In this study,the effects of low temperature on aluminum(Ⅲ)(Al)hydrolysis were examined both theoretically and experimentally by constructing a solubility diagram for amorphous aluminum hydroxide(Al(OH)_3(am))and a d...In this study,the effects of low temperature on aluminum(Ⅲ)(Al)hydrolysis were examined both theoretically and experimentally by constructing a solubility diagram for amorphous aluminum hydroxide(Al(OH)_3(am))and a distribution diagram of hydrolyzed Al species.First,thermodynamic data of Al species at 4℃were calculated from that at 25℃.A well confirmed polymeric Al species, AlO_4Al_(12)(OH)_(24)^(7+)(Al_(13)),was involved in building the diagrams and,correspondingly,the non-linear simultaneous equations wit...展开更多
A method was developed for preparing high purity Al30O8(OH)56(H2O)_(24)^(18)+(Al30) through elimination of impurities by complexation.Polyaluminum chloride II(PAC_(30))with Al_(c )content of 75%was adopted as the sour...A method was developed for preparing high purity Al30O8(OH)56(H2O)_(24)^(18)+(Al30) through elimination of impurities by complexation.Polyaluminum chloride II(PAC_(30))with Al_(c )content of 75%was adopted as the source of Al_(30).The PAC_(30)was prepared under conditions of total aluminum concentration 0.1 mol/L and OH^-/Al ratio 2.2 to obtain the highest content of Al_(30).A precipitation/metathesis method,organic solvent precipitation method and organic complexation method were examined to separate and purify Al_(30).It was found that only by the organic complexation method could high purity Al_(30)products be obtained in large yield economically.In the experiments,benzoic acid was used as the coordinating reagent to decompose the main impurity AlO_4Al_(12)(OH)_(24)(H_2O)_(12)^(7+)(Al_(13)),and the Al_(30)product could be obtained by precipitation and metathesis operations.It was noteworthy that the decomposition of impurities by benzoic acid could be completed in 2 hr.The Al_(30)product was characterized by Ferron assay,^(27)Al-NMR,SEM,XRD and TGA.The results showed that the purity of the Al_(30)product could exceed 92%.展开更多
Decomposition of the polycation Al_(13)O_(4)(OH)_(2)4(H_(2)O)_(12)^(7+)(Al_(13)) promoted by ligand is a vital subject to advance our understanding of natural and artificial occurrence and evolution of aluminum ions,e...Decomposition of the polycation Al_(13)O_(4)(OH)_(2)4(H_(2)O)_(12)^(7+)(Al_(13)) promoted by ligand is a vital subject to advance our understanding of natural and artificial occurrence and evolution of aluminum ions,especially in the case of acidic condition that dissolved Al^(3+)species can be released from the Al-bearing substances.However,the microscopic pathway of synchronous proton-promoted and ligand-promoted decomposition process for Al_(13)is still in the status of ambiguity.Herein,we applied differential mass spectrometry method and DFT calculation to study the initial detailed process of Al_(13)decomposition under the presence of proton and salicylic acid (H_(2)Sal).Mass results showed that the mononuclear Al^(3+)-H_(2)Sal complexes dominated the resulting Al species,whereas the monodentate complex Al_(13)HSal6+was not observed in the spectra.The difference of decomposition levels between the ligand/Al ratio 0.2 and 0.5 cases revealed that proton and ligand performed synergistic effect in initial Al_(13)decomposition process,and the proton transfer determined the ring closure efficiency.The ring closure reaction is the prerequisite for the collapse of Al_(13)structure and detachment of the mononuclear complex.DFT calculations reveal that hydrogen bond plays an important role in inducing the formation of chelated complex accompanying proton transfer.Attachment of protons at the bridging OH^(-)can elongate and weaken the critical bond between targeted Al^(3+)and μ4-O_(2)-resulting from delocalization of electron pairs in the oxygen atom.These results demonstrate the detailed mechanism of Al_(13)composition promoted by ligand and proton,and provide significant understanding for further application and control of Al_(13).展开更多
