Metsulfuron-methyl molecularly imprinted polymer（MIP）-coated stir bar was prepared for sorptive extraction of sulfonylurea herbicides in complex samples.The MIP-coating was about 21.3 μm thickness with the relative...Metsulfuron-methyl molecularly imprinted polymer（MIP）-coated stir bar was prepared for sorptive extraction of sulfonylurea herbicides in complex samples.The MIP-coating was about 21.3 μm thickness with the relative standard deviation（RSD） of 4.4%（n=10）.It was homogeneous and porous with good thermal stability and chemical stability.The extraction capability of the MIP-coating was 2.8 times over that of the non-imprinted polymer（NIP）-coating in hexane.The MIP-coating exhibited selective adsorption ability to the template and its analogues.The extraction conditions,including extraction solvent,desorption solvent,extraction time,desorption time and stirring speed,were optimized.A method for the determination of six sulfonylurea herbicides by MIP-coated stir bar sorptive extraction coupled with high performance liquid chromatography（HPLC） was developed.The linear range was 10―200 μg/L and the detection limits were within a range of 2.0―3.3 μg/L.It was also applied to the analysis of sulfonylurea herbicides in spiked river water,soil and rice samples.展开更多
In this paper, a novel SPME mode, PDMS-coated solid glass microspheres （SGMs）, were prepared by sol-gel method. Using homemade thermal desorption unit coupled with CGC-FID, six PAHs as model analytes, the performanc...In this paper, a novel SPME mode, PDMS-coated solid glass microspheres （SGMs）, were prepared by sol-gel method. Using homemade thermal desorption unit coupled with CGC-FID, six PAHs as model analytes, the performance of the new mode was characterized. The new extractive phase exhibited high thermal stability and satisfactory extraction capability. The detection limits were 0.01-0.045 ng/mL, and the linearity was from 0.5 ng/mL to 96 ng/mL. The R.S.D.s of repeatability for retention time and peak area were all within 0.074% and 6.7%, respectively. The recoveries of the PAHs were 78-127% from the samples taken from river water.展开更多
Sediment-associated processes, such as sediment erosion, deposition, and pore water diffusion/advection affect sorptive contaminant transport. By considering these processes, we developed an equation to simulate conta...Sediment-associated processes, such as sediment erosion, deposition, and pore water diffusion/advection affect sorptive contaminant transport. By considering these processes, we developed an equation to simulate contaminant transport. Erosion and deposition processes are considered as erosion and deposition fluxes of sediment, and adsorption-desorption processes of contaminants by sediment are simulated using the Langmuir Equation. Pore water diffusion is calculated based on the contaminant concentration gradient across the sediment-water interface. Pore water advection is estimated using pore water contained in the sediments of erosion flux. The equation is validated to simulate total phosphorus concentrations in Guanhe estuary in the northern Jiangsu, China. The simulated total phosphorus concentrations show better agreement with field observations compared to estimations that do consider sediment-associated processes.展开更多
Dispersion in time-oscillatory electro-osmotic flows in a slit micro-channel under the effect of kinetic sorptive exchange at walls is theoretically investigated using the homogenization method. The two walls of the c...Dispersion in time-oscillatory electro-osmotic flows in a slit micro-channel under the effect of kinetic sorptive exchange at walls is theoretically investigated using the homogenization method. The two walls of the channel are considered to be made up of different materials, and therefore have different zeta potentials and sorption coefficients. A general expression for the Taylor dispersion coefficient under different zeta potentials as well as various sorption conditions at the walls is derived analytically. The dispersion coefficient is found to be dependent on the oscillation frequency, the Debye parameter, the species partition coefficient, the reaction kinetics and the ratio of the wall potentials. The results demonstrate that the presence of wall sorption tends to enhance the dispersion when the oscillation frequency is low, but the effect is negligible in high-frequency oscillatory flows. Moreover, it is found that the dispersion coefficient could be significantly changed by adjusting the relative wall potentials for low-frequency flows.展开更多
A stir bar sorptive extraction （SBSE） technique was developed by the use of polypyrrole （PPy） sorbent, electropolymerized on the surface of a rod, as a possible alternative to solid-phase microextraction （SPME）....A stir bar sorptive extraction （SBSE） technique was developed by the use of polypyrrole （PPy） sorbent, electropolymerized on the surface of a rod, as a possible alternative to solid-phase microextraction （SPME）. Liquid desorption was subsequently employed to transfer the extracted analytes into the injection port of a gas chromatogra- phy-mass spectrometry （GC-MS）. The PPy sorbent including polypyrrole-dodecyl sulfate （PPy-DS） was deposited on the surface of a stainless steel rod from the corresponding aqueous electrolyte by applying a constant deposition potential. The developed method was applied to the trace level extraction of BTEX （benzene, toluene, ethylbenzene, o,p-xylene） from aqueous sample. Optimization of influential experimental conditions including the voltage of power supply, the time of PPy electrodeposition, the extraction temperature, the ionic strength and the extraction time were also investigated. The detection limits of the method under optimized conditions were in the range of 0.01-0.1 ng.mL^-1. The relative standard deviations （RSD） at a concentration level of 1 ng.mL^-1 were obtained between 8% and 13% （n=6）. The calibration curves of BTEX showed linearity in the range of 0.03 to 600 ngomL 1. The proposed method was successfully applied to the extraction of some selected BTEX from river water samples and the relative recoveries were higher than 90% for all the analytes.展开更多
