engines13, or it can be decomposed into hydrogen and then be used in hydrogen fuel cells or hydrogen stations. As a result, we can move the wind of the U.S. prairies to the crowded urban areas of the U.S.
Mostly because of the fertilizer use, ammonia manufacture is a major industry. At room temperature, the ammonia synthesis reaction is exothermic and hence&#8212;at least, in principle&#8212;spontaneous14, however, achieving the reaction under ambient conditions is extremely difficult because of the strong nitrogen-nitrogen bond15. To overcome this, Fritz Haber famously used high temperatures to achieve fast kinetics, but these high temperatures meant that the reverse reaction inhibited the production. To reduce the inhibitions of this reverse reaction, Haber used high pressure to improve conversion. He carried out the large-scale reaction in a gun barrel, which still decorates the BASF plant in Ludwigshafen.
The necessity to use both high temperature and pressure when the reaction could potentially run under much more modest conditions has frustrated chemists for over a century2. Even after the process was commercialized, Karl Bosch and a huge cohort at BASF churned through the entire periodic table looking for better catalysts. While Bosch had little success, the search still continues. Even last year, a new research program aimed at seeking a new catalyst was initiated16,17. The detailed chemistry of ammonia synthesis is now well understood14, and if the search for the new catalyst is successful, it would certainly be worth the effort. However, in our view, the past failures reduce the chance of future success.
In the following text, small-scale ammonia synthesis process is described, and the motivation to investigate an alternative process is explained.
The Small-Scale Process:
Wind-Generated Ammonia 
We are improving the Haber-Bosch process for synthesizing ammonia, seeking a much smaller, simpler process which can be operated locally but produces negligible amounts of carbon dioxide. The feasibility of local ammonia manufacture from wind has already been demonstrated in a pilot plant located in Morris, MN, and shown in Figure 118. Morris sits on the Buffalo Ridge, a formation of sixty miles of rolling hills in the southwest corner of Minnesota. The ridge has unusually steady, strong wind, rolling across the prairie. As a result, it is a mecca for wind-generated electricity.
With this electricity, we already manufacture ammonia from wind, using this plant which is forty thousand times smaller than the existing commercial operations for fossil fuels. Some wind-generated electricity is used to make nitrogen from air by pressure swing adsorption, an established method for air separation used, for example, for patients with emphysema who need oxygen-enriched air. However, more of the electricity is used to make hydrogen by electrolysis of water. These gases are combined over a conventional catalyst in the process shown schematically in Figure 2. After the reaction, the gases are separated by chilling to condense the liquid ammonia. The unreacted gases, as well as the uncondensed ammonia, are recycled.
Details of the Pilot Plant 
In our pilot plant, the University of Minnesota Renewable Hydrogen and Ammonia Pilot Plant, the electric power is provided from a co-located 1.65 MW wind turbine. The pilot plant uses approximately 10% of the power generated, with the remaining power used at the University of Minnesota, Morris campus.
The hydrogen production system uses an electrolyzer, a booster compressor, and a thermal chiller. This system produces 0.54 kg of hydrogen gas per hour, which is stored at 2,400 psi using 24 kWh of electricity. Water from an on-site well is purified using a reverse osmosis and deionization system. The water is then supplied to the electrolyzer at a rate of up to 15 L/h. Nitrogen is generated using a nitrogen generator, a pre-air compressor, an air dryer, and a booster compressor. The nitrogen gas is stored at 2,400 psi using approximately 6 kWh of electricity.
The synthesis of ammonia uses a custom skid. It includes a compressor, a reactor, a refrigeration cooling loop, and a 20 kW electric heater. The skid uses approximately 28 kWh of electricity to produce 2.7 kg of ammonia per hour which is then stored at 150 psi. The ammonia production process is controlled with integrated PLC and HMI systems. The produced hydrogen and nitrogen are stored on site in 18 nitrogen storage tanks and 54 hydrogen storage tanks. The ammonia is also stored onsite within a 3,100-gallon vessel.
Wind Generation is Expensive 
The electricity for this process is made from wind, and so the fuel for making ammonia is free, without using any fossil fuel. However, the capital costs for this pilot plant are dominated by the investments for hydrogen production and for ammonia synthesis. The operations to date suggest that the cost of making small-scale ammonia are about twice that of conventional ammonia based on fossil fuels. While we continue to optimize our process, we believe that small-scale wind generated ammonia will not be competitive at the current natural gas prices. The capital costs per mass ammonia made could be reduced by a larger conventional process, or by an alternative process like that described next in this paper.
The Absorption Process:
Absorption Enhances Production 
The catalyst used for ammonia synthesis has remained almost unchanged during the last century19. As a result, we have carried out a different approach in this research. We apply the current catalyst and operating temperature, but absorb ammonia at modest pressures as soon as it is formed. We recycle any unreacted hydrogen and nitrogen. The process is schematically like that in Figure 3, similar to the conventional process, but with a packed bed absorber replacing the condenser.
Initial Reaction Kinetics Do Not Change 
