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Article

Preparation of the New Magnetic Nanoadsorbent Fe3O4@SiO2-yl-VP and Study on the Adsorption Properties of Hg (II) and Pb (II) in Water

by
Dun Chen
1,*,
Jianxin Chen
2,
Wanyong Zhou
3 and
Amatjan Sawut
3
1
Key Laboratory of Functional Polymer, Xinjiang Education Institute, Urumqi 830043, China
2
Xinjiang Hongyuan Construction Group Co., Ltd., Kekdala 835000, China
3
College of Chemistry, Xinjiang University, Urumqi 830017, China
*
Author to whom correspondence should be addressed.
Magnetochemistry 2024, 10(12), 105; https://doi.org/10.3390/magnetochemistry10120105
Submission received: 24 October 2024 / Revised: 6 December 2024 / Accepted: 10 December 2024 / Published: 13 December 2024
(This article belongs to the Special Issue Applications of Magnetic Materials in Water Treatment)
Browse Figures
Figure 1
<p>Diagram of application and detection methods of magnetic nanoadsorbents.</p> "> Figure 2
<p>Structural diagrams of different magnetic nanoadsorbents.</p> "> Figure 3
<p>The FT-IR spectra of Fe<sub>3</sub>O<sub>4</sub>, Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl and Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP.</p> "> Figure 4
<p>EDS spectra of Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP (<b>a</b>), Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP adsorbing mercury ions (<b>b</b>) and lead ion (<b>c</b>).</p> "> Figure 5
<p>XRD pattern of Fe<sub>3</sub>O<sub>4</sub>, Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl, and Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP.</p> "> Figure 6
<p>The magnetic hysteresis curves of Fe<sub>3</sub>O<sub>4</sub>, Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl, and Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP.</p> "> Figure 7
<p>TG curves of Fe<sub>3</sub>O<sub>4</sub>, Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl, and Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP.</p> "> Figure 8
<p>SEM image of Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP.</p> "> Figure 9
<p>TEM image of Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP.</p> "> Figure 10
<p>The effect of initial concentration on the adsorption quantity.</p> "> Figure 11
<p>Adsorption isotherms of Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP for Hg (II) and Pb (II).</p> "> Figure 12
<p>The effect of pH on the removal efficiency of Hg (II) and Pb (II) ions using Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP.</p> "> Figure 13
<p>Adsorption kinetic curves of Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP for Hg (II) and Pb (II).</p> "> Figure 14
<p>The effect of reused times on the adsorption capacities.</p> "> Scheme 1
<p>The synthetic route of Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>-yl-VP.</p> ">
Versions Notes

Abstract

:
This article reports the preparation of a novel functionalized magnetic nanoadsorbent through an addition reaction between Fe3O4 nanoparticles coated with allyl silica gel and 4-pyridinyl ethylene. A detailed characterization of Fe3O4@SiO2-yl-VP was conducted. Among them, in the infrared spectrum, we can easily see that the absorption peak of the C=C stretching vibration at 1660 cm−1 in the raw material disappears after the addition reaction, indicating the successful grafting of polymer on the surface of silica gel. The appearance of N element in the EDS spectrum also proves the successful completion of the addition reaction and the successful synthesis of Fe3O4@SiO2-yl-VP. At pH = 5 and pH = 7, it only takes half an hour for Fe3O4@SiO2-yl-VP to achieve maximum adsorption capacities of 85.06 and 73.78 mg/g for Hg (II) and Pb (II), respectively. The adsorption process conforms to the Langmuir model and the pseudo-first- and pseudo-second-order kinetic models and can be reused 11 times, demonstrating excellent reusability.