In this study,two novel spherical/hollow metal-organic frameworks were successfully synthesized,and further modified by a mild non-covalent modification strategy with dopamine and 1,4-benzenedithiol(BDT)as polymeric m...In this study,two novel spherical/hollow metal-organic frameworks were successfully synthesized,and further modified by a mild non-covalent modification strategy with dopamine and 1,4-benzenedithiol(BDT)as polymeric monomers to obtain pB DT@PDA-Ni-MOF and p BDT@PDA-Ni/Co-MOF,respectively.The results showed that the above MOFs possessed extremely fast adsorption rates and ideal adsorption capacities for sulfonamides(SAs)and the modified MOFs exhibited enhanced adsorption capacities for SAs owing to a large number of additional functional groups.Then,benefit of their regular morphology and size,a facile syringe-assisted dispersive solid phase extraction(S-DSPE)method was developed for efficient detection of SAs,which will provide a powerful tool for monitoring trace level of SAs in aqueous environment.展开更多
To study the static bending creep properties of glass fiber reinforced wood,glass fiber reinforced poplar(GFRP)specimens were obtained by pasting glass fiber on the upper and lower surfaces of Poplar(Populus euramevic...To study the static bending creep properties of glass fiber reinforced wood,glass fiber reinforced poplar(GFRP)specimens were obtained by pasting glass fiber on the upper and lower surfaces of Poplar(Populus euramevicana,P),the performance of Normal Creep(NC)and Mechanical Sorptive Creep(MSC)of GFRP and their influencing factors were tested and analyzed.The test results and analysis show that:(1)The MOE and MOR of Poplar were increased by 17.06%and 10.00%respectively by the glass fiber surface reinforced composite.(2)The surface reinforced P with glass fiber cloth only exhibits the NC pattern of wood and loses the MSC characteristics of wood,regardless of the constant or alternating changes in relative humidity.(3)The instantaneous elastic deformation,viscoelastic deformation,viscous deformation and total creep deflection of GFRP are positively correlated with the stress level of the external load applied to the specimen.Still,the specimen’s creep recovery rate is negatively correlated with the stress level of the external load applied to the specimen.The static creep deflection and viscous deformation of GFRP increase with the increase of the relative humidity of the environment.(4)The MSC maximum creep deflection of GFRP increased by only 7.41%over the NC maximum creep deflection,but the MSC maximum creep deflection of P increased by 199.25%over the NC maximum creep deflection.(5)The Burgers 4-factor model and the Weibull distribution equation can fit the NC and NC recovery processes of GFRP well.展开更多
A method for the analysis of trace polycyclic aromatic hydrocarbons（PAHs） in aqueous samples has been established by polydimethylsiloxane（PDMS） rod aided stir bar sorptive extraction（SBSE）. The homemade PDMS rod...A method for the analysis of trace polycyclic aromatic hydrocarbons（PAHs） in aqueous samples has been established by polydimethylsiloxane（PDMS） rod aided stir bar sorptive extraction（SBSE）. The homemade PDMS rod has a size of 30 mm×3 mm o.d. with a volume of ca. 200 μL, stable in thermal desorption process. The enriched PAHs by the PDMS rod were released in a homemade thermal desorption system coupled with gas chromatography. Experimental parameters for extraction of six PAHs were optimized including extraction time, pH, ionic strength and temperature of solution. The procedure has good recoveries of 80.0%―100.3% and very low limits of detection of 4.0―33 ng/L. PAHs in rain and river water were analyzed by this method.展开更多
Within the framework of Migr’Hycar research project, the fate of oil spill was studied with the aim to characterize their physical-chemical behaviour. For this purpose, seven petroleum oils commercially available wer...Within the framework of Migr’Hycar research project, the fate of oil spill was studied with the aim to characterize their physical-chemical behaviour. For this purpose, seven petroleum oils commercially available were tested and the distributions of the water soluble components were determined according to two experimental devices;laboratory conditions and pilot conditions in Polludrome. In the dissolved fraction, 41 polycyclic aromatic hydrocarbons and their derivates were quantified, among them are 16 EPA priority pollutants. A coupling of the stir bar sorptive extraction method and high performance gas chromatography mass spectrometry were used. Analyses showed that naphthalenes series constitute the major part of the water soluble fraction from fresh oils. In fact, light and heavy molecules have different contributions to solubilization kinetics. From the results, a linear correlation was established between the density of oils and the times of maximum solubilization. Moreover, the effect of 10% ethanol in gasoline was observed on the profile of solubilized PAHs in water. Kinetic patterns obtained with Polludrome showed the influence of surface water/oil ratio (WOR) on the volatilization process. Compared to laboratory conditions, the dynamic conditions of Polludrome led to an enhanced evaporation process, thus shifting the solubility peak.展开更多
A simple method was developed to relate soil sorptivity to hydraulic diffusivity and water absorption experiments were conducted utilizing one-dimensional horizontal soil columns to validate the relationship. In addit...A simple method was developed to relate soil sorptivity to hydraulic diffusivity and water absorption experiments were conducted utilizing one-dimensional horizontal soil columns to validate the relationship. In addition, an estimation method for hydraulic diffusivity with disc infiltrometer was developed. The results indicated a favorable fit of the theoretical relation to the experimental data. Also, the experiment with disc infiltrometer for estimating the diffusivity showed that the new method was feasible.展开更多
Steam-cured condition is found to cause larger porosity and worse properties of concrete compared with normal curing condition. For the sake of seeking effective measurements to eliminate this bad effect of steam-cure...Steam-cured condition is found to cause larger porosity and worse properties of concrete compared with normal curing condition. For the sake of seeking effective measurements to eliminate this bad effect of steam-cured condition on concrete, the water sorptivity and pore structure of steam-cured concretes exposed to different subsequent curing conditions were investigated after steam-curing treatment. The capillary absorption coefficient and porosity of the corresponding concretes were analyzed, and their mechanisms were also discussed. The results indicate that water sorptivity and pore structure of steam-cured concrete are greatly influenced by the curing condition used in subsequent ages. Exposure steam-cured concrete to air condition has an obviously bad effect on its properties and microstructures. Adopting subsequent curing of immersing steam-cured concrete into about 20℃ water after steam curing period can significantly decrease its capillary absorption coefficient and porosity. Steam-cured concrete with 7 d water curing has minimum capillary absorption coefficient and total porosity. Its water sorptivity is decreased by 23% compared with standard curing concrete and the porosity is 9.6% lower. Moreover, the corresponding gradient of water sorptivity and porosity of steam-cured concrete both decrease, thus mictostructure of concrete becomes more homogeneous.展开更多
