Phenol in waste water threatens human health and is difficultly to be decomposed by nature.Efficient degradation of high-loaded phenol in water under mild condition is still a great challenge.Herein,ionic liquids with...Phenol in waste water threatens human health and is difficultly to be decomposed by nature.Efficient degradation of high-loaded phenol in water under mild condition is still a great challenge.Herein,ionic liquids with tungstate anion were designed and prepared.It was found that dodecyltrimethylammonium tungstate could catalyzed degradation of phenol into gases and water thoroughly at 323 k in 8 h.Tungstate anion revealed good catalytic oxidative activity and long carbon chain group connecting with cation of ionic liquids enriched phenol around catalysts,which induced the complete degradation of phenol at mild conditions.Increasing the amounts of hydrogen peroxide benefited to the total degradation of phenol.In addition,the ionic liquid could be reused for its excellent thermal stability.Our work provided a different strategy to treat waste water containing phenol efficiently.展开更多
Visible-light-responsive ternary metal tungstate(MWO_4) photocatalysts are being increasingly investigated for energy conversion and environmental purification applications owing to their striking features, including ...Visible-light-responsive ternary metal tungstate(MWO_4) photocatalysts are being increasingly investigated for energy conversion and environmental purification applications owing to their striking features, including low cost,eco-friendliness, and high stability under acidic and oxidative conditions. However, rapid recombination of photoinduced electron–hole pairs and a narrow light response range to the solar spectrum lead to low photocatalytic activity of MWO_4-based materials, thus significantly hampering their wide usage in practice. To enable their widespread practical usage, significant efforts have been devoted, by developing new concepts and innovative strategies. In this review, we aim to provide an integrated overview of the fundamentals and recent progress of MWO_4-based photocatalysts. Furthermore, different strategies, including morphological control, surface modification, heteroatom doping, and heterojunction fabrication, which are employed to promote the photocatalyticactivities of MWO_4-based materials, are systematically summarized and discussed. Finally, existing challenges and a future perspective are also provided to shed light on the development of highly efficient MWO_4-based photocatalysts.展开更多
Alkali salts of tungsten based heteropoly acids with different central atom such as P, Si and Co were prepared and evaluated for transes- terification of both edible and non-edible oils to their corresponding fatty ac...Alkali salts of tungsten based heteropoly acids with different central atom such as P, Si and Co were prepared and evaluated for transes- terification of both edible and non-edible oils to their corresponding fatty acid methyl esters. The catalyst of sodium salt of tungstic acid with Co as central atom (Na5CoW12O40) showed optimum activity towards transesterification compared with other heteropoly tungstates. The catalysts activities were correlated with the observed physico-chemical characteristics derived from FT-infrared (FT-IR), X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD). The Na5CoW12O40 catalyst exhibiting high activity even at 65 ℃ is due to the presence of strong acidic as well as basic sites. The disclosed catalyst is tolerable towards water and free fatty acids present in the oils. The influence of catalyst loading, reaction time and reaction temperature is studied to optimize the reaction parameters.展开更多
A method based on the combination of coprecipitation with inductively coupledplasma atomic emission spectrometry (ICP-AES) was developed for the determination of impurities inhigh-purity sodium tungstate. Six elements...A method based on the combination of coprecipitation with inductively coupledplasma atomic emission spectrometry (ICP-AES) was developed for the determination of impurities inhigh-purity sodium tungstate. Six elements (Co, Cu, Fe, Mn, Ni, and Pb) were coprecipitated bylanthanum hydroxide so as to be concentrated and separated from the tungsten matrix. Effects of somefactors on the recoveries of the analytes and on the residual amount of sodium tungstate wereinvestigated, and the optimum conditions for the coprecipitation were proposed. Matrix-matchingcalibration curve method was used for the analysis. It is shown that the elements mentioned abovecan be quantitatively recovered. The detection limits for Co, Cu, Fe, Mn, Ni, and Pb are 0.07, 0.4,0.2, 0.1, 0.6, and 1.3 μg·g^(-1), respectively. The recoveries vary from 92.5% to 108%, and therelative standard deviations (RSDs) are in the range of 3.1%-5.5%.展开更多
