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1.
Modified Sorrel’s cement was prepared by the addition of ferric chloride. The modified cement (MF5) was analyzed and characterized
by different methods. Adsorption of Gd(III) and U(VI) ions in carbonate solution has been studied separately as a function
of pH, contact time, adsorbent weight, carbonate concentration, concentration of Gd(III) and U(VI) and temperature. From equilibrium
data obtained, the values of Δ H, Δ S and Δ G were found to equal −30.9 kJ ⋅ mol−1, −85.4 J ⋅ mol−1 ⋅,K−1, and −5.4 KJ ⋅ mol−1, respectively, for Gd(III) and 18.9 kJ ⋅ mol−1, 67.8 J ⋅ mol−1 K−1 and −1.3 KJ ⋅ mol−1, respectively, for U(VI). The equilibrium data obtained have been found to fit both Langmuir and Freundlich adsorption isotherms.
The batch kinetic of Gd(III) and U(VI) on modified Sorrel’s cement (MF5) with the thermodynamic parameters from carbonate
solution were studied to explain the mechanistic aspects of the adsorption process. Several kinetic models were used to test
the experimental rate data and to examine the controlling mechanism of the adsorption process. Various parameters such as
effective diffusion coefficient and activation energy of activation were evaluated. The adsorption of Gd(III) and U(VI) on
the MF5 adsorbent follows first-order reversible kinetics. The forward and backward constants for adsorption, k
1and k
2 have been calculated at different temperatures between 10 and 60∘C. Form kinetic study, the values of Δ H
* and Δ S
* were calculated for Gd(III) and U(VI) at 25∘C. It is found that Δ H
* equals −14.8 kJmol−1 and 7.2 kJmol−1 for Gd(III) and U(VI), respectively, while Δ S
* were found equal −95.7 Jmol−1K−1 and −70.5 Jmol−1K−1 for Gd(III) and U(VI), respectively. The study showed that the pore diffusion is the rate limiting for Gd(III) and (VI). 相似文献
2.
The adsorption of dibenzothiophene (DBT) in hexadecane onto NaY zeolite has been studied by performing equilibrium and kinetic
adsorption experiments. The influence of several variables such as contact time, initial concentration of DBT and temperature
on the adsorption has been investigated. The results show that the isothermal equilibrium can be represented by the Langmuir
equation. The maximum adsorption capacity at different temperatures and the corresponding Langmuir constant (K
L
) have been deduced. The thermodynamic parameters (ΔG
0,ΔH
0,ΔS
0) for the adsorption of DBT have also been calculated from the temperature dependence of K
L
using the van’t Hoff equation. The value of ΔH
0,ΔS
0 are found to be −30.3 kJ mol−1 and −33.2 J mol−1 K−1 respectively. The adsorption is spontaneous and exothermic. The kinetics for the adsorption process can be described by either
the Langmuir model or a pseudo-second-order model. It is found that the adsorption capacity and the initial rate of adsorption
are dependent on contact time, temperature and the initial DBT concentration. The low apparent activation energy (12.4 kJ mol−1) indicates that adsorption has a low potential barrier suggesting a mass transfer controlled process. In addition, the competitive
adsorption between DBT, naphthalene and quinoline on NaY was also investigated. 相似文献
3.
M. Mufazzal Saeed Abdul Ghaffar 《Journal of Radioanalytical and Nuclear Chemistry》1998,232(1-2):171-177
The nature of adsorption behavior of Au(III) on polyurethane (PUR) foam was studied in 0.2M HCl aqueous solution. The effect
of shaking time and amount of adsorbent were optimized for 3.16·10−5M solution of Au(III) in 0.2M HCl. The classical Freundlich and Langmuir adsorption isotherms have been employed successfully.