Soil wettability and water repellency, two important soil physical properties, play an important role in water retention and water conductivity in arid and semi-arid regions. To date, there is a lack of information on...Soil wettability and water repellency, two important soil physical properties, play an important role in water retention and water conductivity in arid and semi-arid regions. To date, there is a lack of information on soil water repellency in calcareous soils of western lran. In this study, soil water repellency and its affecting factors were studied using 20 soil series collected from Hamadan Province~ western Iran. The effects of soil properties including organic carbon content （SOC）, total nitrogen （TN）, C：N ratio, texture, CaCO3 content, and both fungal and bacterial activities on water repellency were investigated using air-dried, oven-dried and heated soil samples. Water repellency index （WRI） was determined using the short-time sorptivity （water/ethanol） method. To distinguish the actual effects of SOC, a set of soil samples were heated at 300 ~C to remove SOC and then WRI was measured on the heated samples. Relative water repellency index （RWRI） was defined as the change of WRI due to heating relative to the oven-dry WRI value. Results of the WRI values showed that the soils were sub-critically water-repellent. Pasture soils had higher WRI values compared to tilled soils, resulting from high SOC and TN, and high activities of bacteria and fungi. It was observed that SOC, TN, fungal activity, and SOC：clay ratio had significant positive impacts on WRI. Strong positive correlations of RWRI with SOC, TN and fungal activity were also observed. Pedotransfer functions derived for predicting WRI showed that the WRI values had an increasing trend with the increases in fungal activity, salinity, alkalinity and fine clay content, but showed a decreasing trend with increasing bacterial activity.展开更多
The capillary absorption of water by unsaturated cement-based material is the main reason of degradation of the structures subjected to an aggressive environment since water often acts as the transporting medium for d...The capillary absorption of water by unsaturated cement-based material is the main reason of degradation of the structures subjected to an aggressive environment since water often acts as the transporting medium for damaging contaminants. It is well known that the capillarity coefficient and sorptivity are two important parameters to characterize the water absorption of porous materials. Generally, the former is used to describe the penetration depth or height of water transport, which must be measured by special and advanced equipment. In contrast, the sorptivity represents the relationship between cumulative volume of water uptake and the squareroot of the elapsed time, which can be easily measured by the gravimetric method in a normal laboratory condition. In the present study, an analytical method is developed to build up a bridge between these two parameters, with the purpose that the sorptivity or the gravimetric method can be used to predict the penetration depth of water absorption. Additionally, a new model to explain the dependence of sorptivity on initial water content of the material is developed in order to fit the in situ condition. The comparison of predicted results by the analytical method with experimental data or numerical calculation results, as well as some previous models, validates the feasibility of the methods presented in this paper.展开更多
The permeability and sorptivity properties of the two prestressed concrete containment buildings （PCCBs） of a nuclear power plant in South China, which had been under operation for 5 years, were measured by using th...The permeability and sorptivity properties of the two prestressed concrete containment buildings （PCCBs） of a nuclear power plant in South China, which had been under operation for 5 years, were measured by using the autoclam permeability system. The air permeability, sorptivity and water permeability indexes of No.1 PCCB are smaller than or equal to 0.11 ln（102 Pa）/min, 0.98×10 ^7 m3/minl/2 and 1.93×10 ^7 m3/min1/2, respectively, and the air permeability, sorptivity and water permeability indexes of No.2 PCCB are smaller than or equal to 0.17 In（102 Pa）/min, 1.6×10 ^7 m3/min1/2 and 4.43 ×10 ^7 m3/min1/2, respectively. Based on the criteria for evaluating the protective quality of concrete structures in terms of their permeability and sorptivity properties, proposed by the research organization of the autoclam permeability system, the protective quality of No. 1 PCCB is still in very good grade and that of No.2 PCCB is not in very good grade but in good grade, and the in-service inspection of the protective quality of No.2 PCCB should be strengthened in the future.展开更多
This study aims to estimate the hydrodynamic properties of soils under various agricultural practices in the Tougou catchment in northern Burkina Faso. The methodology adopted is based on the determination of the unsa...This study aims to estimate the hydrodynamic properties of soils under various agricultural practices in the Tougou catchment in northern Burkina Faso. The methodology adopted is based on the determination of the unsaturated hydraulic conductivity and capillary sorptivity close to saturation. This method relies on the measurement of the transient infiltration flux at the soil surface with imposed hydraulic head varying from -60 to -20 mm. These tests are carried out on control, stony line, half-moon and zai plots. The results show a difference in hydrodynamic parameters according to the agricultural practices. The unsaturated hydraulic conductivity is 33.1 cm/h, 13.1 cm/h, 20.3 cm/h and 4.0 cm/h for zai, control, stony line and half-moon plots respectively. The unsaturated hydraulic conductivity is 33.1 cm/h, 13.1 cm/h, 20.3 cm/h and 4.0 cm/h for zai, control, stony line and half-moon plots respectively. The pores participating to water transfer also differ. The mean size of drainable pores is 43.7, 56.2, 22.3 and 87.2 pm on control, stony line, half-moon and zai plots respectively.展开更多
