The process of emulsifier-free copolymerization of the Styrene-Butyl Acrylate-K_sS_sO_s-water in the presence of Barium Sulfate(BS)powder was investigated under varied conditions within the range of BS powder quantity...The process of emulsifier-free copolymerization of the Styrene-Butyl Acrylate-K_sS_sO_s-water in the presence of Barium Sulfate(BS)powder was investigated under varied conditions within the range of BS powder quantity,initiator concentration and reaction temperature.Experimental results showed that the rate of polymerization is proportional to 0.3-power of the BS quantity and 1.3-power of the initiator concentration.There is a linear relationship of 2/3-power for the conversion and time.A process for the polymerization is propose to explain the experimental results.展开更多
The EDTA dianhydride reacted with diazacrown ethers to obtain the water-soluble EDTA-diazacrown ether polymers 1~3. The effects of crown ether ring in the polymer chains including its cavity size on the solubilizati...The EDTA dianhydride reacted with diazacrown ethers to obtain the water-soluble EDTA-diazacrown ether polymers 1~3. The effects of crown ether ring in the polymer chains including its cavity size on the solubilization of barium sulfate to water were investigated by comparison with the crown ring-free analogue 4. The result shows that the polymer 2 is the efficient solubilizer of BaSO4 and the highest solubilization efficiency of the BaSO4to water is up to 72.5%.展开更多
To investigate soapless emulsion copolymerization in the presence of a solid phase, copolymerization experiments were carried out for the styrene-butyl acrylate-K_2S_2O_8-water system by using barium sulfate powder,wh...To investigate soapless emulsion copolymerization in the presence of a solid phase, copolymerization experiments were carried out for the styrene-butyl acrylate-K_2S_2O_8-water system by using barium sulfate powder,which is assumed to be chemically inert.Reaction conditions were varied with respect to barium sulfate powder quantity,initiator concen- tration and temperature.These factors were investigated with respect to the effect on reaction rate and conversion,polymer particle number and diameter,and latex stability.展开更多
In this study, surface modification of barium sulfate was investigated using several model molecules for chemical treatment: ethanesulfonic acid, butyric acid, trimethoxy(propyl) silane and phosphoric acid 2-hydroxyet...In this study, surface modification of barium sulfate was investigated using several model molecules for chemical treatment: ethanesulfonic acid, butyric acid, trimethoxy(propyl) silane and phosphoric acid 2-hydroxyethyl methacrylate. Samples were characterized by FT-IR and TGA to check the capability of these model molecules to interact with BaSO<sub>4</sub> surface. The results pointed out the presence of an organic layer around the surface after the chemical treatment even after several washings to remove all species in excess. Model molecules were grafted onto BaSO<sub>4</sub> surface and grafted density was determined. It reveals that phosphoric acid and carboxylic acid are the best candidates for the modification of BaSO<sub>4</sub> surface. Both can be used as anchoring groups to modify the hydrophilic balance of barium sulfate surface in order to avoid the formation of aggregates and to improve the compatibility of this filler within hydrophobic polymer matrix.展开更多
The aim of the present work is to study the effect of Nano-barium sulfate additions on the physic-mechanical properties of hardened cement pastes. Nano-barium sulfate was prepared by the precipitation method. Eight mi...The aim of the present work is to study the effect of Nano-barium sulfate additions on the physic-mechanical properties of hardened cement pastes. Nano-barium sulfate was prepared by the precipitation method. Eight mixes of filled cement pastes containing 0.5 wt%, 1.0 wt%, 1.5 wt% and 2.0 wt% of both nano-barium sulfate and micro-limestone were prepared and compared to the base OPC. The hydration characteristics were evaluated by the measure of combined water content, bulk density, total porosity and compressive strength for samples hydrated up to 90 days. The progress of hydration reactions was followed up by XRD analysis. The morphology and microstructure were studied by SEM. Nano-size barium sulfate acted as a nucleating agent and enhanced the hydration of cement pastes up to 2.0% mass content. Also, the microstructure was improved considerably. Accordingly, nano-size barium sulfate can be used successfully in the preparation of filled cement.展开更多