Edge-to-edge matching(E2EM)model was used to predict the potency of LaB_(6) as the heterogeneous nucleation substrate for primary Al_(13)Mn_(4)Si_(8) phase formed during the solidification of Al−Si−Cu−Mn heat-resistan...Edge-to-edge matching(E2EM)model was used to predict the potency of LaB_(6) as the heterogeneous nucleation substrate for primary Al_(13)Mn_(4)Si_(8) phase formed during the solidification of Al−Si−Cu−Mn heat-resistant alloy.There are five pairs of orientation relationships(ORs)between LaB_(6) and Al_(13)Mn_(4)Si_(8) phases which meet the criteria of E2EM model.One pair of plane ORs((110)LaB_(6)//(110)Al_(13)Mn_(4)Si_(8))are demonstrated by TEM observation.This strongly indicates that the LaB_(6) phase can act as the heterogeneous nucleation substrate for the primary Al_(13)Mn_(4)Si_(8) phase.1.0 wt.%of Al−2La−1B master alloy was also added into Al−12Si−4Cu−2Mn alloy to evaluate the refining effect by microstructure observation and tensile test.Experimental results show that addition of Al−2La−1B master alloy can significantly refine the primary Al_(13)Mn_(4)Si_(8) phase,supporting the prediction accuracy of E2EM model.However,such refinement of primary Al_(13)Mn_(4)Si_(8) phase does not lead to an improvement in strength.This is due to the larger difference in elastic modulus between the finally formed Al_(13)Mn_(4)Si_(8) phase and aluminum matrix than that of Al_(15)Mn_(3)Si_(2) phase.展开更多
A polyaluminum chloride (PAC) sample was prepared using a slow alkalinetitration method. The Bio-Gel P-100 gel column chromatographic technique was used to separate andcharacterize the various forms of aluminum presen...A polyaluminum chloride (PAC) sample was prepared using a slow alkalinetitration method. The Bio-Gel P-100 gel column chromatographic technique was used to separate andcharacterize the various forms of aluminum present in the prepared PAC solution. The effluents froma gel column were monitored using online chemical method: AI-Ferron timed complexationspectropho-tometry and by ^(27)Al nuclear magnetic resonance (NMR) spectroscopy. Effects ofdifferent experimental conditions such as eluent flow rate, ionic strength and pH on separation ofAl_(13) were investigated. Experimental results indicated that molecule size exclusion was not theonly parameter affecting the column chromatographic separation efficiency of Al_(13) but moleculecharge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pHresulted in increase in the separation efficiency. Experimental results clearly indicated that byvarying the experimental conditions, it is possible to produce pure Al_(13) species using a gelcolumn chromatographic technique.展开更多
In order to investigate the characteristics of pure Nano-Al_(13) ,Nano-Al_(13) was separated and purified from a series of poly-aluminum chloride(PAC)solutions which had the same Al_(13) percentage but different total...In order to investigate the characteristics of pure Nano-Al_(13) ,Nano-Al_(13) was separated and purified from a series of poly-aluminum chloride(PAC)solutions which had the same Al_(13) percentage but different total Al concentrations,by using column chromatography,ethanol-acetone resolving and SO_(4)^(2−)/Ba^(2+)displacement.The Al_(13) species yield was characterized by Al-ferron timed complexation spectropho-tometry and 27Al-NMR(nuclear magnetic resonance).The coagulation efficiency of Nano-Al_(13) ,PAC and AlCl_(3) in synthetic water was also investigated by Jar tests.The dynamic process and aggregation state of kaolin suspensions coagulating with Nano-Al_(13) ,PAC and AlC_(13) were similarly investigated using a photometric dispersion analyzer 2000(PDA2000).The experimental results indicated that the ethanol-acetone resolving method was simple and could separate the PAC solution at different concentrations,while column chromatography could separate PAC solutions at low concentrations.The SO_(4)^(2−)/Ba^(2+)displacement method could separate PAC solutions at high concentrations.However,extra inorganic cation and anion could be added in the solution during separation.The coagulation efficiency and dynamic experimental results showed that Nano-Al_(13) with high positive-charged species was effective in removing turbidity and color.The dynamic process results showed that Nano-Al_(13) also had the best recovery capability after shearing compared with PAC and AlCl3 because the Nano-Al_(13) conformation is more effective in charge neutralization.展开更多
文摘In this study,the effects of low temperature on aluminum(Ⅲ)(Al)hydrolysis were examined both theoretically and experimentally by constructing a solubility diagram for amorphous aluminum hydroxide(Al(OH)_3(am))and a distribution diagram of hydrolyzed Al species.First,thermodynamic data of Al species at 4℃were calculated from that at 25℃.A well confirmed polymeric Al species, AlO_4Al_(12)(OH)_(24)^(7+)(Al_(13)),was involved in building the diagrams and,correspondingly,the non-linear simultaneous equations wit...
