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Global Atmospheric Evolution: Impact of Anthropogenic Activities
Hydrogen cyanide fixed as sodium cyanide was assayed by a
potentiometric method with a silver nitrate solution in the presence of
ammoniac.
Carbonyl compounds fixed as hydrazones were separated and assayed
by high performance liquid chromatography.
Isocyanates converted to stable derivatives by 1-(2- methoxyphenyl)
piperazine were also analyzed by high performance liquid
chromatography.
Hydrocarbons were separated by gas chromatography, and mass
spectrometry allowed for qualitative and quantitative analyses.
Carbon monoxide reacted on palladium and cacotheline; the formed
deri vati ve was determined by visible spectrophotometry.
3 RESULTS AND DISCUSSION
3.1 Acrylic varnish
DT A showed a decomposition endothermal peak at 392°C and another thermal
peak at 485°C, corresponding to an exothermal phenomenon. TG showed a twostep decomposition. The first step was steep.
From 240°C to 425°C the weight loss was 82%, or a rate of weight loss of 2,23%
min. The second step corresponded to the exothermal phenomenon: the weight
loss was about 15% from 425° to 509°C, i.e. a rate of weight loss of 0,88 %/min.
Results of carbonyl compound assays (Table 1) showed the prevalence of
acetaldehyde (69%), acrolein (13%) and formaldehyde (10%). They formed 92%
of the total amount of aldehydes and ketones.
These results prevailed on the industrial users to choose a lower heating
temperature for their thermal treatment. Therefore, thermal analyses had been
realized up to 350°C, with a heating rate of 90°C/min (Table 2).
DT A showed only two endothermal phenomena at about 167°C and 340°C but no
exothermal peak. TO presented only one stage of weight loss, beginning at 230°C,
with a rate of 1,65%/min.
Analyses of aldehydes and ketones showed the predominance of acetaldehyde and
formaldehyde which together represented 91,5% of all carbonyl compounds, but
only a very low amount of acrolein was found (Table 2).
It was very important to avoid both an exothermal phenomenon and a highly
irritant gas emission.
Global Atmospheric Evolution: Impact of Anthropogenic Activities
Hydrogen cyanide fixed as sodium cyanide was assayed by a
potentiometric method with a silver nitrate solution in the presence of
ammoniac.
Carbonyl compounds fixed as hydrazones were separated and assayed
by high performance liquid chromatography.
Isocyanates converted to stable derivatives by 1-(2- methoxyphenyl)
piperazine were also analyzed by high performance liquid
chromatography.
Hydrocarbons were separated by gas chromatography, and mass
spectrometry allowed for qualitative and quantitative analyses.
Carbon monoxide reacted on palladium and cacotheline; the formed
deri vati ve was determined by visible spectrophotometry.
3 RESULTS AND DISCUSSION
3.1 Acrylic varnish
DT A showed a decomposition endothermal peak at 392°C and another thermal
peak at 485°C, corresponding to an exothermal phenomenon. TG showed a twostep decomposition. The first step was steep.
From 240°C to 425°C the weight loss was 82%, or a rate of weight loss of 2,23%
min. The second step corresponded to the exothermal phenomenon: the weight
loss was about 15% from 425° to 509°C, i.e. a rate of weight loss of 0,88 %/min.
Results of carbonyl compound assays (Table 1) showed the prevalence of
acetaldehyde (69%), acrolein (13%) and formaldehyde (10%). They formed 92%
of the total amount of aldehydes and ketones.
These results prevailed on the industrial users to choose a lower heating
temperature for their thermal treatment. Therefore, thermal analyses had been
realized up to 350°C, with a heating rate of 90°C/min (Table 2).
DT A showed only two endothermal phenomena at about 167°C and 340°C but no
exothermal peak. TO presented only one stage of weight loss, beginning at 230°C,
with a rate of 1,65%/min.
Analyses of aldehydes and ketones showed the predominance of acetaldehyde and
formaldehyde which together represented 91,5% of all carbonyl compounds, but
only a very low amount of acrolein was found (Table 2).
It was very important to avoid both an exothermal phenomenon and a highly
irritant gas emission.