Frequently Asked Questions:
How do you recover solvents from Nitrocellulose based ink or paint systems?
The following information and recommendations detail how to recover solvents from Nitrocellulose based ink and paint systems. This information is based on years of experience recovering solvents from Nitrocellulose mixtures.
Nitrocellulose is an ester of cellulose with nitric acid, and it helps keep pigments dispersed in solvent. It also acts as a binder for the pigments after the solvent evaporates.
Nitrocellulose is unstable at temperatures above 180 degrees C and decomposes exothermically into a gas. Nitrocellulose should never be heated to this temperature or contact any surfaces above this temperature. Decomposition of Nitrocellulose creates Nitrous oxides. These unpleasant gases are brown in color and should not be inhaled.
Nitrocellulose does not decompose at temperatures below 100 degrees C. Only very slight decomposition occurs in the temperature range of 100 to 110 degrees C. Actual cases of heating Nitrocellulose mixtures for extended periods of time in tile temperature range of 100 to 110 degrees C. have not showed signs of decomposition.
DISTILLATION PROCEDURES:
Solvent should be recovered from Nitrocellulose based inks under relatively low and controlled temperatures in order to prevent decomposition of the Nitrocellulose. Solvents that have high boiling points must be distilled under a vacuum. Solvents boil at much lower temperatures when a vacuum is used. The lower distillation temperature enables solvent extraction without exceeding the decomposition temperature of nitrocellulose.
When recovering solvent from waste streams containing Nitrocellulose products, special precautions must be taken.
Residues containing Nitrocellulose can degrade if overheated. Degradation will usually release unpleasant brown fumes.
Degradation can occur when the residues have been allowed to become 'dry', ie. all the solvent has been removed and the residues continue to be heated. Degradation also occasionally occurs in the presence of solvent, when residues clinging to the sides of the unit can 'dry out' as the level drops.
The chances of degradation occurring can be minimized by observing the following:
Add either paraffin wax or old oil to each batch. This will keep the residues moist after all the solvent has been removed.
Keep process temperatures as low as possible. Ask G-Tech for advice on the correct process conditions as these will vary with the solvent used. Vacuum assistance is strongly recommended to reduce process temperatures.
Keep the Recovery Unit throughly clean. Do not allow old residues to build up.
Should a degradation occur and fumes are emitted from the unit, switch the unit off and leave it with cooling water running until it is cold, then remove the residue. Under no circumstance open the lid while the unit is still warm.
What are the physical specifications of the solvents used in the processes described?
| Solvent |
Molecular Weight |
Boiling Point (Celcius) |
LEL Vol % |
LEL @ 25degC g/m3 |
Sol in Water @ 20degC % wt |
| Acetone |
58 |
56 |
2.15 |
55.7 |
Completely |
| Benzene |
78 |
80 |
1.40 |
42.2 |
0.08 |
| n-Butyl Acetate |
116 |
126 |
1.70 |
88.0 |
1.0 |
| n-Butyl Alcohol |
74 |
118 |
1.45 |
47.9 |
7.8 |
| iso-Butyl Alcohol |
74 |
108 |
1.68 |
55.5 |
8.5 |
| Carbon Tetrachloride |
154 |
77 |
N/A |
N/A |
0.08 |
| Chloroform |
119 |
61 |
N/A |
N/A |
0.8 |
| Cyclo-hexane |
84 |
80 |
1.35 |
45.4 |
<0.001 |
| Cyclohexanone |
98 |
156 |
3.20 |
140 |
2.3 |
| 1.2 Dichloroethene |
99 |
84 |
6.2 |
255 |
0.87 |
| 1.1 Dichloroethylene |
97 |
37 |
9.7 |
420 |
0.021 |
| Ethyl Acetate |
88 |
77 |
2.25 |
80.5 |
7.9 |
| Ethyl Alcohol |
46 |
78 |
3.3 |
63.1 |
Completely |
| n-Heptane |
100 |
98 |
1.05 |
43.7 |
0.005 |
| n-Hexane |
86 |
69 |
1.25 |
42.9 |
0.014 |
| Methyl Alcohol |
32 |
65 |
6.72 |
89.2 |
Completely |
| Methyl Ethyl Ketone |
72 |
80 |
1.81 |
58.2 |
26 |
| Methyl iso-Butyl Ketone |
102 |
116 |
1.4 |
58.2 |
1.7 |
| Methylen Chloride |
85 |
41 |
N/A |
N/A |
2.0 |
| n-Pentane |
72 |
36 |
1.3 |
38.4 |
0.036 |
| Perchloroethylene |
156 |
121 |
N/A |
N/A |
0.04 |
| n-Propyl Acetate |
102 |
101 |
2.0 |
91.1 |
1.8 |
| iso-Propyl Acetate |
102 |
89 |
2.0 |
91.1 |
2.9 |
| n-Propyl Alcohol |
60 |
97 |
2.15 |
57.6 |
Completely |
| iso-Propyl Alcohol |
50 |
82 |
2.02 |
54.1 |
Completely |
| iso-Propyl Ether |
102 |
68 |
1.3 |
55.2 |
0.9 |
| Styrene |
104 |
145 |
1.1 |
46.9 |
0.025 |
| Tetrahydrofuran |
72 |
66 |
1.84 |
59.0 |
Completely |
| Toluene |
92 |
111 |
1.3 |
53.3 |
0.047 |
| 1,1,1, Trichloroethane |
133 |
74 |
N/A |
N/A |
0.17 |
| Trichloroethene |
131 |
87 |
12 |
653.9 |
0.1 |
| Xylene |
106 |
138-144 |
1.0 |
47.3 |
<0.001 | |