An unusual inorganic-organic hybrid hexatungstate complex [Cu(phen)3][W6O19] 1 (C36H24 CuN6O19W6, Mr= 2011.20) was hydrothermally synthesized and characterized by singlecrystal X-ray diffraction, IR spectrum, UV-V...An unusual inorganic-organic hybrid hexatungstate complex [Cu(phen)3][W6O19] 1 (C36H24 CuN6O19W6, Mr= 2011.20) was hydrothermally synthesized and characterized by singlecrystal X-ray diffraction, IR spectrum, UV-VIS spectrum and elemental analyses. This compound crystallizes in the monoclinic system, space group C2/c with a = 19.1005(11), b = 11.2585(11), c = 20.2867(15) A, β= 102.177(2)°, V= 4264.4 A^ 3, μ(MoKa) = 16.691 mm^-1, Dc = 3.133 g/cm^3, Z = 4, F(000) = 3628, the final R = 0.0338 and wR = 0.0798 for 4090 observed reflections with I 〉 2σ(I). The result of structure determination shows that the crystal structure is constructed from [W6O19]^2- cluster anions and [Cu(phen)3]^2+ complex fragments, which are held together into a three-dimensional network through hydrogen-bonding interactions.展开更多
AIM: To evaluate the effect of sodium tungstate on visual evoked potentials(VEPs) in diabetic rats.· METHODS: Wistar rats were randomly divided into three groups as normal control, diabetic control and diabet...AIM: To evaluate the effect of sodium tungstate on visual evoked potentials(VEPs) in diabetic rats.· METHODS: Wistar rats were randomly divided into three groups as normal control, diabetic control and diabetic rats treated with sodium tungstate. Diabetes was induced by single intraperitoneal injection of streptozotocin(50 mg/kg). Sodium tungstate [40 mg/(kg·d)]was administered for 12 wk and then VEPs were recorded.Additionally, thiobarbituric acid reactive substance(TBARS) levels were measured in brain tissues.·RESULTS: The latencies of P1, N1, P2, N2 and P3 waves were significantly prolonged in diabetic rats compared with control group. Diabetes mellitus caused an increase in the lipid peroxidation process that was accompanied by changes in VEPs. However, prolonged latencies of VEPs for all components returned to control levels in sodium tungstate-treated group. The treatment of sodium tungstate significantly decreased brain TBARS levels and depleted the prolonged latencies of VEP components compared with diabetic control group.· CONCLUSION: Sodium tungstate shows protective effects on visual pathway in diabetic rats, and it can be worthy of further study for potential use.展开更多
The expanded industrial experiments were conducted with practical industrial liquor to separate free alkali from sodium tungstate solution by electrolysis with cation-exchange membrane. Experimental results show that ...The expanded industrial experiments were conducted with practical industrial liquor to separate free alkali from sodium tungstate solution by electrolysis with cation-exchange membrane. Experimental results show that on the condition that the temperature is 50-55 degreesC and the current density is 1000 A/m(2), the single electrolysis cell is operated stably and 80% free-alkali in mass fraction is separated from the anode feed liquor of sodium tungstate, with electric efficiency up to more than 88% and the unit energy consumption E lower than 1900 kWh/t; while three electrolysis cells in series are operated, under the condition that the temperature is 60-65 degreesC and the current density is 1000 A/m(2), the electric efficiency can reach higher than 88% and the unit energy consumption E can be lower than 2250 kWh/t.展开更多
New cadmium and rare earth metal tungstates with the formula Cd0.25RE0.50 0.25WO4 (RE=Nd, Sin, Eu, Gd, D-statistical distrib- uted vacancies in cation sublattice) were synthesized by the solid-state reaction between...New cadmium and rare earth metal tungstates with the formula Cd0.25RE0.50 0.25WO4 (RE=Nd, Sin, Eu, Gd, D-statistical distrib- uted vacancies in cation sublattice) were synthesized by the solid-state reaction between CdWO4 and corresponding RE2W209. The obtained phases crystallize in the scheelite type structure. The Cd0.25RE0.5 0.25WO4 compounds were characterized by X-ray diffractometer (XRD), (DTA-TG), infrared (IR) and EPR methods.展开更多
