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Web-Only Document 8: Alternative Aircraft Anti-Icing Formulations with Reduced Aquatic Toxicity and Biochemical Oxygen Demand Airport Cooperative Research Program University of South Carolina Prepared in partnership with Infoscitex Corporation Molecular Knowledge Systems Inc. Wisconsin State Laboratory of Hygiene CH2M HILL U.S. Geological Survey Contractorâs Final Report for ACRP Project 02-01 Submitted August 2010 ACRP
ACKNOWLEDGMENT This work was sponsored by the Federal Aviation Administration (FAA) in cooperation with the Airport Cooperative Research Program (ACRP) Oversight Committee (AOC). It was conducted through ACRP, which is administered by the Transportation Research Board (TRB) of the National Academies. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, Transit Development Corporation, or AOC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.
Contents Acknowledgments ............................................................................................................................. ix Acronyms and Abbreviations .......................................................................................................... x Section 1: Introduction ............................................................................................................. 1-1 Background ................................................................................................................................. 1-2 Objectives of the Phase 2 Research .......................................................................................... 1-2 Report Structure ......................................................................................................................... 1-2 Section 2: Summary of Candidate Deicer Components Evaluated in Test Program ... 2-1 FPD Candidates for ADFs and AAFs ...................................................................................... 2-1 Availability and Pricing ...................................................................................................... 2-3 Flash Point ............................................................................................................................ 2-3 Biological Oxygen Demand ............................................................................................... 2-4 Freezing Point Depressant ................................................................................................. 2-4 Aquatic Toxicity ................................................................................................................... 2-8 Mammalian Health Effects ............................................................................................... 2-10 Summary of Candidates ................................................................................................... 2-10 Freezing Point Depressant Candidates for PDMs ............................................................... 2-11 Availability and Pricing .................................................................................................... 2-12 Flash Point .......................................................................................................................... 2-13 Biological Oxygen Demand ............................................................................................. 2-13 Note on the Definition of BOD ........................................................................................ 2-13 Melting, Penetration, and Undercutting ........................................................................ 2-15 Freezing Point Depression ............................................................................................... 2-15 Aquatic Toxicity ................................................................................................................. 2-16 Mammalian Health Effects ............................................................................................... 2-17 Carbon-Carbon Brake Oxidation and Runway Corrosion .......................................... 2-17 Price ..................................................................................................................................... 2-17 Summary of Candidates ................................................................................................... 2-17 Thickener Candidates .............................................................................................................. 2-19 Thickener Candidates ....................................................................................................... 2-19 Surfactant Candidates ............................................................................................................. 2-22 Corrosion Inhibitor Candidates ............................................................................................. 2-27 Anti-Caking Additive Candidates ......................................................................................... 2-27 Section 3: Experimental Plan .................................................................................................. 3-1 Tier 1 Testing .............................................................................................................................. 3-2 Tier 2 Testing .............................................................................................................................. 3-3 Type IV Aircraft Anti-Icing Formulations ....................................................................... 3-3 Runway Deicers ................................................................................................................... 3-4 Section 4: Tier 1 Results ........................................................................................................... 4-1 Freezing Point Depression ........................................................................................................ 4-1
ALTERNATIVE AIRCRAFT AND AIRFIELD DEICING AND ANTI-ICING FORMULATIONS IV Flash Point .................................................................................................................................. 4-7 Oxygen Demand ........................................................................................................................ 4-9 Methods ................................................................................................................................ 4-9 Results ................................................................................................................................... 4-9 Aquatic Toxicity ....................................................................................................................... 4-13 Methods .............................................................................................................................. 4-13 Results ................................................................................................................................. 4-13 Viscosity .................................................................................................................................... 4-17 Contact Angle........................................................................................................................... 