Abstract
The effects of physical structure (pore structure) on behavior of water in lignite coal and activated carbon (AC) samples were investigated by using Differential Scanning Calorimetry (DSC) and low-temperature X-ray diffraction (XRD) techniques. AC samples with different pore structures were prepared at 800 °C in steam and the results were compared with that of parent lignite coal. The DSC results confirmed the presence of two types of freezable water that freeze at -8 °C (free water) and -42 °C (freezable bound water). A shift in peak position of free water (FW) towards lower temperature was observed in AC samples compared to the lignite coal with decreasing water loading. The amount of free water (FW) increased with increasing gasification conversion. The amounts of free and freezable bound water (FBW) in AC samples were calculated and correlated to pore volume and average pore size. The amount of FW in AC samples is well correlated to the pore volume and average pore size of the samples, while an opposite trend was observed for FBW. The low-temperature XRD analysis confirmed the existence of non-freezable water (NFW) in coal and AC with the boundary between the freezable and non-freezable water (NFW) determined.
| Original language | English |
|---|---|
| Pages (from-to) | 138-147 |
| Number of pages | 10 |
| Journal | Journal of Colloid and Interface Science |
| Volume | 477 |
| DOIs | |
| Publication status | Published - 1 Sept 2016 |
| Externally published | Yes |
Keywords
- Freezable water
- Lignite
- Low temperature DSC
- Low temperature XRD
- Non-freezable water
- Pore-water interaction