1. Introduction

With the rapid development of modern metallurgy, battery, and energy industries, some heavy metals, such as lead and mercury, have entered the water bodies, causing serious environmental pollution. In order to cope with this challenge, countries all over the world have taken measures to strengthen the investment of water restoration work in order to improve the control capacity of heavy metal pollution.
At present, the treatment methods for heavy metal ions such as lead and mercury in industrial sewage include the adsorption method, the electrochemical method, the microbial degradation method, the membrane filtration method, and others [1,2]. Among them, the adsorption method has been widely used, boasting advantages in terms of low energy consumption, convenient operation [3,4], and renewable and low-cost materials. Commonly used adsorbents include natural porous materials, metal–organic frameworks, covalent organic frameworks, activated carbon, and nanoparticle materials [5,6,7,8]. Generally speaking, high-performance adsorbents usually have the characteristics of large specific surface area, good pore structure matching, good stability, and easy production, but in industrial wastewater treatment, the repeated recycling of adsorbent is an important index by which to evaluate its practicability [9]. The traditional filtration and centrifugal method is complicated, costly, and less effective. Therefore, there is an urgent need to develop a viable adsorbent that can be separated from the environment and easily collected.
In recent years, the synthesis and application of magnetic nanoparticles (MNPs) with outstanding advantages, such as supermagnetic performance, low toxicity, high specific surface area, and being easy to recover, have attracted widespread attention [10]. Researchers, by modifying the surface of MNPs, not only improve their adsorption capacity, renewable ability, target selectivity, and stability in acidic medium; they also avoid the aggregation of magnetic particles in the treatment of heavy metal ions and pollutants in water samples (the application of the magnetic nanoadsorbent and the detection method are shown in Figure 1). The modified materials include sponges, hydrogels, carbon nanotubes, graphene/graphene oxide, molecularly imprinted polymers, covalent organic frameworks, layered double hydroxides, metal–organic frameworks, organic compounds containing functional groups, etc. The formed magnetic nanoadsorbents are represented by sponges, beads, CNTs, G/GO, MIPs, COFs, LDHs, MOFs, and FUN, respectively, and their structures are shown in Figure 2.
The magnetic sponge (Spongs) is mainly used for oil pollution removal and oil–water separation, and the adsorbent is poorly functionalized in the preparation process. The application is limited to some extent [11]. The magnetic beads (Beads) are mainly used for softening water. Preprocessing is required before its use, and the procedure is highly complicated [12]. Magnetic carbon nanotubes (CNTs) and graphene/graphene oxide (G/GO) are ideal for extracting and concentrating organic pollutants from various matrices, but there is a high preparation cost for this type of adsorbent, as well as poor dispersity [13,14]. Magnetic molecular imprinted polymers (MIPs) can act as selective adsorbents for some compounds and ions and are well suited for the selective extraction of fluorine/chlorine compounds, herbicides, and flavonoids. However, the disadvantage is that it is difficult to prepare, and the functional groups are difficult to introduce [6,15]. Magnetic covalent organic frameworks (COFs) have the advantages of selective and tunable porosity, easy functionalization, satisfactory chemical and thermal stability, a large specific surface area, and ordered channels. However, the disadvantages are limitations in the rapid, intuitive, and quantitative analysis of harmful substances [7,8,16]. Layard double hydroxides (LDHs) are suitable for water treatment and the purification industry, but the disadvantages are obvious; one is that the number of active sites is small; another is that to enhance activity, we can only increase the lateral size and thickness, resulting in excess [17,18]. Magnetic metal–organic frameworks (MOFs) have a large surface area and different porosities; multiple functional groups in structure; high thermal stability; and adjustable shape, size, and selectivity. They are widely used to separate toxic substances in gases, liquids, and environmental samples and to remove metal ions and polar and nonpolar organic matter. But such adsorbents are usually limited by pore size and are unstable [19,20,21].
Magnetic nanoadsorbents with grafting functional groups (FUN) are usually coated with silica gel on the surface of MNPs; then, functional groups are grafted onto the silica gel. Silicone is not only an adsorbent material that can adsorb more heavy metal ions; it also has a tight and stable binding with MNPs. At the same time, silicone reduces the aggregation of MNPs. Functional groups are generally efficient heavy metal ion coordination groups, which have good adsorption capacity for heavy metal ions. In addition, FUN have the advantages of a large specific surface area, strong adsorption capacity, uniform dispersion, stable structure, renewability, and convenient recovery, and they are widely used for adsorbing heavy metal ions in wastewater [22,23,24].
Generally, how high-performance functional groups such as pyridyl and thiol groups can be quickly and efficiently grafted onto adsorbents is a key consideration for researchers when preparing FUN. In this article, a novel FUN adsorbent, Fe3O4@SiO2-yl-VP, was rapidly and effectively synthesized through an addition reaction between Fe3O4 nanoparticles coated with allyl silica gel and 4-pyridine ethylene. Usually, functional groups are grafted onto the surface of magnetic materials through substitution reactions or simple mixing under adhesive conditions [25,26,27,28,29]. We attempted an addition reaction and successfully synthesized an adsorbent, providing a new method for the synthesis of FUN. Fe3O4@SiO2-yl-VP not only has a low preparation cost and a simple and fast synthesis method but has also shown excellent adsorption performance, renewable performance, and convenient recovery in extracting Hg (II) and Pb (II) from industrial wastewater, making it a promising heavy metal ion adsorbent.

