Rh has been widely studied as a catalyst for the promising hydrazine oxidation reaction that can replace oxygen evolution reactions for boosting hydrogen production from hydrazine-containing wastewater.Despite Rh bein...Rh has been widely studied as a catalyst for the promising hydrazine oxidation reaction that can replace oxygen evolution reactions for boosting hydrogen production from hydrazine-containing wastewater.Despite Rh being expensive,only a few studies have examined its electrocatalytic mass activity.Herein,surface-limited cation exchange and electrochemical activation processes are designed to remarkably enhance the mass activity of Rh.Rh atoms were readily replaced at the Ni sites on the surface of NiOOH electrodes by cation exchange,and the resulting RhOOH compounds were activated by the electrochemical reduction process.The cation exchange-derived Rh catalysts exhibited particle sizes not exceeding 2 nm without agglomeration,indicating a decrease in the number of inactive inner Rh atoms.Consequently,an improved mass activity of 30 A mg_(Rh)^(-1)was achieved at 0.4 V versus reversible hydrogen electrode.Furthermore,the two-electrode system employing the same CE-derived Rh electrodes achieved overall hydrazine splitting over 36 h at a stable low voltage.The proposed surface-limited CE process is an effective method for reducing inactive atoms of expensive noble metal catalysts.展开更多
Studies on the spatial variability of the soil cation exchange capacity （CEC） were made to provide a theoretical basis for an ecological tea plantation and management of soil fertilizer in the tea plantation. Geosta...Studies on the spatial variability of the soil cation exchange capacity （CEC） were made to provide a theoretical basis for an ecological tea plantation and management of soil fertilizer in the tea plantation. Geostatistics were used to analyze the spatial variability of soil CEC in the tea plantation site on Mengding Mountain in Sichuan Province of China on two sampling scales. It was found that, （1） on the small scale, the soil CEC was intensively spatially correlative, the rate of nugget to sill was 18.84% and the spatially dependent range was 1 818 m, and structural factors were the main factors that affected the spatial variability of the soil CEC; （2） on the microscale, the soil CEC was also consumingly spatially dependent, and the rate of nugget to sill was 16.52%, the spatially dependent range was 311 m, and the main factors affecting the spatial variability were just the same as mentioned earlier. On the small scale, soil CEC had a stronger anisotropic structure on the slope aspect, and a weaker one on the lateral side. According to the ordinary Kriging method, the equivalence of soil CEC distributed along the lateral aspect of the slope from northeast to southwest, and the soil CEC reduced as the elevation went down. On the microscale, the anisotropic structure was different from that measured on the small scale. It had a stronger anisotropic structure on the aspect that was near the aspect of the slope, and a weaker one near the lateral aspect of the slope. The soil CEC distributed along the lateral aspect of the slope and some distributed in the form of plots. From the top to the bottom of the slope, the soil CEC increased initially, and then reduced, and finally increased.展开更多
As soil cation exchange capacity （CEC） is a vital indicator of soil quality and pollutant sequestration capacity,a study was conducted to evaluate cokriging of CEC with the principal components derived from soil phy...As soil cation exchange capacity （CEC） is a vital indicator of soil quality and pollutant sequestration capacity,a study was conducted to evaluate cokriging of CEC with the principal components derived from soil physico-chemical properties.In Qingdao,China,107 soil samples were collected.Soil CEC was estimated by using 86 soil samples for prediction and 21 soil samples for test.The first two principal components （PC1 and PC2） together explained 60.2% of the total variance of soil physico-chemical properties.The PC1 was highly correlated with CEC （r=0.76,P0.01）,whereas there was no significant correlation between CEC and PC2 （r=0.03）.The PC1 was then used as an auxiliary variable for the prediction of soil CEC.Mean error （ME） and root mean square error （RMSE） of kriging for the test dataset were-1.76 and 3.67 cmolc kg-1,and ME and RMSE of cokriging for the test dataset were-1.47 and 2.95 cmolc kg-1,respectively.The cross-validation R2 for the prediction dataset was 0.24 for kriging and 0.39 for cokriging.The results show that cokriging with PC1 is more reliable than kriging for spatial interpolation.In addition,principal components have the highest potential for cokriging predictions when the principal components have good correlations with the primary variables.展开更多
Polymer-grafted ion exchange adsorbents were of great interest for the development of high-performance protein chromatography in biopharmaceutical and related fields.In this work,protein retention was systematically i...Polymer-grafted ion exchange adsorbents were of great interest for the development of high-performance protein chromatography in biopharmaceutical and related fields.In this work,protein retention was systematically investigated in ion exchange chromatography packed respectively with dextran-grafted cation exchange adsorbents containing sulphopropyl(SP)ligand,SP Sepharose XL and Capto S,and non-grafted cation exchange adsorbent,SP Sepharose FF,using five proteins.With an increase of buffer p Hs,retention factors of proteins decreased among all the adsorbents,demonstrating the dominant role of electrostatic interaction for protein binding on cation exchange adsorbents.The evidences further revealed that the scattered positive charges on the surface of protein molecules,rather than net charge of protein molecule,determined protein retention on cation exchange adsorbent.Likely,counterions including NH4^+,K^+,Na^+and Mg^2+exhibited distinct influence on protein retention.It was well ascribed to solvent-mediated indirect ion-macromolecule interactions and direct ion-macromolecule interactions.Compared with SP Sepharose FF,polymer structure in dextran-grafted cation exchange adsorbents ultimately brought about different ligand distributions and smaller pore sizes,thereby regulating protein retention in cation exchange chromatography.By comparing the retention of myoglobin andβ-lactoglobulin B in SP Sepharose XL and Capto S,we reasonably speculated that the enhancement of nonelectrostatic interaction caused by reducing the space arm length was a major reason for an increasing retention factor of myoglobin in Capto S.The results in this research help us understand adsorption mechanism of protein in polymer-grafted adsorbents and give scientific guidance for the development of chromatographic materials.展开更多
