CO2 Emitted from the Production of Ingeo Biopolymer

NatureWorks LLC has created new Ingeo biopolymers claiming to be the first polymers showing a significant reduction in greenhouse

gas emissions such as carbon dioxide.Carly SchulzCHEM4101

December 4th, 2009

Experiment• Problem: An analytical technique must be developed to

quantify the amount of CO2 emitted from the production of PLA.

• Purpose: To compare this amount of CO2 emitted with the amount emitted from the production of other polymers and determine if the Ingeo Biopolymer does indeed produce the least amount of CO2, making it a more earth friendly or green process. A large amount of CO2 in the earth’s atmosphere may cause damage to the environment since it is a greenhouse gas. Life exists only because of the natural greenhouse effect, because this process regulates the earth's temperature. If the greenhouse effect did not exist, the earth would be covered in ice. The amount of heat trapped in the atmosphere determines the temperature on earth, which depends on concentrations of atmospheric greenhouse gasses and the amount of time these gasses remain in the atmosphere. The most important greenhouse gasses are carbon dioxide, CFC's (Chlorofluorocarbons), nitrogen oxides and methane.

• Hypothesis: The amount of CO2 emitted can be approximated through accurate analytical techniques and experimental methods such as FTIR. The amount (grams) of CO2 emitted from the production of 1 ton of PLA is less than the amount of CO2 emitted from the production of 1 ton of other similar polymers.

What’s the deal?• Right now Ingeo biopolymer is made from dextrose (plant sugar) that is derived

from corn. (Other sources include wheat, sugar beets, and sugar cane.) • This is used to make ingeo fibers and plastics. During this process Nature Works

claims to emit less greenhouse gases, particularly CO2• The nature-based plastic Nature Works® PLA is made from the starch in the corn

or other plants, which is converted to sugar by grinding instruments. • Microorganisms convert the sugar into lactic acid through fermentation. The

Lactic acid molecules then link to form lactide monomer rings. • These rings open and link together to form a long chain of polylactide polymer.

(Polymerization) This polymer is now in plastic form, and is formed into pellets. This process will most likely not convert all of the dextrose to PLA. The atom economy and efficiency could be calculated using a balanced equation.

• An analysis of the mass of PLA should be obtained in order to compare the ratio of kg of CO2 emitted versus kg of polymer for many samples in order to determine if ingeo biopolymer (PLA) is in fact a “more green” process.

Possible Techniques to Quantify Amount of CO2 Emissions

• Spectroscopy:– UV-VIS Absorption: The amount of Ingeo polymer that is generating the CO2 is

detectable by UV-VIS absorption but it cannot be directly used to measure the amount of CO2

– Fluorescence: Based in the molecular structure and formula, CO2 is predicted to not be fluorescent under standard conditions. It has a low molecular rigidity, no delocalized electrons, a linear optimized geometry, no hydrogens, and a small quantum yield, all of which tend to cause molecules to be less fluorescent.

– Infrared Spectrometry: *CO2 be detected by a Fourier Transform Infrared Spectrometer*

The following detectors are insensitive to noncombustible gases:– Atomic Absorption Spectrometry/AAS: C and O have are non metals and have resonance

lines shorter than 200nm, which is the detection limit, so without a vacuum spectrometer, this technique will not be suitable. Also, CO2 is a gas at room temperature and it sublimes around -56.6 degrees Celsius.

– Atomic Emission Spectroscopy/AES: Similarly, vacuum instrumentation would be required since the emission lines fall below 150-160nm (ultraviolet/visible region) in wavelength.

– Inductively coupled plasma-atomic emission spectroscopy/ICP-AES: Atmospheric components absorb radiation at wavelengths less than 180nm. Also, there are only 1 or 2 useful emission lines for CO2

Possible Techniques to Quantify Amount of CO2 Emissions

• Mass Spectrometry:• Ionization Methods: Isotope dilution mass spectrometry or IDMS can be used

to quantify CO2 and other gases by diluting an unknown amount of CO2 , with a known amount of isotopically enriched spike material of the same substance, and then using a technique known as isotope ratio mass spectrometry. In this technique, two reference blends are prepared by diluting a pure sample of CO2 with the highly enriched spike.

• Mass Analyzers: CO2 has a molecular weight under 100 a.m.u. so a MS/MS or tandem mass spectrometry experiment wouldn’t be applicable. However, PLA could be quantified with high-performance liquid chromatography/tandem mass spectrometry. (HPLC-MS/MS). The benefits of such an experiment would include high precision. Tandem mass spectroscopy uses an ionization source to produce ions. The ions are put into a mass analyzer, which selects a “precursor ion” and sends it into an interaction cell. Here, the precursor ion can decompose spontaneously, react with a collision gas, or interact with a laser beam and produce “product ions”. Product ions are fragments that are analyzed by a second mass analyzer and finally detected by an ion detector.