The Freundlich parameters 1/n and adsorption capacityK are 0.488±0.016 and (1.40±0.22)·10−2 mol·g−1, respectively. The Langmuir constants of saturation capacityM and binding energyb are (1.66±0.08)·10−4mol·g−1 and 40294±2947 l·g−1, respectively, indicating the monolayer chemical sorption. The mean free energy (E) of adsorption of Au(III) on PUR foam has been evaluated using D-R isotherm and found to be 11.5±0.16 kJ·mol−1 reflecting the ion exchange type of chemical adsorption. The effect of temperature on the adsorption has also been studied.
the isosteric heat of adsorption was found to be 44.03±1.66 kJ·mol−1. The thermodynamic parameters of ΔG, ΔH, ΔS and equilibrium constantK
c
have been calculated. The negative values of ΔG, ΔH and ΔS support that the adsorption of Au(III) on PUR foam is spontaneous, exothermic and of ion exchange chemisorption. The nature
of the Au(III) species sorbed on PUR foam have been discussed. 相似文献
4.
N,N-dimethyl-3-oxa-glutaramic acid was purified and characterized by 1H-NMR, Fourier transform infrared spectroscopy (FT-IR) and elemental analysis. The thermal decomposition of the title compound
was studied by means of thermogravimetry differential thermogravimetry (TG-DTG) and FT-IR. The kinetic parameters of its second-stage
decomposition reaction were calculated and the decomposition mechanism was discussed. The kinetic model function in a differential
form, apparent activation energy and pre-exponential constant of the reaction are 3/2 [(1−α)1/3−1]−1, 203.75 kJ·mol−1 and 1017.95s−1, respectively. The values of ΔS
≠, ΔH
≠ and ΔG
≠ of the reaction are 94.28 J·mol−1·K−1, 203.75 kJ·mol−1 and 155.75 kJ·mol−1, respectively.
Supported by the National Natural Science Foundation of China (Grant No. 20106009) 相似文献
5.
Joanna Wiśniewska 《Transition Metal Chemistry》2007,32(1):107-111
The kinetics of the oxidation of promazine by trisoxalatocobaltate(III) were studied in the presence of a large excess of
the cobalt(III) in tris buffer solution using u.v.–vis spectroscopy ([CoIII] = (0.6 − 2) × 10−3
M, [ptz] = 6 × 10−5
M, pH = 6.6–7.8, I = 0.1 M (NaCl), T = 288−308 K, l = 1 cm). The reaction proceeds via two consecutive reversible steps. In the first step, the reaction leads to formation of cobalt(II) species and a stable cationic
radical. In the second step, cobalt(III) is reduced to cobalt(II) ion and a promazine radical is oxidized to the promazine
5-oxide. Linear dependences of the pseudo-first-order rate constants (k
1 and k
2) on [CoIII] with a non-zero intercept were established for both redox processes. Rates of reactions decreased with increasing concentration
of the H+ ion indicating that the promazine and its radical exist in equilibrium with their deprotonated forms, which are reactive
reducing species. The activation parameters for reactions studied were as follows: ΔH≠ = 44 ± 1 kJ mol−1, ΔS≠ = −100 ± 4 JK−1 mol−1 for the first step and ΔH≠ = 25 ± 1 kJ mol−1, ΔS≠ = −169 ± 4 J K−1 mol−1 for the second step, respectively. Mechanistic consequences of all the results are discussed. 相似文献
6.
L. M. Cotoruelo M. D. Marqués A. Leiva J. Rodríguez-Mirasol T. Cordero 《Adsorption》2011,17(3):539-550
The adsorption processes of three aromatic chemicals onto activated carbons (ACs) from aqueous solutions have been studied.
Eucalyptus kraft lignin obtained from cellulose industry as a residual biomass has been used to prepare activated carbons
by physical activation with CO2. The influences of the activation time on the surface areas and pore volumes of the ACs were analyzed. The physicochemical
properties and the surface chemical structure of the adsorbents have been studied by means of N2 and CO2 adsorption, ultimate analysis, XPS, TPD and SEM. XPS and TPD spectra of the ACs have suggested the presence of aromatic rings
and carbon-oxygen functional groups in the solid surfaces. The potential use of the ACs for the removal of acetaminophen (paracetamol),
salicylic acid and benzoic acid has been investigated at different pH, temperature and contact time. The adsorption equilibrium
data have been correlated to Langmuir isotherm model. The thermodynamic study has been developed, the values of ΔH, ΔG, and ΔS have been calculated and they indicated that the processes are endothermic for acetaminophen and exothermic for salicylic
and benzoic acids. The analysis of the kinetic experiments showed that the effective diffusivities are low; 10−12 to 10−11 cm2/s, and they are the corresponding to intraparticle mass transfer, which appears as the controlling step for the net adsorption
processes. 相似文献
7.