Acarbose, a potent α-glucosidase inhibitor, is widely used as an oral anti-diabetic drug for the treatment of the type 2, non-insulin-dependent diabetes. In this work, a gel type strong acid cation exchange resin 001...Acarbose, a potent α-glucosidase inhibitor, is widely used as an oral anti-diabetic drug for the treatment of the type 2, non-insulin-dependent diabetes. In this work, a gel type strong acid cation exchange resin 001×4 was applied to isolate acarbose from fermentation broth. It was demonstrated that cation exchanger 001×4 displayed a large adsorption capacity and quick exchange rate for acarbose. The static adsorption equilibrium data were well fitted to the Langmuir equation. Column adsorption experiments demonstrated that high dynamic adsorption capacity was reached at bed height of 104.4 mm, feed flow rate of 1.0 ml·min 1and acarbose concentration of 4.0 mg·ml 1.Under the optimized conditions, the column chromatography packed with cation exchanger 001×4 recovered 74.3%(by mass) of acarbose from Actinoplanes utahensis ZJB-08196 fermentation broth with purity of 80.1%(by mass),demonstrating great potential in the practical applications in acarbose separation.展开更多
In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxide...In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxides/hydroxides composite(FeMg/CER)was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water environment.Characteristics of FeMg/CER were determined by techniques such as Fouriertransform infrared spectroscopy,scanning electron microscopy,and Xray diffraction.The results showed that FeMg/CER material had a high nitrate adsorption capacity of 200 mg NO_(3)^()·g^(1)with a fast equilibrium adsorption time of 30 min at pH 5.In addition,it had good durability of at least 10 times of regeneration,which could be applied to practical water and wastewater treatment.展开更多
Pyrolysis is a cost-effective and safe method for the disposal of radioactive spent resins.In this work,the catalytic effects of V_(2)O_(5) on the pyrolysis of cation exchange resin are investigated for the first time...Pyrolysis is a cost-effective and safe method for the disposal of radioactive spent resins.In this work,the catalytic effects of V_(2)O_(5) on the pyrolysis of cation exchange resin are investigated for the first time.The results show that it is a better catalyst than others so far studied and achieves a lowering of final pyrolysis temperature and residual rate simultaneously when aided by physical blending.The maximum reductions of the final pyrolysis temperature and the residual rate are 173℃and 11.9%(in weight),respectively.Under the action of V_(2)O_(5),low-temperature(445℃)removal of partial sulfonic acid groups occurs and the pyrolysis of the resin copolymer matrix is promoted.This is demonstrated by the analysis of pyrolysis residues at different temperatures by X-ray photoelectron spectroscopy(XPS)and element analysis.The catalytic activity of V_(2)O_(5) is determined by effects both at acid sites and oxidation-reduction centers via H2-TPR(temperature programmed reduction),V_(2)-TPD(temperature programmed desorption),CV_(2)-TPD,and NH3-TPD.The catalytic effect of oxidation-reduction centers in V_(2)O_(5) is achieved by close contact with the sulfur bond through chemisorption under the effect of acid sites.V_(2)O_(5) is also believed to be the reason for the removal of partial sulfonic acid groups at lower temperatures(445℃).V_(2)O_(5) is an effective catalyst for spent resin pyrolysis and can be further applied in industry.展开更多
The sluggish kinetics for water oxidation is recognized as one of the major problems for the unsatisfied photoelectrochemical(PEC) performance. Herein, we developed a feasible strategy based on in-situ selective surfa...The sluggish kinetics for water oxidation is recognized as one of the major problems for the unsatisfied photoelectrochemical(PEC) performance. Herein, we developed a feasible strategy based on in-situ selective surface cation exchange, for activating surface water oxidation reactivity toward boosted PEC water oxidation of BiVO_(4) photoanodes with fundamentally improved surface charge transfer. The asconstructed Co/BiVO_(4) photoanodes exhibit 2.6 times increase in photocurrent density with superior stability, in comparison to those of pristine counterpart. Moreover, the faradaic efficiency of as-fabricated photoanode can be up to ~ 95% at 1.23 V(vs. RHE). The unique selective replacement of Bi by Co on the surface could modify the electronic structure of BiVO_(4) with reduced energy barrier of the deprotonation of OH^(+) to O, thus favoring the overall excellent PEC performance of Co/BiVO_(4) photoanode.展开更多
This study describes the kinetics and thermodynamics of the esterification of acidified oil with methanol catalyzed by sulfonated cation exchange resins（SCER）. The effects of the mass ratio of methanol to acidified ...This study describes the kinetics and thermodynamics of the esterification of acidified oil with methanol catalyzed by sulfonated cation exchange resins（SCER）. The effects of the mass ratio of methanol to acidified oil,reaction temperature,and catalyst loading were studied to optimize the conditions for maximum conversion of free fatty acids（FFAs）. The results showed that the optimal conversion rate of FFAs was 91.87% at the mass ratio of methanol to acidified oil of 2.5：1.0,reaction temperature of 65.0 °C,catalyst loading of 5.0 g and reaction time of 8.0 h. The external and internal mass transfer resistances were negligible based on the experimental results and a pseudo-homogeneous kinetic model was proposed for the esterification. The activation energy and thermodynamic parameters including G,S and H were determined. The conversion rates of FFAs obtained from the established model were in good agreement with the experimental data.展开更多
More than 500 datasets from the literature have been used to evaluate the relationships of specific surface area (SSA),cation exchange capacity (CEC) and activity versus the liquid limit (LL).The correlations gave R^2...More than 500 datasets from the literature have been used to evaluate the relationships of specific surface area (SSA),cation exchange capacity (CEC) and activity versus the liquid limit (LL).The correlations gave R^2 values ranging between 0.71 and 0.92.Independent data were also used to validate the correlations.Estimated SSA values slightly overestimate the measured SSA up to 100 m^2/g.Regarding the estimated CEC values,they overestimated the measured CEC values up to 20 meq/(100 g).A probabilistic approach was performed for the correlations of SSA,CEC and activity versus LL.The analysis shows that the relations of SSA,CEC and activity with LL are robust.Using the LL values,it is possible to assess other basic engineering properties of clays.展开更多
