Faculty of Energy and Fuels, AGH University of Science and Technology, 30 Mickiewicza Avenue, 30-059, Krakow, Poland.
Depto. de Industrias, Facultad de Ciencias Exactas y Naturales, Instituto de Tecnología de Alimentos y Procesos Químicos ITAPROQ, CONICET, Universidad de Buenos Aires, Int. Güiraldes 2620, Ciudad Universitaria, (C1428BGA), Buenos Aires, Argentina.
Sci Rep. 2022 Sep 12;12(1):15301. doi: 10.1038/s41598-022-19383-2.
This paper presents the results of a study on the influence of the degree of impregnation and activation temperature on the formation of the porous structure of activated carbons (ACs) obtained from Pine cones by the chemical activation process using potassium hydroxide as an activator. The advanced new numerical clustering based adsorption analysis (LBET) method, together with the implemented unique numerical procedure for the fast multivariant identification were applied to nitrogen and carbon dioxide adsorption isotherms determined for porous structure characterization of the ACs. Moreover, the Quenched Solid Density Functional Theory (QSDFT) method was chosen to determine pore size distributions. The results showed a significant influence of the primary structure of Pine cones on the formation of the porous structure of the developed ACs. Among others, it was evidenced by a very high degree of surface heterogeneity of all the obtained ACs, irrespective of the degree of impregnation with potassium hydroxide and the activation temperature. Moreover, the analysis of carbon dioxide adsorption isotherms showed, that the porous structure of the studied ACs samples contains micropores accessible only to carbon dioxide molecules. The results also showed a significant advantage of the LBET method over those conventionally used for porous structure analysis based on Brunauer-Emmett-Teller (BET) and Dubinin-Raduskevich (DR) equations, because it takes into account surface heterogeneities. The novel analyses methods were more fully validated as a reliable characterization tool, by extending their application to the isotherms for ACs developed from the same precursor by phosphoric acid activation, and for samples arising from these ACs, further subjected to additional post-treatments. The effect of the raw material used as precursor was moreover analysed by comparison with previous reported results for other ACs. The complementarity of the results obtained with the LBET and QSDFT methods is also noteworthy, resulting in a more complete and reliable picture of the analyzed porous structures.
本文介绍了一项研究的结果，该研究探讨了浸渍程度和活化温度对使用氢氧化钾作为活化剂通过化学活化过程从松果中获得的活性炭（AC）的多孔结构形成的影响。先进的新基于数值聚类的吸附分析（LBET）方法，以及针对 AC 多孔结构特性确定的氮和二氧化碳吸附等温线快速多变量识别的实施独特数值程序，被应用于研究。此外，选择了淬火固体密度泛函理论（QSDFT）方法来确定孔径分布。研究结果表明，松果的初级结构对所开发的 AC 多孔结构的形成有显著影响。其中，所有获得的 AC 都具有非常高的表面异质性，这表明了这一点，而与氢氧化钾的浸渍程度和活化温度无关。此外，二氧化碳吸附等温线的分析表明，所研究的 AC 样品的多孔结构包含仅可被二氧化碳分子进入的微孔。结果还表明，LBET 方法相对于传统的基于 Brunauer-Emmett-Teller（BET）和 Dubinin-Raduskevich（DR）方程的多孔结构分析方法具有显著优势，因为它考虑了表面异质性。通过将其应用于由相同前体通过磷酸活化开发的 AC 的等温线以及源自这些 AC 并进一步进行其他后处理的样品，对新的分析方法进行了更充分的验证，作为可靠的表征工具。通过与其他 AC 的先前报道结果进行比较，还分析了用作前体的原材料的影响。LBET 和 QSDFT 方法获得的结果的互补性也值得注意，这导致了对分析多孔结构的更完整和可靠的描述。