Experiments with this system at low conversion show an initial reaction rate that is consistent with many of the earlier studies on this system3,14,15,20,21,22,23, as shown in Figure 4. The left panel shows the initial rates, which vary strongly with temperature. While these rates also vary with pressure, the variations are smaller, as shown in the right panel. In our new process, we use the same catalyst and similar operating conditions, but seek ways to improve ammonia production by using absorption at a lower pressure. We thus hope to reduce the capital costs for ammonia synthesis.
Absorption Enhances Conversion 
In our work, we replaced the condenser in the small process with a packed bed, which is a cylindrical vessel filled with small particles of the absorbent. We have emphasized absorbents made primarily of magnesium chloride and calcium chloride11,24. Such ammine absorbents have two effects. First, they reduce the ammonia concentration present in the recycled gases to near zero. Second, they effectively reduce the time for separation to near zero. This strategy is productive25,26,27. For example, in Figure 5, we show that the rate of making ammonia, which is proportional to the drop in the total pressure in the system, is much greater with absorption than without. In particular, the reaction at 90 bar, shown by the red circles, is less complete than the reaction with the absorbent, shown by the blue triangles27. This is true even though the reaction without absorbent takes place at a pressure almost twice that of the reaction with absorption. In earlier experiments (not shown here), we also showed that the eventual conversion of the process is about 20% without absorbent but over 95% with absorbent.
The rate of reaction varies much less with temperature with absorption than without. This is shown in Figure 6, which again reports ammonia synthesis as total pressure versus time27. Changing the reaction temperature by 60 &#176;C has little effect on the reaction rate. This contrasts with the initial rates in Figure 4, which shows a change of reaction rate of almost an order of magnitude. The results in Figure 4 and Figure 6 are different because the effect of the reverse reaction has been reduced, so the chemical kinetics are no longer the only step responsible for the overall rate.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Experimental Apparatus</td>
			<td style="width:131px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Magnesium Chloride</td>
			<td style="width:131px;">Sigma Aldrich</td>
			<td style="width:119px;">7786-30-3</td>
			<td>St. Louis, MO</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Calcium Chloride</td>
			<td style="width:131px;">Sigma Aldrich</td>
			<td style="width:119px;">10043-52-4</td>
			<td>St. Louis, MO</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ultra Pure Hydrogen</td>
			<td style="width:131px;">Matheson</td>
			<td>SG PHYF30050</td>
			<td>New Brighton, MN</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ultra Pure Nitrogen</td>
			<td style="width:131px;">Matheson</td>
			<td>SG G1881112</td>
			<td>New Brighton, MN</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Iron Based Catalyst</td>
			<td style="width:131px;">Clariant/Sud Chemie</td>
			<td style="width:119px;">-</td>
			<td>Charlotte, NC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Variable Piston Pump</td>
			<td style="width:131px;">PumpWorks Inc.</td>
			<td style="width:119px;">PW2070N</td>
			<td>Minneapolis, MN</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Omega Ceramic Heater</td>
			<td style="width:131px;">Omega</td>
			<td style="width:119px;">CRFC-36/115-A</td>
			<td>Stamford, CT</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PID Controller</td>
			<td style="width:131px;">Omega</td>
			<td style="width:119px;">CN96211TR</td>
			<td>Stamford, CT</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Signal Conditioner</td>
			<td style="width:131px;">Omega</td>
			<td style="width:119px;">DRG-SC-TC</td>
			<td>Stamford, CT</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Pressure Transducer</td>
			<td style="width:131px;">WIKA</td>
			<td style="width:119px;">50426877</td>
			<td>Lawrenceville, Georgia</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Mass Flow Controller</td>
			<td style="width:131px;">Brooks Instruments</td>
			<td style="width:119px;">SLA5850</td>
			<td>Hatefield, PA</td>
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			<td height="21" style="height:21px;width:216px;">Name</td>
			<td style="width:131px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments</td>
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			<td height="21" style="height:21px;width:216px;">Pilot Plant</td>
			<td style="width:131px;"></td>
			<td style="width:119px;"></td>
			<td></td>
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			<td height="21" style="height:21px;">Electrolyzer</td>
			<td style="width:131px;">Proton OnSite</td>
			<td style="width:119px;">H6 Series</td>
			<td>Wallingford, CT</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gas Booster</td>
			<td style="width:131px;">PDC Machine</td>
			<td style="width:119px;">3 2500&#160;</td>
			<td>Warminster, PA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Wind Turbine</td>
			<td style="width:131px;">Vestas</td>
			<td style="width:119px;">V82</td>
			<td>Portland, OR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Chiller</td>
			<td style="width:131px;">Thermal Care</td>
			<td style="width:119px;">SQ Series</td>
			<td>Niles, IL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Water Purifier</td>
			<td style="width:131px;">Elga Pure Lab</td>
			<td style="width:119px;">S-15</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Nitrogen Generator</td>
			<td style="width:131px;">Innovative Gas System</td>
			<td style="width:119px;">NS-10</td>
			<td>Huoston, TX</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Air Compressor</td>
			<td style="width:131px;">Hydrovane</td>
			<td style="width:119px;">HV05</td>
			<td></td>
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ammonia synthesis at low pressure

