The potential—pH diagrams of the Cr-H2O system at temperatures of 298, 323, 373 and 423 K were established through thermodynamic calculation with coupling of experimental results. The potential—pH diagram at 298 K a...The potential—pH diagrams of the Cr-H2O system at temperatures of 298, 323, 373 and 423 K were established through thermodynamic calculation with coupling of experimental results. The potential—pH diagram at 298 K agrees well with the previously reported results. Based on the potential—pH diagrams of the Cr-H2O and Fe-H2O systems, IR spectra and XRD pattern, the existence forms of iron in the potassium chromate were analyzed, and the methods of iron removal were investigated. The results show that the existence forms of iron in the potassium chromate are potassium ferrate. These results are instructive and helpful to the hydrometallurgical processing of chromite ore.展开更多
For aqueous interfacial reactions involving H+and OH-, the interfacial pH varies dynamically during the reaction process, which is a key factor determining the reaction performance. Herein, the kinetic relevance betwe...For aqueous interfacial reactions involving H+and OH-, the interfacial pH varies dynamically during the reaction process, which is a key factor determining the reaction performance. Herein, the kinetic relevance between the interfacial pH and reaction rate is deciphered owing to the success in establishing the transport equations of H+/OH- in unbuffered solutions, and is charted as a current(j)–pH diagram in the form of an electrochemical response. The as-described j–pH interplay is experimentally verified by the oxygen reduction and hydrogen evolution reactions. This diagram serves to form a panoramic graphic view of pH function working on the interfacial reactions in conjunction with the Pourbaix’s potential–pH diagram, and particularly enables a kinetic understanding of the transport effect of H+and OH-on the reaction rate and valuable instruction toward associated pH control and buffering manipulation.展开更多
The values of GΘ,EΘ or pH from 110 to 160℃ were calculated and the relevant potential expressions were obtained.E-pH diagrams of ZnS-H2O system at oxygen partial pressure of 0.8 MPa,ionic activity of 1.0 and differ...The values of GΘ,EΘ or pH from 110 to 160℃ were calculated and the relevant potential expressions were obtained.E-pH diagrams of ZnS-H2O system at oxygen partial pressure of 0.8 MPa,ionic activity of 1.0 and different temperatures were drawn through thermodynamical calculation.With the temperature increasing,the stable regions of S and Zn(Ⅱ) in the E-pH diagrams become gradually larger,but the amplification decreases over 150℃.The impacts of leaching parameters,such as temperature,liquid to solid ratio,initial acidic concentration,leaching time,oxygen partial pressure and stirring speed on the leaching rate of Zn(Ⅱ) and conversion rate of S in the single factor of high pressure leaching experiment of ZnS in autoclave,were studied.The leaching residue was examined by X-ray fluorescence(XRF) chemical composition identification and X-ray diffraction(XRD) phase identification,and the content of the leaching solution was tested by inductively coupled plasma-atomic emission spectrometry(ICP).The experimental results indicate that the leaching rate of zinc increases from 60.05% to 97.85% and the conversion rate of sulfur increases from 38.90% to 80.92% with the temperature increasing from 110℃ to 150℃,5:1 of liquid-to-solid ratio,150 g/L of initial acidic concentration,120 min of leaching time,0.8 MPa of oxygen partial pressure,and 480 r/min of stirring speed,which tend to be stable over 150℃.The experimental results correspond with theoretical calculation.展开更多
Phosphorus is an important element for larch (\%Larix gmelinii\% Rupr.)root development.P-availability in rhizosphere is close with root exudates or excretions,e.g.,organic acid exudation,proton excretion.These materi...Phosphorus is an important element for larch (\%Larix gmelinii\% Rupr.)root development.P-availability in rhizosphere is close with root exudates or excretions,e.g.,organic acid exudation,proton excretion.These materials from roots will affect pH value of rhizosphere.The aim of this paper were to study on pH changes at different P-stress conditions,and to test on the relation between available P and pH in rhizosphere.This work was carried out under pot experiment and field soil smaple analysis.Larch seedlings,1 and 2-year-old,were planted into sand pots.Nutrient solution with different P contents (0,0.035,0.071 and 0.142g·L -1 respectively) were supplied everyday.There were 2 replicates for 1-year-old seedlings,5 replicates for 2-year-old seedlings at ecch P-level treatment.After 1-year-old seedlings growing for 40 days and 2-year-old seedlings growing for 90 days,seedlings were taken out and used to visualize acidification by means of an agar plate technique.The result showed that pH of rhizosphere decreased from 6.40 to 4.73～4.84 in 1-year-old seedlings and to 5.30～5.50 in 2-year-old after 36h incubation.Average pH decreased were 1.56～1.67 for 1-year-old seedlings,and 0.90～1.10 for 2-year-old seedlings.There was not significant,for pH variations in rhizosphere,among four kind treatments.The pH change was not affected by P-level.The result of soil sample analysis,from 12-year-old,21-year-old,and 40-year-old pure larch stands respectively,indicated that the pH changes in rhizosphere is 0.11,0.04,and 0.09,respectively,lower than that in the non-rhizosphere,acidification is not significant,While the available P in the rhizosphere is 18.1%,86.5% and 23.4%,higher than that in the non-rhizosphere in three stands.The correlation between pH variations and available P was not remarkable at this analysis.This means that there was no relationship between the available P and pH change of rhizosphere in larch root system.展开更多
基金Project(2007CB613501) supported by the National Basic Research Program of ChinaProject(2006BAC02A05) supported by the National Science and Technology Pillar Program of ChinaProject(50904058) supported by the National Natural Science Foundation of China
文摘The potential—pH diagrams of the Cr-H2O system at temperatures of 298, 323, 373 and 423 K were established through thermodynamic calculation with coupling of experimental results. The potential—pH diagram at 298 K agrees well with the previously reported results. Based on the potential—pH diagrams of the Cr-H2O and Fe-H2O systems, IR spectra and XRD pattern, the existence forms of iron in the potassium chromate were analyzed, and the methods of iron removal were investigated. The results show that the existence forms of iron in the potassium chromate are potassium ferrate. These results are instructive and helpful to the hydrometallurgical processing of chromite ore.
