title: Zinc interaction with struvite during and after mineral formation.
abstract: Sorption of Zn with struvite was assessed both during and after mineral formation at pH 9.0 for 1-100 μM (0.065-6.54 mg L(-1)) aqueous Zn. The Zn loadings of recovered solids were lower when Zn was present during struvite precipitation compared to when Zn was added to struvite-bearing solutions. X-ray absorption fine structure spectroscopy confirmed that Zn added to struvite-bearing solutions at concentrations≤5 μM sorbed as both octahedral and tetrahedral complexes (Zn-O 1.98-2.03 Å), with evidence for bidentate configuration (Zn-P 3.18 Å). Bidentate complexes were incorporated into the near-surface structure, contributing to distortion of the struvite ν3 PO4(3-) band in the Fourier transform infrared spectra. At Zn concentrations>5 μM, tetrahedral monodentate adsorbates (Zn-O 1.98 Å) dominated, transitioning to a Zn-phosphate precipitate at 100 μM. When Zn is present during struvite precipitation, octahedral monodentate sorbates detected at 1 μM (Zn-O 2.08-2.10 Å; Zn-P 3.60-3.64 Å) polymerized at 5-50 μM, ultimately forming a Zn-hydroxide precipitate at 100 μM. The lowest initial Zn concentrations (0.065 mg L(-1)) and resultant solid loadings from precipitation experiments (13 mg kg(-1)) are consistent with those reported for struvite recovered from wastewater, suggesting that similar Zn sorption processes may occur in more complex systems.
authors.affiliation: School of Earth and Environmental Sciences, Queens College, City University of New York , Queens, New York 11367, United States.
authors.forename: Ashaki A
authors.initials: AA
authors.lastname: Rouff
authors.forename: Karen M
authors.initials: KM
authors.lastname: Juarez
mesh_terms: D017616:Magnesium Compounds / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D000069877:Struvite; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy; D015032:Zinc / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D008903:Minerals; D010710:Phosphates; D014874:Water Pollutants, Chemical; D000069877:Struvite; D015032:Zinc