Mesoporous Organic-inorganic Hybrid Siliceous Hollow Spheres: Synthesis and VOCs Adsorption

doi:10.15541/jim20210638

Abstract

Abstract:

Mesoporous organic-inorganic hybrid siliceous hollow spheres (MOSs) were successfully synthesized by co-condensation of tetraethylorthosilicate (TEOS) and 1, 2-bis(triethoxysilyl)ethane (BTSE) with reverse micelle as template under basic condition. Structure and property of the prepared samples were characterized by different methods. The MOSs was used for VOCs removal with commercial silica gel (SG) and activated carbon (AC) as references. It is found that the sample with initial BTSE/(BTSE+TEOS) molar ratio of 10% (MOS-10%) displays uniform hollow mesostructure with the highest static VOCs adsorption capacities (1.28 g·g^-1 n-hexane, 1.25 g·g^-1 toluene and 1.14 g·g^-1 92# gasoline), and the lowest water vapor adsorption capacity of 0.630 g·g^-1. Dynamic single component (n-hexane, toluene adsorption under dry condition or n-hexane adsorption under high humidity condition, 95% RH) adsorption results show that MOS-10% has the best breakthrough times, adsorption capacities, and hydrophobicity. For binary component (n-hexane and toluene) adsorption, MOS-10% preferred to adsorb n-hexane rather than adsorb toluene. The higher dynamic VOCs capacity of MOS is attributed to the cooperation of the introduced organic groups, surface area and pore volume. The MOSs with high VOCs removal capacity and excellent recyclability show great potential for VOCs adsorption.

Key words: mesoporous organic-inorganic hybrid siliceous hollow sphere, VOCs adsorption, stability, desorption

CLC Number:

O613

WANG Hongning, HUANG Li, QING Jiang, MA Tengzhou, HUANG Weiqiu, CHEN Ruoyu. Mesoporous Organic-inorganic Hybrid Siliceous Hollow Spheres: Synthesis and VOCs Adsorption[J]. Journal of Inorganic Materials, 2022, 37(9): 991-1000.

Figures/Tables 25

Fig. 1 TEM images of MOSs with different initial BTSE/ (BTSE+TEOS) molar ratios (a) MOS-0; (b) MOS-5%; (c) MOS-7.5%; (d) MOS-10%; (e) MOS-12.5%; (f) MOS-15%

Fig. 2 N2 sorption isotherms (a) and pore size distributions (b) of MOSs with different initial BTSE/(BTSE+TEOS) molar ratios (A) MOS-0; (B) MOS-5%; (C) MOS-7.5%; (D) MOS-10%; (E)MOS-12.5%; (F) MOS-15%. In (a), the Y-axis values of (B-F) are 300, 600, 800, 1000, and 1300 m2·g-1, respectively. In (b), the Y-axis values of (B-F) are 0.1, 0.4, 0.8, 1.0, 1.2, and 1.4 cm3·g-1, respectively

Table 1 Structural parameters of MOSs with different initial BTSE/(BTSE+TEOS) molar ratios

Sample	S_BET/ (m²·g^-1)	V_t/ (cm³·g^-1)	Pore size/ nm
MOS-0	591	0.721	2.5
MOS-5%	612	0.722	2.7
MOS-7.5%	612	0.776	2.8
MOS-10%	696	0.887	2.6
MOS-12.5%	655	0.873	2.7
MOS-15%	648	0.857	2.7

Fig. 3 FT-IR spectra of MOSs with different initial BTSE/ (BTSE+TEOS) molar ratios (A) MOS-0; (B) MOS-5%; (C) MOS-7.5%; (D) MOS-10%; (E) MOS- 12.5%; (F) MOS-15%; (G) CTAB

Fig. 4 XRD patterns of MOSs with different initial BTSE/ (BTSE+TEOS) molar ratios (A) MOS-0; (B) MOS-5%; (C) MOS-7.5%; (D) MOS-10%; (E) MOS- 12.5%; (F) MOS-15%

Fig. 5 TGA curves of MOSs with different initial BTSE/ (BTSE+TEOS) molar ratios (A) MOS-0; (B) MOS-5%; (C) MOS-7.5%; (D) MOS-10%; (E) MOS- 12.5%; (F) MOS-15%;

Fig. 6 Histograms of static VOCs (n-hexane, toluene and 92# gasoline) adsorption capacities (a, c, e) and desorption efficiencies (b, d, f) of different samples (A) MOS-0; (B) MOS-5%; (C) MOS-7.5%; (D) MOS-10%; (E) MOS-12.5%; (F) MOS-15%; (G) SG; (H) AC