The quantification of soil infiltration is necessary for the estimation of water accessibility in soils for plant growth and development. Field infiltration tests runs were conducted on agricultural soils in three irr...The quantification of soil infiltration is necessary for the estimation of water accessibility in soils for plant growth and development. Field infiltration tests runs were conducted on agricultural soils in three irrigation sites of Northern Ghana. The field data were fitted into Green and Ampt, Kostiakov, Philip, Holtan, Soil Conservation Service and Horton infiltration models for the determination of the unknown model parameters. Regression analysis at 95% confidence level using GraphPad Prism 8. Laboratory and field data on infiltration were used for the model fitting and the unknown parameters were determined using the calibrated models. The <i>k</i> and <i>n</i> parameters of Kostiakov model at Bontanga study site were found to be <i>k</i> = 28.0027 and <i>n</i> = 0.5902, <i>k</i> = 17.0294 and <i>n</i> = 0.4504 for Golinga and <i>k</i> = 23.0356 and <i>n</i> = 0.6339 for Libga. For all the models, the coefficient of determination ranged from 0.7612 to 0.9876 indicating strong relationships. Only Holtan model gave different values at all the three study sites. The parameter <i>GIa</i> and <i>i<sub>c</sub></i><i> </i>of the Holtan model drawn from hydrologic soil group were the same at all the study sites because of the same vegetative cover and surface conditions. The study observed the values of the parameters to have influenced the models’ performance.展开更多
This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeabil...This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m<sup>3</sup>) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO<sub>2</sub> which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)<sub>2</sub> crystals, converting it into CaH<sub>2</sub>O<sub>4</sub>Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.展开更多
This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeabil...This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m<sup>3</sup>) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO<sub>2</sub> which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)<sub>2</sub> crystals, converting it into CaH<sub>2</sub>O<sub>4</sub>Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.展开更多
CONSPECTUS:Increasing demand for high-purity fine chemicals and a drive for process intensification of large-scale separations have driven significant work on the development of highly engineered porous materials with...CONSPECTUS:Increasing demand for high-purity fine chemicals and a drive for process intensification of large-scale separations have driven significant work on the development of highly engineered porous materials with promise for sorption-based separations.While sorptive separations in porous materials offer energy-efficient alternatives to longstanding thermal-based methods,the particulate nature of many of these sorbents has sometimes limited their large-scale deployment in high-throughput applications such as gas separations,for which the necessary high feed flow rates and gas velocities accrue prohibitive operational costs.These processability limitations have been historically addressed through powder shaping methods aimed at the fabrication of structured sorbent contactors based on pellets,beads or monoliths,commonly obtained as extrudates.These structures overcome limitations such as elevated pressure drops commonly recorded across powder adsorption beds but often accrue thermal limitations arising from elevated particle density and aggregation,which ultimately cap their maximum separation performance.Furthermore,the harsh mechanical strain to which powder particles are subjected during contactor fabrication,in the form of extrusion/compression forces,can result in partial pore occlusion and framework degradation,further limiting their performance.Here,we present the development of porous fiber sorbents as an alternative sorbent contactor design capable of addressing sorbent processability limitations while enabling an array of performance-maximizing heat integration capabilities.This new sorbent form factor leverages pre-existing know-how from hollow fiber spinning to produce fiber-shaped sorbent contactors through the phase inversion of known polymers in a process known as dry-jet/wet quenching.The process of phase inversion allows microporous sorbent particles to be latched onto a macroporous polymer matrix under mild processing conditions,thus making it compatible with soft porous materials prone to amorphization under traditional pelletization conditions.Sorbent fibers can be created with different geometries through control of the spinning apparatus and process,offering the possibility to produce monolithic and hollow fibers alike,the latter of which can be integrated with thermalization fluid flows.In this Account,we summarize our progress in the field of fiber sorbents from both design and application standpoints.We further guide the reader through the evolution of this field from the early inceptive work on zeolite hollow fibers to recent developments on MOF fibers.We highlight the versatile nature of fiber sorbents,both from the composition,fabrication and structure points of view,and further demonstrate how fiber sorbents offer alternative paths in tackling new and challenging chemical separation challenges like direct air capture(DAC),with a final perspective on the future of the field.展开更多