Javed MR Rashid MH Nadeem H Riaz M Perveen R 《Applied biochemistry and biotechnology》2009,157(3):483-497
Monomeric extracellular endoglucanase (25 kDa) of transgenic koji (Aspergillus oryzae cmc-1) produced under submerged growth condition (7.5 U mg−1 protein) was purified to homogeneity level by ammonium sulfate precipitation and various column chromatography on fast protein
liquid chromatography system. Activation energy for carboxymethylcellulose (CMC) hydrolysis was 3.32 kJ mol−1 at optimum temperature (55 °C), and its temperature quotient (Q
10) was 1.0. The enzyme was stable over a pH range of 4.1–5.3 and gave maximum activity at pH 4.4. V
max for CMC hydrolysis was 854 U mg−1 protein and K
m was 20 mg CMC ml−1. The turnover (k
cat) was 356 s−1. The pK
a1 and pK
a2 of ionisable groups of active site controlling V
max were 3.9 and 6.25, respectively. Thermodynamic parameters for CMC hydrolysis were as follows: ΔH* = 0.59 kJ mol−1, ΔG* = 64.57 kJ mol−1 and ΔS* = −195.05 J mol−1 K−1, respectively. Activation energy for irreversible inactivation ‘E
a(d)’ of the endoglucanase was 378 kJ mol−1, whereas enthalpy (ΔH*), Gibbs free energy (ΔG*) and entropy (ΔS*) of activation at 44 °C were 375.36 kJ mol−1, 111.36 kJ mol−1 and 833.06 J mol−1 K−1, respectively. 相似文献
8.
Liang Xue Feng-Qi Zhao Xiao-Ling Xing Zhi-Ming Zhou Kai Wang Hong-Xu Gao Jian-Hua Yi Rong-Zu Hu 《Journal of Thermal Analysis and Calorimetry》2010,102(3):989-992
The thermal decomposition behavior of 3,4,5-triamino-1,2,4-triazole dinitramide was measured using a C-500 type Calvet microcalorimeter
at four different temperatures under atmospheric pressure. The apparent activation energy and pre-exponential factor of the
exothermic decomposition reaction are 165.57 kJ mol−1 and 1018.04 s−1, respectively. The critical temperature of thermal explosion is 431.71 K. The entropy of activation (ΔS
≠), enthalpy of activation (ΔH
≠), and free energy of activation (ΔG
≠) are 97.19 J mol−1 K−1, 161.90 kJ mol−1, and 118.98 kJ mol−1, respectively. The self-accelerating decomposition temperature (T
SADT) is 422.28 K. The specific heat capacity of 3,4,5-triamino-1,2,4-triazole dinitramide was determined with a micro-DSC method
and a theoretical calculation method. Specific heat capacity (J g−1 K−1) equation is C
p = 0.252 + 3.131 × 10−3
T (283.1 K < T < 353.2 K). The molar heat capacity of 3,4,5-triamino-1,2,4-triazole dinitramide is 264.52 J mol−1 K−1 at 298.15 K. The adiabatic time-to-explosion of 3,4,5-triamino-1,2,4-triazole dinitramide is calculated to be a certain value
between 123.36 and 128.56 s. 相似文献
9.