An ion exchanger was prepared by sulfonation of cork-waste chars. The exchange properties of the resultant material were characterized using Na+, Ca2+ or Fe3+ aqueous solutions. The content of metal ions in the soluti...An ion exchanger was prepared by sulfonation of cork-waste chars. The exchange properties of the resultant material were characterized using Na+, Ca2+ or Fe3+ aqueous solutions. The content of metal ions in the solutions were determined by atomic absorption spectrometry. On the basis of the results obtained, the chemical equilibrium and its thermodynamic aspects related to the ion exchange process were studied. It was found that equilibrium constant K varies by the order: Na+<Ca2+<Fe3+, its value increasing with increasing temperature, and that △H°>0 and △5°>0, with -△G° following the sequence: Ca2+>Na+>Fe3+.展开更多
Macroporous poly [(chloromethyl) styrene-co-divinylbenzene] continuous rod was prepared by direct polymerization of the monomers in the presence of a porogenic diluent inside an empty chromatographic column. A new ...Macroporous poly [(chloromethyl) styrene-co-divinylbenzene] continuous rod was prepared by direct polymerization of the monomers in the presence of a porogenic diluent inside an empty chromatographic column. A new 'in-situ' technique was used to modify the synthesized polymer rod for a weak cation exchanger and it has been used successfully for the separation of biopolymers. It was found that the back pressure of the continuous rod column was much lower and its surface was proved to be modified well.展开更多
Elemental doping confined in atomically-thin 2 D semiconductors offers a compelling strategy for constructing high performance photocatalysts.Although impressive progress has been achieved based on co-thermolysis meth...Elemental doping confined in atomically-thin 2 D semiconductors offers a compelling strategy for constructing high performance photocatalysts.Although impressive progress has been achieved based on co-thermolysis method,the choices of dopants as well as semiconductor hosts are still quite limited to yield the elaborate photocatalyst with atomic-layer-confined doping defects,owing to the difficulty in balancing the reaction kinetics of different precursors.This study shows that the cation exchange reaction,which is dictated by the Pearson's hard and soft acids and bases(HSAB)theory and allowed to proceed at mild temperatures,can be developed into a conceptually new protocol for engineering elemental doping confined in semiconductor atomic layers.To this aim,the two atomic layers of a new type of 2 D photocatalyst PdSe0_(3)(PdSe0_(3)2 ALs,1.1 nm)are created by liquid exfoliation and exploited as a proof-of-concept prototype.It is demonstrated that the Mn(Ⅱ)dopants with controlled concentrations can be incorporated into PdSeO_(3)2 ALs via topological Mn^(2+) for-Pd^(2+) cation exchange performed in water/isopropanol solution at 30℃.The resulting Mn-doped PdSeO_(3)2 ALs present enhanced capacity for driving photocatalytic oxidation reactions in comparison with their undoped counterparts.The findings here suggest that the new route mediated by post synthetic cation exchange promises to give access to manifold 2 D confined-doping photocatalysts,with little perturbations on the thickness,morphology,and crystal structure of the atomically-thin semiconductor hosts.展开更多
Monovalent cation perm-selective membrane(MCPMs)allow fast and selective transport of monovalent cations,and they are promisingly required for extraction of special ions,such as lithium extraction,acid recovery and se...Monovalent cation perm-selective membrane(MCPMs)allow fast and selective transport of monovalent cations,and they are promisingly required for extraction of special ions,such as lithium extraction,acid recovery and sea salt production.Herein,we report a novel strategy to design the critical functional layers of MCPMs with both space charge repulsion and cross-linked dense screenability.The in-situ depo-sition polymerization of pyrrole was carried out on the surface of sulfonated polyphenyl sulfone(SPPSU)substrate membrane followed by cross-linking quaternization of the polypyrrole(PPy)layer with diiodi-nated functional molecules,thus,the membrane obtained more excellent selective permeability and sta-ble transport properties of monovalent cations.It confirms that the designed PPy layers with charged sur-face and cross-linking structure improved the hydrophilicity,facilitated cation transport and increased ion flux.Meanwhile,for the dense PPy layer,the charged cross-linked structure endowed the functional layer with the synergistic characteristics of Donnan exclusion and pore size sieving for positively charged ions,which improved the monovalent cation perm-selectivity of the membranes.At a constant current density of 5.1 mA/cm^(2),the optimal membrane exhibited superior perm-selectivity(P^(Na)_(Mg)=2.07)and monovalent cation flux(J_(Na+)=2.80×10^(−8)mol cm^(−2)s^(−1))during electrodialysis.展开更多
The polystyrene cation exchange resin was exchanged by La 3+ and then were carbonized to make resin carbon material. The electrochemical properties of the resin carbon material as the electrode of the lithium ion...The polystyrene cation exchange resin was exchanged by La 3+ and then were carbonized to make resin carbon material. The electrochemical properties of the resin carbon material as the electrode of the lithium ion cell were investigated. The test results show that comparing with the polystyrene cation exchange resin without adulterating, the contents of hydrogen, oxygen and sulfur are changed obviously for the resin carbon material derived from the La 3+ adulterating polystyrene cation exchange resin. The contents of hydrogen and oxygen are increased, and the one of sulfur is decreased. The test results also indicate that it is more easily to form the stratum graphite minicrystal structure with bigger diameter for the La 3+ adulterating resin. According to the electrochemical test results, the electrode derived from La 3+ adulterating polystyrene cation exchange resin has much better electrochemical property, and the capacity of charge and discharge of the electrode is increased about 30 mAh·g -1 in average.展开更多
