Mechnisms for adsorbent optimization of geogenic arsenic groundwater remediation
Final Report Abstract
Rapid small scale column tests (RSSCT) have been proved as an efficient method to predict the performance of full-scale FBA systems. In a typical RSSCT experiment, a small column packed with an adsorbent with a small particle size is used to simulate the performance of pilot or full scale KBA systems. Because of the similarity of mass transfer processes and hydrodynamic characteristics between the small and large columns, the two breakthrough curves are expected to be analogous. The RSSCT columns were designed to predict full-scale column tests using a proportional diffusion RSSCT scaling approach, and will be applied on the new nano-TiO2 FBA material suggested by the Chinese partner. The effects of initial As concentration, pH, and EBCT on breakthrough curves will be predicted by a homogeneous surface diffusion model (HSDM), with adsorption isotherms predicted by a surface complexation model (SCM) approach. To achieve this plan, the batch equilibrium adsorption experiments with reduced oxyanion species of As(V) and Sb(V) in nano-TiO2 adsorbent particle suspensions, with and without addition of competing ions will also be further performed in the future. The research of Chinese groups has studied the arsenic, phosphate, and antimony removal mechanisms at the molecular scale using multiple complementary spectroscopic techniques on goethite, GFH, and nano-TiO2. The results has answered three scientific and technical questions: first, a new adsorbent media is produced and optimized for groundwater As removal as effective as the already established but high-cost FBA materials of the NSF-International list. Second, the molecular level mechanism of As and Sb adsorption in the presence of competing ions is clearly understood. Our publications will provide a major prerequisite to adopt the alternative adsorptive media on the NSF-lnternational list of recommended FBA fillings to build trust for their wider acceptance and use in waterworks for drinking water production.
Publications
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Low-Molecular-Weight Organic Acid Complexation Affects Antiniony(III) Adsorption by Granular Ferric Flydroxidc. Environ. Sci. Technol. 2019, 539, 5221-5229
Xiaochen Li, Tatiana Reich, Michael Kersten, and Chuanyong Jing
