Abstract Biochar is widely used as adsorbent and catalyst carrier. Penicillin V Potassium residue (PVPR) as a hazardous waste with high organic content has the great potential to produce biochar. The adsorption performance and loading capacity of biochar largely depend on the pore structure, surface area and other physical properties. In this paper, PVPR and its pyrolysis biochar were characterized by Scanning electron microscopy (SEM), Atomic Force Microscope (AFM) and Brunauer–Emmett–Teller (BET) analysis methods. Then the changes of their 2D surface morphology, 3D roughness and pore structure with the pyrolysis temperature were analyzed using the box fractal dimension (D B ), power spectral density fractal dimension (D P ), and Frenkel-Halsey-Hill fractal dimension (D F ), respectively. Based on the above analysis, grey relational analysis was introduced to evaluate the factors affecting the surface fractal dimensions of biochars. Results indicated that the raw sample had smooth surfaces and lower fractal dimension. The release of volatiles during pyrolysis resulted in a large number of slit-shaped microporous structures on the surface of biochar. D B and D F of the biochar obtained at 400-500℃ were in the range of 1.8-1.9 and 2.8-2.9, respectively, indicating that the biochar had a more complex 2D surface morphology and pore structure. Besides, D P of the biochar obtained at 500℃ reached the maximum value, showed that the biochar had roughest surface. As the pyrolysis temperature increased to 600-700℃, the pores were transformed to the ink bottle-shaped mesopores due to the organic matter reduced greatly. Meanwhile, the K-salts on the char surface transferred from organic phase to inorganic phase. The grey correlation between D P and average roughness (Ra) reached 0.8687. Besides, the grey correlation between internal surface area of the pore and D F (high) reached 0.9362, respectively. The findings will provide guidance for further studies on the adsorption and catalytic characteristics of biochar from PVPR pyrolysis.

中文翻译：

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青霉素 V 钾渣热解生物质炭的分形特征

摘要 生物炭广泛用作吸附剂和催化剂载体。青霉素 V 钾渣 (PVPR) 作为一种有机含量高的危险废物，具有生产生物炭的巨大潜力。生物炭的吸附性能和负载能力在很大程度上取决于孔隙结构、表面积等物理性质。在本文中，PVPR 及其热解生物炭通过扫描电子显微镜 (SEM)、原子力显微镜 (AFM) 和 Brunauer-Emmett-Teller (BET) 分析方法进行了表征。然后使用箱形分形维数（DB ）、功率谱密度分形维数（DP ）和Frenkel-Halsey-Hill 分形维数（DF ）分析其2D 表面形貌、3D 粗糙度和孔隙结构随热解温度的变化，分别。根据以上分析，引入灰色关联分析来评价影响生物炭表面分形维数的因素。结果表明，原始样品具有光滑的表面和较低的分形维数。热解过程中挥发物的释放导致生物炭表面出现大量狭缝状微孔结构。400-500℃得到的生物炭的DB和DF分别在1.8-1.9和2.8-2.9的范围内，表明该生物炭具有更复杂的二维表面形貌和孔隙结构。此外，在500℃获得的生物炭DP达到最大值，表明生物炭表面最粗糙。随着热解温度升高到600-700℃，有机质大大减少，孔道转变为墨瓶状介孔。同时，炭表面的钾盐从有机相转移到无机相。DP与平均粗糙度（Ra）之间的灰色相关性达到0.8687。此外，孔隙内表面积与DF（高）之间的灰色相关性分别达到0.9362。该研究结果将为进一步研究 PVPR 热解生物炭的吸附和催化特性提供指导。