4-19 Down-Selection of Components for Tier 2 Testing ............................................................. 4-20 FPDs .................................................................................................................................... 4-20 Thickeners .......................................................................................................................... 4-22 Surfactants .......................................................................................................................... 4-22 Corrosion Inhibitors ......................................................................................................... 4-23 Section 5: Tier 2 Results .......................................................................................................... 5-1 Aircraft Type IV Anti-Icing Fluids .......................................................................................... 5-1 Testing FPDs/Water and Thickeners ............................................................................... 5-3 FPDs/Water and Surfactants .......................................................................................... 5-10 FPDs/Water, Thickeners and Surfactants ..................................................................... 5-14 FPDs/Water, Thickeners, Surfactants, and Corrosion Inhibitors .............................. 5-20 Environmental Characteristics .............................................................................................. 5-21 Aquatic Toxicity ................................................................................................................ 5-21 Biochemical Oxygen Demand ......................................................................................... 5-24 Runway Deicers ....................................................................................................................... 5-25 Section 6: Degradation Pathways for Down-Selected Deicer Components .................. 6-1 DEG ............................................................................................................................................. 6-1 Tergitol L-64 ............................................................................................................................... 6-2 TEA .............................................................................................................................................. 6-3 Carbopol EZ-4 ............................................................................................................................ 6-3 Section 7: Conclusions ............................................................................................................. 7-1 General Conclusions ................................................................................................................. 7-1 Oxygen Demand ........................................................................................................................ 7-2 Aquatic Toxicity ......................................................................................................................... 7-2 Pavement Deicers ...................................................................................................................... 7-3 Section 8: Future Research topics .......................................................................................... 8-1 Section 9: References ............................................................................................................... 9-1 Appendices A Potential ADF FPDs Identified in Search .......................................................................... A-1 B Details on Candidate ADF FPDs Recommended for Further Evaluation .................... B-1 C Potential PDM FPDs Identified In Search ......................................................................... C-1 D Details on Candidate PDM FPDs Recommended for Further Evaluation ................... D-1 E Details on Candidate Surfactants Recommended for Further Evaluation ................... E-1 F Candidate Corrosion Inhibitors Recommended for Further Investigation ................. F-1
CONTENTS V The information in this document is summarized in ACRP Research Results Digest 9: Alternative Aircraft and Pavement Deicers and Anti-Icing Formulations with Improved Environmental Characteristics. Readers can purchase or read ACRP Research Results Digest 9 at http://www.trb.org/Publications/Blurbs/163408.aspx.
ALTERNATIVE AIRCRAFT AND AIRFIELD DEICING AND ANTI-ICING FORMULATIONS VI Tables TABLE 2-1. Structural group representation of FPDs. ................................................................ 2-2 TABLE 2-2. ThOD of some current FPDs. .................................................................................... 2-5 TABLE 2-3. 96-hour C. dubia LC50 of some current deicing/anti-icing products. ................... 2-8 TABLE 2-4. 96-hour P. promelas LC50 of some current deicing/anti-icing products. ............. 2-9 TABLE 2-5. Candidate FPDs recommended for further evaluation. ...................................... 2-10 TABLE 2-6. Structural group representation of FPDs potentially useful for PDMs. ............ 2-12 TABLE 2-7. ThOD values for FPDs. ............................................................................................ 2-13 TABLE 2-8. Freezing points of aqueous deicing chemical solutions. ..................................... 2-14 TABLE 2-9. Estimated concentrations for limiting eutectic temperature. ............................. 2-16 TABLE 2-10. Candidate freezing point depressants recommended for further evaluation. ....................................................................................................................................... 2-18 TABLE 2-11. Candidate thickeners. ............................................................................................. 2-22 TABLE 2-12. Non-ionic surfactant categories. ........................................................................... 2-24 TABLE 2-13. Candidate surfactants. ............................................................................................ 2-26 TABLE 3-1. Number of components and deicer formulations tested in Tiers 1 and 2. ......... 3-1 TABLE 3-2. Tier 1 deicing/anti-icing formulation tests. ............................................................ 3-1 TABLE 3-3. Tier 2 tests for Type IV and runway PDMs. ............................................................ 3-1 TABLE 4-1. Number of alternative deicing components ordered and available for testing. ......................................................................................................................................... 4-1 TABLE 4-2. Typical results for freezing point depression. ........................................................ 4-2 TABLE 4-3. Results of freezing point depression and flash point testing for FPDs. .............. 4-4 TABLE 4-4. Cost of FPD on a neat basis (in order of increasing cost).a .................................... 4-7 TABLE 4-5. Summary of FPD mixture aircraft and runway deicing/anti-icing agents meeting performance and safety requirements. .......................................................................... 