Over the past few decades, coordination polymers/metal organic frameworks （CPs/MOFs） have drawn a great deal of attention for diverse applications due to their advantages of intrinsically ttLnable chemical structure...Over the past few decades, coordination polymers/metal organic frameworks （CPs/MOFs） have drawn a great deal of attention for diverse applications due to their advantages of intrinsically ttLnable chemical structure, flexible architecture, high pore volume, high surface area, multifunctional properties, etc. To date, numerous CPs/MOFs have been developed and employed for the treatment and control of gaseous pollutants, such as volatile organic compounds （VOCs）, through capture, sorptive removal, and catalytic degradation. Nevertheless, there are also some key drawbacks and challenges for the practical application of these systems （e.g., poor selectivity, high energy （and fiscal） cost, high synthesis cost, low capacity, and difficulties in regeneration and recycling）. In this review, recent developments in CPs/MOFs research are described with their associated mechanisms for capture, sorptive removal, and catalytic degradation of VOCs. To this end, we discuss the key variables and challenges for afforded abatement of VOCs through CPs/MOFs technologies. Hopefully, this review will help the scientific community set future directions for the advancement of CPs/MOFs techniques for the effective management of diverse environmental issues.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.21127008,21075140,21105133,90817012)the Key Program of Natural Science Foundation of Guangdong Province,China(No.9251027501000004)+1 种基金the Cooperation Project in Industry,Education and Research of Guangdong Province and Ministry of Education of China(No.2010B090400142)the Fundamental Research Funds for the Central Universities of China
文摘Metsulfuron-methyl molecularly imprinted polymer（MIP）-coated stir bar was prepared for sorptive extraction of sulfonylurea herbicides in complex samples.The MIP-coating was about 21.3 μm thickness with the relative standard deviation（RSD） of 4.4%（n=10）.It was homogeneous and porous with good thermal stability and chemical stability.The extraction capability of the MIP-coating was 2.8 times over that of the non-imprinted polymer（NIP）-coating in hexane.The MIP-coating exhibited selective adsorption ability to the template and its analogues.The extraction conditions,including extraction solvent,desorption solvent,extraction time,desorption time and stirring speed,were optimized.A method for the determination of six sulfonylurea herbicides by MIP-coated stir bar sorptive extraction coupled with high performance liquid chromatography（HPLC） was developed.The linear range was 10―200 μg/L and the detection limits were within a range of 2.0―3.3 μg/L.It was also applied to the analysis of sulfonylurea herbicides in spiked river water,soil and rice samples.
文摘In this paper, a novel SPME mode, PDMS-coated solid glass microspheres （SGMs）, were prepared by sol-gel method. Using homemade thermal desorption unit coupled with CGC-FID, six PAHs as model analytes, the performance of the new mode was characterized. The new extractive phase exhibited high thermal stability and satisfactory extraction capability. The detection limits were 0.01-0.045 ng/mL, and the linearity was from 0.5 ng/mL to 96 ng/mL. The R.S.D.s of repeatability for retention time and peak area were all within 0.074% and 6.7%, respectively. The recoveries of the PAHs were 78-127% from the samples taken from river water.
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.200802940014)
文摘Sediment-associated processes, such as sediment erosion, deposition, and pore water diffusion/advection affect sorptive contaminant transport. By considering these processes, we developed an equation to simulate contaminant transport. Erosion and deposition processes are considered as erosion and deposition fluxes of sediment, and adsorption-desorption processes of contaminants by sediment are simulated using the Langmuir Equation. Pore water diffusion is calculated based on the contaminant concentration gradient across the sediment-water interface. Pore water advection is estimated using pore water contained in the sediments of erosion flux. The equation is validated to simulate total phosphorus concentrations in Guanhe estuary in the northern Jiangsu, China. The simulated total phosphorus concentrations show better agreement with field observations compared to estimations that do consider sediment-associated processes.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant No.HKU 715510E)
文摘Dispersion in time-oscillatory electro-osmotic flows in a slit micro-channel under the effect of kinetic sorptive exchange at walls is theoretically investigated using the homogenization method. The two walls of the channel are considered to be made up of different materials, and therefore have different zeta potentials and sorption coefficients. A general expression for the Taylor dispersion coefficient under different zeta potentials as well as various sorption conditions at the walls is derived analytically. The dispersion coefficient is found to be dependent on the oscillation frequency, the Debye parameter, the species partition coefficient, the reaction kinetics and the ratio of the wall potentials. The results demonstrate that the presence of wall sorption tends to enhance the dispersion when the oscillation frequency is low, but the effect is negligible in high-frequency oscillatory flows. Moreover, it is found that the dispersion coefficient could be significantly changed by adjusting the relative wall potentials for low-frequency flows.
文摘A stir bar sorptive extraction （SBSE） technique was developed by the use of polypyrrole （PPy） sorbent, electropolymerized on the surface of a rod, as a possible alternative to solid-phase microextraction （SPME）. Liquid desorption was subsequently employed to transfer the extracted analytes into the injection port of a gas chromatogra- phy-mass spectrometry （GC-MS）. The PPy sorbent including polypyrrole-dodecyl sulfate （PPy-DS） was deposited on the surface of a stainless steel rod from the corresponding aqueous electrolyte by applying a constant deposition potential. The developed method was applied to the trace level extraction of BTEX （benzene, toluene, ethylbenzene, o,p-xylene） from aqueous sample. Optimization of influential experimental conditions including the voltage of power supply, the time of PPy electrodeposition, the extraction temperature, the ionic strength and the extraction time were also investigated. The detection limits of the method under optimized conditions were in the range of 0.01-0.1 ng.mL^-1. The relative standard deviations （RSD） at a concentration level of 1 ng.mL^-1 were obtained between 8% and 13% （n=6）. The calibration curves of BTEX showed linearity in the range of 0.03 to 600 ngomL 1. The proposed method was successfully applied to the extraction of some selected BTEX from river water samples and the relative recoveries were higher than 90% for all the analytes.