Fig. 8 Breakthrough curves for n-hexane of SG (■), AC (●) and MOS-10% (▲) under dry condition for the (a) first time and (b) fifth time and comparison of the qe (c) and desorption efficiency (d) of 5 times

Fig. 9 Toluene breakthrough curves on MOS-10% under dry condition

Fig. 10 Yoon and Nelson model fitting for 5 times adsorption of n-hexane (a) and toluene (b) on MOS-10% under dry condition Colorful figures are available on website

Fig. 11 n-hexane breakthrough curves on MOS-10% under 95% RH

Fig. 12 Simultaneous breakthrough adsorption n-hexane (a) and toluene (b) on MOS-10% under dry condition, comparison of the equilibrium adsorption capacities (c) and desorption efficiency (d) for 5 times, respectively

Table S1 Structural parameters of AC and SG

Sample	S_BET/(m²·g^-1)	S_m/(m²·g^-1)	V_t/(cm³·g^-1)	V_m/(cm³·g^-1)	Pore size/nm
AC	1451	973	1.03	0.48	5.6
SG	430	15	0.710	0.010	6.9

Table S2 TGA results of different MOSs under nitrogen atmosphere in the range of 30-900 ℃ (10 ℃/min)

Sample	First event		Second event		Residual mass /%
Sample	(Tons-T_f )/℃	Δm/%	（Tons-T_f )/℃	Δm/%
MOS-0	30-200	1.7	200-900	8.1	90.2
MOS-5%	30-200	1.7	200-900	7.6	90.7
MOS-7.5%	30-200	1.9	200-900	12.6	85.5
MOS-10%	30-200	5.3	200-900	20.1	74.6
MOS-12.5%	30-200	1.5	200-900	7.9	90.6
MOS-15%	30-200	1.4	200-900	9.0	89.6

Table S3 Water vapor adsorption capacities, desorption efficiencies and the densities of surface hydroxyl groups of different samples

Sample	Adsorption		Desorption		-OH/(×10²⁰, g^-1)
Sample	Average/(g·g^-1)	STDE^a/%	Average/%	STDE^a/%	-OH/(×10²⁰, g^-1)
MOS-0%	0.903	0.0168	99.4	0.205	3.11
MOS-5%	0.667	0.0177	99.3	0.329	2.35
MOS-7.5%	0.656	0.0165	99.4	0.283	2.31
MOS-10%	0.630	0.0137	99.4	0.134	2.23
MOS-12.5%	0.697	0.0156	99.4	0.230	2.44
MOS-15%	0.697	0.0136	99.4	0.365	2.45
SG	0.433	0.0984	97.7	0.867	1.72
AC	0.482	0.0305	93.5	11.1	1.77

Table S4 Comparison of dynamic n-hexane adsorption parameters on different samples for 5 times under dry condition

Sample	t_b/min	t_e/min	q_e/(g·g^-1)	Desorption efficiency/%
MOS-10%-1st	50	104	1.23	99.8
MOS-10%-2nd	48	102	1.20	99.5
MOS-10%-3rd	46	100	1.19	99.4
MOS-10%-4th	48	102	1.22	99.6
MOS-10%-5th	48	102	1.21	99.2
SG-1st	16	72	0.361	98.9
SG-2nd	14	70	0.321	97.5
SG-3rd	14	70	0.334	98.7
SG-4th	12	72	0.321	98.6
SG-5th	10	72	0.343	97.6
AC-1st	38	50	0.574	73.7
AC-2nd	28	44	0.465	83.6
AC-3rd	28	42	0.461	90.9
AC-4th	26	44	0.452	98.6
AC-5th	24	42	0.458	97.2

Table S5 Comparison of dynamic toluene adsorption parameters on MOS-10% for 5 times under dry condition

	t_b/min	t_e/min	q_e/(g·g^-1)	Desorption efficiency/%
1st	48	100	1.21	99.7
2nd	46	98	1.18	99.5
3rd	44	96	1.17	99.3
4th	46	98	1.18	99.4
5th	46	98	1.18	99.1

Table S6 Structural parameters of MOS-10% and AC before and after 5 times dynamic n-hexane adsorption under dry condition

Sample	S_BET/(m²·g^-1)	S_m/(m²·g^-1)	V_t/(cm³·g^-1)	V_m/(cm³·g^-1)	Pore size/nm
MOS-10%	696	0	0.887	0	2.64
MOS-10%-5th	638	0	0.830	0	2.64
AC	1654	652	1.06	0.48	5.58
AC-5th	1310	395	0.880	0.38	5.51

