Abstract
A large amount of almond shells are disposed of every year. The anatomical and chemical characteristics of almond shells are investigated in this paper in order to contribute to better utilization of these shells. The micromorphology, surface elements, thermal stability, crystallization, chemical composition, and relative properties of almond shells are analyzed. Under observation by microscope and electron microscope, the diameter of almond shells is 300–500 μm for large holes, and 40–60 μm for small holes present in the shell. X-ray photoelectron spectroscopy shows the elements of almond shells include C (72.27%), O (22.88%), N (3.87%), and Si (0.87%). The main chemical constituents of cellulose, hemicellulose and lignin in almond shells account for 38.48%, 28.82% and 29.54%, respectively. The alkaline extract content of almond shells is 14.03%, and benzene alcohol extraction is 8.00%. The benzene alcohol extractives of almond shells mainly contain 17 types of organic compound, including benzene ring, ethylene, carbon three bond, and other mufti-functional groups. Thermal stability analysis shows almond shells mainly lose weight at 260 °C and 335 °C. These characteristics indicate that almond shells have the capacity to be used in composites and absorption materials.
Highlights
Biomass nutshell is a large yield crop residue which is generally discarded or incinerated
Almond shells have well-developed pore structure, as illustrated in Figure 1, where a row of large holes can be seen distributed in the cross section
Observed by microscope and electron microscope, almond shells have the diameter of 300–500 μm for large holes, and 40–60 μm for small holes
Summary
Biomass nutshell is a large yield crop residue which is generally discarded or incinerated. This pollutes the environment, and wastes a large amount of resources. In order to avoid this, many scholars have undertaken research into its potential uses, including the use of biomass nut shells to produce activated carbon. Ahmad et al used peanut shell adsorption of trichloroethylene for cleaning water [1], while Lan et al prepared activated carbon from Hawaii nut shells [2]. Prepared activated carbon from walnut shells, and studied its properties [3], and Yang et al formulated high specific surface area activated carbon from coconut shells by microwave heating [4].
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