2. Experimental Section

2.1. Synthesis of Fe3O4@SiO2-yl

MNPs were prepared according to the literature [30].
Add 0.20 g of MNPs and 30.00 mL of anhydrous ethanol to a 100 mL three-necked bottle, and sonicate for over 15 min. After the MNP is evenly dispersed, add 1.00 mL of allyl triethoxysilane and 1.00 mL of distilled water to a three-necked bottle. Mechanical stirring for 6 h under room temperature nitrogen protection. The product is separated by an external magnetic field, cleaned with anhydrous ethanol, and dried in a vacuum oven at 60 ° C for 6 h.

2.2. Synthesis of Fe3O4@SiO2-yl-VP

Add 50 mL anhydrous toluene to a 100 mL three-necked bottle, then add Fe3O4@SiO2-yl, excessive 4-vinylpyridine (4-VP), and an appropriate amount of dioxane and azodiisobutyronitrile. Mechanically stir, vacuum, and store under nitrogen protection at 70 °C for 24 h. Among them, the monomer concentration is 1 mol/L, and the initiator concentration is 0.005 mol/L. After the reaction is completed, the product is separated by an external magnet, washed repeatedly with anhydrous ethanol, and dried in a vacuum oven at 60 °C for 6 h to obtain the product Fe3O4@SiO2-yl-VP. The synthesis route is shown in Scheme 1.

3. Results and Discussion

3.1. Characterization

3.1.1. Infrared Spectrum Analysis of Fe3O4@SiO2-yl-VP

Figure 3 shows the IR spectrum of Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP. The figure shows that 590 cm−1 is the stretching vibration peak [31] of O-Fe in Fe3O4. For Fe3O4@SiO2-yl, the strong absorption peak of 1096 cm−1 is the stretching vibration of Si–O–Si [32], and the absorption peak of 1660 cm−1 is the stretching vibration of C=C. For Fe3O4@SiO2-yl-VP, except for the characteristic peak of 590 cm−1 O-Fe and 1096 cm−1 Si-O-Si, 1400~1600 cm−1 is the stretching vibration peak of the pyridine ring, and the stretching vibration absorption peak of 1660 cm−1 C=C disappears, indicating that the C=C of the allyl group in Fe3O4@SiO2-yl has been consumed by addition reaction, proving that Fe3O4@SiO2-yl-VP has been successfully synthesized.

3.1.2. EDS Spectrum Analysis of Fe3O4@SiO2-yl-VP

After conducting adsorption capacity tests, the adsorbent was magnetically separated and dried, followed by EDS analysis. Figure 4 shows the EDS spectrum of Fe3O4@SiO2-yl-VP and its adsorption of Hg (II) or Pb (II). About Fe3O4@SiO2-yl-VP, it can be seen from the figure that it contains five elements: C, N, O, Si, and Fe. The grafting of pyridine rings into the complex introduces a new element N, which also proves the smooth completion of the addition reaction, and Fe3O4@SiO2-yl-VP synthesis is successful. From the other two EDS spectra, Hg (II) or Pb (II) can be clearly seen, indicating that Fe3O4@SiO2-yl-VP has a good adsorption performance for Hg (II) and Pb (II).

3.1.3. XRD Pattern Analysis of Fe3O4@SiO2-yl-VP

Figure 5 shows the XRD pattern of pure Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP, and six characteristic peaks of pure Fe3O4, 2ϴ = 30.1°, 35.5°, 43.3°, 53.4°, 57.2°, and 62.5°; these are related to the (220), (311), (400), (422), (511), and (440) planes of Fe3O4 spinel structure [30]. Fe3O4@SiO2-yl-VP also has the same characteristic peak, suggesting the successful formation of the composite material, with a magnetic core and a shell consisting of and inorganic SiO2 layer and a VP-based polymeric shell.

