1 Introduction
2 Experimental
2.1 Preparation of activated carbons
2.2 Analytical procedures
2.3 Adsorption studies
2.3.1 Adsorption from gas phase
2.3.2 Adsorption from liquid phase
3 Results and discussion
3.1 Elemental composition of the chars and activated carbons
Sample | Ash | VM*
|
C
daf
**
|
H
daf
|
N
daf
|
S
daf
|
O
daf
***
| Yield |
---|---|---|---|---|---|---|---|---|
CC | 1.0 | 64.6 | 43.8 | 6.2 | 1.7 | 0.0 | 48.3 | – |
CC5 | 2.9 | 17.3 | 85.6 | 3.1 | 0.4 | 0.0 | 10.8 | 26.1 |
CC8 | 7.0 | 11.6 | 85.5 | 0.9 | 0.3 | 0.0 | 13.3 | 16.6 |
CC5PA | 4.4 | – | 86.5 | 1.5 | 0.8 | 0.0 | 11.2 | 76.7 |
CC8PA | 7.6 | – | 89.9 | 0.7 | 0.6 | 0.0 | 8.8 | 79.1 |
CC5CA | 0.6 | – | 86.4 | 0.9 | 0.7 | 0.0 | 12.0 | 62.1 |
CC8CA | 0.7 | – | 91.1 | 0.6 | 0.6 | 0.0 | 7.8 | 67.0 |
3.2 Textural parameters of chars and activated carbons
Sample | Total surface area [m2/g] | Micropore area [m2/g] | External area [m2/g] | Total pore volume [cm3/g] | Micropore volume [cm3/g] | Mesopore volume [cm3/g] |
V
mic/V
t
| Average pore diameter [nm] |
---|---|---|---|---|---|---|---|---|
CC5 | 19 | 8 | 10.8 | 0.026 | 0.002 | 0.024 | 0.08 | 5.56 |
CC8 | 43 | 34 | 7.6 | 0.05 | 0.02 | 0.03 | 0.40 | 4.68 |
CC5PA | 352 | 337 | 14.9 | 0.21 | 0.19 | 0.02 | 0.90 | 2.44 |
CC8PA | 566 | 552 | 13.5 | 0.33 | 0.30 | 0.03 | 0.91 | 2.30 |
CC5CA | 1213 | 1164 | 49.1 | 0.73 | 0.63 | 0.10 | 0.86 | 2.42 |
CC8CA | 747 | 735 | 12.4 | 0.43 | 0.40 | 0.03 | 0.93 | 2.29 |
3.3 Acid-base properties of the chars and activated carbons
Sample | pH | Acidic groups [mmol/g] | Basic groups [mmol/g] | Total content of surface oxides [mmol/g] |
---|---|---|---|---|
CC5 | 9.8 | 0.00 | 1.04 | 1.04 |
CC8 | 10.5 | 0.16 | 1.51 | 1.67 |
CC5PA | 9.5 | 0.00 | 1.83 | 1.83 |
CC8PA | 10.0 | 0.08 | 1.72 | 1.80 |
CC5CA | 5.2 | 1.23 | 0.35 | 1.58 |
CC8CA | 5.0 | 1.61 | 0.08 | 1.69 |
3.4 Sorption capacities of the chars and activated carbons toward nitrogen dioxide
Sample | Dry conditions [mg/g] | Wet conditions [mg/g] |
---|---|---|
CC5 | 0.0 | 0.0 |
CC8 | 12.8 | 25.9 |
CC5PA | 26.2 | 18.3 |
CC8PA | 35.4 | 14.4 |
CC5CA | 40.6 | 17.0 |
CC8CA | 48.4 | 28.0 |
3.5 Sorption abilities of the chars and activated carbons toward H2S
Sample | Dry conditions [mg/g] | Wet conditions [mg/g] | ||
---|---|---|---|---|
D | MD | W | MW | |
CC5 | 0.0 | 0.0 | 0.0 | 0.0 |
CC8 | 6.7 | 9.5 | 8.7 | 7.8 |
CC5PA | 16.5 | 19.7 | 18.0 | 10.8 |
CC8PA | 19.5 | 49.2 | 45.1 | 29.4 |
CC5CA | 5.0 | 5.4 | 6.8 | 5.0 |
CC8CA | 4.1 | 6.1 | 6.3 | 4.7 |
3.6 Sorption abilities from liquid phase
Sample | Iodine adsorption [mg/g] | Methylene blue adsorption [mg/g] |
---|---|---|
CC5 | 190 | 12 |
CC8 | 530 | 6 |
CC5PA | 680 | 18 |
CC8PA | 890 | 78 |
CC5CA | 1230 | 216 |
CC8CA | 1360 | 270 |