Water Disinfection: Unleashing the Power of Bicarbonate Ions in Chitosan-Silver Nanocomposite for Greener and More Efficient Silver Utilization

The paper reveals the synergetic effect of bicarbonate alkalinity in enhancing the disinfection of silver-based nanocomposite film. This study originates from an in-depth investigation into how critical ions and natural organic matter in freshwater influence disinfection. The results show that the higher concentrations of chlorides (>400 mg/L) and natural organic matter (>1.5 mg/L) adversely affected the composite disinfection ability as expected. Intriguingly, the nanocomposite shows enhanced disinfection in the presence of bicarbonate alkalinity and hardness. A detailed investigation shows that bicarbonate plays a vital role in enhancing disinfection. The studies reveal a synergy between bicarbonate and Ag⁺ released from a nanocomposite film. The bicarbonates disturb the transmembrane potential gradient (ΔpH), weaken the proton motive force of (Escherichia coli), and enable an increased penetration of Ag⁺ into the cell, resulting in enhanced production of reactive oxygen species and cell damage. This synergetic effect could help reduce the costs and concentration of Ag⁺ required for disinfection and their associated risks. The cytotoxic studies against human cell lines (HaCaT) confirm that AgNC-treated water is safe for consumption. The synergetic disinfection effect of silver with bicarbonate in water helps in developing more resource-efficient and reliable silver-based disinfection systems.