Oxidation of Selected Pharmaceuticals in Water Matrices by Bromine and Chlorine

The bromination of five selected pharmaceuticals (metoprolol, naproxen, amoxicillin, hydrochlorotiazide and phenacetin) in ultrapure water and in three water matrices (a groundwater, a surface water from a public reservoir and a secondary effluent from a WWTP) was investigated. The apparent rate constants for the bromination reaction were determined as a function of the pH, and the sequence obtained for the reaction rate was amoxicillin > naproxen >> hydrochlorotiazide ≈ phenacetin ≈ metoprolol. The proposal of a kinetic mechanism, which specifies the dissociation of bromine and each pharmaceutical according to their pKa values and the pH allowed the determination of the intrinsic rate constants for every elementary reaction. The influence of the main operating conditions (pH, initial bromine dose, and the water matrix) on the degradation of pharmaceuticals was established. In addition, the presence of bromide in chlorination experiments was investigated. The presence of bromide in wastewaters and drinking waters in the range of 10 to several hundred μg L-1 accelerated slightly the oxidation of the selected pharmaceuticals during chorine disinfection.

Authors:

• Juan L. Acero
• F. Javier Benitez
• Francisco J. Real
• Gloria Roldan
• Francisco Casas

Keywords:

• Pharmaceuticals
• bromine
• chlorine
• apparent andintrinsic rate constants
• water matrices
• degradation rates

References:

[1] Reemtsma, T., Weiss, S., Mueller, J., Petrovic, M., Gonzalez, S.,
Barcelo, D., Ventura, F., Knepper, T.P., 2006. Polar pollutants entry into
the water cycle by municipal wastewater: a European perspective.
Environ. Sci. Technol. 40 (17), 5451-5458.
[2] Kim, S.D., Cho, J., Kim, I.S., Vanderford, B.J., Snyder, S.A., 2007.
Occurrence and removal of pharmaceuticals and endocrine disruptors in
South Korean surface, drinking, and waste waters. Water Res. 41 (5),
1013-1021.
[3] Lee, Y., von Gunten, U., 2009. Transformation of 17╬▒-Ethinylestradiol
during water chlorination: effects of bromide on kinetics, products, and
transformation pathways. Environ. Sci. Technol. 43, 480-487.
[4] Quintana, J. B., Rodil, R., Lopez-Mahia, P., Muniategui-Lorenzo, S.,
Prada-Rodriguez, D., 2010. Investigating the chlorination of acídic
pahrmaceuticals and by-product formation aided by an experimental
design methodology. Water Res. 44, 243-255.
[5] Guo, G., Lin, F., 2009. The bromination kinetics of phenolic compounds
in aqueous solutions. J. Hazard. Mat. 170, 645-651.
[6] Pinkernell, U., Nowack, B., Gallard, H., von Gunten, U., 2000. Methods
for the photometric determination of reactive bromine and chlorine
species with ABTS. Water Res. 34, 4343-4350.
[7] Gallard, H., Pellizzari, F., Croue, J. P., Legube, B., 2003. Rate constants
of reaction of bromine with phenols in aqueous solutions. Water Res. 37,
2883-2892.
[8] Acero, J. L., Benitez, F. J., Real., F. J., Roldan, G., 2010. Kinetics of
aqueous chlorination of some pharmaceuticals and their elimination from
water matrices. Water Res. 44, 4158-4170.
[9] Westerhoff, P., Chao, P., Mash, H., 2004. Reactivity of natural organic
matter with aqueous chlorine and bromine. Water Res. 38, 1502-1513.