基金supported by the National Key R&D Program of China(No.2019YFC1905501)the National Natural Science Foundation of China(Nos.22104145 and 22174129)+3 种基金Nature Science Foundation of Zhejiang Province(No.LZY21E030001)Natural Science Foundation of Gansu Province(No.21JR7RA078)Youth Collaborative Innovation Alliance Fund of LICP(No.HZJJ21–06)the“Light of West China”Program from Chinese Academy of Science。
文摘In this study,two novel spherical/hollow metal-organic frameworks were successfully synthesized,and further modified by a mild non-covalent modification strategy with dopamine and 1,4-benzenedithiol(BDT)as polymeric monomers to obtain pB DT@PDA-Ni-MOF and p BDT@PDA-Ni/Co-MOF,respectively.The results showed that the above MOFs possessed extremely fast adsorption rates and ideal adsorption capacities for sulfonamides(SAs)and the modified MOFs exhibited enhanced adsorption capacities for SAs owing to a large number of additional functional groups.Then,benefit of their regular morphology and size,a facile syringe-assisted dispersive solid phase extraction(S-DSPE)method was developed for efficient detection of SAs,which will provide a powerful tool for monitoring trace level of SAs in aqueous environment.
基金The present work was financially sponsored by the National Natural Science Foundation of China(Grant No.31960291).
文摘To study the static bending creep properties of glass fiber reinforced wood,glass fiber reinforced poplar(GFRP)specimens were obtained by pasting glass fiber on the upper and lower surfaces of Poplar(Populus euramevicana,P),the performance of Normal Creep(NC)and Mechanical Sorptive Creep(MSC)of GFRP and their influencing factors were tested and analyzed.The test results and analysis show that:(1)The MOE and MOR of Poplar were increased by 17.06%and 10.00%respectively by the glass fiber surface reinforced composite.(2)The surface reinforced P with glass fiber cloth only exhibits the NC pattern of wood and loses the MSC characteristics of wood,regardless of the constant or alternating changes in relative humidity.(3)The instantaneous elastic deformation,viscoelastic deformation,viscous deformation and total creep deflection of GFRP are positively correlated with the stress level of the external load applied to the specimen.Still,the specimen’s creep recovery rate is negatively correlated with the stress level of the external load applied to the specimen.The static creep deflection and viscous deformation of GFRP increase with the increase of the relative humidity of the environment.(4)The MSC maximum creep deflection of GFRP increased by only 7.41%over the NC maximum creep deflection,but the MSC maximum creep deflection of P increased by 199.25%over the NC maximum creep deflection.(5)The Burgers 4-factor model and the Weibull distribution equation can fit the NC and NC recovery processes of GFRP well.
基金Supported by the Natural Science Foundation of Shandong Province, China(No.ZR2010BM035)
文摘A method for the analysis of trace polycyclic aromatic hydrocarbons（PAHs） in aqueous samples has been established by polydimethylsiloxane（PDMS） rod aided stir bar sorptive extraction（SBSE）. The homemade PDMS rod has a size of 30 mm×3 mm o.d. with a volume of ca. 200 μL, stable in thermal desorption process. The enriched PAHs by the PDMS rod were released in a homemade thermal desorption system coupled with gas chromatography. Experimental parameters for extraction of six PAHs were optimized including extraction time, pH, ionic strength and temperature of solution. The procedure has good recoveries of 80.0%―100.3% and very low limits of detection of 4.0―33 ng/L. PAHs in rain and river water were analyzed by this method.
文摘Within the framework of Migr’Hycar research project, the fate of oil spill was studied with the aim to characterize their physical-chemical behaviour. For this purpose, seven petroleum oils commercially available were tested and the distributions of the water soluble components were determined according to two experimental devices;laboratory conditions and pilot conditions in Polludrome. In the dissolved fraction, 41 polycyclic aromatic hydrocarbons and their derivates were quantified, among them are 16 EPA priority pollutants. A coupling of the stir bar sorptive extraction method and high performance gas chromatography mass spectrometry were used. Analyses showed that naphthalenes series constitute the major part of the water soluble fraction from fresh oils. In fact, light and heavy molecules have different contributions to solubilization kinetics. From the results, a linear correlation was established between the density of oils and the times of maximum solubilization. Moreover, the effect of 10% ethanol in gasoline was observed on the profile of solubilized PAHs in water. Kinetic patterns obtained with Polludrome showed the influence of surface water/oil ratio (WOR) on the volatilization process. Compared to laboratory conditions, the dynamic conditions of Polludrome led to an enhanced evaporation process, thus shifting the solubility peak.
基金Project supported by the Hundred Talents Program of the Chinese Academy of Sciences, the National Basic Research Program of China (No. 2005CB121103) and the National Natural Science Foundation of China (Nos. 40371057 and 50479065).
文摘A simple method was developed to relate soil sorptivity to hydraulic diffusivity and water absorption experiments were conducted utilizing one-dimensional horizontal soil columns to validate the relationship. In addition, an estimation method for hydraulic diffusivity with disc infiltrometer was developed. The results indicated a favorable fit of the theoretical relation to the experimental data. Also, the experiment with disc infiltrometer for estimating the diffusivity showed that the new method was feasible.
