Water disinfection using photosensitizers immobilized on chitosan.
We have designed experiments to test the idea that the photodynamic effect can be used to lower microbial levels in a flow of water using a sensitizer incorporated into a polymeric membrane. We have selected a naturally derived, wettable polymer, chitosan, which can be reinforced with nylon. Photosensitizers of singlet oxygen formation were incorporated into translucent chitosan membranes by adsorption [5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin, p-THPP], by dissolution and casting [5,10,15,20-tetrakis(p-aminophenyl)porphyrin, p-TAPP], and by covalent attachment by reactive dyeing [zinc(II) phthalocyanine tetrasulfonic acid, ZnPcS]. Preliminary evaluation of photomicrobicidal activity in static systems against Escherichia coli revealed some activity in each case, and showed that the phthalocyanine/chitosan membrane was the most effective. A novel photodisinfection reactor was designed and constructed as a model for a large-scale water-flow system. Using the novel reinforced ZnPcS/chitosan membrane as the photosensitizing surface, a significant photokill of E. coli was observed, thus providing proof of concept.
Bonnett
Raymond
R
Department of Chemistry, Queen Mary, University of London, Mile End Road, London EI 4NS, UK. r.bonnett@qmul.ac.uk
Krysteva
Milka A
MA
Lalov
Ivo G
IG
Artarsky
Spas V
SV
D048271:Chitosan / Q000737:chemistry*; D004202:Disinfectants / Q000737:chemistry / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D011166:Porphyrins / Q000737:chemistry / Q000494:pharmacology*; D014867:Water / Q000737:chemistry*
D004202:Disinfectants; D017319:Photosensitizing Agents; D011166:Porphyrins; D014867:Water; D048271:Chitosan