3.1.4. Magnetic Analysis

From Figure 6, which represents the magnetization curves of the initial magnetic nanoparticles (Fe3O4), silica-covered magnetic nanoparticles (Fe3O4@SiO2-yl), and the final adsorbent material (Fe3O4@SiO2-yl-VP), it can be seen from the shape of the curve that the materials show superparamagnetic behavior [33]. The saturation magnetization strengths of Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP are 58.56, 43.92, and 37.23 Am2/kg, respectively. Compared to Fe3O4, the saturated magnetic strength of the functionalized adsorbent decreased by 14.64 and 21.33, respectively. However, the magnetization strength of the adsorbent is still greater than 35 Am2/kg, and rapid separation can still be achieved through a magnetic field [34].

3.1.5. Thermogravimetric (TG) Analysis

Figure 7 is a thermogravimetric diagram. We can see that Fe3O4 and Fe3O4@SiO2-yl caused weight losses of 8.06% and 17.82% at 181~850 °C and 172~850 °C, respectively. For Fe3O4@SiO2-yl-VP, concerning the peak position, it can be divided into three stages: 0~150 °C, 150~650 °C, and 650~850 °C. Corresponding to the thermogravimetric diagram analysis, in the first stage, there is weight loss of 3.5%, which may be caused by the volatilization of water and residual organic matter [35]. There is a weight loss of 15.2% in the second stage. The temperature range of 150~650 °C may be caused by the decomposition of polymers, including the decomposition of pyridine functional groups and the breaking of C–C, C–N, C–H bonds, and Si–O bonds, among other factors. Weight loss in the third stage is 4.0%, which may be due to the high-temperature conversion of the magnet [36]. From the fact that the maximum weight loss rate in the second stage is organic matter, it can be concluded that the polymer has been successfully grafted onto the surface of Fe3O4@SiO2.

3.1.6. SEM Analysis of Fe3O4@SiO2-yl-VP

In the scanning electron microscope image of Fe3O4@SiO2-yl-VP (Figure 8), a magnetic cluster structure can be observed. These magnetic clusters are composed of a core formed by the controlled agglomeration of tens to hundreds of magnetic nanoparticles. MNPs are wrapped by a white silica gel layer, which gives the overall structure a white spherical appearance. The silica gel surface is further modified by organic molecules, leading to the roughness of the silica gel surface structure. This morphology is consistent with the typical structure of such nanoadsorbent materials, where the silane layer coats the magnetic core and is then covered by a polymeric layer.

3.1.7. TEM Analysis of Fe3O4@SiO2-yl-VP

Figure 9 shows Fe3O4@SiO2-yl-VP transmission electron microscopy image. The structure is observed as a magnetic cluster. This magnetic cluster is composed of a core formed by the tight aggregation of individual magnetic nanoparticles. The outer layer is a composite of silane and polymer.

3.2. Research on Adsorption Performance

3.2.1. Saturated Adsorption Capacity and Thermodynamic Analysis

Maximum adsorption capacity was measured, respectively, by 0.10 g of Fe3O4@SiO2-yl-VP with 50.00 mL of various concentrations of single-target metal ion solutions. In order to reach the “saturation”, single-target metal ion concentration was increased till the plateau values (adsorption capacity values) were obtained.
Under optimal conditions, the adsorption capacity of the adsorbent was investigated. It can be clearly seen from Figure 10 that the process of adsorption of Hg (II) or Pb (II) is basically the same, which may be related to the same mechanism of adsorption of these two metal ions by Fe3O4@SiO2-yl-VP. In the initial stage, the adsorbent has multiple adsorption sites, and the adsorption capacity increases with the initial concentration of Hg (II) or Pb (II) solution. In the later stage, the adsorption capacity tends to saturate as the adsorption sites are gradually occupied by metal ions. After calculation, the maximum adsorption capacities of Fe3O4@SiO2-yl-VP for Hg (II) and Pb (II) are 85.06 and 73.78 mg/g, respectively. The adsorption capacity of mercury ions is greater than that of lead ions, as reported in other studies [37,38]. The reason is complex; it is possibly due to the easy coordination of mercury ions relative to lead ions for the same adsorbent.
We fit the adsorption isotherm models of Langmuir and Freundlich for Hg (II) and Pb (II), respectively. The adsorption isotherm equation is as follows [39]:
C e Q e = 1 Q m a x b + C e Q m a x ,
ln ⁡ Q e = ln ⁡ k F + 1 n ln ⁡ C e .
In the formula, Qe is the equilibrium adsorption capacity (mg/g); Ce is the concentration of Hg (II) and Pb (II) ions after reaching equilibrium (mg/L); Qmax is the saturated adsorption capacity (mg/g); and b, kF, and n are constants.
The adsorption isotherms of Fe3O4@SiO2-yl-VP for Hg (II) and Pb (II) ions are shown in Figure 11. It can be seen that the Langmuir adsorption isotherm fits well with the scatter plot of Fe3O4@SiO2-yl-VP adsorption for Hg (II) and Pb (II), which can also be verified from Table 1. According to the Langmuir model, the theoretical values of saturated adsorption capacity are 83.86 and 71.79 mg/g, which are very close to the experimental values of 85.06 and 73.78 mg/g. The fitting coefficients of Langmuir for Hg (II) and Pb (II) ions are R2 = 0.9403 and 0.9980, respectively, which are larger than the corresponding Freundlich fitting coefficients, i.e., R2 = 0.7006 and 0.9016. This indicates that the Langmuir model can be used to fit the experimental data for the adsorption process of Hg (II) and Pb (II) ions by Fe3O4@SiO2-yl-VP.

