Mixed first and zero order kinetics in the electrooxidation of sulfamethoxazole at a boron-doped diamond (BDD) anode
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Pharmaceutical residues in the aquatic environment represent an emerging environmental problem, because many pharmaceuticals are refractory towards conventional waste water treatment. This study focussed on the oxidation of the sulfonamide antibiotic sulfamethoxazole (SMX) at a boron-doped diamond anode, at which reactive hydroxyl radicals are formed. Electrochemical oxidation led to mineralization with high current efficiency, but without the formation of known toxic products of partial oxidation. A “mixed” kinetic order with respect to substrate concentration was observed; the kinetics could be shifted in the direction of either diffusion control (first order in SMX) or current control (zero order in SMX) by adjusting the substrate concentration and current density. Alternatively, the electrooxidation could be described by a model, applicable to a wide range of reaction conditions, in which the kinetic orders with respect to current and initial substrate concentration were approximately 0.4 and 0.5, respectively.
KeywordsSulfamethoxazole Boron-doped diamond anode Electrochemical oxidation Diffusion vs. current control Mineralization
We thank the Natural Sciences and Engineering Research Council of Canada for financial support and Dr H. Lee for assistance with the bacterial assays.
- 2.Perret A, Haenni W, Niedermann P, Skinner N, Comninellis Ch, Gandini D (1998) Proc Electrochem Soc 97:275Google Scholar
- 5.Morao A, Lopez A, Pessou de Amorim M, Goncalves M (2004) Electrochim Acta 49:1587Google Scholar
- 7.Both VM, Comninellis Ch (1999) Process/System Engineering 70:165Google Scholar
- 12.Ternes T (2001) ACS Symp Ser 791:39Google Scholar
- 33.Lovrek M, Zorc B, Butula I (1998) Acta Pharm (Zagreb) 48:31Google Scholar
- 34.Goyal RN, Srivastava RK (1990) Indian J Chem 29A:635Google Scholar
- 35.Husain S, Krishna Murty ASR, Prasad PR, Sekar R (1995) Indian Drugs 32:336Google Scholar
- 38.Lehmann DF, Liu A, Newman N, Blair DC (1999) J Clin Pharmacol 39:533Google Scholar
- 39.Bard AJ, Faulkner LR (2000) Electrochemical methods: fundamentals and applications, 2nd edn. Wiley, New York, Chapter 3Google Scholar
- 41.Rajeshwar K, Ibanez JG (1997) Environmental electrochemistry. Academic Press, San Diego, CA, Chapter 2Google Scholar