Development of LC-HGAFS method for direct measurement of monothioarsenate and application for its adsorption characteristics

Sorption of Monothioarsenate to the Natural Sediments and Its Competition with Arsenite and Arsenate

“…For the high concentration of 0.667 mmol/L MTAs V (which is equivalent to 50.00 mg As/L) ( Figure 2 c), Q t increases rapidly to 181.00 μg/g within 50 min, then increases slowly to 219.50 μg/g before 8 h, and finally keeps stable after that. In the initial stage, Q t increases rapidly because there are enough reactive sites on the surface of the sediment to adsorb a large number of MTAs V [ 33 ]. This stage becomes longer with the increasing concentration of MTAs V , which may be because it needs more time for the higher concentration of MTAs V to be adsorbed by the solid phase.…”

“…This stage becomes longer with the increasing concentration of MTAs V , which may be because it needs more time for the higher concentration of MTAs V to be adsorbed by the solid phase. After that, MTAs V adsorption becomes slower, and the adsorption rate decreases, which may be because internal diffusion becomes the dominant process in this stage, and the internal diffusion resistance increases with more MTAs V adsorbed by the solid phase [ 33 ]. From 8 h to 12 h, all the adsorption of different concentrations of MTAs V reaches equilibrium when the internal diffusion resistance is very high and the mass concentration driving force is too low to force MTAs V to be adsorbed by the solid phase.…”

“…This crystal is dissolved into 10 mL fresh oxygen-free water and then recrystallized by adding 5 mL anhydrous ethanol to obtain the standard MTAs V . The purity is determined to be 98% using the Liquid Chromatography Hydride-Generation Atomic Fluorescence (LC-HG-AFS) method [ 33 ]. The major component is determined to be Na 3 AsSO 3 ·7H 2 O and impurity is arsenite using the X-ray powder diffraction (XRD) (X’Pert3, Netherlands, Cu target, λ = 1.54056 Å).…”

“…The concentrations of As species including MTAs V , arsenite, and arsenate are determined using Liquid Chromatography Hydride-Generation Atomic Fluorescence (LC-HG-AFS) according to our previously reported method [ 33 ]. The pH value is measured using a Hach-HQ30d analyzer.…”