Sulfide-modified magnetic titanium dioxide microparticles for the adsorption and solid-phase extraction of toxic metals in aqueous samples

Abstract

In this work, sulfide-modified magnetic titanium dioxide microparticles (magnetic TiO2-µPs@S) were synthesized and studied for adsorption-based removal and extraction of Cd(II), Co(II), Cu(II), Mn(II), and Ni(II) ions in aqueous solutions before FAAS analysis. The magnetic TiO2-µPs@S was well characterized by UV-vis, FTIR, XRD, SEM, and EDS techniques, and the material was well functionalized, pure, and had a slightly rod-like morphology. Under optimized conditions, initial concentration of 10 mg/L, sample solution pH of 7, adsorbent dose of 0.5 g/L, agitation speed of 200 rpm, and contact time of 45 min, the magnetic TiO2-µPs@S exhibited an adsorption capacity of 24.0, 34.9, 37.6, 38.5, and 27.9 mg/g for Cd(II), Co(II), Cu(II), Mn(II), and Ni(II), respectively. Then after, the desorption experiment was conducted using 5 mL of 0.2 M HNO3 as an eluting solvent. The method showed excellent linearity (R 2 ≥ 0.998) in 0.05–10 mg/L concentration range. The limits of detection and quantification of the developed method were found to be in the range of 0.14–0.81 and 0.47–2.73 µg/L, consecutively, indicating high sensitivity of the proposed method, and <3% RSD was obtained. Furthermore, its practical applicability was assessed on tap water, lake water, and wastewater samples, and satisfactory percent recovery values, 84.5–114%, were acquired. These results indicate the potential applicability of the developed method. In general, the magnetic TiO2-µPs@S can be used as an effective adsorbent for removing heavy metals, and the adsorbent-based solid-phase extraction can be considered a promising technique for extracting and enriching heavy metals from aqueous solutions.