Fursemide is the chemical compound 4-chloro-2-(furan-2-ylmethylamino)-5-(aminosulfonyl) benzoic acid. It was oxidized by diperiodatocuprate(III)
in alkali solutions, and the oxidation products were identified as furfuraldehyde and 2-amino-4-chloro-5-(aminosulfonyl) benzoic
acid. The reaction kinetics were studied spectrophotometrically. The reaction was observed to be first order in [oxidant]
and fractional order each in [fursemide] and [periodate], whereas added alkali retarded the rate of reaction. The reactive
form of the oxidant was inferred to be [Cu(H3IO6)2]−. A mechanism consistent with the experimental results was proposed, in which oxidant interacts with the substrate to give
a complex as a pre-equilibrium state. This complex decomposed in a slow step to give a free radical that was further oxidized
by reaction with another molecule of DPC to yield 2-amino-4-chloro-5-(aminosulfonyl) benzoic acid and furfuraldehyde in a
fast step. This reaction was studied at 25, 30, 35, 40 and 45 °C, and the activation parameters E
a,ΔH
#,ΔS
# and ΔG
# were determined to be 51 kJ⋅mol−1,48.5 kJ⋅mol−1,−63.5 J⋅K−1⋅mol−1 and 67 kJ⋅mol−1, respectively. The value of log 10
A was calculated to be 6.8. 相似文献
10.
Adsorption of vanadium(V) from aqueous solution onto ZnCl2 activated carbon developed from coconut coir pith was investigated to assess the possible use of this adsorbent. The influence
of various parameters such as agitation time, vanadium concentration, adsorbent dose, pH and temperature has been studied.
First, second order, Elovich and Bangham’s models were used to study the adsorption kinetics. The adsorption system follows
second order and Bangham’s kinetic models. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms have been employed
to analyze the adsorption equilibrium data. Equilibrium adsorption data followed all the four isotherms—Langmuir, Freundlich,
D-R and Temkin. The Langmuir adsorption capacity (Q
0) was found to be 24.9 mg g− 1 of the adsorbent. The per cent adsorption was maximum in the pH range 4.0–9.0. The pH effect and desorption studies showed
that ion exchange mechanism might be involved in the adsorption process. Thermodynamic parameters such as ΔG
0, ΔH
0 and ΔS
0 for the adsorption were evaluated. Effect of competitive anions in the aqueous solution such as PO4
3 −, SO4
2−, ClO4
−, MoO4
2−, SeO3
2−, NO3
− and Cl− was examined. SEM and FTIR were used to study the surface of vanadium(V) loaded ZnCl2 activated carbon. Removal of vanadium(V) from synthetic ground water was also tested. Results show that ZnCl2 activated coir pith carbon is effective for the removal of vanadium(V) from water. 相似文献
11.
H. X. Ma B. Yan Y. H. Ren Y. Hu Y. L. Guan F. Q. Zhao J. R. Song R. Z. Hu 《Journal of Thermal Analysis and Calorimetry》2011,103(2):569-575
3,3-Dinitroazetidinium (DNAZ) salt of perchloric acid (DNAZ·HClO4) was prepared, it was characterized by the elemental analysis, IR, NMR, and a X-ray diffractometer. The thermal behavior
and decomposition reaction kinetics of DNAZ·HClO4 were investigated under a non-isothermal condition by DSC and TG/DTG techniques. The results show that the thermal decomposition
process of DNAZ·HClO4 has two mass loss stages. The kinetic model function in differential form, the value of apparent activation energy (E
a) and pre-exponential factor (A) of the exothermic decomposition reaction of DNAZ·HClO4 are f(α) = (1 − α)−1/2, 156.47 kJ mol−1, and 1015.12 s−1, respectively. The critical temperature of thermal explosion is 188.5 °C. The values of ΔS
≠, ΔH
≠, and ΔG
≠of this reaction are 42.26 J mol−1 K−1, 154.44 kJ mol−1, and 135.42 kJ mol−1, respectively. The specific heat capacity of DNAZ·HClO4 was determined with a continuous C
p mode of microcalorimeter. Using the relationship between C
p and T and the thermal decomposition parameters, the time of the thermal decomposition from initiation to thermal explosion (adiabatic
time-to-explosion) was evaluated as 14.2 s. 相似文献
12.