Ammonia can be synthesized at low pressure by the use of an ammonia selective absorbent. The process can be driven with wind energy, available locally in areas requiring ammonia for synthetic fertilizer. Such wind energy is often called &#34;stranded,&#34; because it is only available far from population centers where it can be directly used.
In the proposed low pressure process, nitrogen is made from air using pressure swing absorption, and hydrogen is produced by electrolysis of water. While these gases can react at approximately 400 &#176;C in the presence of a promoted conventional catalyst, the conversion is often limited by the reverse reaction, which makes this reaction only feasible at high pressures. This limitation can be removed by absorption on an ammine-like calcium or magnesium chloride. Such alkaline metal halides can effectively remove ammonia, thus suppressing the equilibrium constraints of the reaction. In the proposed absorption-enhanced ammonia synthesis process, the rate of reaction may then be controlled not by the chemical kinetics nor the absorption rates, but by the rate of the recycle of unreacted gases. The results compare favorably with ammonia made from a conventional small scale Haber-Bosch process.

A pilot plant in Morris, MN has demonstrated the feasibility of using wind for local ammonia manufacture18, as shown in Figure 1. The wind generates electricity, which is used to make nitrogen and hydrogen through the pressure swing absorption of air and through the electrolysis of water, respectively. A reactor uses a conventional catalyst to combine the nitrogen and hydrogen gases, making ammonia. The ammonia is then separated using ...

Watch this Scientific Journal Video about Ammonia Synthesis at Low Pressure at JoVE.com

Ammonia Synthesis at Low Pressure

Ammonia can be synthesized at low pressure by using a conventional catalyst and an ammonia selective absorbent.

Ammonia can be synthesized at low pressure by the use of an ammonia selective absorbent. The process can be driven with wind energy, available locally in ...

