Unknown

Dataset Information

0

Arsenic mobilization from iron oxides in the presence of oxalic acid under hydrodynamic conditions.


ABSTRACT: Oxalic acid potentially enhances pump-and-treat for groundwater As remediation by accelerating mobilization. This study examines how oxalic acid mobilizes As from Fe(III)-oxide coated sand under hydrodynamic conditions. Four columns were packed with metal-substituted ferrihydrite or goethite to 1% Fe, presorbed to 50% As surface coverage, and reacted with pH?=?2.2 artificial groundwater amended with 10?mM oxalic acid at 1?m day-1. Arsenic elution was affected by both As and Fe speciation. Although the As(V) columns experienced faster substrate dissolution, As(V) elution was delayed by re-adsorption, whereas As(III) elution was rapid due to pH decrease that prevented re-adsorption. Cr-ferrihydrite and Ni-goethite dissolved both effectively initially but then diverged. The Cr-ferrihydrite columns experienced continuous stoichiometric Fe and Cr release, and As release could be sustained. The Ni-goethite columns initially experienced nonstoichiometric Fe and Ni release, and As release was extensive. Such release, however, was not sustained. We hypothesized that Ni-goethite contained sites with distinct reactivity, and oxalic acid targeted readily-dissolved, sorption-dense sites. Our data indicate that oxalic acid-enhanced pump-and-treat methods would be easier to apply to aquifers dominated by As(III), requiring less amendment to be injected; such oxalic acid-enhanced methods remove reactive sediment Fe and As, potentially preventing future groundwater contamination.

SUBMITTER: Sun J 

PROVIDER: S-EPMC6431252 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

Similar Datasets

| S-EPMC4826786 | biostudies-literature
| S-EPMC3697499 | biostudies-literature
| S-EPMC4837041 | biostudies-literature
| S-EPMC8381759 | biostudies-literature
| S-EPMC2246110 | biostudies-literature
| S-EPMC7556726 | biostudies-literature
| S-EPMC6406033 | biostudies-literature
| S-EPMC4294815 | biostudies-literature
| S-EPMC1087527 | biostudies-literature
| S-EPMC518762 | biostudies-literature