Sorption of the pharmaceuticals carbamazepine and naproxen to dissolved organic matter: Role of structural fractions

Adi Maoz, Benny Chefetz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

107 Scopus citations

Abstract

Pharmaceutical compounds and dissolved organic matter (DOM) are co-introduced into the environment by irrigation with reclaimed wastewater and/or application of biosolids. In this study, we evaluate the role and mechanism of interaction of the pharmaceuticals naproxen and carbamazepine with structural fractions of biosolids-derived DOM. Sorption interactions were estimated from dialysis-bag experiments at different pHs. Sorption of naproxen and carbamazepine by the hydrophobic acid fraction exhibited strong pH-dependence. With both pharmaceuticals, the highest sorption coefficients (KDOC) were at pH 4. With the hydrophobic neutral fraction, pH affected only naproxen sorption (decreasing with increasing pH). Among the hydrophilic DOM fractions, the hydrophilic acid fraction exhibited the highest KDOC value for carbamazepine, probably due to their bipolar character. In the hydrophilic acid fraction-naproxen system, significant anionic repulsion was observed with increasing pH. The hydrophilic base fraction contains positively charged functional groups. Therefore with increasing ionization of naproxen (with increasing pH), KDOC to this fraction increased. The hydrophilic neutral fraction exhibited the lowest KDOC with both studied pharmaceuticals. The KDOC value of carbamazepine with the bulk DOM sample was higher than the calculated KDOC value based on sorption by the individual isolated fractions. The opposite trend was observed with naproxen at pH 8: the calculated KDOC value was higher than the value obtained for the bulk DOM. These results demonstrate that DOM fractions interact with each other and do not act as separate sorption domains.

Original languageAmerican English
Pages (from-to)981-989
Number of pages9
JournalWater Research
Volume44
Issue number3
DOIs
StatePublished - Feb 2010

Bibliographical note

Funding Information:
This research was supported by a research grant from BARD (No. IS-3822-06), the United States-Israeli Binational Agricultural Research and Development Fund.

Keywords

  • Binding
  • DOM
  • Fractionation
  • Hydrophilic
  • Hydrophobic
  • Municipal wastewater
  • Pharmaceutical
  • Sludge

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