Isolation of Pd(II) and Au(III) from highly chloride containing aqueous samples by chelating resin and identification their interaction mechanism by density functional theory

In the present study, a new chelating sorbent was created by covalently attaching N-((6-(2-thienyl)pyridin-2-yl)methyl)propan-1-amine to the surface of silica (THIOPAM-SG). The sorbent structure was confirmed by C, H, N, S elemental analysis and FT-IR spectroscopy, and subsequently used for the column solid-phase extraction (SPE) of Pd(II) and Au(III) from environmental waters for their accurate and sensitive quantification using flame atomic absorption spectrometry. Key parameters influencing the extraction of Pd(II) and Au(III) was studied. The material demonstrated excellent adsorptive performance towards Pd(II) and Au(III) ions under acidic conditions (0.1 M HCl) at a high sample flow rate of 7.5 mL/min. The retained analytes on the SPE column were easily stripped using 3.0% thiourea in 1.0 M HCl (10 mL) at sample flow rate of 2.5 mL/min. The THIOPAM demonstrated the ability to collect collect trace level of Pd(II) and Au(III) ions from large volume of aqueous samples providing a enrichment factor of 50. The detection limits (3σ) of the developed method for Pd(II) and Au(III) ions were computed to be 1.04 µg/L and 0.38 µg/L, respectively. By the determination of Pd(II) and Au(III) ions at 0.4 mg/L, the quantitative recoveries (≥95%) and low RSD values (≤2.0%) were obtained. The uptake capacity of THIOPAM for Au(III) and Pd(II) ions was figured out to be 52.1 mg/g and 51.2 mg/g, respectively. The proposed novel SPE method was effectively used to quantify Pd(II) and Au(III) trace-level concentrations in various environmental water samples, such as tap, sea, river, and deionized waters. Furthermore, the DFT/HSEh1PBE/LanL2DZ method was applied to determine the coordination environment and interactions between Pd(II) and Au(III) with THIOPAM, as well as to investigate the frontier molecular orbital surfaces and energies and chemical reactivity parameters.