DESALINATION
·
2023
·
IF 9.9
Huiying Ding,Yuting Liu,Zhong Zhang,Yanjun Cheng,Jiahao Mo,Lu Elfa Peng,Cheng Xiang,Hongchang Pei,Xianhui Li
In the synthesis of the polyamide nanofiltration (NF) membrane, the hydrogen chloride is a by-product generated at the organic interface from interfacial polymerization , which reduces the reactivity of amine monomers due to protonation . Herein, a strategy of addition of an organic base in the organic phase to neutralize the H + was reported. The performances of the membranes produced using three organic bases with different chain lengths were explored. The results showed that the organic base neutralized the H + and promoted the rate of interfacial condensation reaction , which facilitated the formation of a dense and thin polyamide layer. Moreover, compared to control membrane, the membrane modified by organic base exhibited higher water permeance without sacrificing salt rejection. Higher diffusion rate of HCl through PES substrate compared to NF membrane indicated that HCl diffusion was mainly affected by the resistance of polyamide layer. Molecular simulations demonstrated that triethylamine (TEA) has lower energy barrier of neutralization and higher reaction heat in comparison with tripropylamine and N, N-diisopropylethylamine. The TEA modified membrane thereby displayed a permeance up to 24.3 L h −1 m −2 bar −1 and Na 2 SO 4 rejection of 98.8 %. This work provided a promising strategy for the regulation of interfacial polymerization in achieving high-permselective nanofiltration.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2014
·
IF 4.908
Xi Quan Cheng,Lu Shao,Cher Hon Lau
A hydrophilic thin-film-composite (TFC) nanofiltration (NF) membrane has been developed through the interfacial polymerization (IP) of amino-functional polyethylene glycol (PEG) and trimesoyl chloride. The selective layer is formed on a polyethersulfone (PES) support that is characterized using FTIR, XPS and SEM, and is dependent on monomer immersion duration, and the concentration of monomers and additives. The higher hydrophilicity alongside the larger pore size of the PEG-based selective layer is the key to a high water flux of 66.0 L m −2 h −1 at 5.0 bar. With mean pore radius of 0.42 nm and narrow pore size distribution , the MgSO 4 rejections of the PEG based PA TFC NF membranes can reach up to 80.2%. The rejection rates for different salts of the novel membranes are in the order of R (MgCl 2 )> R (MgSO 4 )> R (NaCl)> R (Na 2 SO 4 ); indicating a membrane with positive surface charges. The pore sizes and water permeability of these membranes are tailored by varying the molecular weight and molecular architecture of amino-functional PEG. These newly developed TFC NF membranes show great potential for water softening, wastewater treatment and separation and purification of active, pharmaceutical molecules.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2014
·Vol. 4
·期 95
·52808-52814
·
IF 3.708
Qiang Zhao,Yan-Li Ji,Jia-Kai Wu,Ling-Ling Shao,Quan-Fu An,Cong-Jie Gao
Nanofiltration (NF) membranes were prepared from a solution processable polyelectrolyte complex (PEC) between sodium carboxymethyl cellulose (CMCNa) and poly(2-methacryloyloxy ethyl trimethylammonium chloride) (PDMC). Electrostatic complexation structures of the PEC were studied by light transmittance and field emission electron scanning microscopy (FESEM). It is found that the electrostatic complexation structure of the PEC membranes determines their NF performance, which is conveniently tailored via the pH values of casting solutions. For membranes prepared at the optimum solution pH 2.1, their water flux and salt rejection to K2SO4 (1 g L−1) are 18 g m−2 h−1 and 97%, respectively, when the operation pressure and temperature are 0.6 MPa and 25 °C. Both the water permeability and the salt selectivity are substantially improved compared to the pristine CMCNa NF membrane. In addition, antifouling performance of the PEC membrane is improved, coupled with an exceptional stability versus the operation time.