Xiao Liansheng Wang Wei Zhang Qixiu Gong Bofan Cao Jiashu (Department of Metallurgical Science and Engineering, Central South University of Technology, Changsha 410083, China) Abstrac By measuring the electrode polari...Xiao Liansheng Wang Wei Zhang Qixiu Gong Bofan Cao Jiashu (Department of Metallurgical Science and Engineering, Central South University of Technology, Changsha 410083, China) Abstrac By measuring the electrode polarization curves of many kinds of materials and life spans of electrodes through intensifying electrolysis in the process, the appropriate electrode materials for different stages of electrolysis of sodium tungstate solution with membrane have been selected The effects of the electrodes with different shapes on electrolysis have been investigated. The result shows that network electrode is more suitable to electrolysis of sodium tungstate solution.展开更多
A mononuclear tungsten-benzilate, (NH4)2[WO2(Ph2COCOO)2]·2H2O was ob- tained by the reaction of ammonium tungstate(VI) with excess benzilic acid in ethanol solution at pH 5~6. The title compound crystallizes in m...A mononuclear tungsten-benzilate, (NH4)2[WO2(Ph2COCOO)2]·2H2O was ob- tained by the reaction of ammonium tungstate(VI) with excess benzilic acid in ethanol solution at pH 5~6. The title compound crystallizes in monoclinic system, space group P21/n with a = 8.1078(5), b = 25.797(2), c = 13.6815(8) (A。), β = 91.001(1)°, V = 2861.1(3) (A。)3, Dc = 1.719 g/cm3, F(000) = 1472, C28H32N2O10W, Mr = 740.41,μ(MoKα) = 4.097 mm-1 and Z = 4. The full-matrix least-squares refinement resulted in R = 0.033 and Rw = 0.068 for 3974 observed reflections with I >2σ(I). The tungsten atom is six-coordinated by two cis-oxo groups and two bidentate benzilate ligands through deprotonated α-alkoxyl and α-carboxyl groups, forming a stable five-membered chelate ring. The compound has a distorted octahedral geometry, which is mainly attributable to the bulky ligand-ligand repulsions.展开更多
A new technological process for production of talium tungstate from low-grade tungsten-concentrate witha high content of calcium and other impurities has been studied. The experiments showed that average tungstenleach...A new technological process for production of talium tungstate from low-grade tungsten-concentrate witha high content of calcium and other impurities has been studied. The experiments showed that average tungstenleaching efficiency of more than 96. 92 % can be obtained with a low NaOH consumption by using the mechani-cal activating caustic decomposition , and the content of main impurities (P, As, Si) in Na_2WO_4 solution ob-tained is competitive with that from standard wolframite concentrate by traditional caustic decomposition. Afterrecovering caustic liquor by first crystallization, molylxlenum is removed from Na_2WO_4 solution by ion ex-change method. High-purity sodium tungstate is obtained by second crystallization of Na_2WO_4 solution. Thistechnology has the advantages of good adaptability for raw materials, high removing efficiency of impurities,high tungsten recovery and high economic benefit.展开更多
Anodic coatings were prepared by micro-arc oxidation on AZ91HP magnesium alloys in a base solution containing 10 g/L NaOH and 12 g/L phytic acid with addition of 0-8 g/L sodium tungstate.The effects of sodium tungstat...Anodic coatings were prepared by micro-arc oxidation on AZ91HP magnesium alloys in a base solution containing 10 g/L NaOH and 12 g/L phytic acid with addition of 0-8 g/L sodium tungstate.The effects of sodium tungstate on the coating thickness, mass gain,surface morphology and corrosion resistance were studied by eddy current instrument,electronic scales,scanning electron microscope and immersion tester.With the addition of sodium tungstate,the electrolytic conductivity increases and the final voltage decreases.The sodium tungstate has a minor effect on the coating thickness,but lightens the coating color.With increasing sodium tungstate concentration,the size of micropores on the coatings is enlarged and the corrosion resistance of the anodized samples decreases.展开更多
The corrosion inhibition of tungstate, benzotriazole (BTA) and their combination in solutions containing Cl- was studied by electrochemical techniques. The results indicated that the inhibition efficiency of tungstate...The corrosion inhibition of tungstate, benzotriazole (BTA) and their combination in solutions containing Cl- was studied by electrochemical techniques. The results indicated that the inhibition efficiency of tungstate was higher than that of BTA. The efficiency increased with increasing concentration of tungstate or BTA. In the studies of synergistic effect of tungstate and BTA, it had been found that in pH 9.0 solution, the largest R t could be obtained with the concentration ratio of tungstate / BTA being 1∶1. Lowering the pH value of solution would reduce the efficiency of inhibitors, especially in binary inhibitors. Increasing the concentration of Cl- accelerated the corrosion of carbon steel in the solutions with various inhibitors, but the influence of Cl- on corroding rate in binary inhibitors was not so strong as in single component. The results of surface analysis showed that W, C, N, O and Fe elements existed in the protecting film formed with binary inhibitors. The thickness of the film was about 1215 nm.展开更多