Polymorphism of paracetamol 总被引:1,自引:0,他引:1
G. L. Perlovich Tatyana V. Volkova Annette Bauer-Brandl 《Journal of Thermal Analysis and Calorimetry》2007,89(3):767-774
The thermodynamic relationship between crystal modifications of paracetamol was studied by alternative methods. Temperature
dependence of saturated vapor pressure for polymorphic modifications of the drug paracetamol (acetaminophen) was mea sured
and thermodynamic functions of the sublimation process calculated. Solution calorimetry was carried out for the two modifications
in the same solvent. Thermodynamic parameters for sublimation for form I (monoclinic) were found: ΔG
sub298=60.0 kJ mol−1; ΔH
sub298=117.9±0.7 kJ mol−1; ΔS
sub298=190±2 J mol−1 K−1. For the orthorhombic modification (form II), the saturated vapor pressure could only be studied at 391 K. Phase transition
enthalpy at 298 K, ΔH
tr298(I→II)=2.0±0.4 kJ mol−1, was derived as the difference between the solution enthalpies of the noted polymorphs in the same solution (methanol). Based
on ΔH
tr298 (I→II), differences between temperature dependencies of heat capacities of both modifications and the vapor pressure value
of form II at 391 K, the temperature dependence of saturated vapor pressure and thermodynamic sublimation parameters for modification
II were also estimated (ΔG
sub298=56.1 kJ mol−1; ΔH
sub298=115.9±0.9 kJ mol−1; ΔS
sub298=200±3 J mol−1 K−1). The results indicate that the modifications are monotropically related, which is in contrast to findings recently reported
found by classical thermochemical methods. 相似文献
13.
J. Leitner K. Růžička D. Sedmidubský P. Svoboda 《Journal of Thermal Analysis and Calorimetry》2009,95(2):397-402
Heat capacity and enthalpy increments of calcium niobates CaNb2O6 and Ca2Nb2O7 were measured by the relaxation time method (2–300 K), DSC (260–360 K) and drop calorimetry (669–1421 K). Temperature dependencies
of the molar heat capacity in the form C
pm=200.4+0.03432T−3.450·106/T
2 J K−1 mol−1 for CaNb2O6 and C
pm=257.2+0.03621T−4.435·106/T
2 J K−1 mol−1 for Ca2Nb2O7 were derived by the least-squares method from the experimental data. The molar entropies at 298.15 K, S
m0(CaNb2O6, 298.15 K)=167.3±0.9 J K−1 mol−1 and S
m0(Ca2Nb2O7, 298.15 K)=212.4±1.2 J K−1 mol−1, were evaluated from the low temperature heat capacity measurements. Standard enthalpies of formation at 298.15 K were derived
using published values of Gibbs energy of formation and presented heat capacity and entropy data: Δf
H
0(CaNb2O6, 298.15 K)= −2664.52 kJ molt-1 and Δf
H
0(Ca2Nb2O7, 298.15 K)= −3346.91 kJ mol−1. 相似文献
14.
J. N. Zhang Z. C. Tan Q. F. Meng Q. Shi B. Tong S. X. Wang 《Journal of Thermal Analysis and Calorimetry》2009,95(2):461-467
The heat capacities (C
p,m) of 2-amino-5-methylpyridine (AMP) were measured by a precision automated adiabatic calorimeter over the temperature range
from 80 to 398 K. A solid-liquid phase transition was found in the range from 336 to 351 K with the peak heat capacity at
350.426 K. The melting temperature (T
m), the molar enthalpy (Δfus
H
m0), and the molar entropy (Δfus
S
m0) of fusion were determined to be 350.431±0.018 K, 18.108 kJ mol−1 and 51.676 J K−1 mol−1, respectively. The mole fraction purity of the sample used was determined to be 0.99734 through the Van’t Hoff equation.
The thermodynamic functions (H
T-H
298.15 and S
T-S
298.15) were calculated. The molar energy of combustion and the standard molar enthalpy of combustion were determined, ΔU
c(C6H8N2,cr)= −3500.15±1.51 kJ mol−1 and Δc
H
m0 (C6H8N2,cr)= −3502.64±1.51 kJ mol−1, by means of a precision oxygen-bomb combustion calorimeter at T=298.15 K. The standard molar enthalpy of formation of the crystalline compound was derived, Δr
H
m0 (C6H8N2,cr)= −1.74±0.57 kJ mol−1. 相似文献
15.
