EMPLOYMENT OF PHOTOLYTICAL AND PHOTOCATALYTICAL METHODOLOGIES FOR REMOVAL OF CEPHALEXIN IN AQUEOUS SOLUTION
Journal Title: Periódico Tchê Química - Year 2017, Vol 14, Issue 27
Abstract
This study aimed to determine the best conditions for the photodegradation of the antibiotic cephalexin (CPX) in aqueous solution employing UV light, hydrogen peroxide (H2O2), titanium dioxide (TiO2) as catalyst at different pH values. The experiments were followed by spectrophotometry in the UV-VIS region observing the band at 262 nm (λmax). For the photocatalycal tests using homogeneous and heterogeneous catalysts, the parameters were organized in an experimental design 23 in order to observe the influence of each one, as well as the interaction between them at the different pHs studied. The results of the experiments were assessed by means of statistical software, been performing analyses of effects, interactions, response surface and analysis of variance (ANOVA). For the kinetic analysis of the results graphs of ln(A0/A) vs. time were plotted. From the analysis of the results, it was observed that the best conditions found for the photodegradation process were [H2O2] = 1000 mg L-1 and [TiO2] = 50 mg L-1 at pH 4. The kinetic constant of the photocatalysis employing [H2O2] = 1500 mg L-1 at pH 4 was 3.4 times higher than that determined for the photolytical process at pH 4 (k = 10x10-4 min-1). It was possible to verify that the parameters pH, H2O2, as well as the interaction between the parameters H2O2 and TiO2 are significant for the process, and that the best photocatalycal conditions were at pH 4, TiO2 [50 mg L-1] and H2O2 [1000 mg L-1]. In the assay of antimicrobial activity against five bacterial strains it was observed that only two strains, E. coli and A. hydrophila, did not show sensitivity to the photochemically treated drug, showing that in these cases the drug had its antimicrobial activity decreased.
Authors and Affiliations
Mauricio Ferreira ROSA
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