基金Project(2008G031-18) supported by the Ministry of Railway Science and Technology Research Foundation of ChinaProject(2010R50034) supported by the Key Science and Technology Innovation Team Program of Zhejiang Province, ChinaProject(2010QZZD018) supported by Leading-edge Research Program of Central South University,China
文摘Steam-cured condition is found to cause larger porosity and worse properties of concrete compared with normal curing condition. For the sake of seeking effective measurements to eliminate this bad effect of steam-cured condition on concrete, the water sorptivity and pore structure of steam-cured concretes exposed to different subsequent curing conditions were investigated after steam-curing treatment. The capillary absorption coefficient and porosity of the corresponding concretes were analyzed, and their mechanisms were also discussed. The results indicate that water sorptivity and pore structure of steam-cured concrete are greatly influenced by the curing condition used in subsequent ages. Exposure steam-cured concrete to air condition has an obviously bad effect on its properties and microstructures. Adopting subsequent curing of immersing steam-cured concrete into about 20℃ water after steam curing period can significantly decrease its capillary absorption coefficient and porosity. Steam-cured concrete with 7 d water curing has minimum capillary absorption coefficient and total porosity. Its water sorptivity is decreased by 23% compared with standard curing concrete and the porosity is 9.6% lower. Moreover, the corresponding gradient of water sorptivity and porosity of steam-cured concrete both decrease, thus mictostructure of concrete becomes more homogeneous.
文摘Soil wettability and water repellency, two important soil physical properties, play an important role in water retention and water conductivity in arid and semi-arid regions. To date, there is a lack of information on soil water repellency in calcareous soils of western lran. In this study, soil water repellency and its affecting factors were studied using 20 soil series collected from Hamadan Province~ western Iran. The effects of soil properties including organic carbon content （SOC）, total nitrogen （TN）, C：N ratio, texture, CaCO3 content, and both fungal and bacterial activities on water repellency were investigated using air-dried, oven-dried and heated soil samples. Water repellency index （WRI） was determined using the short-time sorptivity （water/ethanol） method. To distinguish the actual effects of SOC, a set of soil samples were heated at 300 ~C to remove SOC and then WRI was measured on the heated samples. Relative water repellency index （RWRI） was defined as the change of WRI due to heating relative to the oven-dry WRI value. Results of the WRI values showed that the soils were sub-critically water-repellent. Pasture soils had higher WRI values compared to tilled soils, resulting from high SOC and TN, and high activities of bacteria and fungi. It was observed that SOC, TN, fungal activity, and SOC：clay ratio had significant positive impacts on WRI. Strong positive correlations of RWRI with SOC, TN and fungal activity were also observed. Pedotransfer functions derived for predicting WRI showed that the WRI values had an increasing trend with the increases in fungal activity, salinity, alkalinity and fine clay content, but showed a decreasing trend with increasing bacterial activity.
基金supported by the Key Programs of Ministry of Education of China(Grant No.109046)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Eduation Ministrythe Program of Innovative Research Team of Education of China(Grant No.IRT0518)
文摘The capillary absorption of water by unsaturated cement-based material is the main reason of degradation of the structures subjected to an aggressive environment since water often acts as the transporting medium for damaging contaminants. It is well known that the capillarity coefficient and sorptivity are two important parameters to characterize the water absorption of porous materials. Generally, the former is used to describe the penetration depth or height of water transport, which must be measured by special and advanced equipment. In contrast, the sorptivity represents the relationship between cumulative volume of water uptake and the squareroot of the elapsed time, which can be easily measured by the gravimetric method in a normal laboratory condition. In the present study, an analytical method is developed to build up a bridge between these two parameters, with the purpose that the sorptivity or the gravimetric method can be used to predict the penetration depth of water absorption. Additionally, a new model to explain the dependence of sorptivity on initial water content of the material is developed in order to fit the in situ condition. The comparison of predicted results by the analytical method with experimental data or numerical calculation results, as well as some previous models, validates the feasibility of the methods presented in this paper.
基金Project(20050487017) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject (2009567) supported by China National Nuclear Corporation
文摘The permeability and sorptivity properties of the two prestressed concrete containment buildings （PCCBs） of a nuclear power plant in South China, which had been under operation for 5 years, were measured by using the autoclam permeability system. The air permeability, sorptivity and water permeability indexes of No.1 PCCB are smaller than or equal to 0.11 ln（102 Pa）/min, 0.98×10 ^7 m3/minl/2 and 1.93×10 ^7 m3/min1/2, respectively, and the air permeability, sorptivity and water permeability indexes of No.2 PCCB are smaller than or equal to 0.17 In（102 Pa）/min, 1.6×10 ^7 m3/min1/2 and 4.43 ×10 ^7 m3/min1/2, respectively. Based on the criteria for evaluating the protective quality of concrete structures in terms of their permeability and sorptivity properties, proposed by the research organization of the autoclam permeability system, the protective quality of No. 1 PCCB is still in very good grade and that of No.2 PCCB is not in very good grade but in good grade, and the in-service inspection of the protective quality of No.2 PCCB should be strengthened in the future.
文摘This study aims to estimate the hydrodynamic properties of soils under various agricultural practices in the Tougou catchment in northern Burkina Faso. The methodology adopted is based on the determination of the unsaturated hydraulic conductivity and capillary sorptivity close to saturation. This method relies on the measurement of the transient infiltration flux at the soil surface with imposed hydraulic head varying from -60 to -20 mm. These tests are carried out on control, stony line, half-moon and zai plots. The results show a difference in hydrodynamic parameters according to the agricultural practices. The unsaturated hydraulic conductivity is 33.1 cm/h, 13.1 cm/h, 20.3 cm/h and 4.0 cm/h for zai, control, stony line and half-moon plots respectively. The unsaturated hydraulic conductivity is 33.1 cm/h, 13.1 cm/h, 20.3 cm/h and 4.0 cm/h for zai, control, stony line and half-moon plots respectively. The pores participating to water transfer also differ. The mean size of drainable pores is 43.7, 56.2, 22.3 and 87.2 pm on control, stony line, half-moon and zai plots respectively.
