INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
IF 3.573
Yuan Li,Rui Yang,Rui Zhang,Bing Cao,Pei Li
Insoluble polyimides (PIs) are ideal materials for organic nanofiltration membranes. However, the membranes have to be prepared using soluble polyamic acid and then converted to PIs via chemical or thermal imidization. The low imidization degree of chemical imidization makes PI membranes easily hydrolyzed in water. On the contrary, a thermally imidized PI has a higher imidization degree and better chemical stability. However, the high imidization temperature (300 °C) often induces pore collapsing, membrane brittleness, and low flux. To overcome the drawbacks of thermal imidization, we developed a dual-coagulant bath method to prepare macrovoid-free poly(4,4′-oxydiphenylene pyromellitimide) membranes. The size, distribution, and connectivity of membrane pores were well controlled by tuning the compositions of the dope and the first coagulant. A series of thermally imidized flat-sheet PI membranes with macrovoid-free structures were prepared. These membranes exhibited good mechanical properties and stable nanofiltration performance in N,N-dimethylformamide solvent. This implied that the membranes were qualified for the separation process under harsh organic environments.
研究领域:
材料科学
·
分离工程
✓ 已验证
产品关联
DOI
高影响因子
BIOMACROMOLECULES
·
2023
·
IF 6.2
Jia Wei,Binqi Wang,Hanmeng Yuan,Zhaoqing Kang,Hongshuai Gao,Yi Nie
Regenerated cellulose fiber (RCF) is an environmentally friendly material with outstanding mechanical properties and recyclability, which has been used in a large number of applications. However, during the spinning process using ionic liquids (ILs) as solvents, the dissolved cellulose continues to degrade and even produces degradation products such as glucose, which can enter the recycled solvent and coagulation bath. The presence of glucose can seriously affect the performance of the produced RCFs and hinder their applications, so it has become critical to clarify the regulation and mechanism of this process. In this study, 1-ethyl-3-methylimidazolium diethyl phosphate ([Emim]DEP) with different glucose contents was selected to dissolve wood pulp cellulose (WPC) and obtained RCFs in different coagulation baths. The effect of glucose content in spinning solution on fiber spinnability was investigated by rheological analysis, and the influence of coagulation bath composition and glucose content on the morphological characteristics and mechanical properties of the RCFs was also studied in depth. The results indicated that the morphology, crystallinity, and orientation factor of RCFs were influenced by the presence of glucose in the spinning solution or coagulation bath, resulting in corresponding changes in mechanical properties, which can provide practical reference and guidance for the industrial production of new type fiber.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Research and Technology-JMR&T
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2020
·
IF 5.289
Jian Sun,Shaofeng Li,Zhilin Ran,Yingxue Xiang
Fe 3 O 4 @TiO 2 magnetic photocatalytic particles were synthesized and characterized. A composite PVDF separation membrane blended with Fe 3 O 4 @TiO 2 particles was prepared by the phase inversion method. The main purpose was to explore the effect of magnetic fields on the performance of membranes during coagulation bath. The structure characterization, permeability, interception ability, and anti-pollution performance of inorganic particle blend membranes were then tested. Results showed that magnetic field coagulation baths have little effect on the pore structure and hydrophilicity of the membrane surface. When the liquid membranes was condensed under a magnetic field, the magnetic photocatalytic particles could migrate at a greater rate to the surface of the membrane. Through performance tests of the PVDF modified membranes, it was found that a magnetic coagulation bath could promote more Fe 3 O 4 @TiO 2 to aggregate on the surface of the membrane, which led to the blend membrane formed under the magnetic coagulation bath had better antifouling performance against humic acid solution under ultraviolet light irradiation. Membranes with 0.5 wt% magnetic photocatalytic particles in a magnetic field coagulation bath performed best. When filtered under the condition of ultraviolet light, its pure water flux was 1752 L/(m 2 h), and the rejection rate of 20 mg/L humic acid solution was 67.17%. The flux attenuation before and after filtration was 38.84%, the flux recovery rate was 91.10%, and the irreversible pollution index was only 8.90%.