研究领域:
材料科学
·
环境工程
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Yuan Wang,Zhaoxian Yang,Lei Liu,Yingbo Chen
In this study, hydrophobic nanofillers (ODA-h-NCs) were firstly synthesized through surface modification of MOF-derived nanocages by octadecylamine (ODA). ODA-h-NCs were then incorporated into poly(piperazine-amide) (PA) active layer to fabricate thin-film nanocomposite (TFN) nanofiltration membranes. The effects of ODA-h-NCs dosage on PA’s properties were characterized and the membrane performances on salt rejections were evaluated. Finally, the TFN nanofiltration membrane with the optimal nanoparticle doping amount was chosen. The experimental results show that the water permeance of the constructed TFN nanofiltration membrane reaches 8.97 L/(m 2 ·h·bar) with 95.8% Na 2 SO 4 rejection when ODA-h-NCs concentration is 0.0075 wt%, which is 1.7 times that of pristine membrane. It is also testified that the prepared TFN nanofiltration membrane possesses good stability through 50-h filtration test. Although the introduction of hydrophobic ODA-h-NCs increases the PA layer thickness, ODA-h-NCs decrease the crosslinking degree of PA layer by inhibiting the piperazine diffusion rate and pathway, their unique porous nanocage structure and large surface area provide additional transport path for water molecules, which equips TFN nanofiltration membrane with higher water flux.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Feng-Yang Zhao,Yan-Li Ji,Xiao-Dan Weng,Yi-Fang Mi,Chun-Chun Ye,Quan-Fu An,Cong-Jie Gao
The poor dispensability of pristine carbon nanotubes in water impedes their implications in thin-film nanocomposite membranes for crucial utilities such as water purification. In this work, high-flux positively charged nanocomposite nanofiltration membranes were exploited by uniformly embedding poly(dopamine) modified multiwall carbon nanotubes (PDA-MWCNTs) in polyamide thin-film composite membranes. With poly(dopamine) modification, fine dispersion of MWCNTs in polyethyleneimine (PEI) aqueous solutions was achieved, which was interracially polymerized with trimesoyl chloride (TMC) n-hexane solutions to prepare nanocomposite membranes. The compatibility and interactions between modified MWCNTs and polyamide matrix were enhanced, attributed to the poly(dopamine) coatings on MWCNT surfaces, leading to significantly improved water permeability. At optimized conditions, pure water permeability of the PEI/PDA-MWCNTs/TMC nanofiltration membrane (M-4) was 15.32 L m–2 h–1 bar–1, which was ∼1.6 times increased compared with that of pristine PEI/TMC membranes. Salt rejection of M-4 to different multivalent cations decreased in the sequence ZnCl2 (93.0%) > MgCl2 (91.5%) > CuCl2 (90.5%) ≈ CaCl2, which is well-suited for water softening and heavy metal ion removal.
研究领域:
材料科学
·
环境工程
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2020
·
IF 7.864
Xiaoxiao Song,Bowen Gan,Saren Qi,Hao Guo,Chuyang Y. Tang,Yong Zhou,Congjie Gao
Transport of water, solutes, and contaminants through a thin film composite (TFC) membrane is governed by the intrinsic structure of its polyamide separation layer. In this work, we systematically characterized the nanoscale polyamide structure of four commercial TFC membranes to reveal the underlying structure–property relationship. For all the membranes, their polyamide layers have an intrinsic thickness in the range of 10–20 nm, which is an order of magnitude smaller than the more frequently reported apparent thickness of the roughness protuberances due to the ubiquitous presence of nanovoids within the rejection layers. Tracer filtration tests confirmed that these nanovoids are well connected to the pores in the substrates via the honeycomb-like opening of the backside of the polyamide layers such that the actual separation takes place at the frontside of the polyamide layer. Compared to SW30HR and BW30, loose membranes XLE and NF90 have thinner intrinsic thickness and greater effective filtration area (e.g., by the creation of secondary roughness features) for their polyamide layers, which correlates well to their significantly higher water permeability and lower salt rejection. With the aid of scanning electron microscopy, transmission electron microscopy, and tracer tests, the current study reveals the presence of nanosized defects in a polyamide film, which is possibly promoted by excessive interfacial degassing. The presence of such defects not only impairs the salt rejection but also has major implications for the removal of pathogens and micropollutants.
