Corrosion potential measurement,electrochemical impedance spectroscopy(EIS) and scanning electronic microscopy(SEM) were employed to study the inhibition of hexamethylenetetramine(HA) on corrosion of AZ31 magnesium al...Corrosion potential measurement,electrochemical impedance spectroscopy(EIS) and scanning electronic microscopy(SEM) were employed to study the inhibition of hexamethylenetetramine(HA) on corrosion of AZ31 magnesium alloy in simulated coolant.HA exhibits good inhibition after the inducement period through strong adsorption on AZ31 magnesium alloy surface.The addition of HA improves the corrosion resistance of the alloy and affects the corrosion potential little.HA is a mixed-type inhibitor that inhibits both anodic and cathodic reactions of AZ31 magnesium alloy in simulated coolant.展开更多
Aluminum,the main impurity in the lixivium of weathered crust elution deposited rare earth ore,not only results in an increasing consumption of precipitant in the rare earth precipitation process,but also lowers the p...Aluminum,the main impurity in the lixivium of weathered crust elution deposited rare earth ore,not only results in an increasing consumption of precipitant in the rare earth precipitation process,but also lowers the purity of final rare earth product.Aluminum in the weathered crust elution-deposited rare earth ore lixivium should be removed.Neutralizing hydrolysis method was employed to remove aluminum from the lixivium.Hexamethylenetetramine was found to be the optimum pH regulator for the removal of aluminum in the low concentration.When used to adjust the pH value of the lixivium to 5.0,aluminum in the lixivium can be effectively removed in the form of aluminum hydroxide precipitation with removal rate of 97.60%.It shows that hexamethylenetetramine has a good effect on the removing of aluminum ions from the lowconcentration lixivium.Moreover,hexamethylenetetramine in removing aluminum from lixivium has little adverse effect on the RE precipitation process.展开更多
Self-assembled complexes between cage com-pounds cucurbit[n = 5—8]urils and hexamethylenetetramine were studied by using NMR techniques. Experimental results reveal that hexamethylenetetramine can lid cucurbit[5]uril...Self-assembled complexes between cage com-pounds cucurbit[n = 5—8]urils and hexamethylenetetramine were studied by using NMR techniques. Experimental results reveal that hexamethylenetetramine can lid cucurbit[5]uril to forming self-assembled capsules in which nothing is encap-sulated yet; the cavity of the cucurbit[7]uril can accommo-date a hexamethylenetetramine molecule to form a self- assembled host-guest inclusion. Moreover, both the cavity interaction of the cucurbit[7]uril with hexamethylenetetra-mine稨Cl and the portal interaction of the dipole carbonyl of the cucurbit[7]uril with hexamethylenetetramine稨Cl lead to form self-assembled capsules in which the hexamethylene-tetramine稨Cl are encapsulated in the hexamethylenetetra-mine稨Cl lidded cucurbit[7]uril. Although the structures of the portal and cavity to cucurbit[5]uril are similar, there is no obvious interaction between decamethylcucurbit[5]uril and hexamethylenetetramine, and also between cucurbit [6]uril or cucurbit[8]uril and hexamethylenetetramine.展开更多
In this experiment, Cu<sup>2+</sup> doped ZnO (Cu-ZnO) nanorods materials have been fabricated by hydrothermal method. Cu<sup>2+</sup> ions were doped into ZnO with ratios of 2, 5 and 7 mol.% (...In this experiment, Cu<sup>2+</sup> doped ZnO (Cu-ZnO) nanorods materials have been fabricated by hydrothermal method. Cu<sup>2+</sup> ions were doped into ZnO with ratios of 2, 5 and 7 mol.% (compared to the mole’s number of Zn<sup>2+</sup>). The hexamethylenetetramine (HMTA) solvent used for the fabrication of Cu-ZnO nanorods with the mole ratio of Zn<sup>2+</sup>:HMTA = 1:4. The characteristics of the materials were analyzed by techniques, such as XRD, Raman shift, SEM and UV-vis diffuse reflectance spectra (DRS). The photocatalytic properties of the materials were investigated by the decomposition of the methylene blue (MB) dye solution under ultraviolet light. The results show that the size of Cu-ZnO nanorods was reduced when the Cu<sup>2+</sup> doping ratio increased from 2 mol.% to 7 mol.%. The decomposition efficiency of the MB dye solution reached 92% - 97%, corresponding to the Cu<sup>2+</sup> doping ratio changed from 2 - 7 mol.% (after 40 minutes of ultraviolet irradiation). The highest efficiency for the decomposition of the MB solution was obtained at a Cu<sup>2+</sup> doping ratio of 2 mol.%.展开更多
The structures of the complexes generated by hexamethylenetetramine and nitric acid have been fully optimized by B3LYP method at the 6-311＋＋G＊＊ and aug-cc-pVTZ levels. The intermolecular hydrogen-bonding interacti...The structures of the complexes generated by hexamethylenetetramine and nitric acid have been fully optimized by B3LYP method at the 6-311＋＋G＊＊ and aug-cc-pVTZ levels. The intermolecular hydrogen-bonding interactions have been calculated by the B3LYP/6-311＋＋G＊＊, B3LYP/aug-cc-pVTZ, MP2（full）/6-311＋＋G＊＊ and CCSD（T）/6-311＋＋G＊＊ methods, respectively. The NBO （nature bond orbital）, AIM （atom in molecule）, temperature effect and solvation effect have been analyzed to reveal the origin of the interactions. The results indicate that the stable hydrogen-bonded complexes could be generated by hexamethylenetetramine and nitric acid. The interactions follow the order of （a）（e）（b）（c）（d）（f）（g）. The C–N bonds which are adjacent to the methylene involving the hydrogen bonds tend to break in the chemical reaction. Due to the exothermic process, low temperature is conducive to the formation of the composition, which tallies with the experimental result.展开更多
文摘Corrosion potential measurement,electrochemical impedance spectroscopy(EIS) and scanning electronic microscopy(SEM) were employed to study the inhibition of hexamethylenetetramine(HA) on corrosion of AZ31 magnesium alloy in simulated coolant.HA exhibits good inhibition after the inducement period through strong adsorption on AZ31 magnesium alloy surface.The addition of HA improves the corrosion resistance of the alloy and affects the corrosion potential little.HA is a mixed-type inhibitor that inhibits both anodic and cathodic reactions of AZ31 magnesium alloy in simulated coolant.
