الفهرس 
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Abstract
In the present thesis one used differential
thermal analysis-thermogravimetery techniques,
XRD, III ab s orp t t on and nitrogen gas adsorption
.to study the t he r-rna I d ecompos I tion of nickel acetate
t-e t r auy dr a te and uranyl acetate d i hy d r-a t e .
A s uunua ry or tmport a nt re s uI t s and conclusion
of various parts e f the present thesis is given
below.
•
The metal acetate used wet’e, nickel acetate
tetrahydrate (HIJII), and urany I acetate d i hy dr-a t e
(Fluka), reagent grade, used without further purification.
The starting materials were sieved and
samples of particle size less than 125!Jm
used for IJTA-TGexperimentals.
The resul t s show the thermal d ecompoa I tLon
where
reaction of nickel acetate tetrahydrate. IJTA-TG
studies showed that nickel acetate tetrahydrate
loses weight in two endothermic step. in atmosphere
of ni t rog en. The first step endotllermic
peak is in the range of 65 to 130°C and is due
to the loss of wat er- of crystallization. Where
as the second endothermic peak is in the range
260 to 3’75°C and is due to decomposition of atlhydrous
salt to give nickel oxide, acetone and CU2·
The DTA curve showed a dented endothermic
peak at about 330°C, which indicates the main
acetate decomposition Occur in at least two stages.
The second stage of the anhydrous salt may indicate
the presence of an intermediate mixed acetateoxide
salt or may indicate the product of carbonate.
In air, the first decompositon step is characterized
by a sharp endothermic peak in the range
of 70-1300c and is again attributed to the loss
of water crystallization. Whereas, the second decomposition
step is exottlermic peak at about 270-
290°C. It can be concluded that the decomposi tion
of the acetone vapor occures on contact with the
oxygen, with the consequent marked endothermal
ac tivity. The DrA curves show that the dehydra tion
occure in one step. Hence, the decomposition of
step II could involve the libration of acetone
and carbon dioxide. However, the intermediate
mixed acetate oxide salt followed by decomposition
to oxide.
The kinetics ·of the isothermal decomposition
of nickel acetate tetrahydrate were studied in
nitrogen and air atmosphere at different temperature
range. The a-t data were analyzed by the
method of L.Il. according to the various kinetic
equa tions. The results show that the best fit
data is obtained according to phase boundary
---~- - -- - - --- -~---- ----- -----------------
141
controlled reaction (H
2
random nucleation model
and H3 function), and
A2· Other models gave
a less statisfactory fit to the experimental data.
Also, we found that H2 model gave highest correlation
coefficient.
The activation parameters for the decomposition
of nickel acetate tetrallydrate were calculated
on the basis of R 2’ R3 models. The activation
energies of the dehydration step were found to be 105
-I
and 90 kJ mol for air and ni trogen atmosphere.
The activation energies
equals 114 kJ mol -1
and 205 k J 1001-1 in air
of the isothermal kinetic
in nitrogen atmosphere,
atmosphere.
The kinetic analysis on the non-isothermal
decomposition of nickel acetate tetrahydrate was
studied. The analysis of TG curves assuming HZ
function, which gave the highest correlation coeficient
in the analysis of isothermal data and made
a cri tical comparison of the three dynamic methods:
Diefallah’s composite method, Coats-Redfern method
and Ozawa integral method.
The kinetics of the decomposition reaction
on the nickel acetate tetrahydrate were studied
in nitrogen and azr- at dLf’f’er-en t heating rate-s
of Z, 5, 10, 15, and 20oC/min. The activation
parameters were calculated according to HZ & ”3 modeL
142
Wherever, Ozawa method gives a more satisfactory
kinetic analysis than that of the other methods.
The thermal decomposition reaction of urany,l
acetate dihydrate were carried out in atmosphere
of nitrogen and air. DTA-TO studies showed that
urany 1 acetate dihydrate loses weigh t in two endothermic
peaks in nitrogen. The first step is a
broad endothermib peak in the range 90-130oC corresponding
to the dehydra tion stage. The second s t.ep
(decomposition step) is also broad endothermic
peak in range of 320-370oC. In air, DTA-TO showed
that uranyl acetate dihydrate loses weight in
two steps. The first step is characterized by a
broad endothermic peak in range of 95-130oC. The
second step starts at 300°C and is characterized by
exothermic peak at 335°C. However, decomposi tion of
the
with
ace tone vapor occures on contac t wi th oxygen
consequent marked exothermic activity.
The kinetic of the isothermal of decomposition
r eac tion of urany I aceta te dihydra te were studied
in nitrogen and air at different temperature
range. The a -t data were analysed by the method
of L. R. according to. the various kinetic equations.
The result show tha t the bes t fi t of da ta is obtained
for random nucleation models and phase boundary
controlled model, other models give a less
satisfactory fits.
The activation parameters for the decompposition
of uranyl acetate dihydrate were calculated
on the basis of A2 and A
3
models.
The kinetics analysis of the non-isothermal
decomposl tion of uranyl acetate dihydrate was
stucJied. The analysis of TO cur-v es assuming A
2
function, which gave the highest correlation coefficient
in the analysis of isotllermal data and
made a critical comparison of the three dynamic
method: Diefallah’s composite, Coats-Refern, and
Ozawa integrals methods.
The kinetics of the decomposi tion reaction
on the nickel acetate tetrahydrate Were studied
in nitrogen and air at different heating rates
of 2, 5, 15, 200C/min.
Some IR, XRD, suraface area measurements were
carried out for different heat treated samples of
nickel acetate and uranyl acetate to support the
TO dynamic measurements.