制备方法对氧化石墨烯氧化程度及对Th(IV)、U(VI)吸附的影响

doi:10.15541/jim20150486

摘要/Abstract

摘要：

采用Hummers方法、优化Hummers方法及改进Hummers方法合成氧化石墨烯, 并通过FT-IR、TGA、XRD、XPS、SEM以及元素分析等手段对制备产物进行了表征。结果表明, 利用优化Hummers方法制备得到的氧化石墨烯具有较高的氧化程度。三种产物对Th(IV)、U(VI)的等温吸附实验结果表明, 采用优化Hummers方法制备的氧化石墨烯对Th(IV)的最大吸附量为192.3 mg/g, 相比于Hummers方法制备产物的吸附能力提高了38.5%; 对U(VI)的最大吸附量为156.2 mg/g, 吸附能力提高了28.1%, 三种样品对Th(IV)、U(VI)的吸附都更加符合Langmuir等温吸附模型。此外, 考察了优化Hummers方法制备的氧化石墨烯吸附Th(IV)、U(VI)的动力学和热力学参数, 证实氧化石墨烯吸附Th(IV)、U(VI)符合准二级动力学方程, 是自发吸热行为。

关键词: 氧化石墨烯制备, 结构, 吸附, Th(IV), U(VI)

Abstract:

Graphene oxide (GO) was prepared from graphite using Hummers' method, improved Hummers' method and modified Hummers' method. The samples were characterized by FT-IR spectroscope, TGA, XRD, XPS,SEM and element analysis. The results showed that graphene oxide was more oxidized prepared by the improved Hummers' method(IGO). The isothermal adsorption experiments of Th(IV) and U(VI) on graphene oxide showed that the maximum adsorption capacity of Th(IV) on IGO was 192.3 mg/g, increased by 38.5% as compared with that of GO prepared by Hummers’ method. The maximum adsorption capacity of U(VI) was 156.2 mg/g, increased by 28.1%. Both of above values are in accord with Langmuir isotherm model. Furthermore, kinetic and thermodynamic parameters of Th (IV) and U(VI) adsorption on IGO were investigated by using batch experiments, confirming that adsorption fits pseudo-second kinetic equations, which are spontaneous and endothermic.

Key words: preparation of graphene oxide, structure, adsorption, Th (IV), U (VI)

中图分类号:

TB34
X591

王晓宁, 孟虎, 马付银, 李峥, 张岚. 制备方法对氧化石墨烯氧化程度及对Th(IV)、U(VI)吸附的影响[J]. 无机材料学报, 2016, 31(5): 454-460.

WANG Xiao-Ning, MENG Hu, MA Fu-Yin, LI Zheng, ZHANG Lan. Influence of Preparation Method on Oxidation Degree of Graphene Oxide and Adsorption for Th (IV) and U(VI)[J]. Journal of Inorganic Materials, 2016, 31(5): 454-460.

图/表 11

图1 HGO、IGO和MGO的红外光谱(a)、热重分析(b)和XRD图谱(c)

Fig. 1 Infrared spectra (a), TGA curves (b) and XRD patterns (c) of HGO, IGO and MGO

图2 (a) HGO, (b) IGO和(c)MGO的C1s XPS图谱

Fig. 2 C1s XPS spectra of (a) HGO, (b) IGO and (c) MGO

表1 HGO、IGO和MGO的Cls XPS的拟合结果

Table1 C1s XPS results of HGO, IGO and MGO

	C=C/%	C-O/%	C=O/%	O=C-O/%	C/O*
HGO	54.8	30.8	10.4	4.0	2.36
IGO	49.3	34.1	8.7	7.9	1.91
MGO	53.2	30.4	9.4	7.0	2.14

表2 HGO, IGO和MGO元素分析结果

Table 2 Element analysis results of HGO, IGO and MGO

	C/%	H/%	O/%
HGO	47.72	2.37	49.91
IGO	40.67	2.43	56.90
MGO	41.95	2.40	55.65

图3 氧化石墨烯(a)HGO、(b)IGO和(c) MGO的SEM照片

Fig. 3 SEM images of graphene oxide (a) HGO, (b) IGO and (c) MGO

表3 U(VI)和Th(IV)吸附的Langmuir和Freundlich吸附模型计算参数

Table 3 Parameters for the Langmuir and Freundlich models of U(VI) and Th(IV) sorption