基金the National Natural Science Foundation of China(51525805,51727812,51808526)。
文摘For aqueous interfacial reactions involving H+and OH-, the interfacial pH varies dynamically during the reaction process, which is a key factor determining the reaction performance. Herein, the kinetic relevance between the interfacial pH and reaction rate is deciphered owing to the success in establishing the transport equations of H+/OH- in unbuffered solutions, and is charted as a current(j)–pH diagram in the form of an electrochemical response. The as-described j–pH interplay is experimentally verified by the oxygen reduction and hydrogen evolution reactions. This diagram serves to form a panoramic graphic view of pH function working on the interfacial reactions in conjunction with the Pourbaix’s potential–pH diagram, and particularly enables a kinetic understanding of the transport effect of H+and OH-on the reaction rate and valuable instruction toward associated pH control and buffering manipulation.
基金Project(JKY2019-10) supported by the State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization,ChinaProject(51804029) supported by the National Natural Science Foundation of China。
基金Project (2007CB613504) supported by the National Basic Research Program of ChinaProject(20050145029) supported by the PhD Programs Foundation of Ministry of Education of ChinaProject(2005221012) supported by the Science and Technology Talents Fund for Excellent Youth of Liaoning Province, China
文摘The values of GΘ,EΘ or pH from 110 to 160℃ were calculated and the relevant potential expressions were obtained.E-pH diagrams of ZnS-H2O system at oxygen partial pressure of 0.8 MPa,ionic activity of 1.0 and different temperatures were drawn through thermodynamical calculation.With the temperature increasing,the stable regions of S and Zn(Ⅱ) in the E-pH diagrams become gradually larger,but the amplification decreases over 150℃.The impacts of leaching parameters,such as temperature,liquid to solid ratio,initial acidic concentration,leaching time,oxygen partial pressure and stirring speed on the leaching rate of Zn(Ⅱ) and conversion rate of S in the single factor of high pressure leaching experiment of ZnS in autoclave,were studied.The leaching residue was examined by X-ray fluorescence(XRF) chemical composition identification and X-ray diffraction(XRD) phase identification,and the content of the leaching solution was tested by inductively coupled plasma-atomic emission spectrometry(ICP).The experimental results indicate that the leaching rate of zinc increases from 60.05% to 97.85% and the conversion rate of sulfur increases from 38.90% to 80.92% with the temperature increasing from 110℃ to 150℃,5:1 of liquid-to-solid ratio,150 g/L of initial acidic concentration,120 min of leaching time,0.8 MPa of oxygen partial pressure,and 480 r/min of stirring speed,which tend to be stable over 150℃.The experimental results correspond with theoretical calculation.
文摘Phosphorus is an important element for larch (\%Larix gmelinii\% Rupr.)root development.P-availability in rhizosphere is close with root exudates or excretions,e.g.,organic acid exudation,proton excretion.These materials from roots will affect pH value of rhizosphere.The aim of this paper were to study on pH changes at different P-stress conditions,and to test on the relation between available P and pH in rhizosphere.This work was carried out under pot experiment and field soil smaple analysis.Larch seedlings,1 and 2-year-old,were planted into sand pots.Nutrient solution with different P contents (0,0.035,0.071 and 0.142g·L -1 respectively) were supplied everyday.There were 2 replicates for 1-year-old seedlings,5 replicates for 2-year-old seedlings at ecch P-level treatment.After 1-year-old seedlings growing for 40 days and 2-year-old seedlings growing for 90 days,seedlings were taken out and used to visualize acidification by means of an agar plate technique.The result showed that pH of rhizosphere decreased from 6.40 to 4.73～4.84 in 1-year-old seedlings and to 5.30～5.50 in 2-year-old after 36h incubation.Average pH decreased were 1.56～1.67 for 1-year-old seedlings,and 0.90～1.10 for 2-year-old seedlings.There was not significant,for pH variations in rhizosphere,among four kind treatments.The pH change was not affected by P-level.The result of soil sample analysis,from 12-year-old,21-year-old,and 40-year-old pure larch stands respectively,indicated that the pH changes in rhizosphere is 0.11,0.04,and 0.09,respectively,lower than that in the non-rhizosphere,acidification is not significant,While the available P in the rhizosphere is 18.1%,86.5% and 23.4%,higher than that in the non-rhizosphere in three stands.The correlation between pH variations and available P was not remarkable at this analysis.This means that there was no relationship between the available P and pH change of rhizosphere in larch root system.