研究领域:
材料科学
·
环境工程
·
膜技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Fan-xin Kong,Lian You,Jia-mei Cao,Qian Liu,Ping Xia,Jin-fu Chen
Holey graphene oxide (HGO) and reduced HGO membranes (rHGO) can overcome high tortuosity and poor stability of GO-based membranes, respectively. In this study, HGO and rHGO membranes were fabricated to try to quantitatively elucidate the etching and reduction time on structure, stability and rejection performance for slat and pharmaceuticals. Water flux of HGO membrane linearly increased ( J v =2.07 t + 1.02, R 2 =0.9931) and Na 2 SO 4 rejection linearly decreased ( R Na2SO4 =−4.37 t + 88.26, R 2 =0.9511), while the membranes stability substantially increased with etching time from 1 to 5 h (water flux variation from 22% to 5% and rejection ratio variation from 17% to 7%) under long-term vibration . Subsequently, water flux of rHGO membranes exponentially decreased ( J v = exp (2.89–0.12 t + 0.0039 t 2 ), R 2 = 0.9996) with reduction time, while slightly improved salt rejection ( R Na2SO4 = exp (2.89–0.12 t + 0.0039 t 2 ), R 2 = 0.9971) were observed. Effective length of actual pathways for GO, HGO 4 and rHGO 4–5 membranes calculated by the mass transfer-based model was 7.37 ± 0.47, 4.48 ± 0.68 and 7.23 ± 1.29 µm, respectively, which were much higher than that geometric thickness of the GO membranes. These results indicated that d -spacing, tortuosity and porosity should be comprehensively considered for membrane design and fabrication. With a series of saccharides as probes, average pore size slightly decreased for HGO 4 ( r p =0.36 nm, S p =0.34) and rHGO 4–5 ( r p =0.33 nm, S p =0.28) membrane compared with GO membranes ( r p =0.38 nm, S p =0.3), demonstrating that etching and following reduction marginally affected the pore size distribution. H 2 O 2 etching increased both water permeability ( A) and its selectivity ( A/B ) for three pharmaceuticals, while the thermal reduction substantially decreased the water flux. Moderate and low rejection ratios for the three pharmaceuticals also demonstrated the importance of trade-off between etching and reduction time and the urgent need for narrowing pore-size distribution for GO-based membranes for water purification .
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
DESALINATION
·
2025
·
IF 9.8
Fuxin Qiu,Fan Liu,Rui Tian,Xutong Han,Kaikai Chen,Qinglin Huang
Polytetrafluoroethylene (PTFE) nanofiltration (NF) membrane has gained increasing attention due to its comprehensive outstanding performance. However, the inherent low surface energy of PTFE makes it difficult to construct a functional NF layer on its surface. In this study, we have presented a novel three-layer of PTFE composite NF membrane with the electrospun PTFE nanofiber membrane as the substrate. During which, the cross-linked polyvinyl alcohol (PVA) was utilized to ensure the high adhesion strength between the polyamide (PA) selective layer and the substrate of PTFE nanofiber membrane. Furthermore, we have further optimized the physical and chemical structure of the composite NF membrane by adjusting the structure and thickness of the PA selective layer and the PVA-GA (glutaraldehyde) layer. When the TMC (1,3,5-benzenetricarbonyl trichloride) and PIP (piperazine) concentration were 2 % and 6 %, the PVA concentration was 2 %, the obtained composite membrane achieved a high multivalent salts rejection rate (99.2 % for Na 2 SO 4 ) and permeation flux (14.41 L∙m −2 ∙h −1 ∙bar −1 ). Additionally, the obtained PTFE composite NF membranes demonstrated durability against solvents and long-term reliability after ultrasonic treatment, acid/alkali treatment, sustained operation for 48 h, and cyclic experiments. These findings offer a practical method for the industry's utilization of PTFE NF substrates in the separation of salt solutions.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
DESALINATION
·
2021
·
IF 9.501
Anqi Tang,Chuanjie Fang,Weilin Feng,Jingyu Lu,Jiaqi Li,Liping Zhu
Developing thin-film composite (TFC) nanofiltration (NF) membranes with high water permeability and salt rejection is highly desirable in water desalination . In this study, a new TFC membrane with high NF performances was developed to achieve such a goal by constructing active separation layer with a special crater-like surface morphology using a rigidly-contorted spirocyclic monomer , 5,5,6′,6′-tetrahydroxy-3,3,3′,3′-tetramethyl spirobisindane (TTSBI), as the co -monomer with piperazine (PIP) in aqueous phase during interfacial polymerization (IP) process. This design endowed the separation layer with the characteristics of low thickness, high microporosity , and high permeation surface area. The pure water permeability was therefore increased to 9.9 L m −2 h −1 bar −1 , approximately two times higher than that of the typical TFC NF membrane prepared with PIP and trimesoyl chloride, without compromise in the rejection (the rejection of Na 2 SO 4 up to 98%). The introduction of TTSBI tuned the diffusion and reaction behaviors of monomers at the aqueous-organic interface and controlled the special microporous structure and surface morphology, which are advantageous to the improvement of water permeability. This study provides new insights for synthesizing highly permeable TFC NF membranes with remarkable rejection characteristics to address the crisis of the current potable water scarcity.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Chenjie Wei,Rongrong Qiang,Ligang Lin,Yixin Gao,Shuyan Ma,Xihang Zhang,Xiaojun Huang