基金financially supported by the National Natural Science Foundation of China(No.51404112)theNational Key Technology R&D Program(No.2012BAC11B07)+3 种基金the Technology Program for Benefitting the People(No.2013GS360203)the Program for Talents Training of“Gan Po Excellence 555 Project”the Program for New Century Excellent Talents in University(No.NCET-10-0183)the Program for Main Subject,Technology Leaders of Jiangxi Province(No.2010DD01200)
文摘Aluminum,the main impurity in the lixivium of weathered crust elution deposited rare earth ore,not only results in an increasing consumption of precipitant in the rare earth precipitation process,but also lowers the purity of final rare earth product.Aluminum in the weathered crust elution-deposited rare earth ore lixivium should be removed.Neutralizing hydrolysis method was employed to remove aluminum from the lixivium.Hexamethylenetetramine was found to be the optimum pH regulator for the removal of aluminum in the low concentration.When used to adjust the pH value of the lixivium to 5.0,aluminum in the lixivium can be effectively removed in the form of aluminum hydroxide precipitation with removal rate of 97.60%.It shows that hexamethylenetetramine has a good effect on the removing of aluminum ions from the lowconcentration lixivium.Moreover,hexamethylenetetramine in removing aluminum from lixivium has little adverse effect on the RE precipitation process.
基金supported by the Natural Science Foundation of Guizhou Province(Grant No.20013025)the Key Project of the Natural Science Foundation of Guizhou Province(Grant No.20023004)+1 种基金the International Collaborative Project of Guizhou Province(Grant No.200211003)and the National Natural Science Foundation of China(Grant No.20261002)
文摘Self-assembled complexes between cage com-pounds cucurbit[n = 5—8]urils and hexamethylenetetramine were studied by using NMR techniques. Experimental results reveal that hexamethylenetetramine can lid cucurbit[5]uril to forming self-assembled capsules in which nothing is encap-sulated yet; the cavity of the cucurbit[7]uril can accommo-date a hexamethylenetetramine molecule to form a self- assembled host-guest inclusion. Moreover, both the cavity interaction of the cucurbit[7]uril with hexamethylenetetra-mine稨Cl and the portal interaction of the dipole carbonyl of the cucurbit[7]uril with hexamethylenetetramine稨Cl lead to form self-assembled capsules in which the hexamethylene-tetramine稨Cl are encapsulated in the hexamethylenetetra-mine稨Cl lidded cucurbit[7]uril. Although the structures of the portal and cavity to cucurbit[5]uril are similar, there is no obvious interaction between decamethylcucurbit[5]uril and hexamethylenetetramine, and also between cucurbit [6]uril or cucurbit[8]uril and hexamethylenetetramine.
文摘In this experiment, Cu<sup>2+</sup> doped ZnO (Cu-ZnO) nanorods materials have been fabricated by hydrothermal method. Cu<sup>2+</sup> ions were doped into ZnO with ratios of 2, 5 and 7 mol.% (compared to the mole’s number of Zn<sup>2+</sup>). The hexamethylenetetramine (HMTA) solvent used for the fabrication of Cu-ZnO nanorods with the mole ratio of Zn<sup>2+</sup>:HMTA = 1:4. The characteristics of the materials were analyzed by techniques, such as XRD, Raman shift, SEM and UV-vis diffuse reflectance spectra (DRS). The photocatalytic properties of the materials were investigated by the decomposition of the methylene blue (MB) dye solution under ultraviolet light. The results show that the size of Cu-ZnO nanorods was reduced when the Cu<sup>2+</sup> doping ratio increased from 2 mol.% to 7 mol.%. The decomposition efficiency of the MB dye solution reached 92% - 97%, corresponding to the Cu<sup>2+</sup> doping ratio changed from 2 - 7 mol.% (after 40 minutes of ultraviolet irradiation). The highest efficiency for the decomposition of the MB solution was obtained at a Cu<sup>2+</sup> doping ratio of 2 mol.%.
基金supported from the Natural Science Foundation of Shanxi Province(2009011014)
文摘The structures of the complexes generated by hexamethylenetetramine and nitric acid have been fully optimized by B3LYP method at the 6-311＋＋G＊＊ and aug-cc-pVTZ levels. The intermolecular hydrogen-bonding interactions have been calculated by the B3LYP/6-311＋＋G＊＊, B3LYP/aug-cc-pVTZ, MP2（full）/6-311＋＋G＊＊ and CCSD（T）/6-311＋＋G＊＊ methods, respectively. The NBO （nature bond orbital）, AIM （atom in molecule）, temperature effect and solvation effect have been analyzed to reveal the origin of the interactions. The results indicate that the stable hydrogen-bonded complexes could be generated by hexamethylenetetramine and nitric acid. The interactions follow the order of （a）（e）（b）（c）（d）（f）（g）. The C–N bonds which are adjacent to the methylene involving the hydrogen bonds tend to break in the chemical reaction. Due to the exothermic process, low temperature is conducive to the formation of the composition, which tallies with the experimental result.
