Hybrid chitosan-silver nanoparticles enzymatically-embedded on cork filter material for water disinfection

Abstract

Microbial contamination remains a major challenge in supply of drinking water 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, received considerable interest. In this study, antibacterial chitosan-silver NPs (CS/AgNPs) were enzymatically grafted on cork matrices to design a water purification point-of-use device. The antibacterial efficiency of the constructed filtering system was further evaluated against severely contaminated with Escherichia coli water (~107 CFU/mL). The system was tested in two operating filtration modes with varied water residence time. 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, a complete bacteria removal was achieved only after increasing the water residence time in the filters up to 8 hours (Experiment II). Durability of the system was demonstrated via performing five disinfection cycles after which the hybrid CS/AgNPs still remained on the cork surface. Importantly, the antibacterial nanocomposite prevented the bacteria attachment and proliferation during all cycles of the disinfection process.