To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using c...To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, Al adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of Al above a certain initial Al concentration (0.1 mmol L-1 for kaolinite and 0.3 mmol L-1 for the Oxisol). The Al hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of Al and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of Al hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. Al hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in Al adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed Al3+ in total adsorbed Al with the increase in soil negative surface charge and eliminated or reduced the acceleration of Al hydrolysis. Different organic anions inhibited the hydrolysis of Al in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al.展开更多
Anodic processes on Cu-10 Al electrode in molten KF-AlF3-Al2O3(saturated) and suspensions were characterized using chronopotentiometric and cyclic voltammetric techniques. Effects of cryolite ratio(CR= x(KF)/x(AlF3)),...Anodic processes on Cu-10 Al electrode in molten KF-AlF3-Al2O3(saturated) and suspensions were characterized using chronopotentiometric and cyclic voltammetric techniques. Effects of cryolite ratio(CR= x(KF)/x(AlF3)), temperature and particle volume fraction(φ) on the electrochemical behaviour of the anode were demonstrated. Initially, the anode was polarised in the galvanostatic mode in melt and suspensions(φ=0.12, 0.15) at 750 ℃ with 0.4 A/cm^2 current density. The anode potential in melt varied between 2.5 and 3.2 V and in suspensions(φ= 0.12) between 3.3 and 3.4 V. XRD analysis was conducted to study the oxide phases on the anode surface. Anode limiting current densities and mass transfer coefficients drastically decreased with the increase of φ in the suspension. The results suggest that the Cu-10 Al electrode works better in suspensions with CR of 1.4 and particle volume fraction of 0.09 at 800 ℃.展开更多
In order to calculate the suspended sediment discharge of the flood debris flows into the main river,a small scale flume test was designed to simulate the process of confluence of Jiangjia Ravine and Xiangjiang River ...In order to calculate the suspended sediment discharge of the flood debris flows into the main river,a small scale flume test was designed to simulate the process of confluence of Jiangjia Ravine and Xiangjiang River in Yunnan province,China.By test observation and data analysis,suspended sediment discharge of Debris flow after its entry into the main river was found to have a close relation with the bulk density,the confluence angle of the Debris flow and the main river,the ratio between per unit width discharge of Debris flow and main river.Based on the measured and simulated results,and statistical analysis,an empirical formula was proposed for the suspended SDR(Sediment Delivery Ratio) of the main river after the confluence of Debris flow.Compared with the observed results of Debris flow in 2009,the error between the data calculated by the empirical formula and the monitored data is only about 10%.展开更多
Polymer dispersants are widely used as grinding aids to reduce the viscosity of mineral particle suspensions and to improve energy efficiency during fine grinding. The authors studied here the effects of polymer dispe...Polymer dispersants are widely used as grinding aids to reduce the viscosity of mineral particle suspensions and to improve energy efficiency during fine grinding. The authors studied here the effects of polymer dispersants of different molecular structure on limestone suspension properties in wet stirred media milling. The polymers differed in their molecular weight and PDI （polydispersity index）. Two traditionally fractionated polymer dispersants having a high PDI （over 2） and one made by controlled radical polymerization having a low PDI （1.2） were tested. It was noticed that these dispersants worked as electrosteric stabilizers and prevented the agglomeration of ground limestone particles. Their addition allowed increased solids concentrations to be used in the grinding experiments and at the same time lowered the particle size and specific energy consumption. The particle sizes obtained were about 1 μm regardless of the dispersant or its dose. The dispersant with a low PDI reduced the viscosity more than did the high PDI dispersants. The results indicate that higher solids concentrations can be used at the same dispersant dose when a low PDI dispersant is used, leading to energy savings via increased throughput. Alternatively, a lower dose of low PDI polymer dispersant than of a high PDI polymer dispersant can be used at the same solids concentration.展开更多
Suspended particulate substances were sampled in the eastem equatorial Pacific in water column from surface to near bottom in five stations in 2005, from which 868 barite crystals were recovered. The barite crystals w...Suspended particulate substances were sampled in the eastem equatorial Pacific in water column from surface to near bottom in five stations in 2005, from which 868 barite crystals were recovered. The barite crystals were examined under scanning electron microscopy. About 61% of the total barites crystals contained detectable Sr by energy dispersive X-ray spectrometry. Barite crystals could be classified into four groups based on their morphology： 1） bladed; 2） ovoid or rounded; 3） arrow-like; and 4） irregularly shaped. The arrow-like barite crystals in natural environment has never been reported before. In addition, about a half of the studied crystals showed features of dissolution as cavities or holes inside of the crystals or around their edges. We found that differential dissolution of barite crystals is consequence of heterogeneous Sr distribution in barite crystals. Our results would help in understanding the biogeochemical processes of marine barite formation and preservation in seawater and marine sediments.展开更多
