Recently, the circular economy aiming at elimination of waste and the continual use of resources has attracted a lot of attentions. In the circular system, the resource recovery uses the recycled wastes as the raw material to manufacture new valuable products. This work focuses on a low-cost process, in which an activated carbon (AC) adsorbent was prepared from waste cation exchange resin by calcination and HNO₃ activation hydrothermal method. Surface structure and chemistry of AC were characterized by SEM, XRD, FTIR and Boehm titration. It was found that the acid treatment could increase the number of pores and the content of oxygen-containing functional groups on AC surface. In the adsorption experiment, Methylene blue (MB) was used to assess the adsorption capacity of AC. Experimental results showed that the highest efficiency of MB removal was achieved by AC with modification of 4M HNO₃, showing the acidification effect on the adsorption capacity of AC. Adsorption isotherms of Langmuir and Freundlich were employed to fit the experimental data. It was shown that MB adsorption on AC is more consistent with Langmuir model that assumes a homogeneous adsorption. In the adsorption kinetic analysis, the adsorption was found to follow the pseudo-second-order model, indicating that adsorption of MB on acidified AC is dominated by chemical adsorption. The study revealed that the waste ion-exchange resin is a proper precursor of carbon adsorbent for MB dye. This low-cost method would specifically reduce the environmental cost of waste disposal.

近年来，以消除浪费和资源持续利用为目标的循环经济备受关注。在循环系统中，资源回收利用回收的废物作为原材料制造新的有价值的产品。这项工作侧重于一种低成本工艺，其中通过煅烧和 HNO ₃从废阳离子交换树脂制备活性炭 (AC) 吸附剂活化水热法。AC的表面结构和化学性质通过SEM、XRD、FTIR和Boehm滴定进行表征。发现酸处理可以增加活性炭表面的孔隙数量和含氧官能团的含量。在吸附实验中，使用亚甲蓝 (MB) 来评估活性炭的吸附能力。实验结果表明，活性炭对 4M HNO _{3 的}改性达到了最高的 MB 去除效率，显示酸化对活性炭吸附能力的影响。Langmuir 和 Freundlich 的吸附等温线被用来拟合实验数据。结果表明，活性炭上的 MB 吸附与假设均匀吸附的朗缪尔模型更一致。在吸附动力学分析中，发现吸附遵循准二级模型，表明 MB 在酸化活性炭上的吸附以化学吸附为主。研究表明，废离子交换树脂是用于 MB 染料的碳吸附剂的合适前体。这种低成本的方法将特别降低废物处理的环境成本。