35W Sculpture’s Reduction on Carbon Monoxide Pollution Presented by: Robert Lange Chemistry 4101Background With the construction of the new 35W bridge, two sculptures were erected out of concrete that is said to have the ability to oxidize car exhaust pollutants, such as carbon monoxide. The outer layer of the sculptures contains the active compound, titanium dioxide, which serves as a catalyst for the chemical reaction called photocatalysis4. Essentially, the titanium dioxide uses the energy of the sun light and air to oxidize carbon monoxide into carbon dioxide4. This process is beneficial since CO is a poisonous greenhouse gas and CO2 can be used by plant life to create oxygen. This is the first use of this technology in the USA, however many European countries and Japan have already been using titanium dioxide on their concrete surfaces4. Given the background information just stated, my analytical problem is: How effective are the 35W bridge sculptures at oxidizing carbon monoxide pollution?Obtaining the sample I would obtain samples of air at three different points of 35W; one a mile northward of the bridge along 35W as a reference of normal CO pollution, one in the middle of the bridge as my main test site, and one directly above a sculpture to ensure they are in fact lowing CO pollution. Since the titanium dioxide catalyst requires sunlight to work, I would take the samples around noon on a sunny, windless day. A personal pump would have to be used to obtain the air sample. A reliable pump I would use would be SKC 222 series pump, which is portable (12oz) and can be set at a flow rate of 200 mL/min5. A Glass wool plug would be inserted in the glass tube to ensure no large particulate entered the sample. The pump would run at each location for 5 minutes gathering one liter of gas at each sample location. When storing the sample, keep it out of sunlight since CO will slowly oxides to CO2, even without the titanium dioxide catalyst.Technique Used Gas chromatography with a mass spectrum detector (GC/MS) will be used to analyze carbon monoxide in the air. Gas chromatography (GC) was chosen because my analyte is already in gas phase and GC is compatible with CO. A mass spectrum (MS) detection was chosen since it can be tunable to CO and can have a low sensitivity of 1 pg3. Below is a block diagram of a GC/MS1. Carrier Gas (He2) Flow Regulator Air Sample Sample injection chamber FSWC column Ion source Mass Analyzer Electron multiplier Detector Readout Transfer LineTechniques Not Used Fluorescence- O2 is a quencher that can affect the fluorescence reading of carbon monoxide, and I am unsure of the amount of O2 in my air sample. HPCL- My analyte is already in gas phase, and getting it stay in a liquid phase would be more sampling handling which could affect my readings. Electrochemistry- This would work for analyzing CO in the air, similar to a CO detector found in homes. I still however chose to use GC for this analysis. Flame-Ionization Detector (FID)- CO is insensitive to this detector. TC Detector- Can be used to detect CO, but sensitivity is not as good as a MS detector.GC/MS Instrument Model and Analysis Specifications An excellent model to use is the GCMS-QP2010 Plus. The MS detector uses a quadrupole for mass analyzing, which would be set to select carbon monoxide at 28 m/z during sample testing. The injection temperature would be set at 110oC and the oven temperature at 50oC. He2 would be the carrier gas at 1 mL/min. The column would be fused silica wall-coated open tubular (FSWC), with the stationary phase being polyethylene since it excels at separating polar species and can be at a max temperature of 250oC1. It wouldn’t be a packed column because that requires a larger flow of carrier gas which would have to separated before entering the MS, which could remove some CO analyte1. This model has a limit of detection of 1 pg1 and a rotary sample valve to increase reproducibility. Since the column is able to coil and the MS uses a quadrupole, it is smaller in size. No other major components in the air, either whole or fragmented, have a m/z of 28 so there are no contaminates in the analysis.Calibration of Instrument To obtain a standard curve for the calibration of the GC, invert a 20 mL vial in water and bubble carbon monoxide into the vial until all the water is displaced by CO. Then add 1, 2.5, 5, 10, 50, and 150 microliters of this stock solution to six separate airtight 20 mL vials2. Add 100 microliters of each vial in the GC/MS at conditions mentioned above. The data obtained is then used to create a calibration curve. A tank of 99.5% carbon monoxide can be bought at Liquid Carbonic (Danbury, CT). When running samples, an airtight syringe is needed and the conditions of the GC/MS mentioned above must be followed. Below is a mass spectrum of CO. When the MS is set as mentioned before, only the CO molecules with 28 m/z will be detected.Analysis After the samples are run, an arbitrary amount of CO will have made it to the detector. To determine the amount of CO in the sample, the calibration curve is used since the concentrations of the standards used to make the curve are known. The limit of detection of this curve should be 1 pg of CO in the sample. The sample should take less than 10 minutes to elute2. After researching about titanium dioxide used on the surface of cement, I found that when a whole road had the catalyst on it, pollution was reduced by 15%4. However, without doing the analysis proposed above, I can still estimate that the total reduction in CO pollution will not be very significant solely because there is not enough concrete with titanium dioxide, only two sculptures. It is however a step in the right direction for reducing pollution.References 1Skoog, Douglas. Principles for Instrumental Analysis, 6th edition. Thomas corporation, 1998. 2Anderson, Collin. “Analysis of Carbon Monoxide in Commercially Treated Tuna and Mahi-Mahi by Gas Chromatography/Mass Spectrometry.” American Chemical Society. 2005. 3Shimadzu Scientific Instruments. 2008, <www.ssi.shimadzu.com/products/product.cfm?product=qp2010plus> 4Chusid, Michael. Photocatalyst, “Self-Cleaning Concrete.” Concrete Decor. August, 2005. Volume 5, Issue 4. 5SKC. October 2, 2008. <www.skcinc.com/pumps/222-3.asp>. Viewed Nov,
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