Surface modification of different functional molecules onto NaREF_(4)(RE=rare earth)upconversion nanoparticles(UCNPs)impart their multiple functionalities.Functional molecules can be loaded onto NaREF_(4) UCNPs throug...Surface modification of different functional molecules onto NaREF_(4)(RE=rare earth)upconversion nanoparticles(UCNPs)impart their multiple functionalities.Functional molecules can be loaded onto NaREF_(4) UCNPs through the formation of coordination bonds between the surface-exposed RE^(3+) ions and the appropriate chemical groups of functional molecules.The density of surface RE^(3+) ions directly determines the loading efficiency of Na REF4 UCNPs.However,NaREF_(4) is a binary cation system,rendering the surface-distributed Na;and RE^(3+) ions remains a mystery.Here,we develop an effective strategy to significantly enhance the density of surface RE^(3+) ions,thus maximizing the loading capacity of NaREF_(4) UCNPs.This strategy is based on a heterovalent cation exchange(HCE)reaction in the surface region in which Na^(+)ions are replaced by RE^(3+) ions.The density of surface ligands enhances from 3.6 to 8.8 molecules/nm^(2) after reaction,suggesting that the loading efficiency increases by approximately 150%.Benefiting from the improved loading capacity,we demonstrate such surface-RE-rich nanoparticles have the ability to offer higher colloidal stability and more desirable photodynamic therapy(PDT)efficacy.This work not only advances our understanding of cation exchange reactions in RE-based nanoparticles,but also provides significant value for considerable applications such as sensing,bioimaging,and therapy.展开更多
FA-Cs mixed-cation perovskite has been reported as a promising candidate for obtaining highly efficient and stable photovoltaic devices.Phenylethylamine iodide(PEAI)post-treatment is a widely used and effective method...FA-Cs mixed-cation perovskite has been reported as a promising candidate for obtaining highly efficient and stable photovoltaic devices.Phenylethylamine iodide(PEAI)post-treatment is a widely used and effective method for surface passivation of FA-Cs perovskite layer in devices.However,it is still controversial whether the PEAI post-treatment would form two-dimensional(2D)perovskite PEA_(2)PbI_(4) capping layer or just result in PEA+terminated surface.Here in this work,the function of PEAI post-treatment on FA-Cs mixed-cation perovskite FA_(1-x)Cs_(x)PbI_(3)(x=0.1–0.9)with varied Cs contents is elucidated.With increased Cs content,the FA-Cs perovskite shows higher resistance to the cation exchange between FA+and PEA+.This Cs-content-dependent cation exchange results in the different PEAI reaction preferences with FA-Cs mixed-cation perovskites.Furthermore,higher Cs content with stronger resistance to cation exchange reaction leads to a wider processing window for post-treatment and defect passivation,which is beneficial for the fabrication of large-scale photovoltaic devices.展开更多
Current researches on the nutritive characteristics of fibrous feedstuff through determining the feedstuff cation exchange capacity (CEC) to evaluate its nutritive value at home and abroad were comprehensively discrib...Current researches on the nutritive characteristics of fibrous feedstuff through determining the feedstuff cation exchange capacity (CEC) to evaluate its nutritive value at home and abroad were comprehensively discribed. and the methods of determining CEC value and the correlation between CEC value and chemical compositions, pH value, and the effect of CEC value on the digestion kinetics in ruminants were also emphatically introduced. The results of research showed that the CEC values of different feedstuff are different, closely correlated with nitrogen and acid detergent fibre (ADF) and lignin (LIG) content of the feedstuff. At the same time, there are markedly effect of CEC value in diet on the nutrients flow of digesta in the digestive tract of ruminants, the degradation rate and digestibility of nutrients in the rumen.展开更多
Strongly acidic cation exchange resin(1x1,H form)has been successfully used as a catalyst in synthesis of diphenyl N-benzyloxycarbonyl-1-aminobenzylphosphonate, N-benzyloxycarbonyl-1-aminobenzylphenylphosphinic acid a...Strongly acidic cation exchange resin(1x1,H form)has been successfully used as a catalyst in synthesis of diphenyl N-benzyloxycarbonyl-1-aminobenzylphosphonate, N-benzyloxycarbonyl-1-aminobenzylphenylphosphinic acid and N-p-tolylsulfonyl-1-aminobenzyl phenylphosphinic acid in high yields.展开更多
N-nitrosodimethylamine（NDMA） precursors consist of a positively charged dimethylamine group and a non-polar moiety, which inspired us to develop a targeted cation exchange technology to remove NDMA precursors. In th...N-nitrosodimethylamine（NDMA） precursors consist of a positively charged dimethylamine group and a non-polar moiety, which inspired us to develop a targeted cation exchange technology to remove NDMA precursors. In this study, we tested the removal of two representative NDMA precursors, dimethylamine（DMA） and ranitidine（RNTD）, by strong acidic cation exchange resin. The results showed that pH greatly affected the exchange efficiency, with high removal（DMA 〉 78% and RNTD 〉 94%） observed at pH 〈 pk_a-1 when the molar ratio of exchange capacity to precursor was 4. The exchange order was obtained as follows： Ca^（2＋）〉 Mg^（2＋）〉 RNTD~＋〉 K~＋〉 DMA~＋〉 NH_4~＋〉 Na~＋. The partition coefficient of DMA~＋to Na~＋was 1.41 ± 0.26, while that of RNTD~＋to Na~＋was 12.1 ± 1.9. The pseudo second-order equation fitted the cation exchange kinetics well. Bivalent inorganic cations such as Ca^（2＋）were found to have a notable effect on NA precursor removal in softening column test. Besides DMA and RNTD, cation exchange process also worked well for removing other 7 model NDMA precursors. Overall, NDMA precursor removal can be an added benefit of making use of cation exchange water softening processes.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry ofEducation(2021R1A2C3011870 and 2019R1A6A1A03033215)the Korea Research Fellowship Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(2020H1D3A1A04081323)
文摘Rh has been widely studied as a catalyst for the promising hydrazine oxidation reaction that can replace oxygen evolution reactions for boosting hydrogen production from hydrazine-containing wastewater.Despite Rh being expensive,only a few studies have examined its electrocatalytic mass activity.Herein,surface-limited cation exchange and electrochemical activation processes are designed to remarkably enhance the mass activity of Rh.Rh atoms were readily replaced at the Ni sites on the surface of NiOOH electrodes by cation exchange,and the resulting RhOOH compounds were activated by the electrochemical reduction process.The cation exchange-derived Rh catalysts exhibited particle sizes not exceeding 2 nm without agglomeration,indicating a decrease in the number of inactive inner Rh atoms.Consequently,an improved mass activity of 30 A mg_(Rh)^(-1)was achieved at 0.4 V versus reversible hydrogen electrode.Furthermore,the two-electrode system employing the same CE-derived Rh electrodes achieved overall hydrazine splitting over 36 h at a stable low voltage.The proposed surface-limited CE process is an effective method for reducing inactive atoms of expensive noble metal catalysts.