The process of synthesis of dimethyl-2,6-naphthalene dicaboxylate from esterification of 2,6-naphthalene dicarboxylic acid (2,6-NDCA) by methanol using sodium tungstate as catalyst was investigated. The orthogonal tes...The process of synthesis of dimethyl-2,6-naphthalene dicaboxylate from esterification of 2,6-naphthalene dicarboxylic acid (2,6-NDCA) by methanol using sodium tungstate as catalyst was investigated. The orthogonal tests method was used for optimizing the process factors. The effects of reaction temperature, mass percentage of catalyst, reaction time and mass ratio of methanol to 2,6-NDCA on the 2,6-NDCA conversion were investigated. It was found that all the four factors had significant effect on the conversion. The optimum reaction conditions were reaction temperature 215 ℃,mass percentage of catalyst 3%, reaction time 3 h, mass ratio of methanol to 2,6-NDCA 6∶1. The 2,6-NDCA conversion at above condition was 92.80%.展开更多
基金financially supported by the National Natural Science Foundation of China(21875265,22293015,22121002)。
文摘Phenol in waste water threatens human health and is difficultly to be decomposed by nature.Efficient degradation of high-loaded phenol in water under mild condition is still a great challenge.Herein,ionic liquids with tungstate anion were designed and prepared.It was found that dodecyltrimethylammonium tungstate could catalyzed degradation of phenol into gases and water thoroughly at 323 k in 8 h.Tungstate anion revealed good catalytic oxidative activity and long carbon chain group connecting with cation of ionic liquids enriched phenol around catalysts,which induced the complete degradation of phenol at mild conditions.Increasing the amounts of hydrogen peroxide benefited to the total degradation of phenol.In addition,the ionic liquid could be reused for its excellent thermal stability.Our work provided a different strategy to treat waste water containing phenol efficiently.
基金support of NSFC 51702284Fundamental Research Funds for the Central Universities (112109*172210171)+2 种基金the Startup Foundation for Hundred-Talent Program of Zhejiang University (112100-193820101/001/022)support of the NSFC 21501138the Science Research Foundation of Wuhan Institute of Technology (K201513)
文摘Visible-light-responsive ternary metal tungstate(MWO_4) photocatalysts are being increasingly investigated for energy conversion and environmental purification applications owing to their striking features, including low cost,eco-friendliness, and high stability under acidic and oxidative conditions. However, rapid recombination of photoinduced electron–hole pairs and a narrow light response range to the solar spectrum lead to low photocatalytic activity of MWO_4-based materials, thus significantly hampering their wide usage in practice. To enable their widespread practical usage, significant efforts have been devoted, by developing new concepts and innovative strategies. In this review, we aim to provide an integrated overview of the fundamentals and recent progress of MWO_4-based photocatalysts. Furthermore, different strategies, including morphological control, surface modification, heteroatom doping, and heterojunction fabrication, which are employed to promote the photocatalyticactivities of MWO_4-based materials, are systematically summarized and discussed. Finally, existing challenges and a future perspective are also provided to shed light on the development of highly efficient MWO_4-based photocatalysts.
文摘Alkali salts of tungsten based heteropoly acids with different central atom such as P, Si and Co were prepared and evaluated for transes- terification of both edible and non-edible oils to their corresponding fatty acid methyl esters. The catalyst of sodium salt of tungstic acid with Co as central atom (Na5CoW12O40) showed optimum activity towards transesterification compared with other heteropoly tungstates. The catalysts activities were correlated with the observed physico-chemical characteristics derived from FT-infrared (FT-IR), X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD). The Na5CoW12O40 catalyst exhibiting high activity even at 65 ℃ is due to the presence of strong acidic as well as basic sites. The disclosed catalyst is tolerable towards water and free fatty acids present in the oils. The influence of catalyst loading, reaction time and reaction temperature is studied to optimize the reaction parameters.
