Effect of Additives on Photodegradation of 1,3,5–Trichlorobenzene in Aqueous Surfactant Solutions

Photolysis of 1,3,5–trichlorobenzene (TCB) in moderate concentration (0.5 mM) in the presence of several additives was examined in 10 mM of cationic and nonionic surfactant solutions. Additions of small amounts of hydrophobic additives, n–dodecanethiol (1 mM), n–dodecyldimethylamine (< 2.5 mM), and N–(n–dodecyl)–N–methylaniline (C₁₂An: < 0.5 mM), were effective for photodechlorination of TCB, while the formation of by–products could not be inhibited perfectly. In contrast, exclusive and efficient dechlorination of TCB in cetyltrimethylammonium chloride solution was achieved in the presence of sodium borohydride (< 5 mM), which was due to the enhanced local concentration of borohydride anions in cationic micelle surfaces.

Key Words :

• Photodechlorination
• Trichlorobenzene
• Surfactant
• Photoelectron transfer
• Additive

ACKNOWLEDGMENTS

This work was supported by a grant–in–aid for 21st Century COE Program from the Ministry of Education, Culture, Sports, Science, and Technology.

Notes

^a[TCB] = 0.5 mM; [surfactant] = 10 mM; light source, high–pressure Hg lamp; irradiation time, 5 min.

^b Solubility of TCB.

^c Conversion yield of TCB.

^d Yields of products based on TCB consumed.

^e Yield < 0.3%.

^a[TCB] = 0.5 mM; [surfactant] = 20 mM; light source, low–pressure Hg lamp; irradiation time, 15 min.

^a[TCB] = 0.5 mM; [surfactant] = 20 mM; light source, high–pressure Hg lamp (> 280 nm); irradiation time, 5 min.

^eCould not be determined because of too small signal.

^fpH of the solution was adjusted to 11.