497-19-8Relevant articles and documents
Dehydration of sodium carbonate monohydrate with indirect microwave heating
Seyrankaya, Abdullah,Ozalp, Bari?
, p. 31 - 36 (2006)
In this study, dehydration of sodium carbonate monohydrate (Na2CO3·H2O) (SCM) in microwave (MW) field with silicon carbide (SiC) as an indirect heating medium was investigated. SCM samples containing up to 3% free moisture were placed in the microwave oven. The heating experiments showed that SCM is a poor microwave energy absorber for up to 6 min of irradiation at an 800 W of microwave power. The heat for SCM calcination is provided by SiC which absorbs microwave. The monohydrate is then converted to anhydrous sodium carbonate on the SiC plate by calcining, i.e. by removing the crystal water through heating of the monohydrate temperatures of over 120 °C. The calcination results in a solid phase recrystallization of the monohydrate into anhydrate. In the microwave irradiation process, dehydration of SCM in terms of indirect heating can be accelerated by increasing the microwave field power.
Thermal decomposition of NaHCO3 powders and single crystals. A study by DSC and optical microscopy
Guarini, G. G. T.,Dei, L.,Sarti, G.
, p. 31 - 44 (1995)
The thermal decomposition of four commercial powders and of differently stored single crystals of sodium hydrogen carbonate is studied by power compensation DSC and by optical and FT-IR microscopy. Independently of manufacturer, specified purity and price, the thermal curves of all the commercial powders show a more or less pronounced low temperature peak preceding the one due to the main decomposition. Such small peak is not observed when samples of laboratory recrystallized material are used. However the thermal behaviour of the latter preparation differs remarkably depending on storage conditions: the material kept in closed glass containers decomposes at temperatures higher than those of the material stored in a desiccator in the presence of concentrated H2SO4. The observation by optical microscopy of the behaviour of the surfaces of single crystals coming from different storage conditions when the temperature is raised in a Kofler heater helps the interpretation of the data collected. The mechanism of the decomposition is discussed and the relevant kinetic parameters reported.
Specificity of decomposition of solids in non-isothermal conditions
Vlase,Vlase,Doca,Doca
, p. 597 - 604 (2003)
The thermal stability of the food additives Na metabisulphite, Na and K acetates, glutamic and citric acids, respective of the pharmaceuticals nifedipine and acetyl salicylic acid was studied by means of the non-isothermal kinetic (Friedman differential m
A method of assessing solid state reactivity illustrated by thermal decomposition experiments on sodium bicarbonate
Heda, Pavan K.,Dollimore, David,Alexander, Kenneth S.,Chen, Dun,Law, Emmeline,Bicknell, Paul
, p. 255 - 272 (1995)
The thermal decomposition of sodium bicarbonate (NaHCO3) was studied under different atmospheres (dry nitrogen, air, and carbon dioxide), with various heating rates in order to characterize the substance. Various non-isothermal methods of kinetic analysis were employed in estimating the Arrhenius kinetic parameters, the activation energy and the frequency factor. All show that the most probable reaction mechanism under dry nitrogen and air is the first-order deceleratory mechanism, whereas under carbon dioxide it is the Avrami-Erofeev equation, with n = 1.5. Thermogravimetric and derivative thermogravimetric analysis (TGA and DTG) were employed for comparing the solid state reactivity of different samples of sodium bicarbonate. The reaction parameters, the extent of the reaction (α) and the reaction temperature were used in comparing the reactivities of various samples of sodium bicarbonate differing in particle sizeand surface area produced by grinding the substance in a ball mill. A m ethod was utilized, termed here the α(sample)-α(reference) (α(s)-α(r)) method, by which the solid state reactivity of these samples could be compared with that of a reference. The terms α(s), α(r) refer to the extent of reaction (here the extent of decomposition) at the same temperature for the sample (s) and reference (r).
Interaction of graphite with hydroxide-salt melts
Zarubitskii,Dmitruk,Zakharchenko
, p. 525 - 528 (2006)
The mechanism and kinetics of graphite dissolution in melts based on sodium hydroxide were studied. The effect of various salt additives on the intensity of the occurring reactions is considered. A method recommended for removal of graphite in the form of remainders of molds and mold cores from titanium casts is described. Pleiades Publishing, Inc., 2006.
