Abstract: Two different porphyrins were incorporated to chitosan membranes aiming photoinactivation of the Gram-negative bacteriaEscherichia coli, which can be present in drinking water due to contamination. The incorporated porphyrin were 5,10,15,20-tetrakis(p-aminophenyl)-porphyrin (p-TAPP) and meso-tetrakis (4-N-metylpyridyl)-porphyrin (TMPyP). To verify the photoactivity of the membranes were employed static and dynamic (water flow system) arrangements containing E. coli exposed to an apparatus containing white LEDs. Evaluation of the static setup showed that both incorporated porphyrins have caused a considerable bactericidal effect under irradiation (3 log reduction in 180 min, for p-TAPP and 5 log reduction in 120 min for TMPyP). Therefore, the photoinactivation was most effective for TMPyP leading to a greater reduction in cell proliferation with shorter irradiation time. The results showed that the dynamic setup, using chitosan membranes containing TMPyP, was effective showing 3 log reduction at 80 min irradiation. These results suggest that the process is valuable and has potential to eliminate microbial contaminants in water.
Keywords: Bacteria, water, photoinactivation, quitosan, photosensitizer.