文摘Studies on the spatial variability of the soil cation exchange capacity （CEC） were made to provide a theoretical basis for an ecological tea plantation and management of soil fertilizer in the tea plantation. Geostatistics were used to analyze the spatial variability of soil CEC in the tea plantation site on Mengding Mountain in Sichuan Province of China on two sampling scales. It was found that, （1） on the small scale, the soil CEC was intensively spatially correlative, the rate of nugget to sill was 18.84% and the spatially dependent range was 1 818 m, and structural factors were the main factors that affected the spatial variability of the soil CEC; （2） on the microscale, the soil CEC was also consumingly spatially dependent, and the rate of nugget to sill was 16.52%, the spatially dependent range was 311 m, and the main factors affecting the spatial variability were just the same as mentioned earlier. On the small scale, soil CEC had a stronger anisotropic structure on the slope aspect, and a weaker one on the lateral side. According to the ordinary Kriging method, the equivalence of soil CEC distributed along the lateral aspect of the slope from northeast to southwest, and the soil CEC reduced as the elevation went down. On the microscale, the anisotropic structure was different from that measured on the small scale. It had a stronger anisotropic structure on the aspect that was near the aspect of the slope, and a weaker one near the lateral aspect of the slope. The soil CEC distributed along the lateral aspect of the slope and some distributed in the form of plots. From the top to the bottom of the slope, the soil CEC increased initially, and then reduced, and finally increased.
基金funded by the National Natural Science Foundation of China (40771095,40725010 and 41030746)the Water Conservancy Science and Technology Foundation of Qingdao City,China (2006003)
文摘As soil cation exchange capacity （CEC） is a vital indicator of soil quality and pollutant sequestration capacity,a study was conducted to evaluate cokriging of CEC with the principal components derived from soil physico-chemical properties.In Qingdao,China,107 soil samples were collected.Soil CEC was estimated by using 86 soil samples for prediction and 21 soil samples for test.The first two principal components （PC1 and PC2） together explained 60.2% of the total variance of soil physico-chemical properties.The PC1 was highly correlated with CEC （r=0.76,P0.01）,whereas there was no significant correlation between CEC and PC2 （r=0.03）.The PC1 was then used as an auxiliary variable for the prediction of soil CEC.Mean error （ME） and root mean square error （RMSE） of kriging for the test dataset were-1.76 and 3.67 cmolc kg-1,and ME and RMSE of cokriging for the test dataset were-1.47 and 2.95 cmolc kg-1,respectively.The cross-validation R2 for the prediction dataset was 0.24 for kriging and 0.39 for cokriging.The results show that cokriging with PC1 is more reliable than kriging for spatial interpolation.In addition,principal components have the highest potential for cokriging predictions when the principal components have good correlations with the primary variables.
基金supported by the National Natural Science Foundation of China(Nos.21476166 and 21878221)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.21621004)。
文摘Polymer-grafted ion exchange adsorbents were of great interest for the development of high-performance protein chromatography in biopharmaceutical and related fields.In this work,protein retention was systematically investigated in ion exchange chromatography packed respectively with dextran-grafted cation exchange adsorbents containing sulphopropyl(SP)ligand,SP Sepharose XL and Capto S,and non-grafted cation exchange adsorbent,SP Sepharose FF,using five proteins.With an increase of buffer p Hs,retention factors of proteins decreased among all the adsorbents,demonstrating the dominant role of electrostatic interaction for protein binding on cation exchange adsorbents.The evidences further revealed that the scattered positive charges on the surface of protein molecules,rather than net charge of protein molecule,determined protein retention on cation exchange adsorbent.Likely,counterions including NH4^+,K^+,Na^+and Mg^2+exhibited distinct influence on protein retention.It was well ascribed to solvent-mediated indirect ion-macromolecule interactions and direct ion-macromolecule interactions.Compared with SP Sepharose FF,polymer structure in dextran-grafted cation exchange adsorbents ultimately brought about different ligand distributions and smaller pore sizes,thereby regulating protein retention in cation exchange chromatography.By comparing the retention of myoglobin andβ-lactoglobulin B in SP Sepharose XL and Capto S,we reasonably speculated that the enhancement of nonelectrostatic interaction caused by reducing the space arm length was a major reason for an increasing retention factor of myoglobin in Capto S.The results in this research help us understand adsorption mechanism of protein in polymer-grafted adsorbents and give scientific guidance for the development of chromatographic materials.