The overall goal of this procedure is to produce ammonia from air, water and wind-generated energy in a low-pressure process with negligible carbon dioxide emissions. This method can help address key issues in ammonia production such as reaction efficiency, product distribution and carbon dioxide emissions. The process uses a solid ammonia-selected absorbent rather than a condenser.Continually removing ammonia from the system decreases the occurrence of the reverse chemical reaction. The main advantage of this process is that it can performed at lower pressure which is safer and less expensive. Cory Marquart and I operate a plant for the conventional process that is 30, 000 times smaller than typical plants.This gives a standard for comparison with the absorbent process. Mike Reese and Cory Marquart are operating the conventional small-scale plant in Morris, Minnesota. Demonstrating the absorption-based process will be Mahdi Malmali, a post-doctoral fellow affiliated with our laboratory.Prior to beginning the process, start up the ammonia generation plant and ramp the catalytic reactor to 440 degrees Celsius. Set the condenser temperature to minus 18 degrees Celsius. Next, turn on the air dryer, the air compressor and the nitrogen generator.Turn on the nitrogen gas booster to fill the nitrogen supply tanks. Turn on the chiller, water deionization unit, electrolyzer and the hydrogen gas booster. Verify that the chiller is operational and cooling liquid is flowing through.Next set the nitrogen inlet regulator to 300 PSI. Open the nitrogen valve to begin pressurizing the process skid. Close the nitrogen bypass valve when the skid reaches 300 PSI.Then, set the hydrogen inlet regulator to 1, 200 PSI and open the hydrogen valve. Once the skid reaches 1, 200 PSI, close the hydrogen valve. Start the skid to begin cycling the one-to-three nitrogen-to-hydrogen gas mixture through the system.After the process has finished, store the condensed ammonia at 150 PSI. To prepare the reactor, use a mortar and pestle to grind the catalyst particles to less than one millimeter in size. Pack the ground catalyst into 0.25-inch tubing.To prepare the absorber, pack 80 grams of calcium chloride or an equivalent amount of another ammonia selective absorbent into a 30-centimeter column with an inner diameter of 2.3 centimeters. Plug the ends of the column with sufficient packing support material to immobilize the absorbent. Install the absorber and the reactor in the experimental apparatus.Heat the reactor to 450 degrees Celsius using the recommended activation temperature procedure while flowing hydrogen through the reactor at 500 SCCM to finish the catalyst activation. Keep the activated catalyst under a blanket of ultra-pure nitrogen gas when the system is idle. To begin the ammonia generation process, close the outlet valve and ramp the reactor to 400 degrees Celsius and the absorber to 180 degrees Celsius.Flush the system with ultra-pure nitrogen gas by repeatedly pressurizing and venting the system. Then, pressurize the system with a one-to-three mixture of nitrogen and hydrogen gases. Stop the nitrogen and hydrogen mass flow controllers.Close the reactor inlet valve. Open the reactor outlet valve and start the recirculation pump. Monitor the reactor and absorber temperatures as the reaction starts and adjust them as necessary to compensate for exothermic processes.Run the process for five hours or until the absorber starts to break through as indicated by a decrease in the change in system pressure over time. Open the nitrogen inlet valve and the ammonia outlet valve and reduce the system to atmospheric pressure. Flow nitrogen through the system at 100 SCCM while heating the absorber for five hours to release the ammonia.The high pressures used in the conventional method are necessary to favor the forward reaction at high temperatures. In the low-pressure separation method, the ammonia is more completely separated before it could undergo the reverse reaction. A significant increase in the rate of conversion was observed relative to the conventional method.The initial reaction rates of the separation method were consistent with published values and separate chemical kinetics experiments. Temperature variation was observed in the initial reaction rates of the reaction absorption method. The overall reaction rate showed much less temperature dependence indicating that the catalytic reaction rate is not a major limiting factor for the conversion rate in the separation method.The absorbent efficiently removed the ammonia from the system, but the capacity of the column decreased after each cycle. Investigation into prolonging the life of the absorbent column is underway. The absorption kinetics were not found to be a significantly limiting factor for ammonia production.The recirculation flow rate was found to correlate with the reaction rate indicating that it is the primary controlling step for the process. This process can make ammonia from air, water and wind. The air and water are sources of nitrogen and hydrogen by pressure-swing absorption and electrolysis respectively.The energy for the process comes from the wind. The Haber-Bosch process is a century-old reaction that feeds a large fraction of the world's population. Trying to improve it has high risk and potentially high reward.Our original idea for this work was to make family farms in rural Minnesota more self-sufficient for their nitrogen fertilizer. The promise of a fuel for energy-short cities by storing wind-based energy as liquid ammonia was an unexpected gain. The key to the absorption-based process is to develop a stable reusable absorbent that efficiently traps ammonia as it is produced.By replacing the conventional condenser with an absorbent bed, we are closer to a cheaper, safer ammonia generation process suitable for small-scale manufacturing.

