CHEMOSPHERE
·
2020
·
IF 5.778
Chao Fang,Xingyu Wang,Rong Xiao,Shunke Ding,Baiyang Chen,Wenhai Chu
Reverse osmosis (RO), a promising technology for removing inorganic salts and a wide range of trace organic pollutants, is widely used in water treatment industry. In this study, the rejection of chlorinated, brominated, and iodinated trihalomethanes (THMs) by a multi-stage RO system was investigated. The results showed that the multi-stage RO system is effective in rejecting THMs, and THMs with large size, high hydrophobicity and low polarity were highly rejected. In the first stage, high percentage of THMs was adsorbed on RO membrane, and the THM rejection was dominated by both hydrophobic adsorption and size exclusion. The contribution of hydrophobic adsorption to THM rejection decreased significantly along RO stages due to decreased feed concentration, but the enhancement of size exclusion still ensured high rejection efficiencies for most THMs, indicating a compensation effect between two rejection mechanisms. Finally, to further understand the rejection in the multi-RO system from a perspective of THM property, multiple linear regression models were built. The impact of n -octanol-water partition coefficient (Log K ow ) was slightly higher than that of stokes radius in the first stage, which was consistent with the rejection mechanism. But dipole moment played an increasingly important role in the second and third stage, weakening the impact of Log K ow on THM rejection.
研究领域:
环境科学
·
水处理工程
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2024
·
IF 8.4
Xin Mao,Nuanyuan Xu,Xinyu Shi,Hui Wen,Changkun Liu
Nanofiltration (NF) is commonly recognized as one of the effective technologies for the separation of magnesium (Mg 2+ ) and lithium (Li + ) from salt-lake brines. Charge repulsion and size exclusion effects often play an important role, whose functions primarily occur at the top surface and the matrix, respectively, of the skin layer. In this study, a novel nanofiltration (NF) membrane is prepared that integrates both size exclusion and charge repulsion effects into the matrix of the skin layer for enhanced Mg 2+ /Li + separation. With the surface-modified hydrophilic polyethylene (PE) membrane as the supporting layer, the prepared NF membrane successfully incorporated Fe 3+ ions into the matrix of the skin layer during the interfacial polymerization (IP). Fe 3+ ions which chelate with amine groups of PEI (aqueous-phase monomers during IP) ensure abundant positive charges within the matrix of the skin layer, providing good hydrophilicity and sustained electrostatic repulsive force against the transmembrane transport of Mg 2+ , and thus the enhanced rejection. Results exhibited a remarkable 92.6 % rejection rate for MgCl 2 and a higher water permeance of 22 LMH/bar, which is 1.57 times greater than that of the traditional PEI-TMC membranes. The nanofiltration process effectively reduced the Mg 2+ /Li + ratio from 50 in the feed to 5.4 in the permeate solution. It is also interesting to find that although the pore size of the skin layer (0.53 nm in radius) exceeds both the hydrated radii of Mg 2+ and Li + , the positive charges within the matrix of the skin layer still provide good selective separation performance, thus effectively breaking the trade-off of permeability and selectivity. This study offers a fresh perspective on the preparation of nanofiltration membranes by systematically exploring the potential of integration of charge repulsion and size exclusion effects into one location, i.e., the matrix of the skin layer for enhanced Mg 2+ /Li + separation performance.
研究领域:
材料科学
·
环境工程
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产品关联
DOI
高影响因子
PROCESS BIOCHEMISTRY
·
2020
·
IF 2.952
Farid Shakerian,Jing Zhao,Shao-Ping Li
A simple method for immobilization of amylase (Am) on montmorillonite (Mt) was developed. Direct immobilization of crude commercial Am was initially evaluated by size exclusion chromatography by considering Am peaks (in comparison to the pure enzyme from the same source), while the immobilized enzyme performance was monitored by anion exchange chromatography. The immobilized Am showed approximately 55.6 ± 0.7 % (n = 3) of the activity of the free enzyme. Both free and immobilized Am showed maximum performance in neutral pH (pH ∼ 7). The immobilized Am maintained more than 60 % of its initial activity after 10 reuse cycles. The immobilized enzyme was successfully applied for starch removal in crude carbohydrates extracted from medicinal plant samples.
