Lv Xifeng, Cao Huan, Zhang Rui, Shen Xuehua, Wang Xiaodong, Wang Fang
The National and Local Joint Engineering Laboratory of High Efficiency and Superior-Quality Cultivation and Fruit Deep Processing Technology of Characteristic Fruit Trees in South Xinjiang, College of Chemistry and Chemical Engineering, Tarim University, Alar 843300, China.
State Key Laboratory of Organic-Inorganic Composites, Beijing 100029, China.
Nanomaterials (Basel). 2023 Jan 29;13(3):552. doi: 10.3390/nano13030552.
The research on the high-value utilization of biomass has good application prospects and is conducive to sustainable development. In this paper, three different types of activators (potassium hydroxide, phosphoric acid, and polypropylene) were used to carbonize jujube branches at high temperatures of 600 °C and 800 °C, and then the PEG/jujube charcoal composite phase change materials (PCM) were prepared by vacuum impregnation of polyethylene glycol (PEG). The results showed that the carbon support activated by polypropylene (PP) had a richer pore size distribution than the other two activation methods, and the 800 °C carbonization carrier loaded PEG had a higher phase change enthalpy than the composite material at 600 °C. The mesoporous and macroporous structures were staggered with PP-activated jujube charcoal at 800 °C, with a specific surface area of 1082.2 m²/g, the melting enthalpy of the composite material reached 114.92 J/g, and the enthalpy of solidification reached 106.15 J/g after PEG loading. The diffraction peak of the composite phase change material was the superposition of PEG and carbon matrix, which proved that the loading process was physical adsorption. After 200 thermal cycles, the melting enthalpy and crystallization enthalpy were only reduced by 4.3% and 4.1%, respectively, and they remained stable and leak-free at the melting point of PEG for 2 h, demonstrating good thermal stability of the composite phase change materials. In summary, PP has obvious advantages over traditional activation, and the carbon-supported PEG phase change composite after PP activation is a biochar energy storage material with excellent performance.
生物质高值化利用的研究具有良好的应用前景，有利于可持续发展。本文采用三种不同类型的活化剂（氢氧化钾、磷酸和聚丙烯）在600℃和800℃的高温下对枣树枝进行碳化，然后通过真空浸渍聚乙二醇（PEG）制备了PEG/枣木炭复合相变材料（PCM）。结果表明，聚丙烯（PP）活化的碳载体比其他两种活化方法具有更丰富的孔径分布，800℃碳化载体负载PEG的相变焓高于600℃的复合材料。800℃下PP活化的枣木炭具有交错的介孔和大孔结构，比表面积为1082.2 m²/g，复合材料的熔融焓达到114.92 J/g，负载PEG后凝固焓达到106.15 J/g。复合相变材料的衍射峰是PEG和碳基体的叠加，证明负载过程为物理吸附。经过200次热循环后，熔融焓和结晶焓分别仅降低了4.3%和4.1%，在PEG熔点下2 h内保持稳定且无泄漏，表明复合相变材料具有良好的热稳定性。综上所述，PP相对于传统活化具有明显优势，PP活化后的碳负载PEG相变复合材料是一种性能优异的生物炭储能材料。
