共挤出法制备双层中空纤维陶瓷复合膜

doi:10.15541/jim20200182

摘要/Abstract

摘要：

中空纤维陶瓷膜具有装填密度高, 传质阻力低, 使用寿命长等优点, 被广泛用于膜分离领域。高度非对称结构的中空纤维膜有利于同时实现高通量与高截留率, 本研究采用共挤出法制备双层中空纤维陶瓷复合膜, 内外层纺丝液分别掺杂平均粒径为1 μm和300 nm的α-Al₂O₃粉体。系统考察了内层纺丝液TiO₂掺杂量、外层纺丝液Al₂O₃/聚醚砜(PESf)质量比和煅烧温度对膜的结构与性能的影响。结果表明, 在内层纺丝液TiO₂掺杂量为2wt%, 外层纺丝液Al₂O₃/PESf质量比为5.60, 烧结温度为1350 ℃的最优条件下, 中空纤维膜断裂负荷为24 N、平均孔径为0.15 μm、去油率为97.5%。

关键词: 双层中空纤维, 共挤出法, TiO₂, Al₂O₃/PESf

Abstract:

Hollow fiber ceramic membranes have been widely accepted in membrane separation due to their advantages of high packing density, low transfer resistance and long-period operation. Fabrication of highly-asymmetric hollow fiber membrane is helpful to achieve high flux as well as high rejection simultaneously. In this work, dual-layer hollow fiber ceramic composite membranes were prepared by the co-extrusion method. The inner and outer suspensions were doped with α-Al₂O₃ powders with average particle sizes of 1 μm and 300 nm respectively. Effects of TiO₂ content in inner suspension, Al₂O₃/polyether sulfone (PESf) mass ratio of outer suspension and calcination temperature on structure and properties of membrane were investigated extensively. When the TiO₂ content was 2wt% in inner suspension, the Al₂O₃/PESf mass ratio was 5.60 in outer suspension and the sintering temperature was 1350 ℃, the hollow fiber membrane got the optimum performance, with fracture load of 24 N, average pore size of 0.15 μm, and oil rejection of 97.5%.

Key words: dual-layer hollow fiber, co-extrusion, TiO₂, Al₂O₃/PESf

中图分类号:

TQ174

刘金云, 张玉亭, 洪周, 刘华, 王圣贤, 顾学红. 共挤出法制备双层中空纤维陶瓷复合膜[J]. 无机材料学报, 2020, 35(12): 1333-1339.

LIU Jinyun, ZHANG Yuting, HONG Zhou, LIU Hua, WANG Shengxian, GU Xuehong. Fabrication of Dual-layer Hollow Fiber Ceramic Composite Membranes by Co-extrusion[J]. Journal of Inorganic Materials, 2020, 35(12): 1333-1339.

图/表 11

表1 双层中空纤维膜纺丝液组成/wt%

Table 1 Suspension composition of dual-layer hollow fiber membrane/wt%

Suspension composition	Inner layer	Outer layer
Solvent (NMP)	33.34	37.81
Al₂O₃ (1 μm)	55.35	/
Al₂O₃ (300 nm)	/	49.15
Polymer (PESf)	9.77	11.34
Additive (PVP)	1.54	1.70

图1 双层中空纤维膜和单层中空纤维膜SEM照片

Fig. 1 SEM images of dual-layer hollow fiber and single-layer hollow fiber Cross-section morphologies of (a, b) dual-layer hollow fiber precursor, (c, d) dual-layer hollow fiber, (e, f) 1 μm single-layer hollow fiber; SEM images of the surface morphology: (g) dual-layer hollow fiber, (h) 1 μm single-layer hollow fiber

表2 单层与双层中空纤维膜的性能比较

Table 2 Comparison of properties between single-layer and dual-layer hollow fiber membranes

Property	η/%	Fracture load/N	Pure water flux/(m³?m^-2?h^-1)	Porosity/%	Average pore size/μm	R_TOC/%
Single-layer (1 μm)	13.0	9	3.52	51.57	0.70	95.4
Single-layer (300 nm)	16.9	19	0.86	48.20	0.13	98.4
Dual-layer (1 μm/300 nm)	14.3	12	2.30	50.89	0.24	97