研究领域:
生物化学
·
制药工程
·
植物学
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产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2014
·
IF 5.9
Shu Xing,Dawei Jiang,Fan Li,Jiang Li,Qian Li,Qing Huang,Linjie Guo,Jiaoyun Xia,Jiye Shi,Chunhai Fan,Lan Zhang,Lihua Wang
DNA nanostructures have attracted great attention due to their precisely controllable geometry and great potential in various areas including bottom-up self-assembly. However, construction of higher-order DNA nanoarchitectures with individual DNA nanostructures is often hampered with the purity and quantity of these “bricks”. Here, we introduced size exclusion chromatography (SEC) to prepare highly purified tetrahedral DNA nanocages in large scale and demonstrated that precise quantification of DNA nanocages was the key to the formation of higher-order DNA nanoarchitectures. We successfully purified a series of DNA nanocages with different sizes, including seven DNA tetrahedra with different edge lengths (7, 10, 13, 17, 20, 26, 30 bp) and one trigonal bipyramid with a 20-bp edge. These highly purified and aggregation-free DNA nanocages could be self-assembled into higher-order DNA nanoarchitectures with extraordinarily high yields (98% for dimer and 95% for trimer). As a comparison, unpurified DNA nanocages resulted in low yield of 14% for dimer and 12% for trimer, respectively. AFM images cleraly presented the characteristic structure of monomer, dimer and trimer, impling the purified DNA nanocages well-formed the designed nanoarchitectures. Therefore, we have demonstrated that highly purified DNA nanocages are excellent “bricks” for DNA nanotechnology and show great potential in various applications of DNA nanomaterials.
研究领域:
生物化学
·
纳米生物学
·
分子生物学
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产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2025
·Vol. 15
·期 16
·12528-12537
·
IF 4.6
Junbo Wang,Jie Jiang,Jing Wang,Shouyuan Hu,Jiahao Hu,Yalong Li,Zhiyu Tao,Chengju Wu,Pei Li,Liang Chen
Nanofiltration has emerged as an effective technique for the selective separation of mono- and divalent ions, such as Mg2+/Li+ mixtures, and plays a crucial role in lithium extraction from salt lakes. In this study, a graphene oxide (GO) membrane with positively charged channels was prepared by crosslinking arginine (Arg) onto GO nanosheets, followed by vacuum filtration to form the membrane, and then thermal reduction (Arg-rGO). The Arg-rGO membrane exhibits high performance in the ion separation of a typical brine with a Mg2+/Li+ mass ratio of 20. The separation factor (SLi/Mg) reached up to 45.6—two times the highest separation factor reported—while maintaining an advanced water permeance of 21.3 L m−2 h−1 bar−1. Furthermore, the Mg2+/Li+ mass ratio was reduced from 20 to 0.2 after two-stage crossflow filtration with high flux under high pressure. The observed separation performance can be attributed to the synergistic effect of electrostatic repulsion and size-exclusion. These findings confirmed efficient separation of Mg2+/Li+ using GO membranes, demonstrating potential for practical application in lithium extraction from salt lakes.
研究领域:
材料科学
·
环境工程
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产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Yihui Yang,Jiahao Mo,Yanjun Cheng,Yang Yang,Xianhui Li
Loose nanofiltration (LNF) membranes have demonstrated exceptional efficacy in removing trace organic pollutants (TrOCs) due to their distinctive structure and efficient solute transport characteristics. Despite significant advancements, the mechanism underlying solute transport within LNF membranes remain to be further elucidated. In this study, the Donnan-Steric Pore Model with Dielectric Exclusion (DSPM-DE) was employed to predict the selectivity and permeability of customized LNF membranes, with these theoretical predictions substantiated through filtration experiments utilizing particles of diverse sizes and charges. The observations reveal that when the pore size considerably exceeds the ionic sizes, the selective transport of organic pollutants and charged ions is predominantly governed by size exclusion rather than electrostatic repulsion. Moreover, in the selective transport of neutral and charged organic pollutants, charged pollutants are preferentially intercepted via electrostatic repulsion, whereas neutral pollutants are primarily influenced by convection and diffusion processes, resulting in partial interception. In addition, the ionization degree of organic substances directly affects the contribution of electrical migration to the retention rate. These observations will provide critical insights into the key solute mass transport processes for the efficient removal of TrOCs using LNF membranes.
