A novel spherical cellulose adsorbent has been prepared by homogeneous graft polymerization of N,N＇-methylenebisacrylamide （MBA） onto cellulose in an ionic liquid, 1-N-butyl-3-methylimidazolium chloride （BMIMC1）,...A novel spherical cellulose adsorbent has been prepared by homogeneous graft polymerization of N,N＇-methylenebisacrylamide （MBA） onto cellulose in an ionic liquid, 1-N-butyl-3-methylimidazolium chloride （BMIMC1）, which was then partially amine methylated through Mannich reaction to get bifunctionalized materials containing both amide and sulphinate moities. Factors affecting the attachment of functional groups were investigated. The adsorbent was characterized by Elemental Analysis （EA）, Fourier Transform Infrared Spectroscopy （FTIR） and Scanning Electron Microscope （SEM）. Cellulose adsorbent was then tested for its potential applications in the reduction adsorption oftrichloroacetic acid （TCAA） from aqueous solutions.展开更多
Cellulose was first grafted with glycidyl methacrylate （GMA） in an ionic liquid via atom transfer radical polymerization （ATRP） and then the introduced epoxy groups were reacted with ethanediamine （EDA） to obtai...Cellulose was first grafted with glycidyl methacrylate （GMA） in an ionic liquid via atom transfer radical polymerization （ATRP） and then the introduced epoxy groups were reacted with ethanediamine （EDA） to obtain an amino adsorbent. The grafting copolymer and the obtained adsorbent were characterized by FTIR, aH NMR, TEM and SEM. The results showed that the grafted copolymers had grafted polymer chains with well-controlled molecu- lar weight and polydispersity, the polymerization was a controlled system. The cellulose adsorbent had numerous micropores on the surface and showed high performance for Cr（VI） adsorption. The adsorption behavior was pH dependent and the sorption equilibrium was achieved within 2 h on the adsorbent.展开更多
The kinetics of atom transfer radical polymerization（ATRP） of methyl methacrylate（MMA） initiated by cellulose based macroinitator, cellulose chloroacetate, performed in ionic liquid（1-N-butyl-3-methylimidazolium ...The kinetics of atom transfer radical polymerization（ATRP） of methyl methacrylate（MMA） initiated by cellulose based macroinitator, cellulose chloroacetate, performed in ionic liquid（1-N-butyl-3-methylimidazolium chloride, BMIMC1）, dimethyl sulfoxide（DMSO） and dimethyl formamide（DMF） were respectively studied in detail. The polymerizations were carried out under homogeneous conditions with CuBr as catalyst and 2,2＇-bipyridine（bpy） as ligand. The dependences of the rate of polymerization on solvent, temperature, monomer/initiator ratio and catalyst/ligand ratio were presented. Plots of ln（[M]0/[M]t） vs. time and molecular weight vs. conversion showed a linear dependence, indicating a constant number of propagating species throughout the polymerization as well as a negligible contribution of termination or transfer reactions. On the basis of an Arrhenius plot, the apparent energy of activation（AEaapp ） for ATRP of MMA in BMIMC1 was 16.6 kJ/mol which is much lower than that in diphenyl ether.展开更多
Quantification of seepage in disconnected river-aquifer systems is significant for local water management and groundwater pollution control, especially in areas with water shortage or contamination. The vadose zone un...Quantification of seepage in disconnected river-aquifer systems is significant for local water management and groundwater pollution control, especially in areas with water shortage or contamination. The vadose zone under riverbeds usually exhibits a multi-layered structure, particularly when paved with low permeability liners. To evaluate the impact of engineering solutions to seepage under such conditions, we proposed an approach by combining GIS and the minimum flux in saturation layer(MFSL) method. MFSL can calculate the stable seepage rate by assessing the dominant low permeability layers(including but not limited to the liners) in multilayered disconnected river-aquifer systems. We used MFSL to calculate local seepage rate, and used GIS to extend the results to a regional scale. The reliability of MFSL is discussed by comparing the results with the double ring infiltration test, the numerical simulation by HYDRUS, and the methods of stream package in MODFLOW, including its improved form. A case study was conducted in the Yongding River with river-aquifer seepage calculated under various conditions, including different river water levels(i.e., under the designated water level, drought stage level, flood stage level and flood inundation level) and with/without low permeability liners(i.e., ecological membranes or geomembrane). Results showed that low permeability liners could greatly reduce the seepage rate. However, if an unlined inundation area exists, the seepage rate may increase greatly. The results indicated that the proposed method was reliable and convenient for calculating long-term, large area seepage in disconnected river-aquifer systems especially those paved with liners.展开更多
A novel spherical cellulose adsorbent with amide and sulphinate groups was used for a first reduction of trichloroacetic acid（TCAA） and a subsequent adsorption of generated species, haloacetic acids. The removal mec...A novel spherical cellulose adsorbent with amide and sulphinate groups was used for a first reduction of trichloroacetic acid（TCAA） and a subsequent adsorption of generated species, haloacetic acids. The removal mechanism involved TCAA reduction by sulphinate groups and the adsorption of the haloacetic acids through electrostatic interaction with amide group. Investigation of product formation and subsequent disappearance reveals that the reduction reactions proceed via sequential hydrogenolysis, and transform to acetate ultimately. Adsorption of haloacetic acids was ascertained by low chloride mass balances（89.3%） and carbon mass balances（75.1%） in solution. The pseudo-first-order rate constant for TCAA degradation was （0.93±0.12） h-1. Batch experiments were conducted to investigate the effect of pH value on the reduction and adsorption process. The results show that the reduction of TCAA by sulphinate groups requires higher pH values while the electrostatic attraction of haloacetic acids by amino group is favorable in more acidic media.展开更多
基金Supported by the Science and Technology Project of Fujian Province Educational Department(JK2013004,JA12040)Science & Technology Development Fund of Fuzhou University(2012-XY-10,2014-XQ-11)the National Natural Science Foundation of China(41372346)
文摘A novel spherical cellulose adsorbent has been prepared by homogeneous graft polymerization of N,N＇-methylenebisacrylamide （MBA） onto cellulose in an ionic liquid, 1-N-butyl-3-methylimidazolium chloride （BMIMC1）, which was then partially amine methylated through Mannich reaction to get bifunctionalized materials containing both amide and sulphinate moities. Factors affecting the attachment of functional groups were investigated. The adsorbent was characterized by Elemental Analysis （EA）, Fourier Transform Infrared Spectroscopy （FTIR） and Scanning Electron Microscope （SEM）. Cellulose adsorbent was then tested for its potential applications in the reduction adsorption oftrichloroacetic acid （TCAA） from aqueous solutions.