3.2.2. Effect of pH

From Figure 12, it can be seen that the process of Fe3O4@SiO2-yl-VP adsorbing Hg (II) or Pb (II) ions is influenced by pH value. Under strong acidic conditions, the N atom on the pyridine ring of Fe3O4@SiO2-yl-VP is prone to protonation, reducing the number of coordinated N atoms and resulting in low removal efficiency. As the pH value increases, the removal efficiency of Hg (II) and Pb (II) ions by Fe3O4@SiO2-yl-VP gradually increases, reaching adsorption equilibrium at pH = 7 and pH = 5, respectively, which is consistent with the literature data [40,41]. If the pH value is too high, the precipitation loss of Hg (II) and Pb (II) ions is too large, which seriously affects the adsorption percentage and should not be considered.

3.2.3. Research on Adsorption Kinetics

Take 100 mL each of 50 mg/L of Hg (II) and Pb (II) water samples, add 0.02 g Fe3O4@SiO2-yl-VP each, stir, and take samples at different times to determine the concentration of heavy metal ions. Calculate the corresponding adsorption amount Qt at the time.
The adsorption kinetics model is used to fit the adsorption process of Hg (II) and Pb (II) ions by Fe3O4@SiO2-yl-VP. Currently, the commonly used equations are the pseudo-first-order kinetic rate equation and the pseudo-second-order kinetic rate equation [42].
The linear form of the pseudo-first-order kinetic rate equation is as follows:
ln ⁡ Q e − Q t = ln ⁡ Q e − k 1 t
In the formula, Qt is the adsorption capacity at any time (mg/g); Qe is the equilibrium adsorption capacity (mg/g); and k1 (min−1) is the pseudo-first-order kinetic rate constant.
The linear form of the pseudo-second-order kinetic rate equation is as follows:
t Q t = 1 k 2 Q e 2 + t Q e
In the formula, Qt is the adsorption capacity at any time (mg/g); Qe is the equilibrium adsorption capacity (mg/g; and k2 is the pseudo-second-order kinetic rate constants g/(mg·min).
The scatter plot analysis of the adsorption of Hg (II) and Pb (II) by Fe3O4@SiO2-yl-VP is shown in Figure 13; the initial adsorption amount increases rapidly with time. This may be due to the fact that Fe3O4@SiO2-yl-VP has multiple functional groups and fully exposed adsorption sites, which improves the efficiency of Hg (II) and Pb (II). With the reduction of adsorption sites and the blockage of adsorbed heavy metal ions on sites, the adsorption amount decreases until reaching adsorption equilibrium at 25 min. Based on the fitting results in Table 2, it can be seen that the fitting coefficients of the pseudo-first-order kinetic model and the pseudo-second-order kinetic model are both greater than 0.93. The theoretical maximum adsorption capacities of Hg (II) and Pb (II) at adsorption equilibrium are not significantly different from the experimental values of 85.06 and 73.78 mg/g, both of which can well fit the adsorption process of Fe3O4@SiO2-yl-VP for Hg (II) and Pb (II). This may be due to the fact that the polymer grafted on VP silica gel has a large volume and a large number of functional groups, which can not only adhere metal ions from the adsorbent diffusion but can also form complexes with Hg (II) and Pb (II) through functional groups for chemical adsorption.

