Synthesis and Antimicrobial Activity of Silver Citrate Complexes

Formation of silver citrate/citric acid complexed solutions was investigated. Although, silver citrate is minimally soluble in water, it can successfully be dissolved in citric acid solutions. The maximum concentration of Ag(I) in solution is estimated at 23 to 25 g/L if the concentration of citric acid is at least 4 mol/L or higher. The dissolution of silver citrate in citric acid solutions was attributed to the formation of silver citrate complexes of a general formula [Ag(3)(C(6)H(5)O(7))(n+1)](3n-). The silver citrate/citric acid solutions, containing more than about 13 g/L Ag(+) ion, have exhibited a decrease in Ag(I) concentration in solution over time, due to crystallization. The crystallization product was attributed to the formation of [Ag(3)C(6)H(5)O(7)](x).nH(2)O. Importantly, the diluted silver citrate/citric acid complexed solutions have exhibited very strong bacteriostatic and bactericidal activities.