TY - JOUR
T1 - The mechanisms of rate enhancing and quenching of trichloroethene photodecay in the presence of sensitizer and hydrogen sources
AU - Chu, Wei
AU - Choy, W. K.
PY - 2002/6/10
Y1 - 2002/6/10
N2 - The reaction mechanisms and rates of trichloroethene (TCE) photodecay in the presence of photosensitizer (acetone, ACE) and hydrogen sources (surfactant and triethylamine, TEA) were investigated. Quantum yields of TCE photodecay in solution with surfactant Brij 35 and optimal ACE dosage are about 25 times higher than in Brij 35 alone. However, with an excess ACE dosage, ACE will act as a light barrier and attenuate the light intensity available for TCE photodegradation. TCE photodegradation follows a two-stage kinetics, in which a lag-phase is followed by a fast decay. The lag-phase distribution depends on initial pH levels and ACE concentrations. The overall TCE removal was found to be higher at high pH level, suggesting that free radical reaction is dominant at high pH levels. The use of additional hydrogen source (TEA) in the reaction can further accelerate the reaction, but overdosing of TEA would quench the reaction. The possible reaction mechanisms of TCE photodecay involving ACE and TEA were proposed, and rate-enhancing and rate-quenching models at low and high TEA concentrations respectively were derived based on the proposed mechanism; they were found useful for predicting the TEC decay quantum yields.
AB - The reaction mechanisms and rates of trichloroethene (TCE) photodecay in the presence of photosensitizer (acetone, ACE) and hydrogen sources (surfactant and triethylamine, TEA) were investigated. Quantum yields of TCE photodecay in solution with surfactant Brij 35 and optimal ACE dosage are about 25 times higher than in Brij 35 alone. However, with an excess ACE dosage, ACE will act as a light barrier and attenuate the light intensity available for TCE photodegradation. TCE photodegradation follows a two-stage kinetics, in which a lag-phase is followed by a fast decay. The lag-phase distribution depends on initial pH levels and ACE concentrations. The overall TCE removal was found to be higher at high pH level, suggesting that free radical reaction is dominant at high pH levels. The use of additional hydrogen source (TEA) in the reaction can further accelerate the reaction, but overdosing of TEA would quench the reaction. The possible reaction mechanisms of TCE photodecay involving ACE and TEA were proposed, and rate-enhancing and rate-quenching models at low and high TEA concentrations respectively were derived based on the proposed mechanism; they were found useful for predicting the TEC decay quantum yields.
UR - http://www.scopus.com/inward/record.url?scp=0035988026&partnerID=8YFLogxK
U2 - 10.1016/S0043-1354(01)00471-7
DO - 10.1016/S0043-1354(01)00471-7
M3 - Journal article
C2 - 12153018
SN - 0043-1354
VL - 36
SP - 2525
EP - 2532
JO - Water Research
JF - Water Research
IS - 10
ER -