Institut Jean Lamour, UMR Université de Lorraine - CNRS 7198, ENSTIB, 27 rue Philippe Séguin, BP 21042, 88051, Epinal cedex 9, France.
Laboratory of Research: Process Engineering and Industrial Systems (LR11ES54), National School of Engineers of Gabès, University of Gabès, 6026, Gabès, Tunisia.
Environ Sci Pollut Res Int. 2018 Jan;25(2):1497-1507. doi: 10.1007/s11356-017-0366-7. Epub 2017 Oct 31.
The main purpose of this study was to understand the effect of time and temperature during the hydrothermal carbonisation (HTC) of olive stones (OS). For that purpose, the severity factor was introduced, by which the effect of the HTC conditions on the resultant products could be described. HTC was carried out at various temperatures (160, 180, 200, 220 and 240 °C) and times (3, 6, 12, 24 and 48 h) for producing 25 hydrochars. The yield to hydrochar varied from 70 to 50%. Hydrochars were all submitted to thermogravimetric and elemental analysis. The liquid fractions were also recovered and analysed in order to valorise OS as completely as possible. Thus, highly added-value products such as furfural and 5-hydroxymethylfurfural were detected. At the highest temperature and time, the hydrochar elemental composition was similar to that of lignite coals. Hydrochars were further carbonised at 900 °C, leading to materials with surface areas as high as 1200 m g and with narrow pore size distributions centred on 0.5 nm. The severity factor allowed finding clear tendencies in the production of hydrochars and derived carbons in terms of yield, composition, and surface area, which would have been hardly analysed if the effects of temperature and time had to be considered separately. We proved that the severity factor, which use is quite uncommon in studies dealing with materials production, is a valuable tool for studying the effects of HTC experimental conditions.
本研究的主要目的是了解水热碳化（HTC）橄榄石（OS）过程中时间和温度的影响。为此，引入了苛刻因子，通过该因子可以描述 HTC 条件对最终产物的影响。HTC 在不同温度（160、180、200、220 和 240°C）和时间（3、6、12、24 和 48 h）下进行，以生产 25 种水热炭。水热炭的产率在 70%至 50%之间变化。所有水热炭都进行了热重和元素分析。还回收了液体馏分并进行了分析，以尽可能完全地利用 OS。因此，检测到了糠醛和 5-羟甲基糠醛等高附加值产品。在最高温度和时间下，水热炭的元素组成与褐煤相似。水热炭进一步在 900°C 碳化，得到的材料表面积高达 1200 m²/g，且孔径分布狭窄，集中在 0.5nm 左右。苛刻因子允许根据产率、组成和表面积在生产水热炭和衍生碳方面找到明确的趋势，如果必须分别考虑温度和时间的影响，这将很难进行分析。我们证明，苛刻因子在处理材料生产的研究中使用相当罕见，但它是研究 HTC 实验条件影响的有价值工具。
