A low-cost waste biomass generated from a food industry, apricot shells, was subjected to alkali modification in order to compare morphology, crystalline structure and thermal stability of native and modified biomass, accompanied by their cellulose-rich fractions. The surface morphology and structure of compared samples were analysed by the scanning electron microscopy (SEM) and mercury porosimetry. Furthermore, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis (TG/DTA) were applied. The results have shown that after alkaline treatment, inter- and intra-particle porosity in the material rises, resulting in increase of the total surface area. The XRD diffractograms showed that crystallinity index increased together with crystallite size, suggesting that modified sample has more ordered crystalline structure than native sample (also confirmed by the FTIR analysis). Although the cellulose-rich fraction extracted from the alkali-modified sample showed higher thermal stability, the overall thermal analysis revealed that alkali-modified biomass has lower thermal stability than the native sample. This indicates that this type of modification will improve the fuel properties of this lignocellulosic biomass and imply its possible application in energy recovery process.

Graphical abstract

对食品工业（杏壳）产生的低成本废生物质进行了碱改性，以比较天然和改性生物质及其富含纤维素的馏分的形态，晶体结构和热稳定性。通过扫描电子显微镜（SEM）和水银孔率法分析了比较样品的表面形态和结构。此外，应用了傅里叶变换红外光谱（FTIR），X射线衍射（XRD）和热分析（TG / DTA）。结果表明，在碱处理之后，材料中的颗粒间和颗粒内孔隙率增加，导致总表面积增加。XRD衍射图表明，结晶度指数随晶粒尺寸的增加而增加，这表明改性样品比天然样品具有更多有序的晶体结构（也由FTIR分析证实）。尽管从碱改性样品中提取的富含纤维素的馏分显示出较高的热稳定性，但总体热分析表明，碱改性生物质的热稳定性低于天然样品。这表明这种类型的修饰将改善木质纤维素生物质的燃料性质，并暗示其在能量回收过程中的可能应用。

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