Template-free Synthesis of Large-Pore-Size Porous Magnesium Silicate Hierarchical Nanostructures for High-Efficiency Removal of Heavy Metal Ions

Abstract

It remains a big challenge to develop high-efficiency and low-cost adsorption materials to remove toxic heavy metal ions in water. Here, we developed a template-free synthesis method to fabricate high surface area and large pore size magnesium silicate hierarchical nanostructures in a mixed solvent of ethanol and water and carefully investigated the corresponding adsorption behavior for Pb2+, Zn2+, and Cu2+ in aqueous solution. The results reveal that the ethanol volume fraction in the solvent plays an important role to optimize the pore structure, which directly determines the adsorption capacity and the adsorption rate for heavy metal ions. When the ethanol volume fraction is beyond 50%, the obtained magnesium silicate presents a flowerlike structure with a hierarchical pore distribution: 0.5–2, 2–30, and 30–200 nm. When the ethanol volume faction is 90%, for example, the sample exhibits a maximum adsorption capacity of 436.68, 78.86, and 52.30 mg/g for Pb2+, Zn2+, and Cu2+ ions, which has a BET surface area of 650.50 m2/g and an average pore diameter of 6.89 nm, respectively. Also, the sample presents excellent repeated adsorption performance after three elutions. The obtained materials show widely promising and practical applications in water treatment in a wide pH range from 2.8 to 5.8.

Research on the Adsorption Behavior of Heavy Metal Ions by Porous Material Prepared with Silicate Tailings

“…Similarly, silicate tailings, as an eco-friendly material, were feasible for the removal of various harmful cations due to their wide specific surface area and high adsorption capacity. In recent years, it has been widely studied that natural silicates and modified silicates could be used as potential adsorbents to remove various heavy metal ions from aqueous solvents [17][18][19][20][21][22]. However, the silicate adsorbents that have been reported were powdered and granulated; these forms of adsorbents were difficult to separate from the solution, and secondary pollution arose easily [23][24][25].…”

A Safe and Efficient Strategy for the Rapid Elimination of Blood Lead In Vivo Based on a Capture–Fix–Separate Mechanism

“…The adsorption kinetics and isotherms of MMS/H under aqueous condition were investigated in detail (Supporting Information, Figures S4–S6 and Tables S2 and S3). The experimental data are suited to pseudo‐first‐order kinetics (R 2 =0.98) and the Langmuir equation (R 2 =0.99), implying that the adsorption process was dominated by chemisorption of MMS/H with Pb 2+ (a detailed explanation can be found in the Supporting Information) . X‐ray photoelectron spectroscopy (XPS) results show that the formation of the ‐NH 2 Pb 2+ complex and the interaction between C=O and Pb 2+ are the two main adsorption mechanisms (Supporting Information, Figure S7).…”

Growth and Removal Behavior of Magnesium Oxide Microspheres towards Methyl Orange and Methylene Blue in Aqueous Solution

“…On the other hand, the removal capacity of methylene blue goes increase with solution pH related to the more positive charge on MgO at high pH and relatively repulsion between similar charges. This difference in adsorption ability for each dye is related to the nature of the pollutant, and surface charge on MgO [24,41].…”

“…There are several pores of different volumes beyond 1 µm range in the MgO microsphere as marked inFigure 4D, and these results also agree with the observed from the morphology. These results suggest that the pores of different size from nanometer (average pore size 28.7 nm) to the micrometer (average pore size 220.0 nm) present in the flower-like MgO microsphere, which may provide a pathway to approach the internal surface area of MgO based on nature of pollutant[22][23][24].…”