文摘A method based on the combination of coprecipitation with inductively coupledplasma atomic emission spectrometry (ICP-AES) was developed for the determination of impurities inhigh-purity sodium tungstate. Six elements (Co, Cu, Fe, Mn, Ni, and Pb) were coprecipitated bylanthanum hydroxide so as to be concentrated and separated from the tungsten matrix. Effects of somefactors on the recoveries of the analytes and on the residual amount of sodium tungstate wereinvestigated, and the optimum conditions for the coprecipitation were proposed. Matrix-matchingcalibration curve method was used for the analysis. It is shown that the elements mentioned abovecan be quantitatively recovered. The detection limits for Co, Cu, Fe, Mn, Ni, and Pb are 0.07, 0.4,0.2, 0.1, 0.6, and 1.3 μg·g^(-1), respectively. The recoveries vary from 92.5% to 108%, and therelative standard deviations (RSDs) are in the range of 3.1%-5.5%.
文摘An unusual inorganic-organic hybrid hexatungstate complex [Cu(phen)3][W6O19] 1 (C36H24 CuN6O19W6, Mr= 2011.20) was hydrothermally synthesized and characterized by singlecrystal X-ray diffraction, IR spectrum, UV-VIS spectrum and elemental analyses. This compound crystallizes in the monoclinic system, space group C2/c with a = 19.1005(11), b = 11.2585(11), c = 20.2867(15) A, β= 102.177(2)°, V= 4264.4 A^ 3, μ(MoKa) = 16.691 mm^-1, Dc = 3.133 g/cm^3, Z = 4, F(000) = 3628, the final R = 0.0338 and wR = 0.0798 for 4090 observed reflections with I 〉 2σ(I). The result of structure determination shows that the crystal structure is constructed from [W6O19]^2- cluster anions and [Cu(phen)3]^2+ complex fragments, which are held together into a three-dimensional network through hydrogen-bonding interactions.
基金Supported by the Research Foundation of Akdeniz University, Turkey
文摘AIM: To evaluate the effect of sodium tungstate on visual evoked potentials(VEPs) in diabetic rats.· METHODS: Wistar rats were randomly divided into three groups as normal control, diabetic control and diabetic rats treated with sodium tungstate. Diabetes was induced by single intraperitoneal injection of streptozotocin(50 mg/kg). Sodium tungstate [40 mg/(kg·d)]was administered for 12 wk and then VEPs were recorded.Additionally, thiobarbituric acid reactive substance(TBARS) levels were measured in brain tissues.·RESULTS: The latencies of P1, N1, P2, N2 and P3 waves were significantly prolonged in diabetic rats compared with control group. Diabetes mellitus caused an increase in the lipid peroxidation process that was accompanied by changes in VEPs. However, prolonged latencies of VEPs for all components returned to control levels in sodium tungstate-treated group. The treatment of sodium tungstate significantly decreased brain TBARS levels and depleted the prolonged latencies of VEP components compared with diabetic control group.· CONCLUSION: Sodium tungstate shows protective effects on visual pathway in diabetic rats, and it can be worthy of further study for potential use.
文摘The expanded industrial experiments were conducted with practical industrial liquor to separate free alkali from sodium tungstate solution by electrolysis with cation-exchange membrane. Experimental results show that on the condition that the temperature is 50-55 degreesC and the current density is 1000 A/m(2), the single electrolysis cell is operated stably and 80% free-alkali in mass fraction is separated from the anode feed liquor of sodium tungstate, with electric efficiency up to more than 88% and the unit energy consumption E lower than 1900 kWh/t; while three electrolysis cells in series are operated, under the condition that the temperature is 60-65 degreesC and the current density is 1000 A/m(2), the electric efficiency can reach higher than 88% and the unit energy consumption E can be lower than 2250 kWh/t.
文摘New cadmium and rare earth metal tungstates with the formula Cd0.25RE0.50 0.25WO4 (RE=Nd, Sin, Eu, Gd, D-statistical distrib- uted vacancies in cation sublattice) were synthesized by the solid-state reaction between CdWO4 and corresponding RE2W209. The obtained phases crystallize in the scheelite type structure. The Cd0.25RE0.5 0.25WO4 compounds were characterized by X-ray diffractometer (XRD), (DTA-TG), infrared (IR) and EPR methods.
文摘Xiao Liansheng Wang Wei Zhang Qixiu Gong Bofan Cao Jiashu (Department of Metallurgical Science and Engineering, Central South University of Technology, Changsha 410083, China) Abstrac By measuring the electrode polarization curves of many kinds of materials and life spans of electrodes through intensifying electrolysis in the process, the appropriate electrode materials for different stages of electrolysis of sodium tungstate solution with membrane have been selected The effects of the electrodes with different shapes on electrolysis have been investigated. The result shows that network electrode is more suitable to electrolysis of sodium tungstate solution.
