Mercapto-modified magnesium silicate micro-particles for efficient extraction and preconcentration of mercury ions from estuary waters

Abstract

Herein, we present a new and robust adsorbent for the extraction and preconcentration of Hg ions from estuary samples based on the modification of magnesium silicate (MgSi) with 2-mercaptobenzoxazole (MBO). The properties, morphology, and composition of the adsorbent before and after modification were characterized via FT-IR, SEM, and XRD analyses. The concentrated ions were measured using cold vapor atomic absorption spectrometry (CVAAS). The effects of critical parameters such as pH value, eluent conditions, flow rate and volume of the sample were studied and optimized. The calibration curve was linear within the range of 0.3–6.0 ng mL⁻¹ (r = 0.9979). The effect of the major coexisting ions constituting 98% of solutes in natural seawaters was examined using artificial seawater samples. The limit of detection (LOD) of the method was 0.09 ng mL⁻¹ (n = 8) under the optimum conditions. The relative standard deviations (RSD, n = 6) at 0.5 and 4.0 ng mL⁻¹ were 4.3% and 3.9%, respectively. The maximum adsorption capacity of the proposed adsorbent was 58 mg g⁻¹. The developed method was successfully applied to determine ultra-trace amounts of mercury ions in estuary waters with recoveries greater than 97%.