Chitosan membranes with a photosensitizer incorporated were developed for the photoinactivation of bacteria in drinking water. The photosensitizers incorporated into chitosan membranes were methylene blue, rose Bengal and two porphyrins: 5,10,15,20-tetrakis(p-aminophenyl)- porphyrin (p-TAPP) and meso-tetrakis(4-N-metylpyridyl)- porphyrin (TMPyP). Evaluation of photoactivity against Escherichia coli suspensions (1×107 cells mL-1) showed that both porphyrins had a considerable bactericidal effect under irradiation at 590 nm (2 log reduction in 120 min for p-TAPP and 4 log reduction in 140 min for TMPyP) or 452 nm (2 log reduction for p-TAPP and 4 log reduction for TMPyP in 120 min). Therefore photoinactivation was most effective for TMPyP when blue light was used, leading to a greater reduction in cell count in a shorter period. These results suggest that photoinactivation is effective with either porphyrin incorporated in a polymeric support and that this system has potential to eliminate microbial contaminants in water.
Chitosan membranes with a photosensitizer incorporated were developed for the photoinactivation of bacteria in drinking water. The photosensitizers incorporated into chitosan membranes were methylene blue, rose Bengal and two porphyrins: 5,10,15,20-tetrakis(p-aminophenyl)- porphyrin (p-TAPP) and meso-tetrakis(4-N-metylpyridyl)- porphyrin (TMPyP). Evaluation of photoactivity against Escherichia coli suspensions (1×107 cells mL-1) showed that both porphyrins had a considerable bactericidal effect under irradiation at 590 nm (2 log reduction in 120 min for p-TAPP and 4 log reduction in 140 min for TMPyP) or 452 nm (2 log reduction for p-TAPP and 4 log reduction for TMPyP in 120 min). Therefore photoinactivation was most effective for TMPyP when blue light was used, leading to a greater reduction in cell count in a shorter period. These results suggest that photoinactivation is effective with either porphyrin incorporated in a polymeric support and that this system has potential to eliminate microbial contaminants in water.