A new method of the multiple rates isotemperature is proposed to define the most probable mechanismg(α) of thermal anlaysis; the iterative isoconversional procedure has been employed to estimate apparent activation e...A new method of the multiple rates isotemperature is proposed to define the most probable mechanismg(α) of thermal anlaysis; the iterative isoconversional procedure has been employed to estimate apparent activation energyE; the pre-exponential factorA is obtained on the basis ofE andg(α). By this new method, the thermal analysis kinetics triplet of dehydration of cobalt oxalate dihydrate is determined, apparent activation energyE is 99.84 kJ·mol?1; pre-exponential factorA is 3.427×109–3.872×109 s?1 and the most probable mechanism belongs to nucleation and growth,A m model, the range ofm is from 1.50 to 1.70. Key words multiple rates isotemperature method - isoconversional method - cobalt oxalate dihydrate - accomodation function - differential scanning calorimetry (DSC) CLC number O 636.1 Foundation item: Supported by the Key Foundation of the Science and Technology Committee of Hubei Province (2001ABA009)Biography: Li Li-qing (1977-), female, Master candidate, research direction: material synthesize and thermal analysis kinetics.展开更多
As a kind of efficient photocatalyst,coordination polymers(CPs) have gained much attention in recent years.However,their safety issue and time-consuming synthesis impede their practical application.Here in this paper ...As a kind of efficient photocatalyst,coordination polymers(CPs) have gained much attention in recent years.However,their safety issue and time-consuming synthesis impede their practical application.Here in this paper we first demonstrate the facile synthesis and photocatalytic degradation performance of 1D α-ferrous oxalate dihydrate(α-FOD),which is one of the simplest CPs.A unique two-pathway photocatalytic mechanism which combines traditional photocatalytic and photo-initiated Fenton oxidations has been proposed.The excellent photocatalytic performance and cost-effective fabrication make α-FOD a new promising candidate for the photocatalytic degradation of organic pollutants in practical applications.展开更多
The thermal decomposition of the magnesium oxalate dihydrate in a static air atmosphere was investigated by TG-DTG techniques. The intermediate and residue of each decomposition were identified from their TG curve. Th...The thermal decomposition of the magnesium oxalate dihydrate in a static air atmosphere was investigated by TG-DTG techniques. The intermediate and residue of each decomposition were identified from their TG curve. The kinetic triplet, the activation energy E, the pre-exponential factor A and the mechanism functionsf（a） were obtained from analysis of the TG-DTG curves of thermal decomposition of the first stage and the second stage by the Popesou method and the Flynn-Wall-Ozawa method.展开更多
An efficient green protocol is described for the preparation of highly functionalized piperidines via a one-pot five-component reaction between aromatic aldehydes,anilines andβ-ketoesters in the presence of oxalic ac...An efficient green protocol is described for the preparation of highly functionalized piperidines via a one-pot five-component reaction between aromatic aldehydes,anilines andβ-ketoesters in the presence of oxalic acid dihydrate as catalyst in ethanol at ambient temperature.The structure as well as the relative stereochemistry of these compounds was confirmed by single X-ray crystallographic analysis.展开更多
In this paper, the mimetic biomineralization of CaC2O4 in lecithin water(PC H2O) ordered systems has been discussed. First, the effect of the aggregation state of PC aqueous solutions on the crystal structure of CaC2O...In this paper, the mimetic biomineralization of CaC2O4 in lecithin water(PC H2O) ordered systems has been discussed. First, the effect of the aggregation state of PC aqueous solutions on the crystal structure of CaC2O4 has been studied. In all experiments, the only precipitated crystal forms obtained are calcium oxalate monohydrate(COM) and calcium oxalate dihydrate(COD). It have been shown that the relative amount of COD in PC H2O systems is much higher than that of in H2O system, and furthermore the aggregation state of PC influences the composition of coprecipitations to some extent. When PC distributing in aqueous solution as single molecules, it acts as inhibitor of COM , and then favors the formation of COD. While PC in micelle existence, the relative amount of COM increases , but is still lower