图2 不同TiO2掺杂量下双层中空纤维膜的XRD图谱

Fig. 2 XRD patterns of dual-layer hollow fiber membranes with different TiO2 contents

表3 TiO2掺杂量对双层中空纤维膜性能的影响

Table 3 Influence of TiO2 content on properties of dual-layer hollow fiber membranes

TiO₂ content/wt%	η/%	Fracture load/N	Pure water flux/ (m³?m^-2?h^-1)	Porosity/%	Average pore size/μm
0	14.3	12	2.30	50.89	0.240
2	14.9	24	1.65	48.05	0.152
5	14.9	22	1.32	49.97	0.147
10	15.2	20	1.21	46.43	0.150
15	15.3	19	1.12	45.68	0.145
20	16.3	17	0.91	43.90	0.141

图3 不同外层纺丝液Al2O3/PESf质量比的双层中空纤维膜SEM照片

Fig. 3 SEM images of dual-layer hollow fiber membranes with different Al2O3/PESf mass ratios in outer suspension (a) 2.75; (b) 4.33; (c) 5.60; (d) 7.50; (e) 13.3

表4 外层纺丝液Al2O3/PESf质量比对双层中空纤维膜性能的影响

Table 4 Influence of Al2O3/PESf mass ratio in outer suspension on properties of dual-layer hollow fiber membranes

Al₂O₃/PESf	Outer suspension viscosity/cP	Fracture load/N	Pure water flux/ (m³?m^-2?h^-1)	Porosity/ %	Mean pore size/μm	R_TOC/%
2.75	7320	21	1.99	49.90	0.180	97.3
4.33	8580	22	1.10	52.26	0.175	97.5
5.60	9720	23	1.41	53.91	0.130	97.5
7.50	11020	25	1.08	53.31	0.125	97.6
13.30	58300	23	0.48	52.54	0.115	97.8

图4 外层纺丝液Al2O3/PESf质量比对双层中空纤维膜孔径分布的影响

Fig. 4 Influence of Al2O3/PESf mass ratio in outer suspension on pore size distribution of dual-layer hollow fiber membranes

图5 不同温度烧结的双层氧化铝中空纤维膜的SEM照片

Fig. 5 SEM images of dual-layer hollow fiber membrane of alumina sintered at different temperatures (a)1250 ℃, (b)1300 ℃, (c) 1350 ℃, (d)1400 ℃

表5 不同烧结温度对双层中空纤维性能的影响

Table 5 Influence of sintering temperature on the properties of dual-layer hollow fiber membranes

Temperature/℃	Fracture load/N	Pure water flux/(m³?m^-2?h^-1)	Porosity/%	Average pore size/μm	R_TOC/%
1250	11	3.23	61.97	0.235	96.7
1300	15	2.34	55.62	0.199	97.4
1350	24	1.20	48.88	0.150	97.5
1400	37	0.26	40.33	0.126	98.3

表6 不同中空纤维陶瓷膜性能比较

Table 6 Comparison in properties of different hollow fiber ceramic membranes

Membranes	Sintering temperature/℃	Average pore size/μm	Pure water flux/ (m³?m^-2?h^-1)	Bending strength/MPa	Fracture load/N	Ref.
Single-Channel Al₂O₃ hollow fiber	1455	0.10	0.664	88.2	-	[28]
Single-Channel Al₂O₃ hollow fiber	1500	0.75	1.280	85.8	-	[29]
4-Channel Al₂O₃ hollow fiber	1500	1.20	2.710	-	22	[25]
7-Channel Al₂O₃ hollow fiber	1350	0.183	1.070	-	14	[30]
7-Channel YSZ/Al₂O₃ hollow fiber	1400	230.00	1.640	-	14	[31]
4-Channel 1 μm/300 nm Al₂O₃ hollow fiber	1350	0.15	1.260	-	24	This work

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