Microencapsulation of phase change materials(Micro PCMs) has been paid special attention because of their extensive applications in saving and releasing energy. Micro PCMs containing paraffin with a melting point of ...Microencapsulation of phase change materials(Micro PCMs) has been paid special attention because of their extensive applications in saving and releasing energy. Micro PCMs containing paraffin with a melting point of 55 ℃ in polystyrene-divinylbenzene(P(St-DVB)) were prepared by suspension-like polymerization. The characterization of microcapsules by FTIR, DSC and TG proved that paraffin had been successfully encapsulated and the proportion of encapsulated paraffin was 49.8%—58.5%. The effects of polyvinylpyrrolidone(PVP) with different molecular weights serving as the suspension stabilizer were investigated in detail. The results illustrated that the type of PVP had a significant influence on the particle size of Micro PCMs. The average diameter of Micro PCMs decreased with an increasing molecular weight of PVP. Moreover, the crosslinker-postaddition method was adopted in this study to improve the morphology of P(St-DVB) Micro PCMs. SEM images showed that when the DVB was added at the 2nd hour of polymerization the morphology of obtained P(St-DVB) Micro PCMs exhibited good sphericity since it could avoid the influence of cross-linker agent during the nucleation period.展开更多
This paper presents the first report of the successful ball-milling exfoliation of graphitic filaments （GANF~ carbon nanofibres） into single layer graphene. The addition of small amounts of solvent during the millin...This paper presents the first report of the successful ball-milling exfoliation of graphitic filaments （GANF~ carbon nanofibres） into single layer graphene. The addition of small amounts of solvent during the milling process makes it possible to enhance the intercalation of the exfoliating agent （melamine） between the graphene layers, thus promoting exceptional exfoliation. Advantage has also been taken of the fact that the Hansen solubility parameters of graphene are different from those of carbon fibres, which allows single and few-layer graphene to be suspended in a particular solvent, thus discriminating them from poorly exfoliated carbon nanofibres.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 40271062).
文摘To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, Al adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of Al above a certain initial Al concentration (0.1 mmol L-1 for kaolinite and 0.3 mmol L-1 for the Oxisol). The Al hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of Al and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of Al hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. Al hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in Al adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed Al3+ in total adsorbed Al with the increase in soil negative surface charge and eliminated or reduced the acceleration of Al hydrolysis. Different organic anions inhibited the hydrolysis of Al in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al.
文摘Anodic processes on Cu-10 Al electrode in molten KF-AlF3-Al2O3(saturated) and suspensions were characterized using chronopotentiometric and cyclic voltammetric techniques. Effects of cryolite ratio(CR= x(KF)/x(AlF3)), temperature and particle volume fraction(φ) on the electrochemical behaviour of the anode were demonstrated. Initially, the anode was polarised in the galvanostatic mode in melt and suspensions(φ=0.12, 0.15) at 750 ℃ with 0.4 A/cm^2 current density. The anode potential in melt varied between 2.5 and 3.2 V and in suspensions(φ= 0.12) between 3.3 and 3.4 V. XRD analysis was conducted to study the oxide phases on the anode surface. Anode limiting current densities and mass transfer coefficients drastically decreased with the increase of φ in the suspension. The results suggest that the Cu-10 Al electrode works better in suspensions with CR of 1.4 and particle volume fraction of 0.09 at 800 ℃.
基金supported by the Key Research Program of the Chinese Academy ofSciences (Grant No.KZZD-EW-05-01)the National Natural Science Foundation of China(Grant No.40871024)
文摘In order to calculate the suspended sediment discharge of the flood debris flows into the main river,a small scale flume test was designed to simulate the process of confluence of Jiangjia Ravine and Xiangjiang River in Yunnan province,China.By test observation and data analysis,suspended sediment discharge of Debris flow after its entry into the main river was found to have a close relation with the bulk density,the confluence angle of the Debris flow and the main river,the ratio between per unit width discharge of Debris flow and main river.Based on the measured and simulated results,and statistical analysis,an empirical formula was proposed for the suspended SDR(Sediment Delivery Ratio) of the main river after the confluence of Debris flow.Compared with the observed results of Debris flow in 2009,the error between the data calculated by the empirical formula and the monitored data is only about 10%.
