Solid-phase extraction for simultaneous separation and preconcentration of Fe(III) and Zn(II) traces using three chelatants and Ramelak bark-derived activated carbon as a new bio-sorbent

Simultaneous Functionalization and Reduction of Magnetic Graphene Oxide by L-Histidine and its Application for Magnetic Separation/Preconcentration of Antioxidant Trace Elements

In the present study, for the first time, the magnetic graphene oxide was simultaneously functionalized and reduced with the aim of imidazole-based L-histidine amino acid (rGO/Fe₃O₄-histidine). The prepared nanocomposite was characterized by field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and vibrating sample magnetometer. The synthesized rGO/Fe₃O₄-histidine nanosheets were implied for solid phase extraction of ultra-trace amounts of Zn²⁺, Cu²⁺_, and Mn²⁺ from biological samples prior to ICP-OES determination. The calibration curves were linear in the concentration ranges of 0.4-182.0, 0.4-215.0, and 0.2-168.5 μg L^-1 for Zn²⁺, Cu²⁺, and Mn²⁺, respectively. The limits of detection were 0.12, 0.10, and 0.04 μg L^-1 for Zn²⁺, Cu²⁺, and Mn²⁺, respectively. The relative standard deviations (RSDs) at 50.0 μg L^-1 for single-sorbent repeatability and sorbent-to-sorbent reproducibility were less than 6.7 and 9.2% (n = 5), respectively. The accuracy of the method was confirmed by the analysis of a serum quality control material (QCM, Seronorm™ Human Serum REF NO 203105) and hair certified reference material (CRM, Human Hair IAEA-086).

Cr(OH)3-NPs-CNC hybrid nanocomposite: a sorbent for adsorptive removal of methylene blue and malachite green from solutions

In this article, Cr(OH)₃ nanoparticle-modified cellulose nanocrystal (CNC) as a novel hybrid nanocomposite (Cr(OH)₃-NPs-CNC) was prepared by a simple procedure and used as a sorbent for adsorptive removal of methylene blue (MB) and malachite green (MG) from aqueous solution. Different kinetic models were tested, and the pseudo-second-order kinetic model was found more suitable for the MB and MG adsorption processes. The BET and Langmuir models were more suitable for the adsorption processes of MB and MG. Thermodynamic studies suggested that the adsorption of MB and MG onto Cr(OH)₃-NPs-CNC nanocomposite was a spontaneous and endothermic process. The maximum adsorption capacities for MB and MG were reached 106 and 104 mg/g, respectively, which were almost two times higher than unmodified CNC. The chemical stability and leaching tests of the Cr(OH)₃-NPs-CNC hybrid nanocomposite showed that only small amounts of chromium were leached into the solution.