基金This research was supported by the National Natural Science Foundation of China，the Natural Science Foundation of Fujian Province
文摘Cellulose was first grafted with glycidyl methacrylate （GMA） in an ionic liquid via atom transfer radical polymerization （ATRP） and then the introduced epoxy groups were reacted with ethanediamine （EDA） to obtain an amino adsorbent. The grafting copolymer and the obtained adsorbent were characterized by FTIR, aH NMR, TEM and SEM. The results showed that the grafted copolymers had grafted polymer chains with well-controlled molecu- lar weight and polydispersity, the polymerization was a controlled system. The cellulose adsorbent had numerous micropores on the surface and showed high performance for Cr（VI） adsorption. The adsorption behavior was pH dependent and the sorption equilibrium was achieved within 2 h on the adsorbent.
基金Supported by the National Natural Science Foundation of China（No.21077024）, the Natural Science Foundation of Fujian Province, China（No.2011 J05026） and the Initial Funding of Fuzhou University, China（No.0460022326）.
文摘The kinetics of atom transfer radical polymerization（ATRP） of methyl methacrylate（MMA） initiated by cellulose based macroinitator, cellulose chloroacetate, performed in ionic liquid（1-N-butyl-3-methylimidazolium chloride, BMIMC1）, dimethyl sulfoxide（DMSO） and dimethyl formamide（DMF） were respectively studied in detail. The polymerizations were carried out under homogeneous conditions with CuBr as catalyst and 2,2＇-bipyridine（bpy） as ligand. The dependences of the rate of polymerization on solvent, temperature, monomer/initiator ratio and catalyst/ligand ratio were presented. Plots of ln（[M]0/[M]t） vs. time and molecular weight vs. conversion showed a linear dependence, indicating a constant number of propagating species throughout the polymerization as well as a negligible contribution of termination or transfer reactions. On the basis of an Arrhenius plot, the apparent energy of activation（AEaapp ） for ATRP of MMA in BMIMC1 was 16.6 kJ/mol which is much lower than that in diphenyl ether.
基金supported by the National Natural Science Foundation of China (51379207, 51321001)Beijing Municipal Science and Technology Project (D090409004009004)
文摘Quantification of seepage in disconnected river-aquifer systems is significant for local water management and groundwater pollution control, especially in areas with water shortage or contamination. The vadose zone under riverbeds usually exhibits a multi-layered structure, particularly when paved with low permeability liners. To evaluate the impact of engineering solutions to seepage under such conditions, we proposed an approach by combining GIS and the minimum flux in saturation layer(MFSL) method. MFSL can calculate the stable seepage rate by assessing the dominant low permeability layers(including but not limited to the liners) in multilayered disconnected river-aquifer systems. We used MFSL to calculate local seepage rate, and used GIS to extend the results to a regional scale. The reliability of MFSL is discussed by comparing the results with the double ring infiltration test, the numerical simulation by HYDRUS, and the methods of stream package in MODFLOW, including its improved form. A case study was conducted in the Yongding River with river-aquifer seepage calculated under various conditions, including different river water levels(i.e., under the designated water level, drought stage level, flood stage level and flood inundation level) and with/without low permeability liners(i.e., ecological membranes or geomembrane). Results showed that low permeability liners could greatly reduce the seepage rate. However, if an unlined inundation area exists, the seepage rate may increase greatly. The results indicated that the proposed method was reliable and convenient for calculating long-term, large area seepage in disconnected river-aquifer systems especially those paved with liners.
基金Supported by the Natural Science Foundation of Fujian Province, China（No.2015J01049）, the Independent Research Project of State Key Laboratory of Photocatalysis on Energy and Environment, China（No.2014C02） and the Science and Technology Project of Fujian Province Educational Department, China（Nos.JK2013004, JA12040）.
文摘A novel spherical cellulose adsorbent with amide and sulphinate groups was used for a first reduction of trichloroacetic acid（TCAA） and a subsequent adsorption of generated species, haloacetic acids. The removal mechanism involved TCAA reduction by sulphinate groups and the adsorption of the haloacetic acids through electrostatic interaction with amide group. Investigation of product formation and subsequent disappearance reveals that the reduction reactions proceed via sequential hydrogenolysis, and transform to acetate ultimately. Adsorption of haloacetic acids was ascertained by low chloride mass balances（89.3%） and carbon mass balances（75.1%） in solution. The pseudo-first-order rate constant for TCAA degradation was （0.93±0.12） h-1. Batch experiments were conducted to investigate the effect of pH value on the reduction and adsorption process. The results show that the reduction of TCAA by sulphinate groups requires higher pH values while the electrostatic attraction of haloacetic acids by amino group is favorable in more acidic media.