基金Supported by the National Basic Research Program of China(2011CB710800)National Special Program for Key Science and Technology of China(2008ZX09204-004)
文摘Acarbose, a potent α-glucosidase inhibitor, is widely used as an oral anti-diabetic drug for the treatment of the type 2, non-insulin-dependent diabetes. In this work, a gel type strong acid cation exchange resin 001×4 was applied to isolate acarbose from fermentation broth. It was demonstrated that cation exchanger 001×4 displayed a large adsorption capacity and quick exchange rate for acarbose. The static adsorption equilibrium data were well fitted to the Langmuir equation. Column adsorption experiments demonstrated that high dynamic adsorption capacity was reached at bed height of 104.4 mm, feed flow rate of 1.0 ml·min 1and acarbose concentration of 4.0 mg·ml 1.Under the optimized conditions, the column chromatography packed with cation exchanger 001×4 recovered 74.3%(by mass) of acarbose from Actinoplanes utahensis ZJB-08196 fermentation broth with purity of 80.1%(by mass),demonstrating great potential in the practical applications in acarbose separation.
基金Vietnam National University-Ho Chi Minh City under grant number A2020-16-01.
文摘In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxides/hydroxides composite(FeMg/CER)was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water environment.Characteristics of FeMg/CER were determined by techniques such as Fouriertransform infrared spectroscopy,scanning electron microscopy,and Xray diffraction.The results showed that FeMg/CER material had a high nitrate adsorption capacity of 200 mg NO_(3)^()·g^(1)with a fast equilibrium adsorption time of 30 min at pH 5.In addition,it had good durability of at least 10 times of regeneration,which could be applied to practical water and wastewater treatment.
基金Project supported by the National Natural Science Foundation of China(No.U1862203)the National Science Fund for Distinguished Young Scholars(No.21525627)the Science Fund for Creative Research Groups of National Natural Science Foundation of China(No.61621002)。
文摘Pyrolysis is a cost-effective and safe method for the disposal of radioactive spent resins.In this work,the catalytic effects of V_(2)O_(5) on the pyrolysis of cation exchange resin are investigated for the first time.The results show that it is a better catalyst than others so far studied and achieves a lowering of final pyrolysis temperature and residual rate simultaneously when aided by physical blending.The maximum reductions of the final pyrolysis temperature and the residual rate are 173℃and 11.9%(in weight),respectively.Under the action of V_(2)O_(5),low-temperature(445℃)removal of partial sulfonic acid groups occurs and the pyrolysis of the resin copolymer matrix is promoted.This is demonstrated by the analysis of pyrolysis residues at different temperatures by X-ray photoelectron spectroscopy(XPS)and element analysis.The catalytic activity of V_(2)O_(5) is determined by effects both at acid sites and oxidation-reduction centers via H2-TPR(temperature programmed reduction),V_(2)-TPD(temperature programmed desorption),CV_(2)-TPD,and NH3-TPD.The catalytic effect of oxidation-reduction centers in V_(2)O_(5) is achieved by close contact with the sulfur bond through chemisorption under the effect of acid sites.V_(2)O_(5) is also believed to be the reason for the removal of partial sulfonic acid groups at lower temperatures(445℃).V_(2)O_(5) is an effective catalyst for spent resin pyrolysis and can be further applied in industry.
基金supported by the project funded by the National Natural Science Foundation of China (52172222, 5197226 and 51972178)the China Postdoctoral Science Foundation(2020 M681966)+1 种基金the exchange project of the sixth ChinaNorthern Macedonia Science and Technology Meeting (6-11)the Natural Science Foundation of Ningbo Municipal Government(202003 N4164 and 2021J145)。
文摘The sluggish kinetics for water oxidation is recognized as one of the major problems for the unsatisfied photoelectrochemical(PEC) performance. Herein, we developed a feasible strategy based on in-situ selective surface cation exchange, for activating surface water oxidation reactivity toward boosted PEC water oxidation of BiVO_(4) photoanodes with fundamentally improved surface charge transfer. The asconstructed Co/BiVO_(4) photoanodes exhibit 2.6 times increase in photocurrent density with superior stability, in comparison to those of pristine counterpart. Moreover, the faradaic efficiency of as-fabricated photoanode can be up to ~ 95% at 1.23 V(vs. RHE). The unique selective replacement of Bi by Co on the surface could modify the electronic structure of BiVO_(4) with reduced energy barrier of the deprotonation of OH^(+) to O, thus favoring the overall excellent PEC performance of Co/BiVO_(4) photoanode.
基金support from the Natural Science Foundation of Shandong Province (Grant no.ZR2013BL010)the Research Excellence Award of Shandong University of Technology and the Zibo Technology Research and Development Program of China (Grant no.2013GG04110)
文摘This study describes the kinetics and thermodynamics of the esterification of acidified oil with methanol catalyzed by sulfonated cation exchange resins（SCER）. The effects of the mass ratio of methanol to acidified oil,reaction temperature,and catalyst loading were studied to optimize the conditions for maximum conversion of free fatty acids（FFAs）. The results showed that the optimal conversion rate of FFAs was 91.87% at the mass ratio of methanol to acidified oil of 2.5：1.0,reaction temperature of 65.0 °C,catalyst loading of 5.0 g and reaction time of 8.0 h. The external and internal mass transfer resistances were negligible based on the experimental results and a pseudo-homogeneous kinetic model was proposed for the esterification. The activation energy and thermodynamic parameters including G,S and H were determined. The conversion rates of FFAs obtained from the established model were in good agreement with the experimental data.