G. Wolf E. Königsberger H. G. Schmidt L.-C. Königsberger H. Gamsjäger 《Journal of Thermal Analysis and Calorimetry》2000,60(2):463-472
Although vaterite is the least stable anhydrous calcium carbonate polymorph, it is formed as a metastable phase in some normal
and pathological biomineralisation processes. In this work, thermodynamic aspects of the vaterite-calcite phase transition
were comprehensively studied. Vaterite samples were prepared by different methods and characterised for the composition, crystal
structure, specific surface and grain size. All products were identified to be pure vaterite by careful X-ray diffraction
measurements. The enthalpy and Gibbs energy of transition were determined by precise calorimetric and potentiometric measurements.
The reliability of the thermodynamic data for the vaterite-calcite phase transition derived from this work was shown by the
use of different calorimetric methods to determine the enthalpy of transition and the independent measurements of heat capacity
and entropy of vaterite. Our recommended values are Δtrs
G*=−2.9±0.2 kJ mol−1 , Δ trs
H *=−3.4±0.2 kJ mol−1 and Δ trs
S *=−1.7±0.9 J K−1 mol−1 , where the uncertainties are given as twice the standard deviations.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Jonathan F. Ojo Jide Ige Grace O. Ogunlusi Olanrewaju Owoyomi Esan S. Olaseni 《Transition Metal Chemistry》2006,31(6):782-785
The kinetics of the reactions between Fe(phen)
3
2+
[phen = tris–(1,10) phenanthroline] and
Co(CN)5X3− (X = Cl, Br or I) have been investigated in aqueous acidic solutions at I = 0.1 mol dm−3 (NaCl/HCl). The reactions were carried out at a fixed acid concentration ([H+] = 0.01 mol dm−3) and the second-order rate constants for the reactions at 25 °C were within the range of (0.151–1.117) dm3 mol−1 s−1. Ion-pair constants K
ip for these reactions, taking into consideration the protonation of the cobalt complexes, were 5.19 × 104, 3.00 × 102 and 4.02 × 104 mol−1 dm−3 for X = Cl, Br and I, respectively. Activation parameters measured for these systems were as follows: ΔH* (kJ K−1 mol−1) = 94.3 ± 0.6, 97.3 ± 1.0 and 109.1 ± 0.4; ΔS* (J K−1) = 69.1 ± 1.9, 74.9 ± 3.2 and 112.3 ± 1.3; ΔG* (kJ) = 73.7 ± 0.6, 75.0 ± 1.0 and 75.7 ± 0.4; E
a
(kJ) = 96.9 ± 0.3, 99.8 ± 0.4, and 122.9 ± 0.3; A (dm3 mol−1 s−1) = (7.079 ± 0.035) × 1016, (1.413 ± 0.011) × 1017, and (9.772 ± 0.027) × 1020 for X = Cl, Br, and I respectively. An outer – sphere mechanism is proposed for all the reactions. 相似文献
17.
A model was proposed to calculate some thermodynamic parameters for the acid dissolution process of a bentonite containing
a calcium-rich smectite as clay mineral along with quartz, opal and feldspar as impurities. The bentonite sample was treated
with H2SO4 by applying dry method in the temperature range 50–150°C for 24 h. The acid content in the dry bentonite-sulphuric acid mixture
was 45 mass%. The total content (x) of Al2O3, Fe2O3 and MgO remained in the undissolved sample after treatment was taken as an equilibrium parameter. An apparent equilibrium
constant, K
a, was calculated for each temperature by assuming K
a=(x
m−x)/x where x
m is the total oxide content of the natural bentonite. Also, an apparent change in Gibbs free energy, ΔG
ao, was calculated for each temperature by using the K
a value. The graphs of lnK
a
vs. 1/T and ΔG
ao
vs. T were drawn and then the real change in both the enthalpy, ΔH
o and the entropy, ΔS
o, values were calculated from the slopes of the straight lines, respectively. Inversely, real ΔG
o and K values were calculated from the real ΔH
o and ΔS
o values through ΔG
o = −RT ln K = ΔH
o − TΔS
o equation. The best ΔH
o and ΔS
o fittings to this relation were found to be 65687 J mol−1 and 164 J mol−1K−1, respectively. 相似文献
18.
