title: Quantifying the influence of humic acid adsorption on colloidal microsphere deposition onto iron-oxide-coated sand.
abstract: This article describes an approach for quantifying microsphere deposition onto iron-oxide-coated sand under the influence of adsorbed Suwannee River Humic Acid (SRHA). The experimental technique involved a triple pulse injection of model latex microspheres (microspheres) in pulses of (1) microspheres, followed by (2) SRHA, and then (3) microspheres, into a column filled with iron-coated quartz sand as a water-saturated porous medium. A random sequential adsorption model (RSA) simulated the gradual rise in the first (microsphere) breakthrough curve (BTC). Using the same model calibration parameters a dramatic increase in concentration at the start of the second particle BTC, generated after SRHA injection, could be simulated by matching microsphere concentrations to extrapolated RSA output. RSA results and microsphere/SRHA recoveries showed that 1 μg of SRHA could block 5.90 ± 0.14 × 10(9) microsphere deposition sites. This figure was consistent between experiments injecting different SRHA masses, despite contrasting microsphere deposition/release regimes generating the second microsphere BTC.
authors.affiliation: School of Planning, Architecture & Civil Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG Northern Ireland, UK.
authors.forename: X
authors.initials: X
authors.lastname: Yang
authors.forename: R
authors.initials: R
authors.lastname: Flynn
authors.forename: F
authors.initials: F
authors.lastname: von der Kammer
authors.forename: T
authors.initials: T
authors.lastname: Hofmann
mesh_terms: D000327:Adsorption; D003102:Colloids; D005290:Ferric Compounds / Q000032:analysis* / Q000737:chemistry; D006812:Humic Substances; D008863:Microspheres; D008956:Models, Chemical; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D003102:Colloids; D005290:Ferric Compounds; D006812:Humic Substances; C000499:ferric oxide; D012822:Silicon Dioxide