		Langmuir			Freundlich
		Q_max/(mg·g^-1)	K_L/(L·mg^-1)	R²	K_F/(mg^1-ⁿ·Lⁿ·g^-1)	1/n	R²
U(VI)	HGO	121.9	0.3306	0.997	48.11	0.2207	0.972
	IGO	156.2	0.1688	0.994	31.43	0.3987	0.963
	MGO	161.2	0.1294	0.993	32.48	0.3801	0.973
Th(IV)	HGO	138.8	0.4199	0.984	53.54	0.2279	0.973
	IGO	192.3	0.6753	0.991	93.13	0.1786	0.971
	MGO	188.6	0.5773	0.975	61.86	0.2981	0.976

图4 HGO、IGO和MGO对U(VI)(a)和Th(IV) (b)的等温吸附线 pH=4±0.05 (a) and C (Th)= 0.05-0.5 mmol/L (b), pH=3±0.05, (T=298.15 K, t=12 h)

Fig. 4 Adsorption isotherms of U(VI) (a) and Th(IV) (b) on the HGO, IGO and MGO C(GO)=0.3 g/L, C(U)=0.05-0.5 mmol/L, pH=4±0.05 (a) and C (Th)= 0.05-0.5 mmol/L (b), pH=3±0.05, (T=298.15 K, t=12 h)

图5 pH对IGO吸附Th(IV)和U(VI)的影响 pH C(GO)=0.4 g/L, C(Th)=0.5 mmol/L, T=298.15 K, t=12 h; C(GO)=0.4 g/L, C(U)= 0.5 mmol/L, T=298.15 K, t=12 h

Fig. 5 Adsorption of Th(IV) and U(VI) on IGO at a function of pH C(GO)=0.4 g/L, C(Th)=0.5 mmol/L, T=298.15 K, t=12 h; C(GO)=0.4 g/L, C(U)= 0.5 mmol/L, T=298.15 K, t=12 h

图6 U(VI)(a)和Th(IV)(b)在水溶液中形态分布模拟图

Fig. 6 The species of U(VI) (a) and Th(IV) (b) in solution

图7 IGO吸附Th(IV)和U(VI)动力学进程(a)和热力学进程(b) C(GO)=0.4 g/L,C(Th)=0.5 mmol/L, pH=3±0.05,T=298.15 K; C(GO)= 0.4 g/L,C(U)= 0.5 mmol/L, pH=4±0.05, T=298.15 K

Fig. 7 Effect of contact time (a) and temperature (b) on the Th(IV) and U(VI) adsorption on IGO C(GO)=0.4 g/L,C(Th)=0.5 mmol/L, pH=3±0.05,T=298.15 K; C(GO)= 0.4 g/L,C(U)= 0.5 mmol/L, pH=4±0.05, T=298.15 K

表4 氧化石墨烯吸附Th(IV)和U(VI)的热力学参数

Table 4 Thermodynamic parameters of Th(IV) and U(VI) adsorption on IGO

Temp./K		ΔH⁰/ (kJ•mol^-1)	ΔS⁰/ (J•mol^-1•K^-1)	ΔG⁰/ (kJ•mol^-1)
Th(IV)	300	5.43	92.05	-22.18
	308			-22.92
	318			-23.84
	328			-24.76
	338			-25.68
U(VI)	300	3.23	80.72	-20.98
	308			-21.62
	318			-22.43
	328			-23.24
	338			-24.05

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