title: Composition and particle size of superparamagnetic corrosion products in tap water.
abstract: Chemical analyses, magnetization, Mössbauer spectrum, and x-ray diffraction measurements were made on solids removed from tap water by means of membrane filters. The taps from which this water was obtained had previously been unused for prolonged periods of time. When these taps were reactivated and water was first drawn, it was observed that the quantity of coarse solids in the water gradually decreased with flow, while at the same time the quantity of fine solids gradually increased. The magnetization, Mössbauer spectra, and x-ray diffraction patterns of the solids showed the presence of a significant number of superparamagnetic particles of magnetite. In the temperature range of our measurements (77 K<T<300 K), paramagnetic iron-based species, particularly lepidocrocite, were also present in the solids. Contaminants such as Pb, Cu, and As were observed to be present in significant amounts, and it is shown that these are adsorbed to the magnetic nanoparticles. It was observed that almost all of the solid particles could be removed by means of 5-microm filters. This removal process can be explained by means of a model which assumes that initial deposition of coarse aggregates of corrosion products on the filters forms a coating, rich in extremely fine iron oxides. The coating has a high capacity for sorption of very small individual particles.
authors.affiliation: Department of Chemistry, The Catholic University of America, Washington, DC 20064, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Barkatt
authors.forename: April L
authors.initials: AL
authors.lastname: Pulvirenti
authors.forename: M A
authors.initials: MA
authors.lastname: Adel-Hadadi
authors.forename: Carol
authors.initials: C
authors.lastname: Viragh
authors.forename: Frank E
authors.initials: FE
authors.lastname: Senftle
authors.forename: Arthur N
authors.initials: AN
authors.lastname: Thorpe
authors.forename: Julius R
authors.initials: JR
authors.lastname: Grant
mesh_terms: D001151:Arsenic / Q000032:analysis; D003300:Copper / Q000032:analysis; D003343:Corrosion; D052203:Ferrosoferric Oxide; D005374:Filtration / Q000379:methods; D007854:Lead / Q000032:analysis; D008280:Magnetics; D053768:Metal Nanoparticles / Q000032:analysis; D008670:Metals / Q000032:analysis*; D010316:Particle Size; D015204:Spectroscopy, Mossbauer; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*; D014961:X-Ray Diffraction
chemical_list: D008670:Metals; D014874:Water Pollutants, Chemical; D014867:Water; D007854:Lead; D003300:Copper; D001151:Arsenic; D052203:Ferrosoferric Oxide