Microscopic Insights into pH-dependent Adsorption of Cd(II) on Molybdenum Disulfide Nanosheets

Lijia DONG; Xiaojie GUO; Xue LI; Chaogui CHEN; Yang JIN; Alsaedi AHMED; Hayat TASAWAR; Qingzhou ZHAO; Guodong SHENG

doi:10.15541/jim20190381

Journals >Journal of Inorganic Materials >Volume 35 >Issue 3 >Page 293 > Article

Journal of Inorganic Materials
Vol. 35, Issue 3, 293 (2020)

Microscopic Insights into pH-dependent Adsorption of Cd(II) on Molybdenum Disulfide Nanosheets

Lijia DONG¹, Xiaojie GUO², Xue LI¹, Chaogui CHEN¹, Yang JIN^1、*, Alsaedi AHMED³, Hayat TASAWAR^3、4, Qingzhou ZHAO⁵, and Guodong SHENG^6、*

Author Affiliations

¹School of Life Science, Shaoxing University, Shaoxing 312000, China

²College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China

³NAAM Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia

⁴Department of Mathematics, Quaid-I-Azam University, Islamabad 44000, Pakistan

⁵College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China

⁶College of Chemistry and Chemical Engineering, Shaoxing Univeristry, Shaoxing 312000, China

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DOI: 10.15541/jim20190381 Cite this Article

Lijia DONG, Xiaojie GUO, Xue LI, Chaogui CHEN, Yang JIN, Alsaedi AHMED, Hayat TASAWAR, Qingzhou ZHAO, Guodong SHENG. Microscopic Insights into pH-dependent Adsorption of Cd(II) on Molybdenum Disulfide Nanosheets[J]. Journal of Inorganic Materials, 2020, 35(3): 293 Copy Citation Text

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. SEM image (a), TEM image (b), XRD pattern (c), FT-IR spectrum (d), Zeta potentials (e), and height cross-section profile (inset) and corresponding AFM image (f) of MoS₂ samples

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SEM image (a), EDX spectra, and corresponding elemental maps (b) for MoS2 nanosheets

. SEM image (a), EDX spectra, and corresponding elemental maps (b) for MoS₂ nanosheets

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. Effects of pH and ionic strength on Cd(II) adsoprtion onto MoS₂ nanosheets

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. Cd(II) adsorption on MoS₂ nanosheets as a function of contact time (a) and the fitting of pseudo-first-order kinetic model (b), pseudo-second-order kinetic model (c) and intra-particle diffusion model (d) at different pH

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. Adsorption isotherms (a) and fitting results of Langmuir (b) and Freundlich (c) sorption isotherms of Cd(II) sorption on MoS₂ at different temperatures and different pH

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. Linear plots of lnK_d versus C_e for Cd(II) at different temperatures and different pH(a), and linear regression plots of lnK^θversus 1/T for Cd(II) sorption on MoS₂ at different pH(b)

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. Normalized, background-subtracted and k³-weighted EXAFS spectra (a) and corresponding RSF magnitudes and imaginary parts (b) of Cd reference samples

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. EXAFS spectra (a) and the corresponding RSF magnitudes and imaginary parts (b) of Cd reference samples

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. Schematic representation of possible sorption sites on the surface of MoS₂

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	pH	q_e/(mg·g^-1)	k₁/h^-1	R²
	4.55	33.023	0.059	0.9896
Pseudo-first-order model	5.34	23.903	0.053	0.9069
	6.12	41.777	0.074	0.9835
	pH	q_e/(mg·g^-1)	k₂/(g·mg^-1·h^-1)	R²
	4.55	35.638	0.038	0.9869
Pseudo-second-order model	5.34	42.230	0.078	0.9978
	6.12	52.659	0.077	0.9986
	pH	C/(mg·L^-1)	k_i/(g·mg^-1·h^-1/2)	R²
	4.55	19.985	2.628	0.942
Intra-particle diffusion model	5.34	32.500	1.877	0.987
	6.12	39.759	3.004	0.980

Table 1.

Parameters of kinetic models for the adsorption of Cd(II) on MoS₂as a function of pH

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	pH	T/K	K_F/(mg^1-ⁿ·Lⁿ∙g^-1)	n	R²
Freundlich equation	4.55	293	1.624	1.440	0.887
		313	4.256	1.160	0.881
		333	7.461	1.052	0.904
	5.34	293	9.363	0.899	0.801
		313	21.627	0.603	0.907
		333	32.734	0.526	0.939
	6.12	293	17.298	0.650	0.812
		313	28.054	0.542	0.935
		333	34.119	0.499	0.919
	pH	T/K	q_max/(mg∙g^-1)	K_L/(L∙mg^-1)	R²
Langmuir equation	4.55	293	0.040	64.516	0.299
		313	0.016	305.157	0.069
		333	0.001	754.717	0.017
	5.34	293	0.036	262.536	0.162
		313	0.132	149.276	0.918
		333	0.236	147.580	0.978
	6.12	293	0.114	140.449	0.759
		313	0.172	152.022	0.974
		333	0.224	151.492	0.978

Table 1.

Parameters of Langmuir and Freundlich equations for the sorption of Cd(II) onto MoS₂ at different temperatures and different pH

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pH	T	ΔG^θ/(kJ/mg)	ΔS^θ/(J∙mg^-1· K^-1)	ΔH^θ/(kJ∙mg^-1)
4.55	293	-19.291	143.66592	22.803
	313	-22.333		22.635
	333	-25.022		22.818
5.34	293	-22.331	147.73978	20.957
	313	-25.312		20.930
	333	-28.239		20.958
6.12	293	-23.412	121.71696	12.251
	313	-25.986		12.111
	333	-28.267		12.265

Table 2.

Parameters of thermodynamics for adsorption of Cd(II) onto MoS₂ at 3 temperatures and different pH

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Sample conditions	shells	R/nm	CN	σ²/nm²
Cd(NO₃)₂(aq)	Cd-O	0.233(4)	6.2(3)	0.0010(1)
Cd(OH)₂	Cd-O	0.238(2)	6.1(4)	0.0014(5)
Cd(OH)₂	Cd-Cd	0.359(3)	5.9(4)	0.0032(5)
CdS	Cd-S	0.259(1)	4.1(3)	0.0024(2)
pH 3.56, sorption	Cd-S	0.255(2)	3.9(5)	0.0027(3)
pH 6.48, sorption	Cd-S	0.257(1)	3.8(4)	0.0023(5)
pH 9.57, sorption	Cd-O	0..34(5)	5.9(6)	0.0016(3)
pH 9.57, sorption	Cd-Cd	0.357(3)	5.6(4)	0.0037(2)