煤矸石负载Fe/FeO<i><sub>x</sub></i>纳米颗粒的制备及其对镉的吸附性能

王姣; 林昶锟; 李逸飞

doi:10.13801/j.cnki.fhclxb.20210906.003

煤矸石负载Fe/FeO_x纳米颗粒的制备及其对镉的吸附性能

doi: 10.13801/j.cnki.fhclxb.20210906.003

王姣^{1, 2, ,},
林昶锟¹,
李逸飞¹

1.
山西大学　环境与资源学院，太原 030006
2.
山西省黄河实验室，太原 030006

基金项目: 国家自然科学基金 (41907265)；山西省青年科技研究基金(201901D211199)；山西省高等学校科技创新项目(2020L0039)；山西大学第十八期本科生科研训练项目(201801403022)；山西省黄河实验室开放基金

详细信息

通讯作者:
王姣，博士，讲师，硕士生导师，研究方向为铁基纳米环境材料、微量元素环境地球化学　 E-mail: wangjiao@sxu.edu.cn

中图分类号: TB332
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出版历程
- 收稿日期: 2021-06-30
- 修回日期: 2021-08-08
- 录用日期: 2021-08-14
- 网络出版日期: 2021-09-06
- 刊出日期: 2022-07-30

Synthesis of gangue-supported Fe/FeO_x nanoparticles with application for adsorption of cadmium

WANG Jiao^{1, 2
, ,},
LIN Changkun¹,
LI Yifei¹

1.
College of Environmental and Resource Science, Shanxi University, Taiyuan 030006, China
2.
Shanxi Laboratory for Yellow River, Taiyuan 030006, China

摘要

摘要: 为了采用一系列工艺对煤矸石进行提纯，采用硼氢化钠化学液相还原法制备了煤矸石负载的Fe/FeO_x纳米颗粒(nFe/FeO_x-Gangue)，用于吸附水中重金属离子Cd(II)。在均匀设计的基础上，考察了铁与煤矸石质量比、硼铁摩尔比、还原速度等因素对nFe/FeO_x-Gangue的影响。采用XRD、TEM、BET和TGA-DSC对合成的样品进行了表征，发现Fe/FeO_x纳米颗粒或独立存在于煤矸石表面，或串联成链吸附在矿物表面、尖锐的边缘和角缘，其中固定在粘土矿物表面的颗粒大部分呈球形，分散良好，偶有少量球状或块状聚集体。多个样品比对结果显示，铁与煤矸石质量比(g/g)应保持在1.6，合适的硼铁摩尔比为4或4.5。吸附结果显示，nFe/FeO_x-Gangue对Cd(II)的去除效果在很大程度上取决于pH值，pH值为5，室温条件下接触10 min后，nFe/FeO_x-Gangue对Cd(II)的去除率达83%，再生的nFe/FeO_x-Gangue在5.0 mg/L溶液中连续第6次吸附Cd(II)效率达99.12%，煤矸石负载的Fe/FeO_x纳米颗粒可应用于水中重金属离子的吸附。
- 煤矸石 /
- Fe/FeO_x纳米颗粒 /
- 湿法生长 /
- 吸附 /
- 镉
Abstract: In this paper, gangue was purified by a series of process and gangue-supported Fe/FeO_x nanoparticles (nFe/FeO_x-Gangue) were prepared by the liquid-phase reduction method under open atmosphere. The factors including Fe:Gangue mass ratios, B:Fe molar ratios, and the reduction speed were investigated based on a uniform design. XRD, TEM, BET and TG-DTA analysis were used for characterization of synthesized samples. The synthesized nFe/FeO_x-Gangue exists on the surface of gangue or adsorbed on surface, sharp edges and angles of small clay in series with an analogous catenulate formation in rank, indicating that the spherical particles immobilized on clay are clearly separated and well dispersed, displaying small amounts of globular or nubbly aggregates. The comparison results of several samples show that the Fe/ Gangue mass ratio (g/g) should be maintained as 1.6, and the appropriate B/Fe molar ratios are 4 or 4.5. After contacting with nFe/FeO_x-Gangue for 10 min, for Cd(II), the adsorption efficiency on nFe/FeO_x-Gangue is 83% at pH 5.0. The removal efficiency of Cd(II) on nFe/FeO_x-Gangue is largely dependent on pH values. The reusability of nFe/FeO_x-Gangue is evaluated and the results indicate that the reborn nFe/FeO_x-Gangue even could adsorb 99.12% of Cd(II) ions in 5.0 mg/L solution for the sixth successive uses. nFe/FeO_x-Gangue is appropriate to remove Cd(II).
- gangue /
- Fe/FeO_x nanoparticles /
- wet growth /
- adsorption /
- cadmium

