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.