Hybrid Chitosan-Silver Nanoparticles Enzymatically Embedded on Cork Filter Material for Water Disinfection

Microbial contamination remains a major challenge in drinking water supplies in developing regions, despite the continuous advances being made in water purification processes. The spread and transmission of pathogens due to consuming unsafe water culminate in waterborne diseases and increased number of deaths worldwide. Recently, the application of nanotechnology for water purification, and in particular the use of antibacterial nanoparticles (NPs) to control microbial contaminations, has received considerable interest. In this study, antibacterial chitosan-silver nanoparticles (CS/AgNPs) were enzymatically grafted on cork matrixes to design a water purification point-of-use device. The antibacterial efficiency of the constructed filtering system was further evaluated against water severely contaminated with Escherichia coli (similar to 10(7) CFU/mL). The system was tested in two operating filtration modes with varied water residence times. The antibacterial nanocomposite decreased the water bacterial contamination by 4 and 5 log CFU/mL when performing a series of continuous short disinfection cycles of 15 min residence time (experiment I). Nevertheless, complete bacteria removal was achieved only after increasing the water residence time in the filters up to 8 h (experiment II). Durability of the system was demonstrated via performing five disinfection cycles after which the hybrid CS/AgNPs remained on the cork surface. Importantly, the antibacterial nanocomposite prevented bacteria attachment and proliferation during all cycles of the disinfection process.