Calcium molybdate(CaMoO4)is the main component of powellite and is a predominant intermediate in the pyrometallurgical and hydrometallurgical process of molybdenum.The extraction of Mo from CaMoO4 by a combination of ...Calcium molybdate(CaMoO4)is the main component of powellite and is a predominant intermediate in the pyrometallurgical and hydrometallurgical process of molybdenum.The extraction of Mo from CaMoO4 by a combination of phosphoric acid and hydrochloric acid was investigated.For further understanding of the leaching mechanism,the effects of five key factors were studied to describe the leaching kinetics.The results indicated that the dissolution rate of CaMoO4 was independent of the stirring speed.Mo extraction significantly increased with increasing HCl concentration and temperature,but decreased with increasing particle size.A shrinking core model with surface chemical reaction was found to withstand the dissolution of CaMoO4.The apparent activation energy was calculated to be 70.879 kJ/mol,and a semi-empirical equation was derived for the rate of reaction.展开更多
This study was conducted to comprehensively evaluate the effects of salicylic acid and sodium molybdate on cold tolerance of an ornamental plant Bougainvillea glabra and to provide a theoretical guidance for landscape...This study was conducted to comprehensively evaluate the effects of salicylic acid and sodium molybdate on cold tolerance of an ornamental plant Bougainvillea glabra and to provide a theoretical guidance for landscape maintenance.B.glabra plants were treated with 0.5 mmol/L salicylic acid and 2.0 μmol/L alone or in combination,and then exposed to low temperature stress before physiological indices were measured.The results showed that all salicylic acid and sodium molybdate treatments reduced the relative conductivity and malondialdehyde( MDA) content of B.glabra to varying extents under the stress of low temperature,and more significant effect was achieved by using the two agents in combination.Oxygen free radicals production rate increased with decreasing temperature from 20 to 6 ℃,but declined with temperature decreasing from 3 to-3 ℃.The SOD activity of the control( CK) was significantly lower than that of other treatments at 0 and-3 ℃.The treatments with salicylic acid and sodium molybdate alone and in combination increased POD activity of B.glabra plants,especially at 0 ℃,as the POD activity of treatments T1,T2 and T3 was significantly higher than that of CK at 0 ℃.In addition,under low temperature stress,the contents of soluble sugar,starch and proline increased initially and decreased subsequently with temperature decreasing.The soluble sugar content at 3 ℃,starch and proline contents at 0 and-3 ℃ in treatments with salicylic acid and sodium molybdate alone and in combination were significantly higher than those of CK.All above results proved that salicylic acid and sodium molybdate are able to improve cold tolerance of B.glabra,and better effect can be achieved by using them together.展开更多
Ammonium tetramolybdate ( NH4 )4[(MoO2)4O3 (R-mal)2]·6H2O(mal= malic acid)and (NH4)4[(MoO2)4O3(S-mal)2)·6H2O have been prepared by the reaction of R and S-malic acid with ammonium heptamolybdate, respectivel...Ammonium tetramolybdate ( NH4 )4[(MoO2)4O3 (R-mal)2]·6H2O(mal= malic acid)and (NH4)4[(MoO2)4O3(S-mal)2)·6H2O have been prepared by the reaction of R and S-malic acid with ammonium heptamolybdate, respectively. The two complexes are enantiomeric and isomorphous. The complex of Risomer crystallizes in monoclinic space group C2 with unit cell parameters:a = 14. 591 (2 ), b = 10. 108(2), c=11. 464(2), β=121. 48(1)°, V=1441. 9(4),Z=2, Fω=1002. 13, Dc=2. 308, Dm=2. 3 g/cm3. F(000) = 988, MoKα radiation (λ=0. 71073 ), μ (MoKα) = 17. 7 cm-1. Final R=0. 027 for 1491 reflections with I>2. 5 σ(I). Analysis of molecular structure reveals that the complex anion contains a (Mo2O5)O(Mo2O5)core with the bridging oxo-group passing through two-fold axis. Each molybdenum is hexacoordinated , and the malate ligand is quadridentated to two molybdenum atoms by the deprotonated hydroxy-, α- and β-carboxylate groups. Principal dimensions are:[Mo=O(t)]av, 1. 705(6); [Mo-O(b)]av, 1. 920(6); Mo-O(hydroxy). 1. 925(6);Mo-O(α-carboxy), 2. 226 (6), and [Mo-O(β-carboxy)av, 2. 296 (5).Lattice water is distributed throughout the cell and together with various types of the anion oxygens, making H-bonding.展开更多
基金Project(2017M610766)supported by China Postdoctoral Science FoundationProject(FRF-BD-17-010A)supported by the Fundamental Research Funds for the Central Universities,China
文摘Calcium molybdate(CaMoO4)is the main component of powellite and is a predominant intermediate in the pyrometallurgical and hydrometallurgical process of molybdenum.The extraction of Mo from CaMoO4 by a combination of phosphoric acid and hydrochloric acid was investigated.For further understanding of the leaching mechanism,the effects of five key factors were studied to describe the leaching kinetics.The results indicated that the dissolution rate of CaMoO4 was independent of the stirring speed.Mo extraction significantly increased with increasing HCl concentration and temperature,but decreased with increasing particle size.A shrinking core model with surface chemical reaction was found to withstand the dissolution of CaMoO4.The apparent activation energy was calculated to be 70.879 kJ/mol,and a semi-empirical equation was derived for the rate of reaction.
