(376f) Chitosan Hydrogels for Adsorbing Silver Ions in Aqueous Solution and Its Bactericidal Properties

Chitosan is a low-cost, versatile biopolymer for many applications. Chitosan hydrogel was fabricated via the phase inversion technology and was tested in water treatment applications: 1) Adsorbing silver metal ions in aqueous solution (To concentrate and recover the precious metal), and 2) Inhibiting bacteria growth on the silver-chelated chitosan beads. It was found that the native chitosan beads present a reasonably good silver sorption properties (~120 mg/L at the concentration of 50 ppm) towards silver ions at a pH of 6. A reduced pH ~ 5.0 was found not significantly beneficial to the ion sorption. The test with a bacteria (E-Coli) demonstrated that the bactericidal capability of native chitosan is significantly enhanced (up to 99% killing within an hour) when adsorbing with silver particle (from AgNO3 solution of 300ppm. The silver was strongly attached to the beads after repeated washing). Preliminary results indicated that native chitosan can be directly used for reclaim the silver ions from aqueous solution, with the additional benefit of enhanced bactericidal performance of the chitosan-Ag complex. Such a combination forms a part of a promising technology for the low-cost pre-treatment of water for water plants.