Showing papers by "Jian Jin published in 2020"

Polyamide nanofiltration membrane with highly uniform sub-nanometre pores for sub-1 Å precision separation.

Abstract: Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Achieving such a precise separation using membranes requires Angstrom scale pores with a high level of pore size uniformity. Herein, we demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization (SARIP). The dynamic, self-assembled network of surfactants facilitates faster and more homogeneous diffusion of amine monomers across the water/hexane interface during interfacial polymerization, thereby forming a polyamide active layer with more uniform sub-nanometre pores compared to those formed via conventional interfacial polymerization. The polyamide membrane formed by SARIP exhibits highly size-dependent sieving of solutes, yielding a step-wise transition from low rejection to near-perfect rejection over a solute size range smaller than half Angstrom. SARIP represents an approach for the scalable fabrication of ultra-selective membranes with uniform nanopores for precise separation of ions and small solutes. Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Here, the authors demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization.

Long-term continuous cropping of soybean is comparable to crop rotation in mediating microbial abundance, diversity and community composition

Abstract: Continuous cropping of soybean causes soil degradation and soybean yield decline, but these effects could be alleviated by crop rotation or the use of long-term continuously cropped soybean systems. However, the mechanism by which biotic and abiotic factors are affected by different cropping systems remain unclear. In this study, we comparatively investigated the bacterial and fungal abundance, diversity and community compositions in the bulk and rhizospheric soils of soybean continuously cropped in the short-term for 3 and 5 years (CC3 and CC5) and in the long-term for 13 years (CC13), as well as cropping rotation with maize in alternately for 5 years (CR5) using qPCR and high-throughput sequencing methods. The results showed that soil pH, and available nutrients such as N, P and K were significantly higher in the bulk soils of CC13 and CR in contrast to CC3 and CC5. The fungi/bacteria ratio was significantly higher in the rhizospheric soils of CC3 and CC5 than that in CR5 and CC13, indicating that short-term continuously cropped soybean decreases bacterial abundance but increases fungal abundance. The bacterial and fungal community structures were significantly altered by different cropping systems, and the soil pH and C/N were the primary soil factors in shifting the bacterial and fungal community structures in the bulk soils, respectively. Bacterial and fungal co-occurrence patterns were remarkably affected by cropping systems, which showed that CC13 and CR5 harbor co-occurrence networks that are more complex than CC3 and CC5. Moreover, CC13 and CR5 increased the relative abundances of potentially beneficial bacteria Bradyrhizobium sp. and Gemmatimonas sp. and fungi Mortierella sp. and Paecilomyces sp. but decreased the relative abundances of the pathogenic fungi Fusarium sp. in contrast to CC3 and CC5, which indicated that long-term continuous cropping of soybean might have generated a possibility of the development of disease-suppressive soils.

MOF Nanosheet-Based Mixed Matrix Membranes with Metal-Organic Coordination Interfacial Interaction for Gas Separation.

Abstract: In the mixed matrix membrane (MMM), the interface between the filler and the polymer matrix will directly affect the gas separation performance of the membranes. Reasonable interfacial design in MMMs is thus important and necessary. In this work, metal-organic coordination interaction is used to construct the interface in metal-organic framework (MOF) nanosheet-based polyimide MMMs where ultrathin Co-benzenedicarboxylate MOF nanosheets (CBMNs) with a thickness less than 5 nm and a lateral size more than 5 μm are synthesized as fillers and a carboxyl-functionalized polyimide (6FDA-durene-DABA) is used as a polymer matrix. Because of the high aspect ratio (>1000) of CBMNs, abundant metal-organic coordination bonds are formed between Co2+ in CBMNs and the -COOH group in 6FDA-durene-DABA. As a result, the 6FDA-durene-DABA/CBMN MMMs exhibit improved separation performance for the CO2/CH4 and H2/CH4 gas pairs with H2/CH4 and CO2/CH4 selectivities up to 42.0 ± 4.0 and 33.6 ± 3.0, respectively. The enhanced interfacial interaction leads to the comprehensive separation performance of CO2/CH4 and H2/CH4 gas pairs approaching or surpassing the 2008 Robeson upper bound. In addition, the CO2 plasticization pressure of the MMMs is significantly enhanced up to ∼20 bar, which is 2 times that of the pure 6FDA-durene-DABA membrane. When separating a mixed gas of CO2/CH4, the selectivity of CO2/CH4 remains stable at around 23 and the CO2 permeability keeps around 400 barrer during the long-term test.

Ultrafast Ion Sieving from Honeycomb-like Polyamide Membranes Formed Using Porous Protein Assemblies.