H. X. Ma B. Yan Z. N. Li J. R. Song R. Z. Hu 《Journal of Thermal Analysis and Calorimetry》2009,95(2):437-444
The title compound 3,3-dinitroazetidinium (DNAZ) 3,5-dinitrosalicylate (3,5-DNSA) was prepared and the crystal structure has
been determined by a four-circle X-ray diffractometer. The thermal behavior of the title compound was studied under a non-isothermal
condition by DSC and TG/DTG techniques. The kinetic parameters were obtained from analysis of the TG curves by Kissinger method,
Ozawa method, the differential method and the integral method. The kinetic model function in differential form and the value
of E
a and A of the decomposition reaction of the title compound are f(α)=4α3/4, 130.83 kJ mol−1 and 1013.80s−1, respectively. The critical temperature of thermal explosion of the title compound is 147.55 °C. The values of ΔS
≠, ΔH
≠ and ΔG
≠ of this reaction are −1.35 J mol−1 K−1, 122.42 and 122.97 kJ mol−1, respectively. The specific heat capacity of the title compound was determined with a continuous C
p mode of mircocalorimeter. Using the relationship between C
p and T and the thermal decomposition parameters, the time of the thermal decomposition from initiation to thermal explosion (adiabatic
time-to-explosion) was obtained. 相似文献
19.
Sayed Z. Mohammadi Mohammad A. Karimi Daryoush Afzali Fatemeh Mansouri 《Central European Journal of Chemistry》2010,8(6):1273-1280
Two series of activated carbon have been prepared by chemical activation of Amygdalus Scoparia shell with phosphoric acid or zinc chloride for the removal of Pb(II) ions from aqueous solutions. Several methods were employed
to characterize the active carbon produced. The surface area was calculated using the standard Brunauer-Emmet-Teller method.
The microstructures of the resultant activated carbon were observed by scanning electron microscopy. The chemical composition
of the surface resultant activated carbon was determined by Fourier transform infrared spectroscopy. In the batch tests, the
effect of pH, initial concentration, and contact time on the adsorption were studied. The data were fitted with Langmuir and
Freundlich equations to describe the equilibrium isotherms. The maximum adsorption capacity of Pb(II) on the resultant activated
carbon was 36.63 mg g−1 with H3PO4 and 28.74 mg g−1 with ZnCl2. To regenerate the spent adsorbents, desorption experiments were performed using 0.25 mol L−1 HCl. Here we propose that the activated carbon produced from Amygdalus Scoparia shell is an alternative low-cost adsorbent for Pb(II) adsorption. 相似文献
20.
Lebedev B. V. Bykova T. A. Lobach A. S. 《Journal of Thermal Analysis and Calorimetry》2000,62(1):257-265
The temperature dependence of the molar heat capacity (C0
p) of hydrofullerene C60H36 between 5 and 340 K was determined by adiabatic vacuum calorimetry with an error of about 0.2%. The experimental data were
used for the calculation of the thermodynamic functions of the compound in the range 0 to340 K. It was found that at T=298.15 K and p=101.325 kPa C0
p (298.15)=690.0 J K−1 mol−1,Ho(298.15)−Ho(0)= 84.94 kJ mol−1,So(298.15)=506.8 J K−1 mol−1, Go(298.15)−Ho(0)= −66.17 kJ mol−1. The standard entropy of formation of hydrofullerene C60H36 and the entropy of reaction of its formation by hydrogenation of fullerene C60 with hydrogen were estimated and at T=298.15 K they were ΔfSo= −2188.4 J K−1 mol−1 and ΔrSo= −2270.5 J K−1mol−1, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献