研究领域:
环境科学
·
膜技术
·
污染控制
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DOI
高影响因子
ANALYTICA CHIMICA ACTA
·
2018
·
IF 5.123
Jucai Xu,Lin Zheng,Lianzhu Lin,Baoguo Sun,Guowan Su,Mouming Zhao
Size-exclusion chromatography (SEC) with wide application in peptide analysis presents challenges in determination of molecular weight distribution due to the relatively low resolution. In this study, a stop-flow reversed phase liquid chromatography (RPLC) × SEC system was constructed, aiming at improving the peptide separation in SEC. As the chromatographic dispersion during stop-flow operation might contribute to the band broadening in the first dimension (1st D) RPLC, the effects of different stop-flow operational parameters on the additional band broadening were quantitatively evaluated. Unlike analytes of large molecular size or long retention time with low effective diffusion coefficient ( D eff ), additional band broadening was evidently observed for analytes of small molecular size and short retention time (high D eff ). Therefore, optimal flow rate , low column temperature and short stop-flow time were suggested for analyzing small molecules of short retention time. The established stop-flow two-dimensional liquid chromatography (2D-LC) was further tested on protein hydrolysates . The resolution was evidently improved for both heart-cutting and comprehensive 2D-LC analysis (despite additional band broadening in RPLC). Compared with heart-cutting analysis with higher 1st D resolution for selective fractions, comprehensive analysis could provide more complete information about the molecular weight distribution of the eluting solutes along RPLC.
研究领域:
分析化学
·
生物化学
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产品关联
DOI
PubMed
高影响因子
FOOD CHEMISTRY
·
2020
·
IF 6.306
Fuge Niu,Yu Jiao,Rui Zhang,Jiamei Fan,Christos Ritzoulis,Weichun Pan,Ang Li
This work studied the quantitation of myofibrillar protein isolated from giant squid by three methods (Bradford, biuret, and direct ultraviolet absorbance). The results were examined in relation to compositional size exclusion chromatography, static light scattering, zeta-potential and thermal analysis; comparisons between the apparent vs. the true protein concentration revealed the existence of disk-like nano protein particles (NPP) with a height of 2–3 nm, diameters ranging from several tens nm to 140 nm, and fractal dimensions d f of less than 1.3. In order to probe the heterogeneity of NPP particles, their properties were studied under consecutive dilutions: the d f decreased from 1.265 to 1.087, the zeta-potential increased from −4.55 mV to −1.83 mV, the denaturation temperature reduced from 63.9 °C to 58.6 °C, and the endothermic enthalpy reduced from 0.529 J s −1 to 0.362 J s −1 . In addition, ca. 90% protein molecules in solution were aggregated to form NPP.
研究领域:
食品科学
·
生物物理学
·
蛋白质化学
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DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2015
·
IF 5.056
Liang Cheng,Li-Ping Zhu,Pei-Bin Zhang,Jian Sun,Bao-Ku Zhu,You-Yi Xu
Here we demonstrate the tunable molecular selectivities and corresponding mechanisms of poly(N-vinyl imidazole) (PVI) gel-filled membranes prepared by UV initiated graft polymerization of N-vinyl imidazole from ultraporous polysulfone (PSf) substrate. The separation performance was investigated in detail by extensive filtration tests with various organic molecules in water of varying pH and also in salt or ethanol aqueous solution. The variation of membrane water permeability and solute rejection with the feed pH was attributed to the sensitive pore size and charge characteristics of the membranes upon reversible protonation of the confined PVI gel. The separation results discerned three main mechanisms, i.e. size exclusion (sieving), electrostatic repulsion (Donnan exclusion) and adsorption. The rejection of the neutral molecules and the large dye molecules was mostly ascribed to size exclusion, while that of the small charged solutes was dominated by the electrostatic interactions including repulsion for cationic ones and attraction for anionic ones (causing specific adsorption). Typically, at pH 3 the protonated membranes rejected ~90% of the small cationic Vitamin B 1 (VB 1 ) and 100% of the anionic Sunset Yellow (SY) before adsorption saturation, in contrast to less than ~20% rejection of the neutral Vitamin B 2 (VB 2 ) having similar molecule size. In the high concentration salt or ethanol solution the membranes still maintained molecular sieving capability. Most notably, the separations of solute mixtures were indeed achieved, depending on the membrane parameters, the solute characteristics as well as the filtration conditions. The PVI gel-filled membranes developed in this work are promising in some specified or environment-sensitive molecular level separations.