Possible Techniques to Quantify Amount of CO2 Emissions

• Capillary Electrophoresis: CO2 as is would not be compatible with CE analysis since it is a neutral molecule. A good analyte for CE is charged. Therefore, a CO2 ion would need to be analyzed by CE, such as CO3

-2.• Electroanalytical Chemistry:

– Cyclic Voltammetry: Electrochemical possible half-reaction for this type of analysis: 2(CO2)(g) + 2(H)+ + 2e- <==> H2C2O4 where E° = -0.49 volt

Where oxalic acid, H2C2O4, is the main product when water is kept out of the solution.

Formic acid, CH2O2 , or carbon monoxide, CO, could also be produced using certain solvents. • Chromatography:

– Gas: Gas-solid chromatography analysis can be used to analyze CO2 using an open tubular column lined with a porous polymer, PLOT, since carbon dioxide is a gaseous species with dipole moments and the pore size of the polymer beads is uniform. An appropriate temperature range for this analysis would have to be high enough so that the CO2 desorbs from the stationary phase so perhaps 350-400 degrees Celsius would suffice. It’s possible that it is highly retained at low temperatures depending on the stationary and mobile phases. Carbon dioxide would be collected from the site of ingeo polymer production and placed into a CO2 tank. From there it would be injected and passed through the column mentioned above and then detected with the FTIR detector.

– Liquid: The polymer could be quantified using HPLC-MS/MS

FTIR Procedure

Instrumentation: The FT/IR-6100

• Resolution:0.5-1.5nm• Drive Speed: 0.5, 1, 2, 3, 4, 5, 6, 7, or 8 mm/sec

(faster than dispersive instrument)• Sample Chamber Size: 200 mm (W) ´ 260 mm

(D) ´ 185 mm (H) Optical path: Center focus, light axis 70 mm high

• Portability: Main FTIR unit Dimensions: 600 (W) ´ 670 (D) ´ 315 (H) mm Weight:56 kg. Power Supply Unit Dimensions:200 (W) ´ 285 (D) ´ 90 (H) mm Weight:4.7 kg

• S/N: 42,000:1 which is higher than a dispersive instrument (4 cm-1, 1 min, near 2,200 cm-1)

• Measurement Wavelength range: 7,800 to 350cm-1

• Interferences: Other greenhouse gases and possible atmospheric contamination, which could be subtracted. Free from stray radiation.

• Selectivity towards the species: fairly high• Robustness: Fairly high• Cost: least expensive model• Highly accurate and precise• Reproducible frequency determinations

• LOD, LOQ, and dynamic range all to be calculated prior to experimentation and construction of a concentration versus absorbance signal plot, but based on previous experiments found in literature, all are conducive to obtaining proper data

• Most importantly, it’s a fairly simple instrument to run

Instrumental parameters specific to this experiment:

– Resolution: 0.5nm– Scan: 64– Gain: 1– Wavelength range: 500-2500 cm-1

Theoretical FTIR Spectrum of CO2

© 2008 by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved. Copyright for NIST Standard Reference Data is governed by the Standard Reference Data Act.

• Since CO2 is a linear molecule, it has two translational degrees of freedom and three rotational degrees of freedom and therefore four vibrational degrees of freedom corresponding to the four vibrational modes• There are two stretching modes since there are two bonds in the CO2 molecule and the two remaining degrees of freedom correspond to two degenerate bending or deformation modes, which are IR active with a peak at 667cm-1

• One stretch is symmetric, which is not IR active since it does not give rise to a large enough change in dipole moment, and the other is asymmetric, which produces a peak at 2349cm-1

Symmetric Stretch

The concentration of CO2 present in the sample is calculated by:1. Identifying the asymmetric C=O stretch peak and the doubly degenerate deformation peak, which is located in the fingerprint region so it may not be used for analysis, and any other greenhouse gas peaks, interferents, and contaminants2. The integrals of the absorbance peaks will be measured and the peak areas will be recorded with identical integration regions for all the spectra.3. A calibration curve from the collected intensity data from the sample of interest along with the known concentrations and intensities of the six standard samples will be constructed. This curve will be created by plotting the peak areas versus concentrations of the standard samples. 4. Then, using the experimental peak area of the unknown sample, the unknown concentration can be calculated.

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.20

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2f(x) = 0.99838961038961 x + 0.00139913419913423R² = 0.998035586309486

Concentration (moles/liter)

Abso

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eak

Area

(a.u

.)

Analysis of results

Results/Conclusion

As one can see, after interpreting this data, and comparing it with that of other experiments, the original hypothesis was correct. The amount of CO2 (kg) emitted from the production of PLA (1 T) is less than the amount of CO2 emitted from the production of other similar polymers (1 T).

The figure above was provided by a company called Synbra Technology bv.

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