Competitive arsenate and phosphate adsorption on α-FeOOH, LaOOH, and nano-TiO2: Two-dimensional correlation spectroscopy study

Abstract Competitive adsorption of arsenate (AsO43−) and phosphate (PO43−) on α-FeOOH, LaOOH, and nano-TiO2 was studied using batch adsorption experiments and in-situ flow cell ATR-FTIR coupled with two-dimensional correlation spectroscopy (2D-COS) for the first time. With a higher temporal resolution, our results found a highly dynamic adsorption sequence for AsO43− and PO43−. When AsO43− and PO43− were simultaneously exposed to the adsorbents at the same concentrations, AsO43− was preferentially adsorbed by α-FeOOH and TiO2, but PO43− adsorption was dominant on LaOOH. The results implied that the PO43− adsorbed on LaOOH had to be remobilized to allow for AsO43− adsorption, but that PO43− …