than that of in H2O system . And when PC aggregates as vesicles, COD forms predominantly. Second, the morphology of CaC2O4 obtained in different reaction systems under different conditions has been also investigated. In H2O system, we observed thin, plate like crystals with serrated edges underISL(low ionic strength) condition and oriented clusters under ISH(high ionic strength) condition. Crystals with two layers arrangement were obtained in micelleordered PC H2O system under ISL condition. And in vesicle ordered PC H2O system, clusters with butterfly like shape were observed. The results obtained revealed a complex dependence of calcium oxalate formation,crystal growth, structure and morphology on the aggregation state of PC H2O systems.展开更多
The thermal behavior of ferrous oxalate dihydrate (FeC2O4·2H2O) was studied by thermogravimetry and differential thermal analysis (TGA and DTA). Three steps could be deduced for the decomposition from the TG,DTG ...The thermal behavior of ferrous oxalate dihydrate (FeC2O4·2H2O) was studied by thermogravimetry and differential thermal analysis (TGA and DTA). Three steps could be deduced for the decomposition from the TG,DTG and DTA curves obtained. One of the steps was the dehydration, the mass loss was 20.1%(the found value was in good agreement with the calculated value). Mathematical analysis with the integral and differential methods showed that the kinetics of dehydration of FeC2O4·2H2O could be explained by F1 mechanism in nitrogen atmosphere. The kinetic equation of dehydration of FeC2O4·2H2O could be expressed as: dα/dt=6.25×1019[exp(-170.27×103/RT)](1-α)展开更多
The mineral of manganese oxalate dihydrate was synthesized in aqueous and organic-water binary solvent system (OWBS), respectively. The samples were characterized by XRD and SEM. The results show that OWBS can effecti...The mineral of manganese oxalate dihydrate was synthesized in aqueous and organic-water binary solvent system (OWBS), respectively. The samples were characterized by XRD and SEM. The results show that OWBS can effectively control the phase and morphology of manganese oxalate dihydrate. The distinction of thermal decompositon of monoclinic and orthogonal manganese oxalate dihydrate can be ascribed to the different linkage mode of manganese cation, oxalate anion and crystallized water in inter-molecules. The kinetic parameters of thermal decomposition were obtained by TG-DTA curves in various scan rates, and notably, porous manganese oxide was prepared from orthogonal manganese oxalate.展开更多
文摘A new method of the multiple rates isotemperature is proposed to define the most probable mechanismg(α) of thermal anlaysis; the iterative isoconversional procedure has been employed to estimate apparent activation energyE; the pre-exponential factorA is obtained on the basis ofE andg(α). By this new method, the thermal analysis kinetics triplet of dehydration of cobalt oxalate dihydrate is determined, apparent activation energyE is 99.84 kJ·mol?1; pre-exponential factorA is 3.427×109–3.872×109 s?1 and the most probable mechanism belongs to nucleation and growth,A m model, the range ofm is from 1.50 to 1.70. Key words multiple rates isotemperature method - isoconversional method - cobalt oxalate dihydrate - accomodation function - differential scanning calorimetry (DSC) CLC number O 636.1 Foundation item: Supported by the Key Foundation of the Science and Technology Committee of Hubei Province (2001ABA009)Biography: Li Li-qing (1977-), female, Master candidate, research direction: material synthesize and thermal analysis kinetics.
基金supported by the National Key Basic Research Program of China(2013CB933200)the National High-tech R&D Program of China(2012AA062703)+1 种基金Jiangsu National Synergetic Innovation Center for Advanced Materials(SICAM)the Youth Innovation Promotion Association CAS(2012200)
文摘As a kind of efficient photocatalyst,coordination polymers(CPs) have gained much attention in recent years.However,their safety issue and time-consuming synthesis impede their practical application.Here in this paper we first demonstrate the facile synthesis and photocatalytic degradation performance of 1D α-ferrous oxalate dihydrate(α-FOD),which is one of the simplest CPs.A unique two-pathway photocatalytic mechanism which combines traditional photocatalytic and photo-initiated Fenton oxidations has been proposed.The excellent photocatalytic performance and cost-effective fabrication make α-FOD a new promising candidate for the photocatalytic degradation of organic pollutants in practical applications.
