1 Introduction
2 Experimental
2.1 Sample preparation
2.2 Analytical procedures
3 Results and discussion
3.1 Elemental composition of the chars and activated carbons
Sample | Ash | Cdaf
| Hdaf
| Ndaf
| Sdaf
| Odaf*
| Yield |
---|---|---|---|---|---|---|---|
M | 9.0 | 49.0 | 11.3 | 3.3 | 0.1 | 36.3 | – |
M5 | 26.1 | 72.3 | 2.1 | 4.5 | 0.3 | 20.8 | 32.1 |
M7 | 30.5 | 77.4 | 0.7 | 4.0 | 0.6 | 17.3 | 25.3 |
M5A7 | 33.9 | 79.8 | 0.4 | 4.8 | 0.4 | 14.6 | 73.0 |
M7A7 | 38.0 | 82.8 | 0.6 | 4.7 | 0.5 | 11.4 | 77.6 |
M5A8 | 49.2 | 59.1 | 2.5 | 5.2 | 0.3 | 32.9 | 59.3 |
M7A8 | 53.9 | 81.0 | 2.3 | 6.9 | 0.6 | 9.2 | 65.5 |
3.2 Textural parameters of the activated carbons
Sample | Surface area (m2/g) | Micropore area (m2/g) | Pore volume (cm3/g) | Micropore volume (cm3/g) | Average pore diameter (nm) |
---|---|---|---|---|---|
M5A7 | 2 | 0.01 | 0.007 | ~0 | 31.78 |
M7A7 | 4 | 0.05 | 0.009 | ~0 | 17.71 |
M5A8 | 206 | 100 | 0.118 | 0.04 | 3.79 |
M7A8 | 125 | 51 | 0.079 | 0.02 | 3.63 |
3.3 Acid–base properties of the precursor, chars and activated carbons
Sample | Acidic groups (mmol/g) | Basic groups (mmol/g) | pH |
---|---|---|---|
M | 5.25 | 1.29 | 4.3 |
M5 | 0.00 | 5.01 | 11.2 |
M7 | 0.00 | 5.20 | 11.6 |
M5A7 | 0.00 | 5.51 | 10.4 |
M7A7 | 0.00 | 5.75 | 11.0 |
M5A8 | 0.00 | 7.74 | 10.6 |
M7A8 | 0.00 | 8.37 | 11.2 |
3.4 Nitrogen dioxide adsorption
Sample | Dry conditions (mg/g) | Mix dry conditions (mg/g) |
---|---|---|
M5A7 | 16.3 | 102.1 |
M7A7 | 13.4 | 26.9 |
M5A8 | 12.0 | 23.1 |
M7A8 | 29.2 | 66.7 |
Material | NO2/Iodine adsorption (mg/g) | Maximum adsorption capacity (mg/g) | References |
---|---|---|---|
Plum stones | NO2
| 65.0 | (Nowicki et al. 2010) |
Sawdust pellets | NO2
| 43.1 | (Pietrzak 2010) |
Waste tires | NO2
| 11.4 | (Hofman and Pietrzak 2011) |
CWZ-22 | Iodine | Min. 750.0 | (Nowicki et al. 2015) |
Norit SX2 | Iodine | Min. 800.0 | (Nowicki et al. 2015) |
Pistachio nut shells | Iodine | 1280.0 | (Nowicki et al. 2015) |
Cherry stones | Iodine | 996.0 | (Pietrzak et al. 2014) |