Abiotic dehalogenation of 1,2-dichloroethane and 1,2-dibromoethane in aqueous solution containing hydrogen sulfide
The detection of significant levels of halogenated aliphatic contaminants in groundwater resources in the United States has spurred a considerable effort to understand the various mechanisms--both microbiological and abiotic--by which these compounds may be transformed. In aerobic environments, the abiotic reactions that predominate are elimination of hydrogen halide (dehydrohalogenation) and nucleophilic substitution by H{sub 2}O (hydrolysis). Little research has examined the rates and pathways of abiotic reactions that may be significant under hypoxic conditions. The dehalogenation of 1,2-dichloroethane (1,2-DCA) and 1,2-dibromoethane (EDB) in phosphate buffer was examined alone, and in phosphate buffer containing hydrogen sulfide. Kinetic runs were conducted at pH 7 over the temperature range from 25 to 87.5 C. Phosphate buffer catalyzed the hydrolysis of both 1,2-SCA and EDB. This catalysis was attributed to the buffer anion HPO4(2-). The rate laws for these transformations exhibit the following form: -d(RX)/dt=(K{sup 1}{sub H}) + K{sub HS{minus}}(HS{sup {minus}}) + K{sub HPO4(2-)}(HPO4(2-))(RX) where RX denotes either 1,2-DCA or EDB, and the rate constants correspond to the overall reactions.
- Research Organization:
- Stanford Univ., CA (USA). Dept. of Civil Engineering
- OSTI ID:
- 6728838
- Report Number(s):
- PB-90-216284/XAB
- Resource Relation:
- Other Information: Pub. in Environmental Science and Technology, Vol. 23, No. 11, 1349-1358(Nov 1989)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHLORINATED ALIPHATIC HYDROCARBONS
DEHALOGENATION
GROUND WATER
DECONTAMINATION
AEROBIC CONDITIONS
ANOXIA
BUFFERS
CATALYSIS
CHEMICAL REACTIONS
HYDROGEN SULFIDES
HYDROLYSIS
PH VALUE
SAMPLE PREPARATION
WATER CHEMISTRY
WATER POLLUTION
CHALCOGENIDES
CHEMISTRY
CLEANING
DECOMPOSITION
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROGEN COMPOUNDS
LYSIS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXYGEN COMPOUNDS
POLLUTION
SOLVOLYSIS
SULFIDES
SULFUR COMPOUNDS
WATER
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)