研究领域:
材料科学
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环境工程
·
膜技术
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Xin Liu,Zhujun Zou,Dong Wang,Dongyu Du,Zhuo Li,Weiyi Li
A key to the sustainable development of membrane technology is the green fabrication of biopolymer membranes, whose filtration performance is comparable to that made from petroleum-based polymers. In this study, chitosan membranes were fabricated via wet precipitation of the alkaline dope; both the composition and temperature of the coagulation bath were regulated to optimize the filtration performance for ultrafiltration. It is revealed by comparing the morphological characterization with the filtration-performance evaluation that the use of pure ethanol as the coagulant at a subzero temperature would be in favor of the formation of a laminated substructure, which can enhance the water permeance not at the cost of decreasing the rejection of micron-sized particles and macromolecules. Optical coherence tomography (OCT) was employed to in-situ characterize the film formation in an effort to understand how the variation in coagulating conditions could change the geometrical and topological characteristics of the resulting membrane. The OCT-based characterization highlights the key role of the Liesegang phenomenon in forming the hierarchical substructures, while resolving the synergistic effects emanating from the ethanol-induced film shrinkage and the structural preservation in the subzero environment.
研究领域:
材料科学
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环境科学
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生物技术
✓ 已验证
产品关联
DOI
高影响因子
PETROLEUM SCIENCE AND TECHNOLOGY
·
2022
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IF 1.695
Xiaocan Zhang,Shuangyong Qing,Xuesong Li,Tiantian Li,Ying Zhang
In order to prepare high-performance natural gas dehydration membranes, effects of coagulation bath were studied during a non-solvent-induced phase separation (NIPS) process. Specifically, concentrations of N-methyl-2-pyrrolidone (NMP) and polyethylene glycol 1000 (PEG 1000) were investigated respectively on the structure and properties of polyetherimide (PEI)-PEG1000 blend membranes. Studies have shown that both coagulation baths, namely, NMP and PEG1000, can affect membrane structures and improve the overall separation performance of the blend membranes. The presence of NMP in the coagulation bath formed a dissolution equilibrium with the membrane to modify the membrane structure and slow down the rate of phase separation, and the separation coefficient was 151.8 with 8% NMP. With the increase of PEG1000 concentration in the coagulation bath, the hydrophilicity of the membrane enhanced, and a separation coefficient of 585.7 was reached at 10% PEG1000.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2024
·Vol. 34
·期 28
·2400197
·
IF 18.5
Xu Zhao,Derui Kong,Jinlong Tao,Na Kong,Pablo Mota-Santiago,Peter A. Lynch,Yanqiu Shao,Jizhen Zhang
Carbon nanotubes (CNTs) are promising blocks for building advanced yarns with unique structural and functional attributes. However, the complexity of fabrication and high cost has hindered the widespread adoption of CNT yarns. In this study, a rapid and continuous twisting wet spun yarn strategy to produce highly densified CNT yarns is presented. The method involves effectively dispersing CNTs in the surfactant dispersion, swiftly removing the surfactant in the coagulation bath and twisting treatment to effectively improve the density of yarn and the orientation of CNT. Detailed characterizations on the influence of each spinning conditions reveal that twisting treatment significantly enhances the packing density of yarns, improves the orientation of CNTs, and mitigates the impact of impurities on conductivity. The resulting CNT yarns exhibit a remarkable tensile strength of 600 MPa, a Young's modulus of ≈40 GPa, and a high conductivity of 8990 S cm −1 . When utilized as a yarn heater, the CNT yarn demonstrates an ultra-fast electrothermal response of over 1000 °C s −1 at a low operating voltage of 5 V. Impressively, the mechanical properties of CNT yarns show good stability during heating. This study provides a perspective of structural engineering for the large-scale preparation of high-performance CNT yarns.
研究领域:
材料科学
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纳米技术
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纺织工程
·
碳材料
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2022
·Vol. 139
·期 20
·52148
·
IF 3.057
Juan Li,Guijing Chen,Shanshan Luo,Huixia Pang,Chengtao Gao,Shaowen Huang,Shan Liu,Shuhao Qin
In this study, styrene-maleic anhydride copolymer/chlorinated polyvinyl chloride composite membranes were prepared via a non-solvent induced phase separation technique. Different porous morphologies of the composite membranes were obtained by controlling the temperature of coagulation bath water. With the coagulation bath temperature increasing, the porous morphology of membrane surface changed from co-continuous pores to isolated-round-pores, and its evolution mechanism was elaborated. The average pore size of membranes surface increased from 17.27 to 48.72 nm, the pure water flux increased from 225.50 to 624.47 L m −2 h −1 , and the rejection rate of Congo red and bovine serum albumin declined gradually with the increase of coagulation bath temperature, but the NaCl rejection was less than 1.0%. The surface segregation behavior of anhydride groups was affected by the phase separation process, which in turn affects the anti-fouling performance of membranes. The composite membranes obtained at the coagulation bath temperature of 20 and 30°C had large surface segregation of anhydride groups and excellent anti-fouling performance. The water flux recovery rate is higher than 90% and the irreversible pollution decline rate is about 5.0%. Meanwhile, the obtained membranes, especially the membrane fabricated at a coagulation bath temperature of 0°C, has good dye/NaCl salt separation performance and can be used for the pretreatment of textile wastewater.