文摘The quantification of soil infiltration is necessary for the estimation of water accessibility in soils for plant growth and development. Field infiltration tests runs were conducted on agricultural soils in three irrigation sites of Northern Ghana. The field data were fitted into Green and Ampt, Kostiakov, Philip, Holtan, Soil Conservation Service and Horton infiltration models for the determination of the unknown model parameters. Regression analysis at 95% confidence level using GraphPad Prism 8. Laboratory and field data on infiltration were used for the model fitting and the unknown parameters were determined using the calibrated models. The <i>k</i> and <i>n</i> parameters of Kostiakov model at Bontanga study site were found to be <i>k</i> = 28.0027 and <i>n</i> = 0.5902, <i>k</i> = 17.0294 and <i>n</i> = 0.4504 for Golinga and <i>k</i> = 23.0356 and <i>n</i> = 0.6339 for Libga. For all the models, the coefficient of determination ranged from 0.7612 to 0.9876 indicating strong relationships. Only Holtan model gave different values at all the three study sites. The parameter <i>GIa</i> and <i>i<sub>c</sub></i><i> </i>of the Holtan model drawn from hydrologic soil group were the same at all the study sites because of the same vegetative cover and surface conditions. The study observed the values of the parameters to have influenced the models’ performance.
文摘This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m<sup>3</sup>) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO<sub>2</sub> which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)<sub>2</sub> crystals, converting it into CaH<sub>2</sub>O<sub>4</sub>Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.
文摘This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m<sup>3</sup>) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO<sub>2</sub> which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)<sub>2</sub> crystals, converting it into CaH<sub>2</sub>O<sub>4</sub>Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.
基金funded by the National Energy Technology Laboratory of the U.S.Department of Energy under Award No.DE FE0032129Advanced Research Projects Agency-Energy(ARPA-E),U.S.Department of Energy,under Award No.DE-AR0001309.
文摘CONSPECTUS:Increasing demand for high-purity fine chemicals and a drive for process intensification of large-scale separations have driven significant work on the development of highly engineered porous materials with promise for sorption-based separations.While sorptive separations in porous materials offer energy-efficient alternatives to longstanding thermal-based methods,the particulate nature of many of these sorbents has sometimes limited their large-scale deployment in high-throughput applications such as gas separations,for which the necessary high feed flow rates and gas velocities accrue prohibitive operational costs.These processability limitations have been historically addressed through powder shaping methods aimed at the fabrication of structured sorbent contactors based on pellets,beads or monoliths,commonly obtained as extrudates.These structures overcome limitations such as elevated pressure drops commonly recorded across powder adsorption beds but often accrue thermal limitations arising from elevated particle density and aggregation,which ultimately cap their maximum separation performance.Furthermore,the harsh mechanical strain to which powder particles are subjected during contactor fabrication,in the form of extrusion/compression forces,can result in partial pore occlusion and framework degradation,further limiting their performance.Here,we present the development of porous fiber sorbents as an alternative sorbent contactor design capable of addressing sorbent processability limitations while enabling an array of performance-maximizing heat integration capabilities.This new sorbent form factor leverages pre-existing know-how from hollow fiber spinning to produce fiber-shaped sorbent contactors through the phase inversion of known polymers in a process known as dry-jet/wet quenching.The process of phase inversion allows microporous sorbent particles to be latched onto a macroporous polymer matrix under mild processing conditions,thus making it compatible with soft porous materials prone to amorphization under traditional pelletization conditions.Sorbent fibers can be created with different geometries through control of the spinning apparatus and process,offering the possibility to produce monolithic and hollow fibers alike,the latter of which can be integrated with thermalization fluid flows.In this Account,we summarize our progress in the field of fiber sorbents from both design and application standpoints.We further guide the reader through the evolution of this field from the early inceptive work on zeolite hollow fibers to recent developments on MOF fibers.We highlight the versatile nature of fiber sorbents,both from the composition,fabrication and structure points of view,and further demonstrate how fiber sorbents offer alternative paths in tackling new and challenging chemical separation challenges like direct air capture(DAC),with a final perspective on the future of the field.
文摘Over the past few decades, coordination polymers/metal organic frameworks （CPs/MOFs） have drawn a great deal of attention for diverse applications due to their advantages of intrinsically ttLnable chemical structure, flexible architecture, high pore volume, high surface area, multifunctional properties, etc. To date, numerous CPs/MOFs have been developed and employed for the treatment and control of gaseous pollutants, such as volatile organic compounds （VOCs）, through capture, sorptive removal, and catalytic degradation. Nevertheless, there are also some key drawbacks and challenges for the practical application of these systems （e.g., poor selectivity, high energy （and fiscal） cost, high synthesis cost, low capacity, and difficulties in regeneration and recycling）. In this review, recent developments in CPs/MOFs research are described with their associated mechanisms for capture, sorptive removal, and catalytic degradation of VOCs. To this end, we discuss the key variables and challenges for afforded abatement of VOCs through CPs/MOFs technologies. Hopefully, this review will help the scientific community set future directions for the advancement of CPs/MOFs techniques for the effective management of diverse environmental issues.