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图 1 提纯煤矸石(a)、nFe/FeO_x-G2 (b)、nFe/FeO_x-G10 (c) 和nFe/FeO_x-G12 (d) 的XRD图谱

Figure 1. XRD patterns of gangue (a), nFe/FeO_x-G2 (b), nFe/FeO_x-G10 (c) and nFe/FeO_x-G12 (d)

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图 2 nFe/FeO_x-G2 (a)、nFe/FeO_x-G10 (b) 和nFe/FeO_x-G12 ((c)~(d)) 的TEM图像

Figure 2. TEM images of nFe/FeO_x-G2 (a)、nFe/FeO_x-G10 (b) and nFe/FeO_x-G12 ((c)-(d))

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图 3 提纯煤矸石、nFe/FeO_x-G2、nFe/FeO_x-G10和nFe/FeO_x-G12的DSC曲线

Figure 3. DSC curves of gangue, nFe/FeO_x-G2, nFe/FeO_x-G10 and nFe/FeO_x-G12

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图 4 提纯煤矸石 (a)、nFe/FeO_x-G2 (b)、nFe/FeO_x-G10 (c) 和nFe/FeO_x-G12 (d) 的TGA曲线

Figure 4. TGA curves of gangue (a), nFe/FeO_x-G2 (b), nFe/FeO_x-G10 (c) and nFe/FeO_x-G12 (d)

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图 5 提纯煤矸石、nFe/FeO_x-G2、nFe/FeO_x-G10和nFe/FeO_x-G12的氮吸附-解吸等温线和PSD曲线

Figure 5. Nitrogen adsorption-desorption isotherms and PSD curves (the insert) of gangue, nFe/FeO_x-G2, nFe/FeO_x-G10 and nFe/FeO_x-G12

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图 6 nFe/FeO_x-Gangue复合材料的Zeta电位图

Figure 6. Electrophoretic mobility data of nFe/FeO_x-Gangue

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图 7 初始溶液pH值对nFe/FeO_x煤矸石吸附Cd(II)的影响

Figure 7. Effect of initial solution pH values on the adsorption of Cd(II) on nFe/FeO_x-Gangue

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图 8 不同吸附剂对Cd(II)的吸附动力学

Figure 8. Adsorption kinetics of Cd(II) on the various adsorbents

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图 9 初始溶液浓度对nFe/FeO_x-Gangue吸附Cd(II)的影响

Figure 9. Effect of initial solution concentration on the adsorption of Cd(II) on nFe/FeO_x-Gangue

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图 10 nFe/FeO_x-Gangue吸附Cd(II)的Langmuir (a)、Freundlich (b) 吸附等温线模型线性拟合结果

Figure 10. Linearized Langmuir (a), Freundlich (b) isotherms for Cd(II) adsorption on nFe/FeO_x-Gangue

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图 11 nFe/FeO_x-Gangue已吸附Cd(II)的解吸和材料的再生性

Figure 11. Desorption of Cd(II) on nFe/FeO_x-Gangue and the reproducibility of nFe/FeO_x-Gangue

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表 1 提纯煤矸石、市售蒙脱石和高岭石的化学组成对比

Table 1. Chemical composition of purified gangue, montmorillonite, and kaolinite wt%

Sample	SiO₂	Al₂O₃	P₂O₅	Na₂O	K₂O	Fe₂O₃	TiO₂	MgO	CaO	MnO	SO₃	Total
Gangue	44.89	20.99	13.301	4.21	1.21	1.16	0.737	0.32	0.05	0.004	0.02	86.89
Montmorillonite	74.55	14.55	0.002	0.28	1.54	0.52	0.118	2.32	2.4	0.064	0.02	96.35
Kaolinite	75.36	14.04	0.002	2.29	5.2	0.91	0.066	0.65	1.4	0.033	0.02	100.01

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表 2 煤矸石负载的Fe/FeO_x纳米颗粒(nFe/FeO_x-Gangue)的制备条件

Table 2. Synthesis conditions for gangue-supported Fe/FeO_x nanoparticles (nFe/FeO_x-Gangue) samples

Sample	Factor 1	Factor 2	Factor 3
Sample	Fe/Gangue mass ratio	B/Fe molar ratio	Reduction speed/(mL·min⁻¹)
nFe/FeO_x-G1	1∶5	7∶2	21.05
nFe/FeO_x-G2	2∶5	13∶2	10.52
nFe/FeO_x-G3	1∶2	3∶1	5.17
nFe/FeO_x-G4	3∶5	6∶1	3.73
nFe/FeO_x-G5	4∶5	5∶2	29
nFe/FeO_x-G6	1∶1	11∶2	11.7
nFe/FeO_x-G7	6∶5	2∶1	7.65
nFe/FeO_x-G8	7∶5	5∶1	4.42
nFe/FeO_x-G9	3∶2	3∶2	54.55
nFe/FeO_x-G10	8∶5	9∶2	15.38
nFe/FeO_x-G11	9∶5	1∶1	11.47
nFe/FeO_x-G12	2∶1	4∶1	4.85
Note: G—Gangue.

