Mechnisms for adsorbent optimization of geogenic arsenic groundwater remediation

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The main purpose of this collaborative proposal is to optimize groundwater arsenic treatment technology. The project is aimed at identifying and optimizing new fixed bed adsorber (FBA) material of Chinese production for the national market capable of effective remediation. The basis of potential success with the research is a collaborative activity according to the complementary advanced scientific methodology and expertise of the PIs. The fundamental research plan involves molecular speciation scale approaches like EXAFS measuring campaigns and both surface complexation modeling (SCM) and molecular dynamics (DFT) modeling. A comparison between established, but expensive, FBA material (German GFH) with a new cheaper adsorbent material proposed by the Chinese partner (nano-TiO2) to predict contaminant breakthrough curves is important for waterworks to determine and plan their future operating costs. Unfortunately, prediction of FBA life cycle time is not yet a trivial task given the quite complex antagonistic and synergistic effects of many co-factors and competitive co-existing ions in groundwater. Together with the rapid small scale column test approach, the results will be used for the first time to derive at parameters for the FBA life cycle prediction based on the homogeneous surface diffusion model code FAST for the nano-TiO2 adsorbate/adsorbent system. For this to achieve in a successful manner, both a spectroscopic surface speciation and the SCM/FAST modeling approaches, i.e. both the complementary expertise of the project partners have to be merged together. Publication of the results of FBA adsorbent characterization in such high-ranking journals as Environmental Science & Technology is nowadays only possible if to compile both advanced micro-spectroscopic characterization of the solid-water interaction of the co-contaminants (the China partner¿s task) with an advanced surface complexation modelling on a molecular speciation scale (the German partner¿s task). These publications provide a major prerequisite to adopt the alternative adsorptive media on the NSF-International list of recommended FBA fillings to build trust for their wider acceptance and use in waterworks for drinking water production.