研究领域:
材料科学
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膜技术
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2020
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IF 2.87
Panpan Zhang,Ke Zhang,Xi Chen,Shuliang Dou,Jiupeng Zhao,Yao Li
In this work, the effect of coagulation bath temperature in different solvent systems [1,4-butyrolactone (GBL)/N,N-dimethylacetamide (DMAC)] on the structure and dielectric properties of polyimide (PI) films was investigated for the first time. The solubility parameter was introduced to explain the formation process of porous PI films. The results showed that the changed tendency of the dielectric constant versus temperature is opposite for the single-solvent system and cosolvent system. For a single DMAC and GBL solvent, the dielectric constants of the films decreased with increasing temperature. In contrast, the dielectric constants increased with the increase in temperature for the GBL/DMAC cosolvent system. Moreover, the measured porosities were applied to estimate the dielectric constants of the PI films. This showed that the porosity increased with increasing temperature for a single-solvent system, while it decreased for a cosolvent system. Scanning electron microscopy images suggested that the variation trends are derived from the different influences of the temperature on the structure and morphology. Thus, this study reveals the effect of coagulation bath temperature on the structure and dielectric properties of porous PI films and provides the guidance for the design and optimization of architectures for high-performance porous films.
研究领域:
材料科学
·
高分子化学
·
电气工程
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2024
·Vol. 141
·期 30
·e55687
·
IF 2.7
Yiwei Zhai,Qianru Kang,Fangbo Zhao,Hongxu Chen,Junqing Li,Hee-Deung Park
In this paper, the effect of the composition of a nonsolvent bath on the physicochemical properties of the polyvinylidene fluoride (PVDF) ultrafiltration membranes were comprehensively investigated using the nonsolvent-induced phase separation method. Three additives (ethanol, glycerol, or NaCl) were added to the water coagulation bath respectively to obtain different membranes. It was found that the microstructure of the membranes changed from finger-like structure to the sponge-like structure with the increase of additives concentration, which successfully improved the retention and mechanical properties of the membranes. In addition, the membrane surface became smoother and more hydrophilic. The membrane fabricated in 30 wt% glycerol bath exhibited outstanding comprehensive properties of retention and anti-fouling, with a water flux of 243.5 L/(m 2 h), a bovine serum albumin rejection of more than 90%, and a flux recovery rate of 97%. From mechanism analysis, the addition of ethanol, glycerol, or NaCl to the coagulation bath altered the thermodynamic stability of the polymer system, and slowed down the rate of solvent and nonsolvent diffusion from a kinetic perspective. This research provides important clues for optimizing the membrane properties, such as flux, rejection, and strength.
研究领域:
膜科学
·
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2021
·
IF 7.086
Hailong Liu,Xiangjun Liao,Yuxia Ren
Amphiphilic copolymers containing hydrophilic and hydrophobic blocks represented by surfactants have proven to be more effective for modifying membranes than hydrophilic copolymers. However, studies on the effects of additive and coagulation bath pH on the morphology and properties of surfactant-modified membranes have rarely been reported. Hence, this study aims to investigate the effects of the additive dosage and the coagulation bath pH on the mechanisms of phase inversion and performance improvement of amphoteric fluorocarbon special surfactant (FS-50) blended PVDF membranes. It was observed that the pure water flux increased from 114.68 LMH/bar of the original membrane M0 to 205.02 LMH/bar of the blend membrane M1, and then to 615.88 LMH/bar of the coagulation-bath-regulated membrane MPH9 with a high BSA rejection rate of 90.86%, showing a two-stage jump. The addition of FS-50 promoted the instantaneous phase inversion of the membrane, allowing the blend membrane to exhibit a higher proportion of pore characteristics and stronger permeability. After that, the mechanisms of the membrane phase inversion process affected by the coagulation bath pH were interpreted according to the pH-response characteristics of FS-50 in terms of charge repulsion effect and compressed double-electron layer effect. Furthermore, the cross-sectional morphology and the surface structure of the membrane prepared in acidic and alkaline coagulation baths were significantly affected by the pH of the coagulation bath, exhibiting different features. For one, the porosity of the membranes gradually decreased as the acidity and alkalinity of the coagulation bath increased, and the membrane MPH9 exhibited both maximum surface and overall porosity. For another, the coagulation bath pH did not negatively affect the contact angle, surface roughness and tensile strength of the membranes. Overall, adjusting the dosage of FS-50 and the pH of the coagulation bath is a promising approach to greatly enhance membrane performance.
研究领域:
材料科学
·
膜技术
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）