Binding of Sulfonamide Antibiotics to CTABr Micelles Characterized Using (1)H NMR Spectroscopy.

Interactions of nine sulfonamide antibiotics (sulfadoxine, sulfathiazole, sulfamethoxazole, sulfamerazine, sulfadiazine, sulfamethazine, sulfacetamide, sulfaguanidine, and sulfanilamide) with cetyltrimethylamonium bromide (CTABr) micelles were examined using (1)H NMR spectroscopy. Seven of the nine provided a significant change in the (1)H NMR chemical shift such that the magnitude and direction (upfield vs downfield) of the chemical shift could be used to propose a locus and orientation of the sulfonamide within the micelle structure. The magnitude of the chemical shift was used to estimate the binding constant for seven sulfonamides with CTABr micelles, providing values and an overall pattern consistent with previous studies of these sulfonamides.

Impact of selected wastewater constituents on the removal of sulfonamide antibiotics via ultrafiltration and micellar enhanced ultrafiltration.

To better understand the environmental mobility of sulfonamide antibiotics and develop improved processes for their removal during wastewater treatment, stirred cell ultrafiltration (UF) experiments were conducted using both synthetic and real wastewater effluent. The interactions between selected sulfonamides (sulfaguanidine, sulfathiazole and sulfamerazine), solids and dissolved organic matter were systematically explored. The further impact of micellar enhanced ultrafiltration (MEUF), a process in which surfactants are added at micellar concentrations to enhance removal of various trace contaminants from aqueous streams, was then explored by using a cationic surfactant, cetyltrimethylammonium bromide (CTAB).

Effects of raw water conditions on solution-state aluminum speciation during coagulant dilution.

The speciation of aluminum in solutions of alum and various prehydrolyzed, aluminum-based water treatment coagulants was investigated by 27Al NMR at 5 degrees C and 25 degrees C. Alum solutions were seen to contain only mononuclear species including an AlSO4(+) complex, while the prehydrolyzed coagulant solutions contained polynuclear aluminum species, as well. The relative proportions of both polynuclear species and AlSO4(+) complex decreased in cold water.