Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
Not a member yet
40778 research outputs found
Sort by
Ladder polymers of intrinsic microporosity from superacid-catalyzed Friedel-Crafts polymerization for membrane gas separation
No full textPolymers of intrinsic microporosity have attracted comprehensive attention in membrane-mediated gas separation because of their rigid and contorted structure that facilitates well-defined microporosity for fast and selective gas transport. We report a new macromolecular design synthesizes semi-ladder and fully-ladder polymers of intrinsic microporosity containing 9H-xanthene units by superacid-catalyzed Friedel-Crafts polymerization named SACPs. The prepared SACP membranes display high microporosity with amorphous chain packing structure, high FFV, and high BET surfaces areas. In particular, SACP-3 exhibited the most elevated BET surfaces area of 568 m(2)/g, fractional free volume (FFV) of 0.243, and bimodal micropore size distribution with two maxima at similar to 5 and similar to 8 angstrom, respectively. Due to its fully ladder architecture, SACP-3 exhibits highly permeable gas transport with CO2 permeability of 6497 Barrer and CO2/CH4 selectivity of 7.8, respectively. The microporosity and gas permeation properties of SACP membranes are also demonstrated to be highly tailorable by employing different monomers. The facile polymerization procedure, excellent solubility and processability, highly diverse tunability, and outstanding gas separation performance render SACP membranes attractive for many membrane mediated gas separation processes
Tracing phosphorus cycle in global watershed using phosphate oxygen isotopes
No full textThe Phosphorus (P) cycle is a crucial biochemical process in the earth system. However, an extensive increase of P input into watersheds destroyed the ecosystem. To explore the effects of internal P loading and external P input in global watersheds, we reviewed the research progress and synthesized the isotope data of experimental results from literatures. An integrated result of the observational and experimental studies revealed that both internal P and external P largely contribute to watershed P loadings in watersheds. Internal P can be released to the overlying water during sediment resuspension process and change of redox conditions near the sediment-water interface. Growing fertilizer application on farmlands to meet food demand with population rise and diet improvement contributed to an huge increase of external P input to watersheds. Therefore, water quality cannot be improved by only reducing internal P or external P loadings. In addition, we found that phosphate oxygen isotope technology is an effectively way to trace the P biogeochemical cycle in watersheds. To better predict the dynamic of P in watersheds, future research integrating oxygen isotope fractionation mechanisms and phosphate oxygen isotope technology would be more effective
The role of diffusion in the nucleation of calcium carbonate
No full textNucleation widely exists in nature, from cloud formation to haze generation. The classical nucleation theory (CNT) was created to describe the nucleation process, but it fails to predict many experimental phenomena due to the short consideration of nanoscale phenomena and macroscale dynamics. Although the attachment and detachment of monomers are considered in the developed model of nucleation, the diffusion of chemicals in the bulk is not valued as supersaturation in the nucleation process so far. Here we employ simulation and experimental approaches to investigate how the diffusion of ions affects the nucleation of calcium carbonate. The diffusion of ions is regulated by the viscosity of solvents and the sonication imposed on the solution. It is found that the nucleation rates increased exponentially with the diffusion coefficient of ions, which is beyond the prediction of CNT. This abnormal finding might be ascribed to the involvement of cluster aggregation in the nucleation of calcium carbonate. This study highlights the significance of chemical diffusion in the nucleation process, which may help to revise the nucleation theory and develop solutions for the rational synthesis of materials, as well as for the control of air pollution. (c) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved
The role of diffusion in the nucleation of calcium carbonate
No full textNucleation widely exists in nature, from cloud formation to haze generation. The classical nucleation theory (CNT) was created to describe the nucleation process, but it fails to predict many experimental phenomena due to the short consideration of nanoscale phenomena and macroscale dynamics. Although the attachment and detachment of monomers are considered in the developed model of nucleation, the diffusion of chemicals in the bulk is not valued as supersaturation in the nucleation process so far. Here we employ simulation and experimental approaches to investigate how the diffusion of ions affects the nucleation of calcium carbonate. The diffusion of ions is regulated by the viscosity of solvents and the sonication imposed on the solution. It is found that the nucleation rates increased exponentially with the diffusion coefficient of ions, which is beyond the prediction of CNT. This abnormal finding might be ascribed to the involvement of cluster aggregation in the nucleation of calcium carbonate. This study highlights the significance of chemical diffusion in the nucleation process, which may help to revise the nucleation theory and develop solutions for the rational synthesis of materials, as well as for the control of air pollution. (c) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved
Chemoenzymatic Cascade Reaction for Green Cleaning of Polyamide Nanofiltration Membrane
No full textChemical cleaning is indispensable for the sustainable operation of nanofiltration (NF) in wastewater treatment. However, the common chemical cleaning methods are plagued by low cleaning efficiency, high chemical consumption, and separation performance deterioration. In this work, a chemoenzymatic cascade reaction is proposed for pollutant degradation and polyamide NF membrane cleaning. Glucose oxidase (GOD) enzymatic reaction in this cascade system produces hydrogen peroxide (H2O2) and gluconic acid to trigger the oxidation of foulants by Fe3O4 catalyzed Fenton reaction. By virtue of the microenvironment (pH and H2O2 concentration) engineering and substrate enrichments, this chemoenzymatic cascade reaction (GOD-Fe3O4) exhibits a favorable degradation efficiency for bisphenol A and methyl blue (MB). Thanks to the strong oxidizing degradation, the water flux of the NF10 membrane fouled by MB is almost completely recovered (similar to 95.8%) after a 3-cycle fouling/cleaning experiment. Meanwhile, the chemoenzymatic cascade reaction improves the applicability of the Fenton reaction in polyamide NF membrane cleaning because it prevents the membrane from damaging by high concentration of H2O2 and inhibits the secondary fouling caused by ferric hydroxide precipitates. By immobilizing GOD on the aminated Fe3O4 nanoparticles, a reusable cleaning agent is prepared for highly efficient membrane cleaning. This chemoenzymatic cascade reaction without the addition of an acid/base/oxidant provides a promising candidate for sustainable and cost-effective cleaning for the polyamide NF membrane