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表 3 提纯煤矸石和nFe/FeO_x-Gangue的比表面积、孔体积和吸附平均孔宽

Table 3. Specific surface area, pore volume and adsorption average pore width of purified gangue and nFe/FeO_x-Gangue samples

Sample	Gangue	nFe/FeO_x-G2	nFe/FeO_x-G10	nFe/FeO_x-G12
S_BET/(m²·g⁻¹)	0.82	67.96	26.73	18.35
V_pore/(cm³·g⁻¹)	0.003	0.243	0.109	0.061
Average pore width/nm	8.59	10.66	11.77	10.11
Note: S_BET—Surface area, calculated from the relative pressures between 0.06 and 0.2; V_pore—Pore volume.

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表 4 nFe/FeO_x-Gangue吸附Cd(II)的动力学模型拟合参数

Table 4. Adsorption kinetic model rate constants for Cd(II) adsorption on nFe/FeO_x-Gangue

$ {{{q}}}_{{\rm{e}},{\rm{e}}{\rm{x}}{\rm{p}}} $/(mg·g⁻¹)	Pseudo first-order model			Pseudo second-order model
$ {{{q}}}_{{\rm{e}},{\rm{e}}{\rm{x}}{\rm{p}}} $/(mg·g⁻¹)	$ {{{k}}}_{1} $/min⁻¹	$ {{{q}}}_{{\rm{e}},{\rm{c}}{\rm{a}}{\rm{l}}} $/(mg·g⁻¹)	r₁²	$ {{{k}}}_{2} $/(g·mg⁻¹·min⁻¹)	$ {q}_{{\rm{e}},{\rm{c}}{\rm{a}}{\rm{l}}} $/(mg·g⁻¹)	r₂²
12.23	−0.0321	12.4329	0.9467	0.0117	10.9218	0.8784
Notes: $ {q}_{{\rm{e}},{\rm{e}}{\rm{x}}{\rm{p}}} $—Experimentally determined equilibrium capacity; $ {q}_{{\rm{e}},{\rm{c}}{\rm{a}}{\rm{l}}} $—Simulated equilibrium capacity; $ {k}_{1} $—Pseudo-first-order rate constant; $ {k}_{2} $—Pseudo-second-order rate constant; r₁²—Linear regression coefficient from pseudo first-order model; r₂²—Linear regression coefficient from pseudo second-order model; Pseudo first-order model—${\rm{lg} }\left({q}_{ {\rm{e} } }-{q}_{ {{t} } }\right)={\rm{lg} }{q}_{ {\rm{e} } }-\dfrac{ {k}_{1} }{2.303}t$, $ {k}_{1} $ and $ {q}_{{\rm{e}},{\rm{e}}{\rm{x}}{\rm{p}}} $ were evaluated using the slopes and intercepts of the linear plots of ${\rm{lg} }\left({q}_{ {\rm{e} } }-{q}_{ { {t} } }\right)$ versus t; Pseudo second-order model—$ \dfrac{t}{{q}_{{{t}}}}=\dfrac{1}{{k}_{2}{{q}_{{\rm{e}}}}^{2}}+\dfrac{1}{{q}_{{\rm{e}}}}t $, $ {q}_{{\rm{e}},{\rm{ }}{\rm{c}}{\rm{a}}{\rm{l}}} $ and $ {k}_{2} $ can be determined from the slope and intercept of plots of $ t/{q}_{{{t}}} $ versus time ($ t $).

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表 5 nFe/FeO_x-Gangue吸附Cd(II)的吸附等温线模型拟合参数

Table 5. Freundlich and Langmuir adsorption parameters for adsorption of Cr(VI) on nFe/FeO_x-Gangue

Adsorbents	Langmuir equation parameters		Freundlich equation parameters
Adsorbents	q_m/(mg·g⁻¹)	R²	q_m/(mg·g⁻¹)	R²
nFe/FeO_x−Gangue	29.04	0.648	149.53	0.975
Notes: $ {q}_{{\rm{m}}} $—Maximum adsorption capacity; R²—Linear regression coefficient.

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