Research

JoVE Journal

Bioengineering

Gold Nanostar Synthesis with a Silver Seed Mediated Growth Method

The physical, chemical and optical properties of nano-scale colloids depend on their material composition, size and shape 1-5. There is a great interest in using nano-colloids for photo-thermal ablation, drug delivery and many other biomedical applications 6. Gold is particularly used because of its low toxicity 7-9. A property of metal nano-colloids is that they can have a strong surface plasmon resonance 10. The peak of the surface plasmon resonance mode depends on the structure and composition of the metal nano-colloids. Since the surface plasmon resonance mode is stimulated with light there is a need to have the peak absorbance in the near infrared where biological tissue transmissivity is maximal 11, 12.
We present a method to synthesize star shaped colloidal gold, also known as star shaped nanoparticles 13-15 or nanostars 16. This method is based on a solution containing silver seeds that are used as the nucleating agent for anisotropic growth of gold colloids 17-22. Scanning electron microscopy (SEM) analysis of the resulting gold colloid showed that 70 % of the nanostructures were nanostars. The other 30 % of the particles were amorphous clusters of decahedra and rhomboids. The absorbance peak of the nanostars was detected to be in the near infrared (840 nm). Thus, our method produces gold nanostars suitable for biomedical applications, particularly for photo-thermal ablation.

We synthesized star shaped gold nanostars using a silver seed mediated growth method. The diameter of the nanostars ranges from 200 to 300 nm and the number of tips vary from 7 to 10. The nanoparticles have a broad surface plasmon resonance mode centered in the near infrared.

The physical, chemical and optical properties of nano-scale colloids depend on their material composition, size and shape 1-5. There is a great interest ...

Induction of Adhesion-dependent Signals Using Low-intensity Ultrasound

In multicellular organisms, cell behavior is dictated by interactions with the extracellular matrix. Consequences of matrix-engagement range from regulation of cell migration and proliferation, to secretion and even differentiation. The signals underlying each of these complex processes arise from the molecular interactions of extracellular matrix receptors on the surface of the cell. Integrins are the prototypic receptors and provide a mechanical link between extracellular matrix and the cytoskeleton, as well as initiating some of the adhesion-dependent signaling cascades. However, it is becoming increasingly apparent that additional transmembrane receptors function alongside the integrins to regulate both the integrin itself and signals downstream. The most elegant of these examples is the transmembrane proteoglycan, syndecan-4, which cooperates with &alpha;5&beta;1-integrin during adhesion to fibronectin. In vivo models demonstrate the importance of syndecan-4 signaling, as syndecan-4-knockout mice exhibit healing retardation due to inefficient fibroblast migration1,2. In wild-type animals, migration of fibroblasts toward a wound is triggered by the appearance of fibronectin that leaks from damaged capillaries and is deposited by macrophages in injured tissue. Therefore there is great interest in discovering strategies that enhance fibronectin-dependent signaling and could accelerate repair processes.
The integrin-mediated and syndecan-4-mediated components of fibronectin-dependent signaling can be separated by stimulating cells with recombinant fibronectin fragments. Although integrin engagement is essential for cell adhesion, certain fibronectin-dependent signals are regulated by syndecan-4. Syndecan-4 activates the Rac1 protrusive signal3, causes integrin redistribution1, triggers recruitment of cytoskeletal molecules, such as vinculin, to focal adhesions4, and thereby induces directional migration3. We have looked for alternative strategies for activating such signals and found that low-intensity pulsed ultrasound (LIPUS) can mimic the effects of syndecan-4 engagement5. In this protocol we describe the method by which 30 mW/cm2, 1.5 MHz ultrasound, pulsed at 1 kHz (Fig. 1) can be applied to fibroblasts in culture (Fig. 2) to induce Rac1 activation and focal adhesion formation. Ultrasound stimulation is applied for a maximum of 20 minutes, as this combination of parameters has been found to be most efficacious for acceleration of clinical fracture repair6. The method uses recombinant fibronectin fragments to engage &alpha;5&beta;1-integrin, without engagement of syndecan-4, and requires inhibition of protein synthesis by cycloheximide to block deposition of additional matrix by the fibroblasts., The positive effect of ultrasound on repair mechanisms is well documented7,8, and by understanding the molecular effect of ultrasound in culture we should be able to refine the therapeutic technique to improve clinical outcomes.