Table S7 Simulation parameters of 5 times dynamic n-hexane and toluene adsorption on MOS-10% under dry condition

	n-hexane			Toluene
	τ₀/min	K׳/min^-1	R²	τ₀/min	K׳/min^-1	R²
1st	63.1	0.150	0.984	58.4	0.0948	0.979
2nd	61.3	0.172	0.990	52.8	0.105	0.977
3rd	56.7	0.174	0.979	51.5	0.114	0.987
4th	57.1	0.169	0.986	54.1	0.111	0.978
5th	58.9	0.165	0.984	54.2	0.110	0.982

Table S8 Dynamic n-hexane adsorption parameters on MOS-10% for 5 times under 95% RH

	t_b/min	t_e/min	q_e,hexane /g·g^-1	q_e,t /g·g^{-1 adsorbent}	q_e,_water/g·g^{-1 adsorbent}	q_e,hexane/ q_e,_water	Desorption efficiency /%
1st	46	100	1.23	1.23	0.006	205	99.6
2nd	44	98	1.20	1.20	0.003	400	99.7
3rd	42	96	1.19	1.19	0.006	199	99.6
4th	42	96	1.21	1.21	0.003	404	99.4
5th	44	98	1.17	1.20	0.008	147	99.2

Table S9 Comparison of simultaneous adsorption n-hexane and toluene parameters on MOS-10% for 5 times under dry condition

	Dynamic adsorption capacity, q_e /(g·g^-1)
	Single component		Bi-component
	n-hexane	Toluene	n-hexane	Toluene	Total VOCs
1st	1.23	1.21	0.642	0.569	1.21
2nd	1.20	1.18	0.631	0.547	1.18
3rd	1.19	1.17	0.613	0.532	1.15
4th	1.22	1.18	0.607	0.550	1.16
5th	1.21	1.18	0.628	0.547	1.18

Fig. S1 N2 adsorption-desorption isotherms (a) and pore size distributions (b) of AC and SG

Fig. S2 Relationship between VOCs adsorption capacities and structure parameters of different samples (A) MOS-0; (B) MOS-5%; (C) MOS-7.5%; (D) MOS-10%; (E) MOS- 12.5%; (F) MOS-15%; (G) SG; (H) AC

Fig. S3 N2 adsorption-desorption isotherms (a) and pore size distributions (b) of MOS-10% and AC, respectively

