Preparation of polyimide-reinforced lignocellulosic nanofibril aerogel and its oil-water separation performance

doi:10.11949/0438-1157.20240985

Abstract

Abstract:

Lignocellulosic nanofibril (LCNF) aerogels have the advantages of high porosity, low density, renewable and reusable raw materials, but their insufficient mechanical properties limit their application in the field of oil-water separation. To address this issue, LCNF/polyimide (PI) composite aerogels were created using freeze-drying and chemical vapor deposition. The results show that the strong hydrogen bond between PI and LCNF endowed aerogels with good mechanical and oil-water separation performance, with elasticity modulus ranging from 9.69 to 11.88 kPa and oil-absorption multiplicity ranging from 73.0 to 103.4 g·g^-1. Compared with M-LCNF aerogels, the elastic modulus of M-LCNF/PI aerogels increased by 1.459—2.015 times, and the adsorption capacity for a variety of organic solvents and oils increased by 1.6—21.0 g∙g^-1. M-LCNF/PI-1.00 aerogels maintained low density (8.66 g∙cm^-3), excellent hydrophobicity (water contact angle of 140.6°), good thermal stability (maximum decomposition rate temperature up to 363.1℃) and excellent thermal insulation performance of 0.04436 W∙m^-1∙K^-1. The adsorption of vacuum pump oil by M-LCNF/PI-1.00 was more consistent with a quasi-secondary kinetic model. The M-LCNF/PI-1.00 still retained 79.1% of the original adsorption capacity after 5 times of extrusion adsorption of anhydrous ethanol, showing good reusability and providing a new strategy for preparing high-performance oil-absorbing materials.

Key words: lignocellulosic nanofibril, polyimide, aerogel, separation, heat insulation, kinetic modeling, recycling

摘要：

木质纤维素纳米纤丝(LCNF)气凝胶具有高孔隙率、低密度、原料可再生及可重复利用等优点，但力学性能不足限制了其在油水分离领域的应用。通过冷冻干燥和化学气相沉积法制备了LCNF/聚酰亚胺(PI)复合气凝胶。结果表明，PI与LCNF之间的强氢键作用赋予了气凝胶良好的力学和油水分离性能，其弹性模量为9.69~11.88 kPa，吸油倍率为73.0~103.4 g∙g^-1。相较M-LCNF气凝胶，M-LCNF/PI气凝胶的弹性模量提升了1.459~2.015倍，吸油倍率提升了1.6~21.0 g∙g^-1。M-LCNF/PI-1.00气凝胶保持了低密度(8.66 g∙cm^-3)、优异的疏水性(水接触角达140.6°)、高热稳定性(最大分解速率温度达363.1℃)及良好的隔热性能(热导率0.04436 W∙m^-1∙K^-1)。M-LCNF/PI-1.00对真空泵油的吸附更符合准二级动力学模型。M-LCNF/PI-1.00挤压吸附无水乙醇5次后，仍保持原吸附倍率的79.1%，表现出良好的可重复使用性，为制备高性能吸油材料提供了新策略。

关键词: 木质纤维素纳米纤丝, 聚酰亚胺, 气凝胶, 分离, 隔热, 动力学模型, 循环利用

CLC Number:

TQ 353.9

Jiashun LI, Wang LI, Zuzeng QIN, Tongming SU, Xinling XIE, Hongbing JI. Preparation of polyimide-reinforced lignocellulosic nanofibril aerogel and its oil-water separation performance[J]. CIESC Journal, 2025, 76(5): 2169-2185.

李家顺, 李旺, 秦祖赠, 苏通明, 谢新玲, 纪红兵. 聚酰亚胺增强木质纤维素纳米纤丝气凝胶制备及其油水分离性能研究[J]. 化工学报, 2025, 76(5): 2169-2185.

Figures/Tables 17

Fig.1 Preparation process of LCNF/PI composite aerogel

Table 1 Composition of hydrophobic aerogels

样品	V_LCNF/ml	V_PI/ml	m_LCNF：m_PI
M-LCNF	10.00	0	—
M-LCNF/PI-0.25	9.75	0.25	39∶1
M-LCNF/PI-0.50	9.50	0.50	38∶2
M-LCNF/PI-0.75	9.25	0.75	37∶3
M-LCNF/PI-1.00	9.00	1.00	36∶4

Fig.2 Schematic diagram of the construction of aerogel

Fig.3 FTIR spectra of raw materials and aerogels

Fig.4 Macroscopic morphology and physical structure parameters of aerogel

Fig.5 SEM images of aerogels

Fig.6 Pore structure of raw materials and aerogels

Table 2 Pore structure parameters of aerogels

样品	比表面积/ (m²∙g^-1)	孔体积/ (cm³∙g^-1)	平均孔直径/ nm
LCNF	2.27	0.0091	32.49
PI	7.50	0.0335	28.61
M-LCNF	2.89	0.0065	16.74
M-LCNF/PI-1.00	26.29	0.0622	11.97

Fig.7 Mechanical properties of aerogels

Fig.8 Hydrophobic properties of aerogels

Fig.9 Thermal stability of aerogels

Table 3 Thermal parameters of aerogel

样品	最大分解速率温度/℃	最大分解速率/(%·℃^-1)	残留量/%	水含量/%
M-LCNF	362.5	-2.053	6.204	5.513
M-LCNF/PI-1.00	363.1	-1.970	6.590	5.644

Fig.10 Oil absorption properties of M-LCNF and M-LCNF/PI-1.00

Fig.11 Oil absorption rate and recycling performance of aerogels

Table 4 Kinetic parameters of vacuum pump oils adsorbed by M-LCNF/PI-1.00

q_e,exp/

(g·g^-1)

准一级动力学模型

准二级动力学模型

k₁/s^-1

q_e,cal/(g·g^-1)

r 12

k₂/(g·g^-1∙s^-1)

q_e,cal/(g·g^-1)

r 22

Table 4 Kinetic parameters of vacuum pump oils adsorbed by M-LCNF/PI-1.00

q_e,exp/

(g·g^-1)

准一级动力学模型

准二级动力学模型

k₁/s^-1

q_e,cal/(g·g^-1)

r 12

k₂/(g·g^-1∙s^-1)

q_e,cal/(g·g^-1)

r 22

79.36

0.01327

119.4

0.8406

4.637×10^-5

81.22

0.9795

Fig.12 Simulation of oil-water separation by M-LCNF/PI-1.00

Fig.13 Mechanism of oil-water separation of M-LCNF/PI-1.00 aerogel

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