This protocol describes the stimulation of cultured fibroblasts with low-intensity pulsed ultrasound, which drives focal adhesion formation and Rac1 activation by mimicking engagement of the transmembrane matrix receptor, syndecan-4. This approach allows investigation of a successful clinical technique at the cellular level, thereby providing opportunities for refinement of the therapy.

In multicellular organisms, cell behavior is dictated by interactions with the extracellular matrix. Consequences of matrix-engagement range from ...

High Throughput Microfluidic Rapid and Low Cost Prototyping Packaging Methods

In this work, 3 different packaging and assembly techniques are presented. They can be classified into two categories: one-time use and reusable packaging techniques.
The one-time use packaging technique employs UV-based and temperature curing epoxies to connect microtubes to access holes, wire-bonding for integrated circuit connections, and silver epoxy for electrical connections. This method is based on a robust assembly technique that can support relatively high pressure close to 1 psi and does not need any support to strengthen the microfluidic architecture.
Reusable packaging techniques consist of PDMS-based microtube interconnectors and anisotropic adhesive films for electrical connections. These devices are more sensitive and fragile. Consequently, Plexiglas support is added to the microfluidic structure to improve the electrical contact when anisotropic adhesive films are used, and also to strengthen the microfluidic architecture. In addition, a micromanipulator is needed to maintain tubes while using a thin PDMS layer to connect them to the access holes. Different PDMS layer thicknesses, ranging from 0.45-3 mm, are tested to compare the best adherence versus injection rates. Applied injection rates are varied from 50-300 &#956;l/hr for 0.45-3 mm PDMS layers, respectively. These techniques are mainly applicable for low-pressure applications. However, they can be extended for high-pressure ones through plasma-oxygen process to permanently seal the PDMS to glass substrates. The main advantage of this technique, besides the fact that it is reusable, consists of keeping the device observable when the microchannel length is very short (in the range of 3 mm or lower).

In this article we describe different techniques for microfluidic rapid prototyping platforms. The proposed techniques are based on ultraviolet (UV) sensitive and temperature curing epoxies, polydimethylsiloxane (PDMS) based tubing, wire-bonding, and anisotropic adhesive films. The assembling procedures presented are developed for both one-time use devices as well as reusable microfluidic systems.

In this work, 3 different packaging and assembly techniques are presented. They can be classified into two categories: one-time use and reusable packaging ...

Design and Construction of Artificial Extracellular Matrix (aECM) Proteins from Escherichia coli for Skin Tissue Engineering

Recombinant technology is a versatile platform to create novel artificial proteins with tunable properties. For the last decade, many artificial proteins that have incorporated functional domains derived from nature (or created de novo) have been reported. In particular, artificial extracellular matrix (aECM) proteins have been developed; these aECM proteins consist of biological domains taken from fibronectin, laminins and collagens and are combined with structural domains including elastin-like repeats, silk and collagen repeats. To date, aECM proteins have been widely investigated for applications in tissue engineering and wound repair. Recently, Tjin and coworkers developed integrin-specific aECM proteins designed for promoting human skin keratinocyte attachment and propagation. In their work, the aECM proteins incorporate cell binding domains taken from fibronectin, laminin-5 and collagen IV, as well as flanking elastin-like repeats. They demonstrated that the aECM proteins developed in their work were promising candidates for use as substrates in artificial skin. Here, we outline the design and construction of such aECM proteins as well as their purification process using the thermo-responsive characteristics of elastin.

Design and Construction of Artificial Extracellular Matrix aECM Proteins from Escherichia coli for Skin Tissue Engineering

Recombinant technologies have enabled material designers to create novel artificial proteins with customized functionalities for tissue engineering applications. For example, artificial extracellular matrix proteins can be designed to incorporate structural and biological domains derived from native ECMs. Here, we describe the construction and purification of aECM proteins containing elastin-like repeats.

Recombinant technology is a versatile platform to create novel artificial proteins with tunable properties. For the last decade, many artificial proteins ...

