Efficient Mercury Removal at Ultralow Metal Concentrations by Cysteine Functionalized Carbon-Coated Magnetite

Abstract

This work reports the preparation and utility of cysteine-functionalized carbon-coated Fe3O4 materials (Cys-C@Fe3O4) as efficient sorbents for remediation of Hg(II)-contaminated water. Efficient removal (90%) of Hg(II) from 1000 ppb aqueous solutions is possible, at very low Cys-C@Fe3O4 sorbent loadings (0.01 g sorbent per liter of Hg(II) solution). At low metal concentrations (5–100 ppb Hg(II)), where adsorption is typically slow, Hg(II) removal efficiencies of 94–99.4% were achievable, resulting in final Hg(II) levels of <1.0 ppb. From adsorption isotherms, the Hg(II) adsorption capacity for Cys-C@Fe3O4 is 94.33 mg g−1, around three times that of carbon-coated Fe3O4 material. The highest partition coefficient (PC) of 2312.5 mgg−1µM−1 was achieved at the initial Hg (II) concentration of 100 ppb, while significantly high PC values of 300 mgg−1µM−1 and above were also obtained in the ultralow concentration range (≤20 ppb). Cys-C@Fe3O4 exhibits excellent selectivity for Hg(II) when tested in the presence of Pb(II), Ni(II), and Cu(II) ions, is easily separable from aqueous media by application of an external magnet, and can be regenerated for three subsequent uses without compromising Hg(II) uptake. Derived from commercially available raw materials, it is highly possible to achieve large-scale production of the functional sorbent for practical applications.

Biochar Derived from Pineapple Leaf Non-Fibrous Materials and Its Adsorption Capability for Pesticides

“…Moreover, results of kinetic studies also suggest that adsorption kinetics were best described by the PSO kinetic model, with a high correlation coefficient ( R 2 > 0.99) and the lowest χ 2 , for single adsorption of pesticides on the NFMBC via prevalent chemisorption processes for all pesticides studied. 61 These results are consistent with previous studies on adsorption of pesticides by biochar sorbents, in which the pseudo-second-order model has a better fit to the experimental data than others. 52 , 57 , 62 Additionally, the higher values of α relative to β in the adsorption process from the Elovich model indicate that the initial rate of adsorption is higher than the desorption rate, 63 implying that NFMBC is an effective sorbent for aqueous pesticide removal.…”

Green synthesis of a magnetite/graphitic carbon nitride 2D nanocomposite for efficient Hg2+ remediation

“…This observation agrees with data from other studies investigating the interaction of Hg 2+ with Fe 3 O 4 that reported no or negligible binding. 36,77–81…”

“…This observation agrees with data from other studies investigating the interaction of Hg 2+ with Fe 3 O 4 that reported no or negligible binding. 36,[77][78][79][80][81] 3.6. Binding coordination studies with 13 C and 15 N NMR A detailed study of the binding constraints of Hg 2+ with the material was analyzed with 13 C and 15 N. The results revealed that Hg 2+ binds to the heptazine structure of g-CN and not the magnetite particles (Fig.…”

Functional Hyperbranched Polythioamides Synthesized from Catalyst‐free Multicomponent Polymerization of Elemental Sulfur†

“…With a constant ratio of m P / m Hg2+ and the initial concentration [Hg 2+ ] 0 range of 5 to 100 mg/L, the removal efficiencies of hb ‐P 1 were generally measured to be above 99.92%, and the remaining [Hg 2+ ] could be decreased to as low as 0.10 μg/L, which was below the limit of drinking water standards of WHO (6 μg/L), U.S. (2 μg/L), China and EU (1 μg/L) (Figure 5 and Table S1). [ 63‐64 ] Similarly, hb ‐P 5 and hb ‐P 6 also showed high removal efficiency, and slightly decreased efficiency with low [Hg 2+ ] 0 compared with hb ‐P 1 , maybe due to the relatively flexible structures compared with hb ‐P 1 .…”