3.2.4. Selection of Eluents

We desorbed the adsorbents for Hg (II) and Pb (II) using acid solutions of different concentrations. The results are shown in Table 3. At room temperature, 1.00 mol/L HCl and 1.00 mol/L HNO3 have the best desorption effect on Hg (II) and Pb (II). Therefore, in this experiment, 1.00 mol/L HCl was selected to desorb Hg (II) and 1.00 mol/L HNO3 to desorb Pb (II).

3.2.5. Reusability of Adsorbents

After conducting 15 adsorption and elution experiments on Fe3O4@SiO2-yl-VP, the optimal number of repeated uses of Fe3O4@SiO2-yl-VP was found. As shown in Figure 14, after 11 repeated uses, the removal efficiency of Fe3O4@SiO2-yl-VP is generally above 90%, indicating that Fe3O4@SiO2-yl-VP has good reusability and stability. The number of repeated uses of Fe3O4@SiO2-yl-VP may be related to the relative stability of the polymer grafted through addition reactions.

4. Conclusions

Compared to the usual preparation of magnetic nanoadsorbents through substitution reactions and simple mixing under bonding conditions, we have successfully prepared Fe3O4@SiO2-yl-VP using a novel addition reaction.
Fe3O4@SiO2-yl-VP not only has low preparation cost and a simple and fast synthesis method; it has paramagnetism. After the experiment is completed, it is easy for Fe3O4@SiO2-yl-VP to magnetically separate from the solution, achieving maximum adsorption capacities of 85.06 mg/g and 73.78 mg/g for Hg (II) and Pb (II) in just half an hour at pH = 5 and pH = 7, respectively. The adsorption process conforms to the Langmuir model, pseudo-first-order kinetic model, and the pseudo-second-order kinetic model.
Magnetic clusters with good homogeneity are obtained (if this aspect is to be proven by subsequent TEM measurements). Magnetic clusters show superparamagnetic properties, with saturation magnetization values suitable for magnetic separation applications. And finally, with respect to the adsorptions of the two metals, with reference to the literature, similar, lower, and higher values were obtained.

Author Contributions

Conceptualization, D.C.; writing—original draft preparation, D.C.; investigation, J.C.; resources, W.Z.; validation, A.S.; writing—review and editing, A.S. and J.C.; supervision, W.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by Natural Science Foundation of Xinjiang Uygur Autonomous Region (grant number, 2024D01A96).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest. Jianxin Chen is an employee of Hongyuan Construction Group Co., Ltd. This paper reflects the views of the authors, not the company.