Abstract: Despite the commercial success of thin film composite polyamide membranes, further improvements to the water permeation of polyamide membranes without degradation in product water quality remain a great challenge Herein, we report the fabrication of an interfacially polymerized polyamide nanofiltration membrane with a novel 3D honeycomb-like spatial structure, which is formed from a tobacco mosaic virus (TMV) porous protein nanosheet-coated microfiltration membrane support TMV nanosheets with uniform pores and appropriate hydrophilicity deposited inside the support membrane pores facilitate the construction of a localized water-oil reaction interface with evenly distributed monomers and guide the formation of a defect-free polyamide layer with a spatial structure that copies the geometry of the membrane cavities Such a 3D morphology possesses ultrahigh specific surface area, leading to unprecedented membrane water permeance as high as 84 L m-2 h-1 bar-1, high MgSO4 rejection of 98%, and monovalent/divalent ion sieving selectivity up to 89

High-performance polyamide nanofiltration membrane with arch-bridge structure on a highly hydrated cellulose nanofiber support

Abstract: Nanofiltration (NF) membranes with outstanding performance are highly demanded for more efficient desalination and wastewater treatment. However, improving water permeance while maintaining high solute rejection by using the current membrane fabrication techniques remains a challenge. Herein, polyamide (PA) NF membrane with arch-bridge structure is successfully prepared via interfacial polymerization (IP) on a composite support membrane of salt-reinforced hydrophilic bacterial cellulose nanofibers (BCNs) nanofilm/polytetrafluoroethylene (BCNs/PTFE). The strong hydration of BCNs promotes Marangoni convection along water/organic solvent interface during the IP process, which creates extra area for interfacial reaction and produces a thin PA active layer with arch-bridge structures. These arch-bridge structures endow the resulting PA active layer with substantial larger active area for water permeation. Consequently, the PA NF membrane exhibits exceptional desalination performance with a permeance up to 42.5 L m−2 h−1 bar−1 and a rejection of Na2SO4 as high as 99.1%, yielding an overall desalination performance better than almost all of the state-of-the-art NF membranes reported so far in terms of perm-selectivity.

Long-term CO2 enrichment alters the diversity and function of the microbial community in soils with high organic carbon

Abstract: The response of soil microorganisms to elevated atmospheric CO2 (eCO2) has the potential to alter the regulation of soil biogeochemical processes including carbon and nutrient cycling. A mechanistic understanding of this microbial response in agricultural systems is essential due to the potential impact on soil quality. This study used an eight-year free-air-CO2 enrichment (SoilFACE) experiment to assess the microbial response to eCO2 in three major agricultural soils (Chromosol, Vertosol, and Calcarosol) planted annually with grain crops. Elevated CO2 increased the number of operational taxonomic unit (OTU) by 14.3%, 13.3% and 4.1% and the Shannon diversity by 3.7%, 4.4%, and 2.6% in the top 5-cm soil layer of the Chromosol, Calcarosol and Vertosol, respectively. The relative abundance of the oligotroph Acidobacteriaceae Subgroup 1 in the top 5-cm soil of the Chromosol and Vertosol was significantly increased by eCO2. Elevated CO2 did not affect community diversity in the 5–10 cm soil layer. The functional attribute analysis of the bacterial communities showed that eCO2 increased pectin and benzene degradation, the pentose phosphate pathway and the production of phytase-6 in the top 5-cm soil of the Chromosol. These results suggest that eCO2 increases the presence of oligotrophs in the bacterial community and overall mineralization of soil organic carbon (SOC) in surface soils with high SOC. Changes in microbial function due to eCO2 likely impact the stability of SOC and, consequently, the quality of farming soils for sustainable crop production.

Effects on Carbon Molecular Sieve Membrane Properties for a Precursor Polyimide with Simultaneous Flatness and Contortion in the Repeat Unit.

Abstract: Carbon molecular sieve (CMS)-based membrane separation is a promising solution for hydrogen separation due to its great advantages on perm-selectivity, thermal stability, and chemical stability. To prepare high-performance CMS membranes, the molecular structure of polymer precursors and their arrangements should be primarily considered. In this work, a benzimidazole-based 6FDA (2,2'-bis(3,4'-dicarboxyphenyl) hexafluoropropane dianhydride)-type polyimide (PABZ-6FDA-PI) is chosen as precursor to prepare the CMS membrane. Effects of chain flatness and contortion in the polyimide precursor on gas-separation performance of CMS membranes were studied in detail by gas adsorption and permeation experiment. The H2 permeability of CMS is up to 9500 Barrer and ideal selectivity of gas pairs of H2 /CH4 and H2 /CO2 is up to 3800 and 13, respectively. The comprehensive performance of hydrogen separation including H2 /CO2 , H2 /N2 , and H2 /CH4 gas pairs is located well above previously reported upper bounds for polymers.

A Single-Walled Carbon Nanotube/Covalent Organic Framework Nanocomposite Ultrathin Membrane with High Organic Solvent Resistance for Molecule Separation.

Abstract: Covalent organic framework (COF)-based membranes are burgeoning candidates for separation technologies owing to their well-ordered channel structures. The exponential interest in the stability of t...

Polyamide Thin Films Grown on PD/SWCNT-Interlayered-PTFE Microfiltration Membranes for High-Permeance Organic Solvent Nanofiltration

Abstract: Porous polymeric support membranes with outstanding organic solvent resistance are highly required for fabricating thin-film composite (TFC) organic solvent nanofiltration (OSN) membranes. In this ...