4-8 TABLE 4-6. Summary of COD and BOD results for candidate FPDs in order of increasing COD. ................................................................................................................................................ 4-11 TABLE 4-7. Screening-level toxicity data for candidate FPDs for three species. .................. 4-14 Table 4-8. Screening-level toxicity data for candidate surfactants for three species. ........... 4-15 TABLE 4-9. Screening-level toxicity data for candidate corrosion inhibitors for three species. ............................................................................................................................................. 4-16 TABLE 4-10. Screening-Level Toxicity Data for Candidate Thickeners for Three Species .............................................................................................................................................. 4-16 TABLE 4-12. Performance testing results for surfactants. ........................................................ 4-20 TABLE 4-13. Down-selection results for candidate FPDs for potential use as aircraft and pavement deicers and anti-icers. ................................................................................................. 4-21 TABLE 4-14. Down-selection rankings for candidate thickeners. ........................................... 4-22 TABLE 4-15. Performance and aquatic toxicity testing results for surfactants. .................... 4-22 TABLE 5-1. Candidate components of Type IV aircraft anti-icing fluids evaluated in Tier 2. ................................................................................................................................................. 5-1 TABLE 5-4. Method of verifying selection of thickeners and surfactants. ............................... 5-2 TABLE 5-5 Method of down-selecting corrosion inhibitors. ..................................................... 5-3 TABLE 5-6. Test matrix to evaluate the effect of thickener concentration on viscosity. ........ 5-5 TABLE 5-7. Concentration of thickeners (wt %) for different FPDs to match viscosity of commercial Type IV anti-icing fluid at different shear rates. .................................................... 5-8 TABLE 5-8. Thickener concentrations selected to match viscosity/shear rate curve of commercial Type IV formulation. .................................................................................................. 5-8
CONTENTS VII TABLE 5-9. Toxicity and costs of thickeners in FPD/water formulations. ............................ 5-10 TABLE 5-10. Liquid surface tension and surface contact angle for neat liquids. .................. 5-11 TABLE 5-11. Properties of FPD/water/surfactant formulations having the same surface tension as a commercial Type IV formulation. ........................................................................... 5-13 TABLE 5-12. Type IV anti-icing formulations containing a thickener and a surfactant. ..... 5-14 TABLE 5-13. Key freezing point depressant properties. ........................................................... 5-18 TABLE 5-14. Formulations used in corrosion testing. ............................................................... 5-20 TABLE 5-15. Sandwich corrosion test results. ............................................................................ 5-20 TABLE 5-16. Total immersion corrosion test results. ................................................................ 5-21 TABLE 5-17. Comparison of theoretical values with measured test results for step-wise Type IV anti-icer formulation construction .......................................................................................... 5-23 Table 5-18. Results from definitive aquatic toxicity testing of final Type IV DEG formulation (95% confidence interval). ............................................................................................................. 5-24 TABLE 5-19. Candidate components and properties of runway deicers to be evaluated. .. 5-25 TABLE 5-20. Moisture pickup of individual components of sodium formate and anti-caking agents. .............................................................................................................................................. 5-26 TABLE 5-21. Anti-caking experiments with sodium formate and potassium citrate. .......... 5-27 TABLE 6-1. Toxicity of Tergitol L-64 degradation products. ..................................................... 6-3 TABLE 6-2. Toxicity of TEA and its degradation products. ....................................................... 6-4 Table A-1. Initial list of candidate FPDs. ...................................................................................... A-1 Table C-1. Initial candidate FPDs. ................................................................................................. C-1 Figures 2-1 Flash points for mixtures of alcohol and water. ................................................................. 2-4 2-2 Freezing point curves for mixtures of ethylene glycol and water. .................................. 2-5 2-3 Construction of a hypothetical freezing point curve. ........................................................ 2-6 2-4 Variation of eutectic point with variation in enthalpy of fusion (âHm is given in units of kJ/mol). ............................................................................................................................... 2-7 2-5 Variation of eutectic point with variation in FPD freezing point (A âHm of 7.5J/mol assumed). ................................................................................................................................. 2-7 2-6 Freezing point depression on a molar basis. ..................................................................... 2-14 2-7 Phase diagram of aqueous sodium chloride. .................................................................... 2-15 2-8 Rheological behavior of typical anti-icing fluid at 0°C. .................................................. 2-19 2-9 Determination of critical micelle concentration. .............................................................. 2-24 4-1 Rack apparatus for freezing point depression tests. .......................................................... 4-2 4-2 Thickener viscosity/shear rate at 5°C and at room temperature. ................................. 4-18 4-3 Comparison of viscosity for surfactants with commercially available Type IV anti-icing formulation at room temperature....................................................................................... 4-19 5-1 Viscosity of Kelzan HP and K1A96 at different concentrations and shear rates for glycerol/water and diethylene glycol/water mixtures .................................................... 5-6 5-2 Viscosity of Carbopol EZ-4 with TEA at different concentrations and shear rates for glycerol/water and diethylene glycol/water mixtures. ................................................... 5-7 5-3 Comparison of viscosity/shear rate data for selected thickener concentrations to commercial Type IV formulation. ........................................................................................ 5-9 5-4 Surface tension for Si/Au surface using data from Table 5-10. ..................................... 5-12