文摘Polymer dispersants are widely used as grinding aids to reduce the viscosity of mineral particle suspensions and to improve energy efficiency during fine grinding. The authors studied here the effects of polymer dispersants of different molecular structure on limestone suspension properties in wet stirred media milling. The polymers differed in their molecular weight and PDI （polydispersity index）. Two traditionally fractionated polymer dispersants having a high PDI （over 2） and one made by controlled radical polymerization having a low PDI （1.2） were tested. It was noticed that these dispersants worked as electrosteric stabilizers and prevented the agglomeration of ground limestone particles. Their addition allowed increased solids concentrations to be used in the grinding experiments and at the same time lowered the particle size and specific energy consumption. The particle sizes obtained were about 1 μm regardless of the dispersant or its dose. The dispersant with a low PDI reduced the viscosity more than did the high PDI dispersants. The results indicate that higher solids concentrations can be used at the same dispersant dose when a low PDI dispersant is used, leading to energy savings via increased throughput. Alternatively, a lower dose of low PDI polymer dispersant than of a high PDI polymer dispersant can be used at the same solids concentration.
基金Supported by the China Ocean Mineral Resources R&D Association(Mas,DYXM-115-02-1-13,DYXM-115-01-3-04)
文摘Suspended particulate substances were sampled in the eastem equatorial Pacific in water column from surface to near bottom in five stations in 2005, from which 868 barite crystals were recovered. The barite crystals were examined under scanning electron microscopy. About 61% of the total barites crystals contained detectable Sr by energy dispersive X-ray spectrometry. Barite crystals could be classified into four groups based on their morphology： 1） bladed; 2） ovoid or rounded; 3） arrow-like; and 4） irregularly shaped. The arrow-like barite crystals in natural environment has never been reported before. In addition, about a half of the studied crystals showed features of dissolution as cavities or holes inside of the crystals or around their edges. We found that differential dissolution of barite crystals is consequence of heterogeneous Sr distribution in barite crystals. Our results would help in understanding the biogeochemical processes of marine barite formation and preservation in seawater and marine sediments.
基金financially supported by the National Natural Science Foundation of China (No. 20973022 and 11472048)the State Key Laboratory of Catalytic Materials and Reaction Engineering (RIPP, SINOPEC)
文摘Microencapsulation of phase change materials(Micro PCMs) has been paid special attention because of their extensive applications in saving and releasing energy. Micro PCMs containing paraffin with a melting point of 55 ℃ in polystyrene-divinylbenzene(P(St-DVB)) were prepared by suspension-like polymerization. The characterization of microcapsules by FTIR, DSC and TG proved that paraffin had been successfully encapsulated and the proportion of encapsulated paraffin was 49.8%—58.5%. The effects of polyvinylpyrrolidone(PVP) with different molecular weights serving as the suspension stabilizer were investigated in detail. The results illustrated that the type of PVP had a significant influence on the particle size of Micro PCMs. The average diameter of Micro PCMs decreased with an increasing molecular weight of PVP. Moreover, the crosslinker-postaddition method was adopted in this study to improve the morphology of P(St-DVB) Micro PCMs. SEM images showed that when the DVB was added at the 2nd hour of polymerization the morphology of obtained P(St-DVB) Micro PCMs exhibited good sphericity since it could avoid the influence of cross-linker agent during the nucleation period.
文摘This paper presents the first report of the successful ball-milling exfoliation of graphitic filaments （GANF~ carbon nanofibres） into single layer graphene. The addition of small amounts of solvent during the milling process makes it possible to enhance the intercalation of the exfoliating agent （melamine） between the graphene layers, thus promoting exceptional exfoliation. Advantage has also been taken of the fact that the Hansen solubility parameters of graphene are different from those of carbon fibres, which allows single and few-layer graphene to be suspended in a particular solvent, thus discriminating them from poorly exfoliated carbon nanofibres.