基金Project supported by the Natural Science Foundation of Hebei Province （No. 202140） and Hebei Education Department （No. 2004325）.
文摘The thermal decomposition of the magnesium oxalate dihydrate in a static air atmosphere was investigated by TG-DTG techniques. The intermediate and residue of each decomposition were identified from their TG curve. The kinetic triplet, the activation energy E, the pre-exponential factor A and the mechanism functionsf（a） were obtained from analysis of the TG-DTG curves of thermal decomposition of the first stage and the second stage by the Popesou method and the Flynn-Wall-Ozawa method.
基金support from the Research Council of the University of Sistan and Baluchestanthe Australian National University
文摘An efficient green protocol is described for the preparation of highly functionalized piperidines via a one-pot five-component reaction between aromatic aldehydes,anilines andβ-ketoesters in the presence of oxalic acid dihydrate as catalyst in ethanol at ambient temperature.The structure as well as the relative stereochemistry of these compounds was confirmed by single X-ray crystallographic analysis.
文摘In this paper, the mimetic biomineralization of CaC2O4 in lecithin water(PC H2O) ordered systems has been discussed. First, the effect of the aggregation state of PC aqueous solutions on the crystal structure of CaC2O4 has been studied. In all experiments, the only precipitated crystal forms obtained are calcium oxalate monohydrate(COM) and calcium oxalate dihydrate(COD). It have been shown that the relative amount of COD in PC H2O systems is much higher than that of in H2O system, and furthermore the aggregation state of PC influences the composition of coprecipitations to some extent. When PC distributing in aqueous solution as single molecules, it acts as inhibitor of COM , and then favors the formation of COD. While PC in micelle existence, the relative amount of COM increases , but is still lower than that of in H2O system . And when PC aggregates as vesicles, COD forms predominantly. Second, the morphology of CaC2O4 obtained in different reaction systems under different conditions has been also investigated. In H2O system, we observed thin, plate like crystals with serrated edges underISL(low ionic strength) condition and oriented clusters under ISH(high ionic strength) condition. Crystals with two layers arrangement were obtained in micelleordered PC H2O system under ISL condition. And in vesicle ordered PC H2O system, clusters with butterfly like shape were observed. The results obtained revealed a complex dependence of calcium oxalate formation,crystal growth, structure and morphology on the aggregation state of PC H2O systems.
文摘The thermal behavior of ferrous oxalate dihydrate (FeC2O4·2H2O) was studied by thermogravimetry and differential thermal analysis (TGA and DTA). Three steps could be deduced for the decomposition from the TG,DTG and DTA curves obtained. One of the steps was the dehydration, the mass loss was 20.1%(the found value was in good agreement with the calculated value). Mathematical analysis with the integral and differential methods showed that the kinetics of dehydration of FeC2O4·2H2O could be explained by F1 mechanism in nitrogen atmosphere. The kinetic equation of dehydration of FeC2O4·2H2O could be expressed as: dα/dt=6.25×1019[exp(-170.27×103/RT)](1-α)
文摘The mineral of manganese oxalate dihydrate was synthesized in aqueous and organic-water binary solvent system (OWBS), respectively. The samples were characterized by XRD and SEM. The results show that OWBS can effectively control the phase and morphology of manganese oxalate dihydrate. The distinction of thermal decompositon of monoclinic and orthogonal manganese oxalate dihydrate can be ascribed to the different linkage mode of manganese cation, oxalate anion and crystallized water in inter-molecules. The kinetic parameters of thermal decomposition were obtained by TG-DTA curves in various scan rates, and notably, porous manganese oxide was prepared from orthogonal manganese oxalate.
