title: Comparison between silver- and copper-modified zeolite-rich tuffs as microbicide agents for Escherichia coli and Candida albicans.
abstract: Zeolite-rich tuff from the State of Chihuahua was modified with silver or copper ions (ZChAg and ZChCu) to evaluate its microbicidal effect against Escherichia coli (E. coli) and Candida albicans (C. albicans) suspended in an aqueous solution in order to compare the microbial disinfection kinetics between bacteria and yeast. The zeolite-rich tuff was treated with AgNO3or CuCl2solutions. The materials obtained were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and the textural properties were also determined by BET-analyses. The concentration of Ag and Cu was verified in the zeolitic materials using neutron activation analysis. The experimental data were adjusted to both Chick and Chik-Watson models to describe the kinetic behavior of the process. It was found that when the mass of ZChAg increased, the survival microorganisms notably decreased. The E. coli and C. albicans showed higher resistance in contact with ZChCu even when the mass of such material was 10-20 times higher than the mass of ZChAg. Chick and Chik-Watson constants showed that the kinetics of the disinfection process depended on the desorption of the exchange ion that modified the structure of the zeolitic material, its concentration in aqueous medium, its oligodynamic properties, and each microorganism's characteristics (Gram-negative bacteria and yeast). The kinetic desorption of Ag and Cu from the corresponding modified-zeolite-rich tuffs was also considered in this work. In this case, the Higuchi and Korsmeyer-Peppas models were applied.
authors.affiliation: Laboratorio de Investigación en Ingeniería Ambiental, Instituto Tecnológico de Toluca, Av. Tecnológico s/n, Ex. Rancho la Virgen, Metepec, México, C.P. 52140, Mexico; Departamento de Química y, Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca s/n, La Marquesa Ocoyoacac, México C.P. 52750, Mexico.
authors.forename: L G
authors.initials: LG
authors.lastname: Rossainz-Castro
authors.affiliation: Laboratorio de Investigación en Ingeniería Ambiental, Instituto Tecnológico de Toluca, Av. Tecnológico s/n, Ex. Rancho la Virgen, Metepec, México, C.P. 52140, Mexico.
authors.forename: I
authors.initials: I
authors.lastname: De-La-Rosa-Gómez
authors.affiliation: Departamento de Química y, Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca s/n, La Marquesa Ocoyoacac, México C.P. 52750, Mexico. Electronic address: teresa.olguin@inin.gob.mx.
authors.forename: M T
authors.initials: MT
authors.lastname: Olguín
authors.affiliation: Departamento de Biología, Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca s/n, La Marquesa Ocoyoacac, México C.P. 52750, Mexico.
authors.forename: D
authors.initials: D
authors.lastname: Alcántara-Díaz
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects*; D003300:Copper / Q000737:chemistry*; D004203:Disinfection / Q000379:methods; D004926:Escherichia coli / Q000187:drug effects*; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D012834:Silver / Q000737:chemistry*; D012835:Silver Nitrate / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D014871:Water Microbiology; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; C083175:clinoptilolite; D017641:Zeolites; D012834:Silver; D003300:Copper; D012835:Silver Nitrate; C029892:cupric chloride
keywords: Candida albicans; Copper: natural-zeolite; Disinfection; Escherichia coli; Silver