文摘More than 500 datasets from the literature have been used to evaluate the relationships of specific surface area (SSA),cation exchange capacity (CEC) and activity versus the liquid limit (LL).The correlations gave R^2 values ranging between 0.71 and 0.92.Independent data were also used to validate the correlations.Estimated SSA values slightly overestimate the measured SSA up to 100 m^2/g.Regarding the estimated CEC values,they overestimated the measured CEC values up to 20 meq/(100 g).A probabilistic approach was performed for the correlations of SSA,CEC and activity versus LL.The analysis shows that the relations of SSA,CEC and activity with LL are robust.Using the LL values,it is possible to assess other basic engineering properties of clays.
文摘An ion exchanger was prepared by sulfonation of cork-waste chars. The exchange properties of the resultant material were characterized using Na+, Ca2+ or Fe3+ aqueous solutions. The content of metal ions in the solutions were determined by atomic absorption spectrometry. On the basis of the results obtained, the chemical equilibrium and its thermodynamic aspects related to the ion exchange process were studied. It was found that equilibrium constant K varies by the order: Na+<Ca2+<Fe3+, its value increasing with increasing temperature, and that △H°>0 and △5°>0, with -△G° following the sequence: Ca2+>Na+>Fe3+.
文摘Macroporous poly [(chloromethyl) styrene-co-divinylbenzene] continuous rod was prepared by direct polymerization of the monomers in the presence of a porogenic diluent inside an empty chromatographic column. A new 'in-situ' technique was used to modify the synthesized polymer rod for a weak cation exchanger and it has been used successfully for the separation of biopolymers. It was found that the back pressure of the continuous rod column was much lower and its surface was proved to be modified well.
基金supported by the National Natural Science Foundation of China(Nos.52072035,51631001,21801015,51702016,51902023,51872030)Joint R&D Plan of Hongkong+3 种基金MacaoTaiwan and Beijing(No.Z191100001619002)the Fundamental Research Funds for the Central Universities(No.2017CX01003)the Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Elemental doping confined in atomically-thin 2 D semiconductors offers a compelling strategy for constructing high performance photocatalysts.Although impressive progress has been achieved based on co-thermolysis method,the choices of dopants as well as semiconductor hosts are still quite limited to yield the elaborate photocatalyst with atomic-layer-confined doping defects,owing to the difficulty in balancing the reaction kinetics of different precursors.This study shows that the cation exchange reaction,which is dictated by the Pearson's hard and soft acids and bases(HSAB)theory and allowed to proceed at mild temperatures,can be developed into a conceptually new protocol for engineering elemental doping confined in semiconductor atomic layers.To this aim,the two atomic layers of a new type of 2 D photocatalyst PdSe0_(3)(PdSe0_(3)2 ALs,1.1 nm)are created by liquid exfoliation and exploited as a proof-of-concept prototype.It is demonstrated that the Mn(Ⅱ)dopants with controlled concentrations can be incorporated into PdSeO_(3)2 ALs via topological Mn^(2+) for-Pd^(2+) cation exchange performed in water/isopropanol solution at 30℃.The resulting Mn-doped PdSeO_(3)2 ALs present enhanced capacity for driving photocatalytic oxidation reactions in comparison with their undoped counterparts.The findings here suggest that the new route mediated by post synthetic cation exchange promises to give access to manifold 2 D confined-doping photocatalysts,with little perturbations on the thickness,morphology,and crystal structure of the atomically-thin semiconductor hosts.
基金supported by the Public Welfare Project of the Science and Technology Committee of Zhejiang Province(No.LGF20B060002)the China Postdoctoral Science Foundation funded project(No.2016M601964)+1 种基金Provincial Key R&D Program of Zhe-jiang Province(No.2019C03094)the National Natural Science Foundation of China(Nos.22075246 and 21776253).
文摘Monovalent cation perm-selective membrane(MCPMs)allow fast and selective transport of monovalent cations,and they are promisingly required for extraction of special ions,such as lithium extraction,acid recovery and sea salt production.Herein,we report a novel strategy to design the critical functional layers of MCPMs with both space charge repulsion and cross-linked dense screenability.The in-situ depo-sition polymerization of pyrrole was carried out on the surface of sulfonated polyphenyl sulfone(SPPSU)substrate membrane followed by cross-linking quaternization of the polypyrrole(PPy)layer with diiodi-nated functional molecules,thus,the membrane obtained more excellent selective permeability and sta-ble transport properties of monovalent cations.It confirms that the designed PPy layers with charged sur-face and cross-linking structure improved the hydrophilicity,facilitated cation transport and increased ion flux.Meanwhile,for the dense PPy layer,the charged cross-linked structure endowed the functional layer with the synergistic characteristics of Donnan exclusion and pore size sieving for positively charged ions,which improved the monovalent cation perm-selectivity of the membranes.At a constant current density of 5.1 mA/cm^(2),the optimal membrane exhibited superior perm-selectivity(P^(Na)_(Mg)=2.07)and monovalent cation flux(J_(Na+)=2.80×10^(−8)mol cm^(−2)s^(−1))during electrodialysis.
文摘The polystyrene cation exchange resin was exchanged by La 3+ and then were carbonized to make resin carbon material. The electrochemical properties of the resin carbon material as the electrode of the lithium ion cell were investigated. The test results show that comparing with the polystyrene cation exchange resin without adulterating, the contents of hydrogen, oxygen and sulfur are changed obviously for the resin carbon material derived from the La 3+ adulterating polystyrene cation exchange resin. The contents of hydrogen and oxygen are increased, and the one of sulfur is decreased. The test results also indicate that it is more easily to form the stratum graphite minicrystal structure with bigger diameter for the La 3+ adulterating resin. According to the electrochemical test results, the electrode derived from La 3+ adulterating polystyrene cation exchange resin has much better electrochemical property, and the capacity of charge and discharge of the electrode is increased about 30 mAh·g -1 in average.