Two‐Dimensional Microporous Material‐based Mixed Matrix Membranes for Gas Separation

Abstract: Since the discovery of graphene and its derivatives, the development and application of two-dimensional (2D) materials have attracted enormous attention. 2D microporous materials, such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), graphitic carbon nitride (g-C3 N4 ) and so on, hold great potential to be used in gas separation membranes because of their high aspect ratio and homogeneously distributed nanometer pores, which are beneficial for improving gas permeability and selectivity. This review briefly summarizes the recent design and fabrication of 2D microporous materials, as well as their applications in mixed matrix membranes (MMMs) for gas separation. The enhanced separation performances of the membranes and their long-term stability are also introduced. Challenges and the latest development of newly synthesized 2D microporous materials are finally discussed to foresee the potential opportunities for 2D microporous material-based MMMs.

Soil quality index evaluation model in responses to six-year fertilization practices in Mollisols

Abstract: Evaluating soil quality is of vital importance to strategize fertilization and management practices for sustaining agricultural productivity. Five fertilization practices were carried out for 6 yea...

Zwitterionic Nanohydrogels-Decorated Microporous Membrane with Ultrasensitive Salt Responsiveness for Controlled Water Transport.

Abstract: Highly sensitive responsiveness is vital for stimuli-responsive membranes. However, it is a great challenge to fabricate stimuli-responsive membranes with ultrahigh gating ratio (the ratio of the salt solution permeating flux to the pure water permeating flux) and high response speed simultaneously. In this work, a salt-responsive membrane with an ultrahigh gating ratio is fabricated via a facile strategy by grafting zwitterionic nanohydrogels onto a poly(acrylic acid)-grafting-poly(vinylidene fluoride) (PAA-g-PVDF) microporous membrane. Due to the synergistic effect of two functional materials, PAA chains and zwitterionic nanohydrogels tethered on PAA chains, this stimuli-responsive membrane exhibits an ultrasensitive salt responsiveness with a gating ratio of up to 8.76 times for Na+ ions, 89.6 times for Mg2+ ions, and 89.3 times for Ca2+ ions. In addition, such zwitterionic nanohydrogels-grafted PAA-g-PVDF (ZNG-g-PVDF) membranes exhibit very rapid responses to stimuli. The permeating flux changes swiftly while altering the feed solution in a continuous filtration process. The excellent salt-responsive characteristics endow such a ZNG-g-PVDF membrane with great potential for applications like drug delivery, water treatment, and sensors.

Elevated CO2 promotes the acquisition of phosphorus in crop species differing in physiological phosphorus-acquiring mechanisms

Abstract: Crop species differ in phosphorus (P) acquisition in P-limiting environments. However, it is not fully understood how elevated atmospheric CO2 concentrations affects these P acquisition mechanisms and the plant's ability to acquire P from soil. This study aimed to investigate the effect of elevated CO2 on P acquisition in crop species with contrasting P acquisition mechanisms. White lupin, faba bean, canola and near-isogenic wheat lines with and without citrate efflux were grown for 70 days in a P-deficient Chromosol soil under ambient (400 ppm) and elevated (800 ppm) CO2. Plant P uptake and P transformation in the rhizosphere were determined. Elevated CO2 promoted total P uptake in white lupin and canola by 84% and 48%, respectively, and decreased the P uptake in the non-citrate-exuding wheat (by 24%) but not the exuding wheat. In white lupin, elevated CO2 enhanced phosphatase activity and depletion of organic P in the rhizosphere. Elevated CO2 increased P uptake by increasing root length which allowed canola to exploit a greater volume of soil for P. In the rhizosphere of faba bean, NaOH-extractable inorganic P was greater under elevated CO2. Crops which rely on organic acid exudation and phosphatases appear to be better adapted to acquiring P under elevated CO2.

Superhydrophilic Sub-1-nm Porous Membrane with Electroneutral Surface for Nonselective Transport of Small Organic Molecules.

Abstract: The study of traditional Chinese medicines (TCMs) is receiving increasing attention worldwide because of their contribution to human health. Developing an effective and sustainable method for screening TCMs is highly desired to accelerate the modernization of TCMs. In this work, we report a neutrally charged membrane made of a positively charged polyelectrolyte electrostatically assembled on a negatively charged superhydrophilic nanoporous membrane. The composite membrane possesses stable electroneutrality in a wide pH range and can precisely and nonselectively separate various charged molecules in TCMs with a transmittance higher than 90% for molecules with molecular weight (Mw) 800. In addition, the membrane exhibits a superior antifouling performance, and the recovery ratio observed during a continuous cycling test of a simulated TCM solution was more than 93%. The combination of superhydrophilicity and electroneutrality in a nanoporous membrane provides a new route for designing nanofiltration membranes for highly efficient molecule separation and is promising for screening TCMs.