基金supported by the National Natural Science Foundation of China (Nos. 21507149, 51338010)the National Water Pollution Control and Treatment Science and Technology Major Project (No. 2015ZX07406005-002)
文摘A method was developed for preparing high purity Al30O8(OH)56(H2O)_(24)^(18)+(Al30) through elimination of impurities by complexation.Polyaluminum chloride II(PAC_(30))with Al_(c )content of 75%was adopted as the source of Al_(30).The PAC_(30)was prepared under conditions of total aluminum concentration 0.1 mol/L and OH^-/Al ratio 2.2 to obtain the highest content of Al_(30).A precipitation/metathesis method,organic solvent precipitation method and organic complexation method were examined to separate and purify Al_(30).It was found that only by the organic complexation method could high purity Al_(30)products be obtained in large yield economically.In the experiments,benzoic acid was used as the coordinating reagent to decompose the main impurity AlO_4Al_(12)(OH)_(24)(H_2O)_(12)^(7+)(Al_(13)),and the Al_(30)product could be obtained by precipitation and metathesis operations.It was noteworthy that the decomposition of impurities by benzoic acid could be completed in 2 hr.The Al_(30)product was characterized by Ferron assay,^(27)Al-NMR,SEM,XRD and TGA.The results showed that the purity of the Al_(30)product could exceed 92%.
基金financially supported by the National Natural Science Foundation of China (Nos.52030003 and 51778604)。
文摘Decomposition of the polycation Al_(13)O_(4)(OH)_(2)4(H_(2)O)_(12)^(7+)(Al_(13)) promoted by ligand is a vital subject to advance our understanding of natural and artificial occurrence and evolution of aluminum ions,especially in the case of acidic condition that dissolved Al^(3+)species can be released from the Al-bearing substances.However,the microscopic pathway of synchronous proton-promoted and ligand-promoted decomposition process for Al_(13)is still in the status of ambiguity.Herein,we applied differential mass spectrometry method and DFT calculation to study the initial detailed process of Al_(13)decomposition under the presence of proton and salicylic acid (H_(2)Sal).Mass results showed that the mononuclear Al^(3+)-H_(2)Sal complexes dominated the resulting Al species,whereas the monodentate complex Al_(13)HSal6+was not observed in the spectra.The difference of decomposition levels between the ligand/Al ratio 0.2 and 0.5 cases revealed that proton and ligand performed synergistic effect in initial Al_(13)decomposition process,and the proton transfer determined the ring closure efficiency.The ring closure reaction is the prerequisite for the collapse of Al_(13)structure and detachment of the mononuclear complex.DFT calculations reveal that hydrogen bond plays an important role in inducing the formation of chelated complex accompanying proton transfer.Attachment of protons at the bridging OH^(-)can elongate and weaken the critical bond between targeted Al^(3+)and μ4-O_(2)-resulting from delocalization of electron pairs in the oxygen atom.These results demonstrate the detailed mechanism of Al_(13)composition promoted by ligand and proton,and provide significant understanding for further application and control of Al_(13).