Rod-based Fabrication of Customizable Soft Robotic Pneumatic Gripper Devices for Delicate Tissue Manipulation

Soft compliant gripping is essential in delicate surgical manipulation for minimizing the risk of tissue grip damage caused by high stress concentrations at the point of contact. It can be achieved by complementing traditional rigid grippers with soft robotic pneumatic gripper devices. This manuscript describes a rod-based approach that combined both 3D-printing and a modified soft lithography technique to fabricate the soft pneumatic gripper. In brief, the pneumatic featureless mold with chamber component is 3D-printed and the rods were used to create the pneumatic channels that connect to the chamber. This protocol eliminates the risk of channels occluding during the sealing process and the need for external air source or related control circuit. The soft gripper consists of a chamber filled with air, and one or more gripper arms with a pneumatic channel in each arm connected to the chamber. The pneumatic channel is positioned close to the outer wall to create different stiffness in the gripper arm. Upon compression of the chamber which generates pressure on the pneumatic channel, the gripper arm will bend inward to form a close grip posture because the outer wall area is more compliant. The soft gripper can be inserted into a 3D-printed handling tool with two different control modes for chamber compression: manual gripper mode with a movable piston, and robotic gripper mode with a linear actuator. The double-arm gripper with two actuatable arms was able to pick up objects of sizes up to 2 mm and yet generate lower compressive forces as compared to elastomer-coated and non-coated rigid grippers. The feasibility of having other designs, such as single-arm or hook gripper, was also demonstrated, which further highlighted the customizability of the soft gripper device, and it's potential to be used in delicate surgical manipulation to reduce the risk of tissue grip damage.

This protocol describes a rod-based approach, combining 3D-printing and soft lithography techniques for fabricating the soft gripper devices. This approach eliminates the need for an external air source by incorporating a chamber component and reduces the chance of occlusion during the sealing process, particularly for miniaturized pneumatic channels.

Soft compliant gripping is essential in delicate surgical manipulation for minimizing the risk of tissue grip damage caused by high stress concentrations ...

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and thus achieving stable water permeability through membranes over time. Here, we report a facile method to prepare hydrogels based on zwitterions for membrane applications. Freestanding films can be prepared from sulfobetaine methacrylate (SBMA) with a crosslinker of poly(ethylene glycol) diacrylate (PEGDA) via photopolymerization. The hydrogels can also be prepared by impregnation into hydrophobic porous supports to enhance the mechanical strength. These films can be characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine the degree of conversion of the (meth)acrylate groups, using goniometers for hydrophilicity and differential scanning calorimetry (DSC) for polymer chain dynamics. We also report protocols to determine the water permeability in dead-end filtration systems and the effect of foulants (bovine serum albumin, BSA) on membrane performance.

This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and ...

Quantifying Microorganisms at Low Concentrations Using Digital Holographic Microscopy (DHM)

Accurately detecting and counting sparse bacterial samples has many applications in the food, beverage, and pharmaceutical processing industries, in medical diagnostics, and for life detection by robotic missions to other planets and moons of the solar system. Currently, sparse bacterial samples are counted by culture plating or epifluorescence microscopy. Culture plates require long incubation times (days to weeks), and epifluorescence microscopy requires extensive staining and concentration of the sample. Here, we demonstrate how to use off-axis digital holographic microscopy (DHM) to enumerate bacteria in very dilute cultures (100-104 cells/mL). First, the construction of the custom DHM is discussed, along with detailed instructions on building a low-cost instrument. The principles of holography are discussed, and a statistical model is used to estimate how long videos should be to detect cells, based on the optical performance characteristics of the instrument and the concentration of the bacterial solution (Table 2). Video detection of cells at 105, 104, 103, and 100 cells/mL is demonstrated in real time using un-reconstructed holograms. Reconstruction of amplitude and phase images is demonstrated using an open-source software package.

Quantifying Microorganisms at Low Concentrations Using Digital Holographic Microscopy DHM

Digital holographic microscopy (DHM) is a volumetric technique that allows imaging samples 50-100X thicker than brightfield microscopy at comparable resolution, with focusing performed post-processing. Here DHM is used for identifying, counting, and tracking microorganisms at very low densities and compared with optical density measurements, plate count, and direct count.

