Bio Resource Center, Institute for Advanced Engineering, Yongin-si 17180, Korea.
Molecules. 2020 Oct 6;25(19):4561. doi: 10.3390/molecules25194561.
Spent activated carbon (SAC) usually exhibits a low specific surface area due to its high ash contents. In this study, pre-treatments, such as heat and acid treatments, were optimized to improve this feature. The heat pre-treatment did not reduce the ash content, nor did it increase the surface area. Because metallic ions adsorbed in SACs turn into ash upon the heat treatment. In the acid pre-treatment, the volatiles and fixed carbon were increased with decreasing ash contents. In this study, it was found that the surface area increase was correlated with the ratio between fixed carbon and ash. Among the pre-treatment methods, the combined heat and acid pre-treatment method highly increased the ratio, and therefore led to the surface area increase. Additionally, the acid pre-treatment was carried out using different types of acid (organic and inorganic acids) solutions to further improve the surface areas. The organic acid treatment caused a significant structural collapse compared to the inorganic acid treatment, decreasing the surface area. In particular, HPO effectively removed ashes adsorbed on the activated carbon surface and regenerated the exhausted activated carbon. Both the heat and acid pre-treatments before chemical activation resulted in the positive effects such as strong desorption of pollutants and ashes within the internal structure of the activated carbon. Therefore, the regeneration introduced in this study is methodically the best method to regenerate SAC and maintain a stable structure.
废活性炭（SAC）通常由于其高灰分含量而表现出低比表面积。在本研究中，优化了预处理，如热处理和酸处理，以改善这一特性。热预处理并没有降低灰分含量，也没有增加表面积。因为吸附在 SAC 中的金属离子在热处理时变成灰分。在酸预处理中，随着灰分含量的降低，挥发分和固定碳增加。在本研究中，发现表面积的增加与固定碳和灰分的比值有关。在预处理方法中，组合的热和酸预处理方法大大提高了该比值，从而导致表面积的增加。此外，还使用不同类型的酸（有机和无机酸）溶液进行了酸预处理，以进一步提高表面积。与无机酸处理相比，有机酸处理导致结构明显坍塌，从而降低了表面积。特别是 HPO 有效地去除了吸附在活性炭表面的灰分，并使耗尽的活性炭得到再生。化学活化前的热处理和酸处理都对活性炭内部结构中的污染物和灰分有很强的解吸作用。因此，本研究中引入的再生方法是一种从方法论上最好的 SAC 再生和维持稳定结构的方法。