基金supported by Jiangsu Key Laboratory Metallic Materials, China (No. BM2007204)the Fundamental Research Funds for the Central Universities, China (No. 2242016k40011)。
文摘Edge-to-edge matching(E2EM)model was used to predict the potency of LaB_(6) as the heterogeneous nucleation substrate for primary Al_(13)Mn_(4)Si_(8) phase formed during the solidification of Al−Si−Cu−Mn heat-resistant alloy.There are five pairs of orientation relationships(ORs)between LaB_(6) and Al_(13)Mn_(4)Si_(8) phases which meet the criteria of E2EM model.One pair of plane ORs((110)LaB_(6)//(110)Al_(13)Mn_(4)Si_(8))are demonstrated by TEM observation.This strongly indicates that the LaB_(6) phase can act as the heterogeneous nucleation substrate for the primary Al_(13)Mn_(4)Si_(8) phase.1.0 wt.%of Al−2La−1B master alloy was also added into Al−12Si−4Cu−2Mn alloy to evaluate the refining effect by microstructure observation and tensile test.Experimental results show that addition of Al−2La−1B master alloy can significantly refine the primary Al_(13)Mn_(4)Si_(8) phase,supporting the prediction accuracy of E2EM model.However,such refinement of primary Al_(13)Mn_(4)Si_(8) phase does not lead to an improvement in strength.This is due to the larger difference in elastic modulus between the finally formed Al_(13)Mn_(4)Si_(8) phase and aluminum matrix than that of Al_(15)Mn_(3)Si_(2) phase.
基金This work was supported by the subproject of '863' Project of China (Grant No. 2002AA601290-5) the Natural Science Foundation of Shandong Province(Grant No. Y2002B03).
文摘A polyaluminum chloride (PAC) sample was prepared using a slow alkalinetitration method. The Bio-Gel P-100 gel column chromatographic technique was used to separate andcharacterize the various forms of aluminum present in the prepared PAC solution. The effluents froma gel column were monitored using online chemical method: AI-Ferron timed complexationspectropho-tometry and by ^(27)Al nuclear magnetic resonance (NMR) spectroscopy. Effects ofdifferent experimental conditions such as eluent flow rate, ionic strength and pH on separation ofAl_(13) were investigated. Experimental results indicated that molecule size exclusion was not theonly parameter affecting the column chromatographic separation efficiency of Al_(13) but moleculecharge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pHresulted in increase in the separation efficiency. Experimental results clearly indicated that byvarying the experimental conditions, it is possible to produce pure Al_(13) species using a gelcolumn chromatographic technique.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50678095).
文摘In order to investigate the characteristics of pure Nano-Al_(13) ,Nano-Al_(13) was separated and purified from a series of poly-aluminum chloride(PAC)solutions which had the same Al_(13) percentage but different total Al concentrations,by using column chromatography,ethanol-acetone resolving and SO_(4)^(2−)/Ba^(2+)displacement.The Al_(13) species yield was characterized by Al-ferron timed complexation spectropho-tometry and 27Al-NMR(nuclear magnetic resonance).The coagulation efficiency of Nano-Al_(13) ,PAC and AlCl_(3) in synthetic water was also investigated by Jar tests.The dynamic process and aggregation state of kaolin suspensions coagulating with Nano-Al_(13) ,PAC and AlC_(13) were similarly investigated using a photometric dispersion analyzer 2000(PDA2000).The experimental results indicated that the ethanol-acetone resolving method was simple and could separate the PAC solution at different concentrations,while column chromatography could separate PAC solutions at low concentrations.The SO_(4)^(2−)/Ba^(2+)displacement method could separate PAC solutions at high concentrations.However,extra inorganic cation and anion could be added in the solution during separation.The coagulation efficiency and dynamic experimental results showed that Nano-Al_(13) with high positive-charged species was effective in removing turbidity and color.The dynamic process results showed that Nano-Al_(13) also had the best recovery capability after shearing compared with PAC and AlCl3 because the Nano-Al_(13) conformation is more effective in charge neutralization.