Barium sulfate aggregates with an average size of 0.5μm were synthesized at pH 7, directed by ethylenediaminetetraacetic acid （EDTA） anions. The particle morphology, chemical composition, and size distribution of t...Barium sulfate aggregates with an average size of 0.5μm were synthesized at pH 7, directed by ethylenediaminetetraacetic acid （EDTA） anions. The particle morphology, chemical composition, and size distribution of the BaSO4 aggregates were characterized. The as-synthesized BaSO4 particles were spherical and comprised many interconnected nanoballs, of which the surface properties were affected by the EDTA anions. The adsorption of EDTA anions reversed the charge and weakened the surface polarity of BaSO4, instigating the formation of aggregates by a self-assembly and transformation process. The resulting BaSO4 particles at pH 9-10 were ellipsoidal and featured smooth surfaces. Based on the zeta potential of BaSO4, variations in the morphology induced by changes in pH were closely related to the adsorption of mono- and multi-valent anions onto the electrical double layer of BaSO4.展开更多
Sulfur poisoning of V_2O_5/BaSO_4–TiO_2（VBT）,V_2O_5/WO_3–TiO_2（VWT） and V_2O_5/BaSO_4–WO_3–TiO_2（VBWT） catalysts was performed in wet air at 350℃ for 3 hr,and activities for the selective catalytic reductio...Sulfur poisoning of V_2O_5/BaSO_4–TiO_2（VBT）,V_2O_5/WO_3–TiO_2（VWT） and V_2O_5/BaSO_4–WO_3–TiO_2（VBWT） catalysts was performed in wet air at 350℃ for 3 hr,and activities for the selective catalytic reduction of NO_x with NH_3 were evaluated for 200–500℃.The VBT catalyst showed higher NO_x conversions after sulfur poisoning than the other two catalysts.The introduction of barium sulfate contributed to strong acid sites for the as-received catalyst,and eliminated the redox cycle of active vanadium oxide to some extent,which resulted in a certain loss of activity.Readily decomposable sulfate species formed on VBT-S instead of inactive sulfates on VWT-S.These decomposable sulfates increased the number of strong acid sites significantly.Some sulfate species escaped during catalyst preparation and barium sulfate was reproduced during sulfur poisoning,which protects vanadia from sulfur oxide attachment to a great extent.Consequently,the VBT catalyst exhibited the best resistance to sulfur poisoning.展开更多
As a kind of green concrete,the mechanical properties and durability of cemented gangue backfill material(CGBM)will be affected if they are in acid mine water with sulfate ions in the long term.To improve the performa...As a kind of green concrete,the mechanical properties and durability of cemented gangue backfill material(CGBM)will be affected if they are in acid mine water with sulfate ions in the long term.To improve the performance of CGBM in acid mine water with sulfate ions,CGBM specimens with different doses of barium hydroxide were immersed in sulfuric acid solutions of different concentrations for 270 days.The changes of mass,ultrasonic pulse velocity(UPV)and compressive strength of the specimens at different ages were analyzed.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to analyze the microstructure and composition of the specimens.The results show that incorporation of barium hydroxide into CGBM specimen can promote the formation of barium sulfate precipitation and inhibit the generation of corrosion products such as ettringite.Meanwhile,barium sulfate precipitation blocks the pore channel invaded by sulfuric acid solution,delaying the progress of corrosion reaction and making the interior of CGBM specimen more complete.And the specimen with 2.0 kg/m^(3)barium hydroxide was more effective in improving performance.This study provides a basis for the ratio design of CGBM in acid mine water with sulfate ions.展开更多
文摘The process of emulsifier-free copolymerization of the Styrene-Butyl Acrylate-K_sS_sO_s-water in the presence of Barium Sulfate(BS)powder was investigated under varied conditions within the range of BS powder quantity,initiator concentration and reaction temperature.Experimental results showed that the rate of polymerization is proportional to 0.3-power of the BS quantity and 1.3-power of the initiator concentration.There is a linear relationship of 2/3-power for the conversion and time.A process for the polymerization is propose to explain the experimental results.
基金the financial support from the National Natural Science Foundation of China(Grant No:29572050).
文摘The EDTA dianhydride reacted with diazacrown ethers to obtain the water-soluble EDTA-diazacrown ether polymers 1~3. The effects of crown ether ring in the polymer chains including its cavity size on the solubilization of barium sulfate to water were investigated by comparison with the crown ring-free analogue 4. The result shows that the polymer 2 is the efficient solubilizer of BaSO4 and the highest solubilization efficiency of the BaSO4to water is up to 72.5%.
文摘To investigate soapless emulsion copolymerization in the presence of a solid phase, copolymerization experiments were carried out for the styrene-butyl acrylate-K_2S_2O_8-water system by using barium sulfate powder,which is assumed to be chemically inert.Reaction conditions were varied with respect to barium sulfate powder quantity,initiator concen- tration and temperature.These factors were investigated with respect to the effect on reaction rate and conversion,polymer particle number and diameter,and latex stability.