Desalination of brackish water and purification of drinking water still pose several challenges. Combination of in-situ hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in polyamic acid (PAA) solution along with imidization reaction provide a novel polyimide/SiO 2 (PI/SiO 2 ) membrane. This is the first synthesis of a PI nanofiltration (NF) membrane with three-dimensional (3D) water channels, ultra-thin skin layer (30 ± 2 nm), and high flux at low operating pressure, by one-step phase inversion method. There was no additional requirement of an acid, since PAA served as a catalyst. The SiO 2 cross-linked network provided the skeletal support, due to hydrogen bonding between PAA-PI and silicon hydroxyl groups. The fabricated PI/SiO 2 membrane demonstrated a water contact angle of 45°, pore size of 1.05 ± 0.15 nm, Zeta potential of −30 mV, and tensile strength of 2.24 MPa when under optimized conditions. The loose PI/SiO 2 NF membrane exhibited salt rejection in the sequence of Na 2 SO 4 (87%)>MgSO 4 (67%)>NaCl (41%)>MgCl 2 (37%), which was consistent with size exclusion and Donnan exclusion effects. In particular, the water flux of 20.4 L/(m 2 h bar) was about 4–15 times higher than that of universal PI-NF membranes. The membrane also exhibited excellent stability for over six days when used for separation. Furthermore, the membrane showed excellent dye (Rose Bengal (RB), Brilliant Blue G (BBG), Amido Black (AB)) rejection of over 90%. To conclude, this work paves a new pathway for the fabrication of PI-NF membranes for efficient NF separation.
研究领域:
材料科学
·
环境工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2015
·
IF 3.091
Daqing Tong,Xiaozu Wang,Mohammad Ali,Christopher Q. Lan,Yong Wang,Enrico Drioli,Zhaohui Wang,Zhaoliang Cui
Hydrophobic membrane is desired to avoid pore wetting phenomenon in membrane distillation (MD). In the present paper, highly hydrophobic Hyflon AD60/PVDF composite hollow fiber membranes were prepared by coating a copolymer (Hyflon AD60) of tetrafluoroethylene (TFE) and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole (TTD) on poly(vinylidene fluoride) (PVDF) membranes. The effects of Hyflon AD60 concentration, coating time, heat-treatment temperature and heat-treatment time on the structures and performances of Hyflon AD60/PVDF composite hollow fiber membranes in vacuum membrane distillation (VMD) process were investigated. The results show that the hydrophobicity of PVDF hollow fiber membrane was significantly improved by coating Hyflon AD60. The optimized Hyflon AD60 concentration, coating time, heat-treatment temperature and heat-treatment time were 0.1 wt%, 10–20 min, 40–50 °C and 9 h, respectively. Employing NaCl solution with concentration of 35 g × L −1 , under a vacuum of 0.09 MPa and feed temperature of 70 °C, the water flux and salt rejection of the composite hollow fiber membrane in VMD process reached to approximately 10 kg × m −2 × h −1 and higher than 99.9 %, respectively, and kept stable, indicating that Hyflon AD60/PVDF composite membrane is an excellent candidate for operation in VMD operation.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
DESALINATION
·
2019
·
IF 6.035
Yuan Gao,Kunmei Su,Xiaotian Wang,Maliang Zhang,Zhenhuan Li,Kang Jia
A novel layer consisting of nano graphene oxide (NGO) sheets was created with disordered arrangement and dual-channel structures on modified Polyphenylene sulfide (PPS) support surface. Polyamide (PA) and Piperazine (PIP) were used to cross-link and fasten the NGO layer, constructing water molecule transport channels. Meanwhile, the interlayer spacing of NGO and transport capacity of polyamide permeation channels could be changed by adjusting PIP content, thereby a large number of small-sized vacancy were formed as water molecular transport channels and played a role in intercepting small molecules and metal salts. Physicochemical structure and application performance of the composite membranes were analyzed using various testing methods, showing that the introduction of polyamide greatly increased water flux and metal salts rejection rate. In particular, M-3 membrane with the best performance was achieved with salt rejections of 48.24%, 92.14%, 92.93% and 91.23% for NaCl, CuSO 4 , ZnSO 4 and AlCl 3 , and a water flux of 40.80 LMH at 0.6 MPa.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）