Microwave-assisted synthesis, crystal structures and thermal behaviour of Na5Y(CO3)4 and Na5Yb(CO3)4·2H2O
Awaleh,Ben Ali,Maisonneuve,Leblanc, Marc
, p. 114 - 120 (2003)
The microwave-assisted synthesis, crystal structure and thermal behavior of two carbonates were discussed. The study was performed using single crystal x-ray diffraction technique. It was found that in both structures Na(1)+ and Yb3+
Kinetic studies on the thermal decomposition of aluminium doped sodium oxalate under isothermal conditions
Jose John,Muraleedharan,Kannan,Abdul Mujeeb,Ganga Devi
, p. 64 - 70 (2012)
The kinetics of thermal decomposition of sodium oxalate (Na 2C2O4) has been studied as a function of concentration of dopant, aluminium, at five different temperatures in the range 783-803 K under isothermal conditions by thermogravimetry (TG). The TG data were subjected to both model fitting and model free kinetic methods of analysis. The model fitting analysis of the TG data shows that no single kinetic model describes the whole α versus t curve with a single rate constant throughout the decomposition reaction. Separate kinetic analysis shows that Prout-Tompkins model best describes the acceleratory stage of the decomposition while the decay region is best fitted with the contracting cylinder model. Activation energy values were evaluated by model fitting and model free kinetic methods for both stages of decomposition. As proposed earlier the results favours a diffusion controlled mechanism for the isothermal decomposition of sodium oxalate.
Quantitative kinetic and structural analysis of geopolymers. Part 1. the activation of metakaolin with sodium hydroxide
Zhang, Zuhua,Wang, Hao,Provis, John L.,Bullen, Frank,Reid, Andrew,Zhu, Yingcan
, p. 23 - 33 (2012)
Isothermal conduction calorimetry (ICC) is used here to measure the kinetics of geopolymerisation of metakaolin by reaction with NaOH solution under a variety of conditions. Three exothermic peaks are observed in the calorimetric curve, and are assigned to the dissolution of metakaolin, the formation of geopolymer with disordered or locally ordered structure, and finally the reorganization and partial crystallization of this inorganic polymer gels. For the purpose of further quantifying the ICC data, the geopolymeric reaction products are assumed to have an analcime-like local structure, and their standard formation enthalpies are estimated from the available data for this structure. This assumption enables ICC to be used for the first time in a quantitative manner to determine the real reaction kinetics of geopolymerization. Increasing the NaOH concentration up to a molar overall Na/Al ratio of 1.1 is seen to enhance the reaction extent observed at 3 days, up to a maximum of around 40% in the high liquid/solid ratio systems studied here, and accelerates the crystallization process. However, further addition of NaOH does not give any additional reaction within this period, or any further acceleration. Raising the reaction temperature from 25 °C to 40°C increases the initial reaction rate but has little effect on the final reaction extent, particularly when Na/Al > 1.
Thermal Decomposition of Solid Sodium Bicarbonate
Ball, Matthew C.,Snelling, Christine M.,Strachan, Alec N.,Strachan, Rebecca M.
, p. 3709 - 3716 (1986)
The thermal decomposition of solid sodium bicarbonate has been studied in the temperature range 360-500 K over a range of partial pressures of carbon dioxide.The effect of water vapour has also been studied.Above 440 K the reaction follows contracting-cube kinetics with an activation energy of 32 kJ mol-1 and a frequency factor of 101 s-1.In this temperature range the presence of water or carbon dioxide has little effect on the kinetics.Below 390 K the reaction follows first-order kinetics.In nitrogen, the activation energy is ca. 64 kJ mol-1, the frequency factor is 105 s-1 and water vapour has little effect.High partial pressures of carbon dioxide increase the activation energy to ca. 130 kJ mol-1 and the frequency factor to 1013.5 s-1.The results of microscopic examination generally confirm the kinetics but show that at low temperatures in nitrogen and carbon dioxide the process are different in detail.
Synthesis, spectroscopy, single crystal XRD and biological studies of multinuclear organotin dicarboxylates
Hussain, Shabbir,Ali, Saqib,Shahzadi, Saira,Tahir, Muhammad Nawaz,Shahid, Muhammad,Munawar, Khurram Shahzad,Abbas, Syed Mustansar
, p. 64 - 72 (2016)
Multinuclear organotin(IV) dicarboxylates of the general formula (Me3Sn)2L·H2O (1), (Ph3Sn)2L (2) and Me2SnL[Sn(Cl)2Me2]2 (3) were synthesized by refluxing disodium iminodiacetate hydrate (Na2L·H2O) with Me3SnCl/Ph3SnCl/Me2SnCl2 in methanol. The elemental analysis (C, H and N) data agreed well with the chemical compositions of the products. IR spectroscopy demonstrated a bridging coordination mode of the carboxylate group. 1H NMR spectroscopy suggested a penta-coordinated environment around the tin(IV) center in complexes 1 and 3. The title complex 3 represents one of the very few examples of organotin(IV) carboxylates showing simultaneously coordination with dimethyltin(IV) as well as dichlorodimethyltin(IV) moieties, by substitution and addition reactions, respectively. The 13C NMR spectroscopy demonstrated the carboxylate-metal linkages. EIMS and ESI spectra verified the molecular skeletons of the products 1-3. Thermogravimetric analysis revealed the bimetallic nature of 2. A single crystal XRD study of 3 has shown a predominantly square pyramidal geometry with some trigonal bipyramidal characteristics around each metal center. The novel products exhibited antibacterial/antifungal potential and their minimal inhibitory concentrations (MIC) were also evaluated. In vitro hemolytic studies on human red blood cells indicated a slightly toxic nature of the synthesized complexes.
