REC-ERC-84-8 December 1984 Engineering and Research Center U. S. Department of the Interior Bureau of Reclamation 7-2090 (4.61) Bureau of Redsmat ZPORT STANDARD TITLE PAGE 3. RECIPIENT’S CATALOG NO. 5. REPORT DATE Oxidation of Formaldehyde Solutions December 1984 Used for the Preservation of Reverse 6. PERFORMING ORGANIZATION CODE Osmosis Membranes D-l 523C 7. AUTHOR(S) 9. PERFORMING ORGANIZATION REPORT NO. W. J. Boegli, A. P. Murphy, and M. K. Price REC-ERC-84-8 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT NO. Bureau of Reclamation Engineering and Research Center Il. CONTRACT OR GRANT NO. Denver, Colorado 80225 13. TYPE OF REPORT AND PERIOD COVERED -2. SPONSORING AGENCY NAME AND ADDRESS Same 14. SPONSORING AGENCY CODE DIBR 5. SUPPLEMENTARY NOTES Microfiche and/or hard copy available at the Engineering and Research Center, Denver, CO Ed: JC 6. ABSTRACT This report presents the results of an experimental study of a new process for the catalytic oxidation, at ambient temperatures, of dilute formaldehyde used in aqueous solutions for the preservation of cellulose acetate reverse osmosis membranes. The oxidation, involving hydrogen peroxide and an iron (ferric chloride) catalyst, was first tested in a bench-scale adiabatic reactor to develop operating curves for several concentrations of formaldehyde and to show the total oxidation time as a function of selected variables. These variables included initial solution temperature, reactant concentration, stirring rate, and the type of purge gas used above the reaction. In a subsequent series of tests, isothermal data were generated for fitting a temperature and concentration-dependent rate equation. The reaction, which proceeds by formic acid production, was shown to be effective in completely oxidizing formaldehyde solutions at concentrations at, or greater than, 250 mg/L to carbon dioxide and water (with formaldehyde vapor detected in the product gas stream at less than 0.4 mg/m3). The oxidation was found to be rate rather than mass diffusion controlled and, based on chemical similitude considerations, can be scaled up directly. Based on the results of the study, recommendations are made for the design and operation of a full-scale reactor for the Yuma Desalting Plant (now being constructed for the Bureau of Reclamation at Yuma, Arizona). An estimate is also provided for the cost of chemicals used in oxidizing a single flushing from a control block (45 000 L) at an assumed concentration of 1200 mg/L. 17. KEY WORD5 AND DOCUMENT ANALYSlS o. DESCRIPTORS-- *desalination/ *reverse osmosis membranes/ ion exchange/ water pu- rification/ *water treatment/ *formaldehyde oxidation/ formaldehyde disposal/ *membrane preservation/ cellulose acetate membranes/ bacteriostat/ pesticide/ organic oxidation b. IDENTIF/ERS-- Yuma Desalting Test Facility, Arizona/ l Yuma Desalting Plant/ Wellton-Mohawk Irrigation District/ c. COSATI Field/Group 13B COWRR: 1302.5 SR IM: 16. DISTRIBUTION STATEMENT 19. SECURITY CLASS -21. NO. OF PAGE (THIS REPORT) Available from the National Technical Information Service, Operations UNCLASSIFIED 57 Division, 5285 Port Royal Road, Springfield, Virginia 22161. 20. SECURITY CLASS 22. PRICE (Microfiche and/or hard copy available from NTIS) (THIS PAGE) UNCLASSIFIED REC-ERC-84-8 OXIDATION OF FORMALDEHYDE SOLUTIONS USED FOR THE PRESERVATION OF REVERSE OSMOSIS MEMBRANES W. J. Boegli A.P. Murphy M.K. Price December 1984 Applied Sciences Branch Division of Research and Laboratory Services Engineering and Research Center SI METRIC Denver, Colorado UNITED STATES DEPARTMENT OF THE INTERIOR * BUREAU OF RECLAMATION ACKNOWLEDGMENTS The authors would like to thank Dr. John Vaughn, Professor of Chemistry, Colorado State University, for his helpful suggestions on kinetics; and Ken Williams, Chemist, U.S. Army Environmental Hygiene Agency, Aberdeen Proving Ground, Maryland, for providing operating conditions for the formaldehyde analysis by ion chromatog- raphy. As the Nation’s principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserv- ing the environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through out- door recreation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major respon- sibility for American Indian reservation communities and for people who live in Island Territories under U.S. Administration. The research covered by this report was funded jointly by the Bureau’s Lower Colorado Regional Office and the Office of Water Research. I The information contained -in this report regarding commercial prod- ucts or firms may not be used for advertising or promotional purposes and is not to be construed as an endorsement of any product or firm by the Bureau of Reclamation. Page Summary .................................................................................................................................. 1 Introduction ............................................................................................................................... 1 The impact of FIFRA .............................................................................................................. 1 Formaldehyde disposal methods ............................................................................................. 1 Adiabatic testing ....................................................................................................................... Beaker tests.. ........................................................................................................................ : Matrix tests ........................................................................................................................... 5 Further testing at standard conditions ..................................................................................... 12 Other considerations of the reaction ........................................................................................ 16 Studies of parameters kept constant in the matrix tests ........................................................... 18 Isothermal: testing ...................................................................................................................... 23 Experimental apparatus and procedure .................................................................................... 23 Results and discussion ........................................................................................................... 27 Design data for the Yuma Desalting Plant.. .................................................................................. Thermodynamics for the known oxidations.. ............................................................................ :: Scale-up ................................................................................................................................ 30 Flushing and disposal of formaldehyde solutions ...................................................................... 32 Conclusions and recommendations ............................................................................................. 32 Bibliography .............................................................................................................................. 33 APPENDIXES Appendix A Ion chromatography ...................................................................................................... 35 1 Formaldehyde analysis by IC ................................................................................. 2 Formate detection ............................................................................................... SE 3 IC chromatogram ................................................................................................. 4 Water contamination ........................................................................................... 1: 5 Daily operation of the IC.. ..................................................................................... 38 Reliability of analytical procedures .................................................................................. 41 G Calculations ................................................................................................................. 43 1 Gas chromatography ............................................................................................ 43 2 Percent carbon from 14C ...................................................................................... 43 3 Formaldehyde and formate ................................................................................... 43 D Assaying stock formaldehyde solutions .......................................................................... 45 E Carbon-l 4 formaldehyde and methyl alcohol .................................................................. 47 Thermodynamics .......................................................................................................... 49 L Power input ................................................................................................................. 53 H Formaldehyde flushing and disposal ............................................................................... 55 I Cost of process ..........................................................................................................