基金financially supported by the National Natural Science Foundation of China(Nos.61805083,31801968,and 51802281)。
文摘Surface modification of different functional molecules onto NaREF_(4)(RE=rare earth)upconversion nanoparticles(UCNPs)impart their multiple functionalities.Functional molecules can be loaded onto NaREF_(4) UCNPs through the formation of coordination bonds between the surface-exposed RE^(3+) ions and the appropriate chemical groups of functional molecules.The density of surface RE^(3+) ions directly determines the loading efficiency of Na REF4 UCNPs.However,NaREF_(4) is a binary cation system,rendering the surface-distributed Na;and RE^(3+) ions remains a mystery.Here,we develop an effective strategy to significantly enhance the density of surface RE^(3+) ions,thus maximizing the loading capacity of NaREF_(4) UCNPs.This strategy is based on a heterovalent cation exchange(HCE)reaction in the surface region in which Na^(+)ions are replaced by RE^(3+) ions.The density of surface ligands enhances from 3.6 to 8.8 molecules/nm^(2) after reaction,suggesting that the loading efficiency increases by approximately 150%.Benefiting from the improved loading capacity,we demonstrate such surface-RE-rich nanoparticles have the ability to offer higher colloidal stability and more desirable photodynamic therapy(PDT)efficacy.This work not only advances our understanding of cation exchange reactions in RE-based nanoparticles,but also provides significant value for considerable applications such as sensing,bioimaging,and therapy.
基金supported by the National Key Research and Development Program of China(2017YFE0127100)the National Natural Science Foundation of China(NSFC,Grant 22025505)+1 种基金the Program of Shanghai Academic Technology Research Leader(Grant 20XD1422200)the Key Laboratory of Resource Chemistry,Ministry of Education(KLRC_ME2003)。
文摘FA-Cs mixed-cation perovskite has been reported as a promising candidate for obtaining highly efficient and stable photovoltaic devices.Phenylethylamine iodide(PEAI)post-treatment is a widely used and effective method for surface passivation of FA-Cs perovskite layer in devices.However,it is still controversial whether the PEAI post-treatment would form two-dimensional(2D)perovskite PEA_(2)PbI_(4) capping layer or just result in PEA+terminated surface.Here in this work,the function of PEAI post-treatment on FA-Cs mixed-cation perovskite FA_(1-x)Cs_(x)PbI_(3)(x=0.1–0.9)with varied Cs contents is elucidated.With increased Cs content,the FA-Cs perovskite shows higher resistance to the cation exchange between FA+and PEA+.This Cs-content-dependent cation exchange results in the different PEAI reaction preferences with FA-Cs mixed-cation perovskites.Furthermore,higher Cs content with stronger resistance to cation exchange reaction leads to a wider processing window for post-treatment and defect passivation,which is beneficial for the fabrication of large-scale photovoltaic devices.
文摘Current researches on the nutritive characteristics of fibrous feedstuff through determining the feedstuff cation exchange capacity (CEC) to evaluate its nutritive value at home and abroad were comprehensively discribed. and the methods of determining CEC value and the correlation between CEC value and chemical compositions, pH value, and the effect of CEC value on the digestion kinetics in ruminants were also emphatically introduced. The results of research showed that the CEC values of different feedstuff are different, closely correlated with nitrogen and acid detergent fibre (ADF) and lignin (LIG) content of the feedstuff. At the same time, there are markedly effect of CEC value in diet on the nutrients flow of digesta in the digestive tract of ruminants, the degradation rate and digestibility of nutrients in the rumen.
文摘Strongly acidic cation exchange resin(1x1,H form)has been successfully used as a catalyst in synthesis of diphenyl N-benzyloxycarbonyl-1-aminobenzylphosphonate, N-benzyloxycarbonyl-1-aminobenzylphenylphosphinic acid and N-p-tolylsulfonyl-1-aminobenzyl phenylphosphinic acid in high yields.
基金supported by the National Natural Science Foundation of China (No.21477059)the National Water Major Project (No.2015ZX07402-002)+2 种基金the Fundamental Research Funds for the Central Universities (No.15CX02016A)the Tsinghua University Initiative Scientific Research Program (No.20131089247)the open project of State Key Joint Laboratory of environmental simulation and pollution control (Tsinghua University)
文摘N-nitrosodimethylamine（NDMA） precursors consist of a positively charged dimethylamine group and a non-polar moiety, which inspired us to develop a targeted cation exchange technology to remove NDMA precursors. In this study, we tested the removal of two representative NDMA precursors, dimethylamine（DMA） and ranitidine（RNTD）, by strong acidic cation exchange resin. The results showed that pH greatly affected the exchange efficiency, with high removal（DMA 〉 78% and RNTD 〉 94%） observed at pH 〈 pk_a-1 when the molar ratio of exchange capacity to precursor was 4. The exchange order was obtained as follows： Ca^（2＋）〉 Mg^（2＋）〉 RNTD~＋〉 K~＋〉 DMA~＋〉 NH_4~＋〉 Na~＋. The partition coefficient of DMA~＋to Na~＋was 1.41 ± 0.26, while that of RNTD~＋to Na~＋was 12.1 ± 1.9. The pseudo second-order equation fitted the cation exchange kinetics well. Bivalent inorganic cations such as Ca^（2＋）were found to have a notable effect on NA precursor removal in softening column test. Besides DMA and RNTD, cation exchange process also worked well for removing other 7 model NDMA precursors. Overall, NDMA precursor removal can be an added benefit of making use of cation exchange water softening processes.