基金Supported by Applied Basic Research Project of Yunnan Province(2017FD087)National Natural Science Foundation of China(31660559)
文摘This study was conducted to comprehensively evaluate the effects of salicylic acid and sodium molybdate on cold tolerance of an ornamental plant Bougainvillea glabra and to provide a theoretical guidance for landscape maintenance.B.glabra plants were treated with 0.5 mmol/L salicylic acid and 2.0 μmol/L alone or in combination,and then exposed to low temperature stress before physiological indices were measured.The results showed that all salicylic acid and sodium molybdate treatments reduced the relative conductivity and malondialdehyde( MDA) content of B.glabra to varying extents under the stress of low temperature,and more significant effect was achieved by using the two agents in combination.Oxygen free radicals production rate increased with decreasing temperature from 20 to 6 ℃,but declined with temperature decreasing from 3 to-3 ℃.The SOD activity of the control( CK) was significantly lower than that of other treatments at 0 and-3 ℃.The treatments with salicylic acid and sodium molybdate alone and in combination increased POD activity of B.glabra plants,especially at 0 ℃,as the POD activity of treatments T1,T2 and T3 was significantly higher than that of CK at 0 ℃.In addition,under low temperature stress,the contents of soluble sugar,starch and proline increased initially and decreased subsequently with temperature decreasing.The soluble sugar content at 3 ℃,starch and proline contents at 0 and-3 ℃ in treatments with salicylic acid and sodium molybdate alone and in combination were significantly higher than those of CK.All above results proved that salicylic acid and sodium molybdate are able to improve cold tolerance of B.glabra,and better effect can be achieved by using them together.
文摘Ammonium tetramolybdate ( NH4 )4[(MoO2)4O3 (R-mal)2]·6H2O(mal= malic acid)and (NH4)4[(MoO2)4O3(S-mal)2)·6H2O have been prepared by the reaction of R and S-malic acid with ammonium heptamolybdate, respectively. The two complexes are enantiomeric and isomorphous. The complex of Risomer crystallizes in monoclinic space group C2 with unit cell parameters:a = 14. 591 (2 ), b = 10. 108(2), c=11. 464(2), β=121. 48(1)°, V=1441. 9(4),Z=2, Fω=1002. 13, Dc=2. 308, Dm=2. 3 g/cm3. F(000) = 988, MoKα radiation (λ=0. 71073 ), μ (MoKα) = 17. 7 cm-1. Final R=0. 027 for 1491 reflections with I>2. 5 σ(I). Analysis of molecular structure reveals that the complex anion contains a (Mo2O5)O(Mo2O5)core with the bridging oxo-group passing through two-fold axis. Each molybdenum is hexacoordinated , and the malate ligand is quadridentated to two molybdenum atoms by the deprotonated hydroxy-, α- and β-carboxylate groups. Principal dimensions are:[Mo=O(t)]av, 1. 705(6); [Mo-O(b)]av, 1. 920(6); Mo-O(hydroxy). 1. 925(6);Mo-O(α-carboxy), 2. 226 (6), and [Mo-O(β-carboxy)av, 2. 296 (5).Lattice water is distributed throughout the cell and together with various types of the anion oxygens, making H-bonding.