Accurately detecting and counting sparse bacterial samples has many applications in the food, beverage, and pharmaceutical processing industries, in ...

Making Conjugation-induced Fluorescent PEGylated Virus-like Particles by Dibromomaleimide-disulfide Chemistry

The recent rise in virus-like particles (VLPs) in biomedical and materials research can be attributed to their ease of biosynthesis, discrete size, genetic programmability, and biodegradability. While they&#39;re highly amenable to bioconjugation reactions for adding synthetic ligands onto their surface, the range in bioconjugation methodologies on these aqueous born capsids is relatively limited. To facilitate the direction of functional biomaterials research, non-traditional bioconjugation reactions must be considered. The reaction described in this protocol uses dibromomaleimides to introduce new functionality in the solvent exposed disulfide bonds of a VLP based upon Bacteriophage Q&#946;. Furthermore, the final product is fluorescent, which has the added benefit of generating a trackable in vitro probe using a commercially available filter set.

Here, we present a procedure to fluorescently functionalize the disulfides on Q&#946; VLP with dibromomaleimide. We describe Q&#946; expression and purification, the synthesis of dibromomaleimide-functionalized molecules, and the conjugation reaction between dibromomaleimide and Q&#946;. The resulting yellow fluorescent conjugated particle can be used as a fluorescence probe inside cells.

The recent rise in virus-like particles (VLPs) in biomedical and materials research can be attributed to their ease of biosynthesis, discrete size, ...

Mouse Model of Pressure Ulcers After Spinal Cord Injury

Pressure ulcers (PUs) are common debilitating complications of traumatic spinal cord injury (SCI) and tend to occur in soft tissues around bony prominences. There is, however, little known about the impact of SCI on skin wound healing in the context of animal models in controlled experimental settings. In this study, a simple, non-invasive, reproducible and clinically relevant mouse model of PUs in the context of complete SCI is presented. Adult male mice (Balb/c, 10 weeks old) were shaved and depilated. Post-depilation (24 h), mice were subjected to laminectomy followed by complete spinal cord transection (T9-T10 vertebrae). Immediately after, a skin fold on the back of the mice was lifted and sandwiched between two magnetic discs held in place for next 12 h, thus creating an ischemic area that developed into a PU over the following days. The wounded areas demonstrated tissue edema and epidermal disappearance by day 3 post-magnet application. PUs spontaneously developed and healed. Healing was, however, slower in the SCI mice compared to control non-SCI mice when the wound was created below the level of SCI. Conversely, no difference in healing was seen between SCI and control non-SCI mice when the wound was created above the level of SCI. This model is a potentially useful tool to study the dynamics of skin PU development and healing after SCI, as well as to test therapeutic approaches that may help heal such wounds.

Here, we describe a simple method to induce clinically relevant skin pressure ulcers (PUs) in a mouse model of spinal cord injury (SCI). This model can be used in pre-clinical studies to screen for different therapeutics for healing PUs in SCI patients.

Pressure ulcers (PUs) are common debilitating complications of traumatic spinal cord injury (SCI) and tend to occur in soft tissues around bony ...

Low-Cost, Volume-Controlled Dipstick Urinalysis for Home-Testing

Dipstick urinalysis provides quick and affordable estimations of multiple physiological conditions but requires good technique and training to use accurately. Manual performance of dipstick urinalysis relies on good human color vision, proper lighting control, and error-prone, time-sensitive comparisons to chart colors. By automating the key steps in the dipstick urinalysis test, potential sources of error can be eliminated, allowing self-testing at home. We describe the steps necessary to create a customizable device to perform automated urinalysis testing in any environment. The device is cheap to manufacture and simple to assemble. We describe the key steps involved in customizing it for the dipstick of choice and for customizing a mobile phone app to analyze the results. We demonstrate its use to perform urinalysis and discuss the critical measurements and fabrication steps necessary to ensure robust operation. We then compare the proposed method to the dip-and-wipe method, the gold standard technique for dipstick urinalysis.

Dipstick urinalysis is a quick and affordable method of assessing one&#8217;s personal state of health. We present a method to perform accurate, low-cost dipstick urinalysis that removes the primary sources of error associated with traditional dip-and-wipe protocols and is simple enough to be performed by lay users at home.