The antimicrobial efficiency of silver activated sorbents

• Published in: Applied surface science 2015-12, Vol.357, p.819-831
• Main Authors: olic, Maja B, Rajakovic-Ognjanovic, Vladana N, Strbac, Svetlana B, Rakocevic, Zlatko Lj, Veljovic, ore N, Dimitrijevic, Suzana I, Rajakovic, Ljubinka V
• Format: Article
• Language: English
• Subjects: Activated; Activated sorbents; Antiinfectives and antibacterials; Antimicrobial activity; Bacteria; C. albicans; E. coli; S. aureus; Silver; Sorbents; Sorption; Staphylococcus aureus; Surface chemistry; Yeast
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.09.032

•Different sorbents were activated by Ag+-ions and modified sorbents were determined by sorption capacities, in range of values: 42.06–3.28mg/g.•Granulated activated carbon (GAC), natural zeolit (Z) and titanium dioxide (T) activated by Ag+-ions were tested against E. coli, S. aureus and C. albicans.•The most successful bacteria removal was obtained using Ag/Z against S. aureus and E. coli, while the yeast cell reduction reached unsatisfactory effect for all three activated sorbents.•XRD, XPS and FE-SEM analysis showed that the chemical state of the silver activating agent affects the antimicrobial activity, as well as the structural properties of the material.•An overall microbial cell reduction, which is performed by separated antimicrobial tests on the Ag+-activated surface and Ag+-ions in aquatic solutions, is a consequence of both mechanisms. This study is focused on the surface modifications of the materials that are used for antimicrobial water treatment. Sorbents of different origin were activated by Ag+-ions. The selection of the most appropriate materials and the most effective activation agents was done according to the results of the sorption and desorption kinetic studies. Sorption capacities of selected sorbents: granulated activated carbon (GAC), zeolite (Z), and titanium dioxide (T), activated by Ag+-ions were following: 42.06, 13.51 and 17.53mg/g, respectively. The antimicrobial activity of Ag/Z, Ag/GAC and Ag/T sorbents were tested against Gram-negative bacteria E. coli, Gram-positive bacteria S. aureus and yeast C. albicans. After 15min of exposure period, the highest cell removal was obtained using Ag/Z against S. aureus and E. coli, 98.8 and 93.5%, respectively. Yeast cell inactivation was unsatisfactory for all three activated sorbents. The antimicrobial pathway of the activated sorbents has been examined by two separate tests – Ag+-ions desorbed from the activated surface to the aqueous phase and microbial cell removal caused by the Ag+-ions from the solid phase (activated surface sites). The results indicated that disinfection process significantly depended on the microbial-activated sites interactions on the modified surface. The chemical state of the activating agent had crucial impact to the inhibition rate. The characterization of the native and modified sorbents was performed by X-ray diffraction technique, X-ray photoelectron spectroscopy and scanning electron microscope. The concentration of adsorbed and released ions was det