基金This work was supported by the Ministry of Science & Technology of China (001CB108906) and the National Natural Science Foundation of China (29933040)
文摘A mononuclear tungsten-benzilate, (NH4)2[WO2(Ph2COCOO)2]·2H2O was ob- tained by the reaction of ammonium tungstate(VI) with excess benzilic acid in ethanol solution at pH 5~6. The title compound crystallizes in monoclinic system, space group P21/n with a = 8.1078(5), b = 25.797(2), c = 13.6815(8) (A。), β = 91.001(1)°, V = 2861.1(3) (A。)3, Dc = 1.719 g/cm3, F(000) = 1472, C28H32N2O10W, Mr = 740.41,μ(MoKα) = 4.097 mm-1 and Z = 4. The full-matrix least-squares refinement resulted in R = 0.033 and Rw = 0.068 for 3974 observed reflections with I >2σ(I). The tungsten atom is six-coordinated by two cis-oxo groups and two bidentate benzilate ligands through deprotonated α-alkoxyl and α-carboxyl groups, forming a stable five-membered chelate ring. The compound has a distorted octahedral geometry, which is mainly attributable to the bulky ligand-ligand repulsions.
文摘A new technological process for production of talium tungstate from low-grade tungsten-concentrate witha high content of calcium and other impurities has been studied. The experiments showed that average tungstenleaching efficiency of more than 96. 92 % can be obtained with a low NaOH consumption by using the mechani-cal activating caustic decomposition , and the content of main impurities (P, As, Si) in Na_2WO_4 solution ob-tained is competitive with that from standard wolframite concentrate by traditional caustic decomposition. Afterrecovering caustic liquor by first crystallization, molylxlenum is removed from Na_2WO_4 solution by ion ex-change method. High-purity sodium tungstate is obtained by second crystallization of Na_2WO_4 solution. Thistechnology has the advantages of good adaptability for raw materials, high removing efficiency of impurities,high tungsten recovery and high economic benefit.
基金Projects(GJJ08363,GJJ09573)supported by the Scientific Research Fund of Jiangxi Provincial Education Department,China
文摘Anodic coatings were prepared by micro-arc oxidation on AZ91HP magnesium alloys in a base solution containing 10 g/L NaOH and 12 g/L phytic acid with addition of 0-8 g/L sodium tungstate.The effects of sodium tungstate on the coating thickness, mass gain,surface morphology and corrosion resistance were studied by eddy current instrument,electronic scales,scanning electron microscope and immersion tester.With the addition of sodium tungstate,the electrolytic conductivity increases and the final voltage decreases.The sodium tungstate has a minor effect on the coating thickness,but lightens the coating color.With increasing sodium tungstate concentration,the size of micropores on the coatings is enlarged and the corrosion resistance of the anodized samples decreases.
基金The authors acknowledge the support of National Natural Science Foundation of P. R. China
文摘The corrosion inhibition of tungstate, benzotriazole (BTA) and their combination in solutions containing Cl- was studied by electrochemical techniques. The results indicated that the inhibition efficiency of tungstate was higher than that of BTA. The efficiency increased with increasing concentration of tungstate or BTA. In the studies of synergistic effect of tungstate and BTA, it had been found that in pH 9.0 solution, the largest R t could be obtained with the concentration ratio of tungstate / BTA being 1∶1. Lowering the pH value of solution would reduce the efficiency of inhibitors, especially in binary inhibitors. Increasing the concentration of Cl- accelerated the corrosion of carbon steel in the solutions with various inhibitors, but the influence of Cl- on corroding rate in binary inhibitors was not so strong as in single component. The results of surface analysis showed that W, C, N, O and Fe elements existed in the protecting film formed with binary inhibitors. The thickness of the film was about 1215 nm.
文摘The process of synthesis of dimethyl-2,6-naphthalene dicaboxylate from esterification of 2,6-naphthalene dicarboxylic acid (2,6-NDCA) by methanol using sodium tungstate as catalyst was investigated. The orthogonal tests method was used for optimizing the process factors. The effects of reaction temperature, mass percentage of catalyst, reaction time and mass ratio of methanol to 2,6-NDCA on the 2,6-NDCA conversion were investigated. It was found that all the four factors had significant effect on the conversion. The optimum reaction conditions were reaction temperature 215 ℃,mass percentage of catalyst 3%, reaction time 3 h, mass ratio of methanol to 2,6-NDCA 6∶1. The 2,6-NDCA conversion at above condition was 92.80%.