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Figure 1. Diagram of application and detection methods of magnetic nanoadsorbents.
Figure 1. Diagram of application and detection methods of magnetic nanoadsorbents.
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Figure 2. Structural diagrams of different magnetic nanoadsorbents.
Figure 2. Structural diagrams of different magnetic nanoadsorbents.
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Scheme 1. The synthetic route of Fe3O4@SiO2-yl-VP.
Scheme 1. The synthetic route of Fe3O4@SiO2-yl-VP.
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Figure 3. The FT-IR spectra of Fe3O4, Fe3O4@SiO2-yl and Fe3O4@SiO2-yl-VP.
Figure 3. The FT-IR spectra of Fe3O4, Fe3O4@SiO2-yl and Fe3O4@SiO2-yl-VP.
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Figure 4. EDS spectra of Fe3O4@SiO2-yl-VP (a), Fe3O4@SiO2-yl-VP adsorbing mercury ions (b) and lead ion (c).
Figure 4. EDS spectra of Fe3O4@SiO2-yl-VP (a), Fe3O4@SiO2-yl-VP adsorbing mercury ions (b) and lead ion (c).
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Figure 5. XRD pattern of Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP.
Figure 5. XRD pattern of Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP.
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Figure 6. The magnetic hysteresis curves of Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP.
Figure 6. The magnetic hysteresis curves of Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP.
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Figure 7. TG curves of Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP.
Figure 7. TG curves of Fe3O4, Fe3O4@SiO2-yl, and Fe3O4@SiO2-yl-VP.
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Figure 8. SEM image of Fe3O4@SiO2-yl-VP.
Figure 8. SEM image of Fe3O4@SiO2-yl-VP.
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Figure 9. TEM image of Fe3O4@SiO2-yl-VP.
Figure 9. TEM image of Fe3O4@SiO2-yl-VP.
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Figure 10. The effect of initial concentration on the adsorption quantity.
Figure 10. The effect of initial concentration on the adsorption quantity.
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Figure 11. Adsorption isotherms of Fe3O4@SiO2-yl-VP for Hg (II) and Pb (II).
Figure 11. Adsorption isotherms of Fe3O4@SiO2-yl-VP for Hg (II) and Pb (II).
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Figure 12. The effect of pH on the removal efficiency of Hg (II) and Pb (II) ions using Fe3O4@SiO2-yl-VP.
Figure 12. The effect of pH on the removal efficiency of Hg (II) and Pb (II) ions using Fe3O4@SiO2-yl-VP.
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Figure 13. Adsorption kinetic curves of Fe3O4@SiO2-yl-VP for Hg (II) and Pb (II).
Figure 13. Adsorption kinetic curves of Fe3O4@SiO2-yl-VP for Hg (II) and Pb (II).
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Figure 14. The effect of reused times on the adsorption capacities.
Figure 14. The effect of reused times on the adsorption capacities.
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Table 1. Isotherm parameters for the adsorption of Hg (II) and Pb (II) ions by Fe3O4@SiO2-yl-VP.
Table 1. Isotherm parameters for the adsorption of Hg (II) and Pb (II) ions by Fe3O4@SiO2-yl-VP.
Metal IonsLangmuir IsothernFreundlich Isothern
Qmax (mg/g)b (L/mg)R2KFnR2
Hg (II)83.861.49980.940357.6998.3820.7006
Pb (II)71.790.25720.998023.7803.4750.9016
Table 2. Kinetic parameters for the adsorption of Hg (II) and Pb (II) ions by Fe3O4@SiO2-yl-VP.
Table 2. Kinetic parameters for the adsorption of Hg (II) and Pb (II) ions by Fe3O4@SiO2-yl-VP.
Metal IonsPseudo-First-Order KineticPseudo-Second-Order Kinetic
Qmax
(mg/g)		K1 (min−1)R2Qmax
(mg/g)		K2
(g mg−1 min−1)		R2
Hg (II)83.9860.25540.977297.100.003060.9327
Pb (II)70.9330.31440.996879.820.005080.9735
Table 3. Recovery (%) of heavy metal ions using different eluents.
Table 3. Recovery (%) of heavy metal ions using different eluents.
EluentsRecovery (%)
Hg (II)Pb (II)
0.50 mol/L HNO392.6594.13
1.00 mol/L HNO393.8699.27
0.50 mol/L H2SO485.3280.27
1.00 mol/L H2SO490.4185.17
0.50 mol/L HCl 91.6392.45
1.00 mol/L HCl 99.4794.12
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Chen, D.; Chen, J.; Zhou, W.; Sawut, A. Preparation of the New Magnetic Nanoadsorbent Fe3O4@SiO2-yl-VP and Study on the Adsorption Properties of Hg (II) and Pb (II) in Water. Magnetochemistry 2024, 10, 105. https://doi.org/10.3390/magnetochemistry10120105

AMA Style

Chen D, Chen J, Zhou W, Sawut A. Preparation of the New Magnetic Nanoadsorbent Fe3O4@SiO2-yl-VP and Study on the Adsorption Properties of Hg (II) and Pb (II) in Water. Magnetochemistry. 2024; 10(12):105. https://doi.org/10.3390/magnetochemistry10120105

Chicago/Turabian Style

Chen, Dun, Jianxin Chen, Wanyong Zhou, and Amatjan Sawut. 2024. "Preparation of the New Magnetic Nanoadsorbent Fe3O4@SiO2-yl-VP and Study on the Adsorption Properties of Hg (II) and Pb (II) in Water" Magnetochemistry 10, no. 12: 105. https://doi.org/10.3390/magnetochemistry10120105

APA Style

Chen, D., Chen, J., Zhou, W., & Sawut, A. (2024). Preparation of the New Magnetic Nanoadsorbent Fe3O4@SiO2-yl-VP and Study on the Adsorption Properties of Hg (II) and Pb (II) in Water. Magnetochemistry, 10(12), 105. https://doi.org/10.3390/magnetochemistry10120105

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