Ge. Orzechowska et al., USE OF SONOCHEMISTRY IN MONITORING CHLORINATED HYDROCARBONS IN WATER, Environmental science & technology, 29(5), 1995, pp. 1373-1379
The U.S. Environmental Protection Agency (EPA) has been examining the
potential of combining sonication with available measurement technolog
ies for monitoring chlorinated hydrocarbons in water. The chloride ion
(Cl-) concentration, conductivity, and pH were measured before and af
ter sonication. Cl- could be detected in aqueous solutions of 3-80 ppm
carbon tetrachloride (CCl4), chloroform (CHCl3), and trichloroethylen
e (TCE) after 1 min of sonication. The increases of Cl- were accompani
ed by increases in conductivity and decreases in pH. The conductivity
changes were higher than expected based on measured Cl-. Ion chromatog
raphy of solutions before and after sonication showed that formate ion
(HCOO-) was also formed. Other ions may have formed as well, but the
concentrations were too low to allow their detection relative to HCOO-
and Cl-. The results achieved serve as proof-of-principle and form a
base of information which can be used to develop ultrasound monitoring
methods for these compounds. Aromatic and polyaromatic chloro compoun
ds represented by chlorobenzene (Ph-Cl) and polychlorobiphenyls (PCBs)
, respectively, did not release Cl- upon sonication as readily as did
CCl4, CHCl3, and TCE. The PCB solutions gave no measurable changes in
either Cl-, conductivity, or pH under the conditions of the experiment
s described.