Cadmium (Cd)-enriched adsorbents wastes possess great environmental risk due to their large-scale accumulation and toxicity in the natural environment. Recycling spent Cd-enriched adsorbents into efficient catalysts for advanced applications could address the environmental issues and attain the carbon neutral goal. Herein, a facile strategy is developed for the first time to reutilize the alkali lignin (AL)-derived biochar (ALB) absorbed with Cd into cadmium sulphide (CdS)/C composite for the efficient methylene blue (MB) removal. The ALB is initially treated with Cd-containing solution, then the recycling ALB samples with adsorbed Cd are converted to the final CdS/C composite using NaS2 as the sulphurizing reagent for vulcanization reaction. The optimal ALB400 demonstrates a high adsorption capacity of 576.0 mg g−1 for Cd removal. Then the converted CdS/C composite shows an efficient MB removal efficiency of 94%. The photodegradation mechanism is mainly attributed to carbon components in the CdS/C composite as electron acceptor promoting the separation of photoelectrons/holes and slowing down the abrasion of CdS particles. The enhanced charge transfer and contact between the carrier and the active site thus improves the removal performance and reusability. This work not only develops a method for removing Cd from wastewater effectively and achieving the waste resource utilization but also further offers a significant guidance to use other kinds of spent heavy metal removal adsorbents for the construction of low-cost and high value-added functional materials.

中文翻译：

---

将吸附镉的碱木质素生物炭回收成经济高效的 CdS/C 光催化剂，用于去除亚甲基蓝

富含镉（Cd）的吸附剂废物由于其在自然环境中的大规模积累和毒性而具有巨大的环境风险。将废富镉吸附剂回收成高效催化剂用于先进应用可以解决环境问题并实现碳中和目标。在此，首次开发了一种简单的策略，将吸收镉的碱木质素（AL）衍生的生物炭（ALB）重新利用到硫化镉（CdS）/C复合材料中，以有效去除亚甲基蓝（MB）。ALB 最初用含 Cd 的溶液进行处理，然后使用 NaS 将回收的 ALB 样品与吸附的 Cd 转化为最终的 CdS/C 复合材料2用作硫化反应的硫化剂。最佳 ALB400 表现出 576.0 mg g 的高吸附容量−1用于去除 Cd。然后，转化后的 CdS/C 复合材料的 MB 去除效率高达 94%。光降解机理主要归因于CdS/C复合材料中的碳成分作为电子受体促进光电子/空穴的分离并减缓CdS颗粒的磨损。载体和活性位点之间增强的电荷转移和接触因此提高了去除性能和可重复使用性。该工作不仅开发了一种有效去除废水中Cd、实现废物资源化的方法，而且对利用其他废旧重金属吸附剂构建低成本、高附加值的功能材料具有重要指导意义。 。