References 28

[1]	ZHAO X S, MA Q, LU G Q M. VOC removal: comparison of MCM-41 with hydrophobic zeolites and activated carbon. Energ. Fuel, 1998, 12(6): 1051-1054. DOI URL
[2]	ZHANG G, FEIZBAKHSHAN M, ZHENG S, et al. Effects of properties of minerals adsorbents for the adsorption and desorption of volatile organic compounds (VOC). Appl. Clay Sci., 2019, 173: 88-96.
[3]	TRAN THANH T, MANH TRUNG T, FELLER J F, et al. Graphene and metal organic frameworks (MOFs) hybridization for tunable chemoresistive sensors for detection of volatile organic compounds (VOCs) biomarkers. Carbon, 2020, 162: 662-662.
[4]	LIU S, PENG Y, YAN T, et al. Modified silica adsorbents for toluene adsorption under dry and humid conditions: impacts of pore size and surface chemistry. Langmuir, 2019, 35(27): 8927-8934. DOI URL
[5]	WANG X, HE Y, LIU C, et al. A controllable asymmetrical/ symmetrical coating strategy for architectural mesoporous organosilica nanostructures. Nanoscale, 2016, 8(28): 13581-13588. DOI URL
[6]	SUN Y, CHEN M, WU L. Controllable synthesis of hollow periodic mesoporous organosilica spheres with radial mesochannels and their degradable behavior. J. Mater. Chem. A, 2018, 6(26): 12323-12333. DOI URL
[7]	BATONNEAU-GENER I, YONLI A, TROUVE A, et al. Tailoring the hydrophobic character of mesoporous silica by silylation for VOC removal. Sep. Sci. Technol., 2010, 45(6): 768-775. DOI URL
[8]	DOU B, HU Q, LI J, et al. Adsorption performance of VOCs in ordered mesoporous silicas with different pore structures and surface chemistry. J. Hazard. Mater., 2011, 186(2/3): 1615-1624. DOI URL
[9]	ZHANG W, QU Z, LI X, et al. Comparison of dynamic adsorption/ desorption characteristics of toluene on different porous materials. J. Environ. Sci., 2012, 24(3): 520-528. DOI URL
[10]	HARTMANN M, BISCHOF C. Mechanical stability of mesoporous molecular sieve MCM-48 studied by adsorption of benzene, n-heptane, and cyclohexane. J. Phys. Chem. B, 1999, 103(30): 6230-6235. DOI URL
[11]	YANG K, SUN Q, XUE F, et al. Adsorption of volatile organic compounds by metal-organic frameworks MIL-101: Influence of molecular size and shape. J. Hazard. Mater., 2011, 195: 124-131.
[12]	HU Q, LI J J, HAO Z P, et al. Dynamic adsorption of volatile organic compounds on organofunctionalized SBA-15 materials. Chem. Eng. J., 2009, 149(1/2/3): 281-288. DOI URL
[13]	KUBO S, KOSUGE K. Salt-induced formation of uniform fiberlike SBA-15 mesoporous silica particles and application to toluene adsorption. Langmuir, 2007, 23(23): 11761-11768. DOI URL
[14]	QIN Y, WANG Y, WANG H, et al. Effect of morphology and pore structure of SBA-15 on toluene dynamic adsorption/desorption performance. 4th International Symposium on Environmental Science and Technology (ISEST), Dalian, 2013:366-371.
[15]	LIU S, CHEN J, PENG Y, et al. Studies on toluene adsorption performance and hydrophobic property in phenyl functionalized KIT-6. Chem. Eng. J., 2018, 334: 191-197.
[16]	DOU B, LI J, HU Q, et al. Hydrophobic micro/mesoporous silica spheres assembled from zeolite precursors in acidic media for aromatics adsorption. Micropor. Mesopor. Mat., 2010, 133(1/2/3): 115-123. DOI URL
[17]	WANG H, TANG M, HAN L, et al. Synthesis of hollow organosiliceous spheres for volatile organic compound removal. J. Mater. Chem. A, 2014, 2(45): 19298-19307. DOI URL
[18]	WANG H, TANG M, ZHANG K, et al. Functionalized hollow siliceous spheres for VOCs removal with high efficiency and stability. J. Hazard. Mater., 2014, 268: 115-123.
[19]	WANG H, RONG X, HAN L, et al. Controlled synthesis of hexagonal mesostructure silica and macroporous ordered siliceous foams for VOCs adsorption. RSC Adv., 2015, 5(8): 5695-5703. DOI URL
[20]	WANG J, FENG S, SONG Y, et al. Synthesis of hierarchically porous carbon spheres with yolk-shell structure for high performance supercapacitors. Catal. Today, 2015, 243: 199-208.
[21]	ZHANG C, WU C, HAN W, et al. Controllable synthesis of multi-morphological hollow mesoporous SiO₂ and adsorption reduction of Cu²⁺ by its composites. Chem. J. Chinese U., 2019, 40(11): 2412-2418.
[22]	王小文, 胡芸, 黄晶. 等. 疏水性分子筛对焦化废水生物处理尾水的吸附过程解析. 环境科学学报, 2012, 3(2): 2058-2065.
[23]	LIU W, MA N, LI S, et al. A one-step method for pore expansion and enlargement of hollow cavity of hollow periodic mesoporous organosilica spheres. J. Mater. Sci., 2017, 52(5): 2868-2878. DOI URL
[24]	GAO M, HAN S, HU Y, et al. A pH-driven molecular shuttle based on rotaxane-bridged periodic mesoporous organosilicas with responsive release of guests. RSC Adv., 2016, 6(33): 27922-27932. DOI URL
[25]	MATYSIAK W, TANSKI T. Analysis of the morphology, structure and optical properties of 1D SiO₂ nanostructures obtained with Sol-Gel and electrospinning methods. Appl. Surf. Sci., 2019, 489: 34-43.
[26]	CHEN J, SUN C, HUANG Z, et al. Fabrication of functionalized porous silica nanocapsules with a hollow structure for high performance of toluene adsorption-desorption. ACS Omega, 2020, 5(11): 5805-5814. DOI URL
[27]	YUAN W W, YUAN P, LIU D, et al. A hierarchically porous diatomite/silicalite-1 composite for benzene adsorption/desorption fabricated via a facile pre-modification in situ synthesis route. Chem. Eng. J., 2016, 294: 333-342.
[28]	RAJABI H, MOSLEH M H, PRAKOSO T, et al. Competitive adsorption of multicomponent volatile organic compounds on biochar. Chemosphere, 2021, 283: 131288.