文摘In this study, surface modification of barium sulfate was investigated using several model molecules for chemical treatment: ethanesulfonic acid, butyric acid, trimethoxy(propyl) silane and phosphoric acid 2-hydroxyethyl methacrylate. Samples were characterized by FT-IR and TGA to check the capability of these model molecules to interact with BaSO<sub>4</sub> surface. The results pointed out the presence of an organic layer around the surface after the chemical treatment even after several washings to remove all species in excess. Model molecules were grafted onto BaSO<sub>4</sub> surface and grafted density was determined. It reveals that phosphoric acid and carboxylic acid are the best candidates for the modification of BaSO<sub>4</sub> surface. Both can be used as anchoring groups to modify the hydrophilic balance of barium sulfate surface in order to avoid the formation of aggregates and to improve the compatibility of this filler within hydrophobic polymer matrix.
文摘The aim of the present work is to study the effect of Nano-barium sulfate additions on the physic-mechanical properties of hardened cement pastes. Nano-barium sulfate was prepared by the precipitation method. Eight mixes of filled cement pastes containing 0.5 wt%, 1.0 wt%, 1.5 wt% and 2.0 wt% of both nano-barium sulfate and micro-limestone were prepared and compared to the base OPC. The hydration characteristics were evaluated by the measure of combined water content, bulk density, total porosity and compressive strength for samples hydrated up to 90 days. The progress of hydration reactions was followed up by XRD analysis. The morphology and microstructure were studied by SEM. Nano-size barium sulfate acted as a nucleating agent and enhanced the hydration of cement pastes up to 2.0% mass content. Also, the microstructure was improved considerably. Accordingly, nano-size barium sulfate can be used successfully in the preparation of filled cement.
基金supported by the Natural Science Foundation of Hebei Province(B2012202106)
文摘Barium sulfate aggregates with an average size of 0.5μm were synthesized at pH 7, directed by ethylenediaminetetraacetic acid （EDTA） anions. The particle morphology, chemical composition, and size distribution of the BaSO4 aggregates were characterized. The as-synthesized BaSO4 particles were spherical and comprised many interconnected nanoballs, of which the surface properties were affected by the EDTA anions. The adsorption of EDTA anions reversed the charge and weakened the surface polarity of BaSO4, instigating the formation of aggregates by a self-assembly and transformation process. The resulting BaSO4 particles at pH 9-10 were ellipsoidal and featured smooth surfaces. Based on the zeta potential of BaSO4, variations in the morphology induced by changes in pH were closely related to the adsorption of mono- and multi-valent anions onto the electrical double layer of BaSO4.
基金the financial support from projects of the Ministry of Science and Technology,China(Nos.2015AA034603,2016YFC0205200)the Science and Technology Department of Zhejiang Province,China(No.2015C31015)
文摘Sulfur poisoning of V_2O_5/BaSO_4–TiO_2（VBT）,V_2O_5/WO_3–TiO_2（VWT） and V_2O_5/BaSO_4–WO_3–TiO_2（VBWT） catalysts was performed in wet air at 350℃ for 3 hr,and activities for the selective catalytic reduction of NO_x with NH_3 were evaluated for 200–500℃.The VBT catalyst showed higher NO_x conversions after sulfur poisoning than the other two catalysts.The introduction of barium sulfate contributed to strong acid sites for the as-received catalyst,and eliminated the redox cycle of active vanadium oxide to some extent,which resulted in a certain loss of activity.Readily decomposable sulfate species formed on VBT-S instead of inactive sulfates on VWT-S.These decomposable sulfates increased the number of strong acid sites significantly.Some sulfate species escaped during catalyst preparation and barium sulfate was reproduced during sulfur poisoning,which protects vanadia from sulfur oxide attachment to a great extent.Consequently,the VBT catalyst exhibited the best resistance to sulfur poisoning.
基金sponsored by the National Natural Science Foundation of China(Grant No.51974192)the Distinguished Youth Funds of National Natural Science Foundation of China(Grant No.51925402)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Project(2021SX-TD001).
文摘As a kind of green concrete,the mechanical properties and durability of cemented gangue backfill material(CGBM)will be affected if they are in acid mine water with sulfate ions in the long term.To improve the performance of CGBM in acid mine water with sulfate ions,CGBM specimens with different doses of barium hydroxide were immersed in sulfuric acid solutions of different concentrations for 270 days.The changes of mass,ultrasonic pulse velocity(UPV)and compressive strength of the specimens at different ages were analyzed.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to analyze the microstructure and composition of the specimens.The results show that incorporation of barium hydroxide into CGBM specimen can promote the formation of barium sulfate precipitation and inhibit the generation of corrosion products such as ettringite.Meanwhile,barium sulfate precipitation blocks the pore channel invaded by sulfuric acid solution,delaying the progress of corrosion reaction and making the interior of CGBM specimen more complete.And the specimen with 2.0 kg/m^(3)barium hydroxide was more effective in improving performance.This study provides a basis for the ratio design of CGBM in acid mine water with sulfate ions.