研究领域:
材料科学
·
环境工程
·
化学工程
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DOI
高影响因子
ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Fangfang Yang,Mian Wu,Yuchao Wang,Saeed Ashtiani,Heqing Jiang
Metal–organic framework (MOF) nanosheets have emerged as promising materials for the construction of molecular sieve membranes due to their nanoscale thickness and highly oriented pore arrays. However, the development of defect-free MOF nanosheet membranes from rigid MOF nanosheets with efficient permselectivity and robust mechanical strength still remains a big challenge. Herein, we develop a facile GO-induced assembly strategy to design continuous and uniform two-dimensional MOF composite membranes, in which the copper 1,4-benzene dicarboxylate (CuBDC) nanosheets present a layer-stacking arrangement. With the assistance of flexible GO, the voids between the junctions of rigid MOF nanosheets are well-repaired, and the interlayer bonding interactions are strengthened, resulting in the fabrication of a continuous nanosheet membrane with robust mechanical strength. The obtained MOF nanosheet-based membranes display remarkable H2/CO2 separation performance with a superior H2 permeance of 9.6 × 10–7 mol m–2 s–1 Pa–1 and an ideal separation selectivity of 95.1 due to the well-defined size exclusion effect, showing great promise for H2 separation and purification. The repair strategy described here could also provide the blueprint for the development of other nanosheet-based membranes.
研究领域:
材料科学
·
化学工程
·
纳米技术
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2017
·
IF 3.981
Jucai Xu,Dongxiao Sun-Waterhouse,Chaoying Qiu,Mouming Zhao,Baoguo Sun,Lianzhu Lin,Guowan Su
The need to improve the peak capacity of liquid chromatography motivates the development of two-dimensional analysis systems. This paper presented a fully automated stop-flow two-dimensional liquid chromatography system with size exclusion chromatography followed by reversed phase liquid chromatography (SEC × RPLC) to efficiently separate peptides. The effects of different stop-flow operational parameters (stop-flow time, peak parking position, number of stop-flow periods and column temperature) on band broadening in the first dimension (1 st D) SEC column were quantitatively evaluated by using commercial small proteins and peptides. Results showed that the effects of peak parking position and the number of stop-flow periods on band broadening were relatively small. Unlike stop-flow analysis of large molecules with a long running time, additional band broadening was evidently observed for small molecule analytes due to the relatively high effective diffusion coefficient ( D eff ). Therefore, shorter analysis time and lower 1 st D column temperature were suggested for analyzing small molecules. The stop-flow two-dimensional liquid chromatography (2D-LC) system was further tested on peanut peptides and an evidently improved resolution was observed for both stop-flow heart-cutting and comprehensive 2D-LC analysis (in spite of additional band broadening in SEC). The stop-flow SEC × RPLC, especially heart-cutting analysis with shorter analysis time and higher 1 st D resolution for selected fractions, offers a promising approach for efficient analysis of complex samples.
研究领域:
分析化学
·
生物化学
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产品关联
DOI
PubMed
高影响因子
CHROMATOGRAPHIA
·
2011
·Vol. 75
·期 1
·7-15
·
IF 1.075
Liu Guihua,Qiu Xuepeng,Bo Shuqin,Ji Xiangling
Chain conformation and local rigidity of two isomerized polyimides (PIs), poly(6FDA/3,3′-DMB) and poly(6FDA/2,2′-DMB) in dimethyl formamide (DMF) with either 0.1 M LiBr or 3.1 mM tetrabutylammonium bromide at 35 °C, are investigated. Size exclusion chromatography (SEC) coupled with multi-angle laser light scattering detector, viscometer, and differential refractive index detector was used. The scaling exponents α and ν related to conformation are estimated from the above results. The values of α and ν for poly(6FDA/3,3′-DMB) are 0.68 ± 0.01 and 0.54–0.55 ± 0.01, respectively. The values of α and ν for poly(6FDA/2,2′-DMB) are 0.65 ± 0.02 and 0.55 ± 0.01, respectively, which indicate that both PIs in DMF have a random coil conformation. In particular, poly(6FDA/3,3′-DMB) exhibits more extended conformation than that of poly(6FDA/2,2′-DMB). Parameters related to chain flexibility of polymers, including persistence length l
p , shift factor M
L (relative molecular weight per unit contour length), and backbone diameter d are evaluated from the relationship between intrinsic viscosity and molecular weight based on the wormlike continuous cylinder model. The three parameters ( l
p , M
L , and d ) indicate that the two samples are flexible chains with local rigidity, and poly(6FDA/3,3′-DMB) is slightly stiffer than poly(6FDA/2,2′-DMB). In addition, influence of salt types on the parameters is also discussed.
研究领域:
高分子化学
·
物理化学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）