Metal nanoparticle-loaded biochars have emerged as promising adsorbent for heavy metal elimination. However, the current preparation approaches predominantly depend on soluble modifying agents, mainly due to the challenge of large metal particles aggregation caused by insoluble modifying agents, resulting in a poor adsorption capacity. It is urgent to overcome the application bottleneck of insoluble modifying agents and prepare high-performance metal-supported adsorbents. Here, we cleverly combined kelp, abundant in sodium alginate with a stable effect, with insoluble calcium sulfite, successfully preparing nano-calcium oxide and calcium sulfide uniformly loaded on biochar surface. By natural aging and artificial aging, calcium carbonate protective layer was constructed on the surface of adsorbent to protect the stability of calcium sulfide. The maximum adsorption capacity of the prepared adsorbent for cadmium ions was up to 386.4 mg/g, which was 23 times higher than that of raw biochar. The adsorption behavior was consistent with Elovich model (R² = 0.983) and Langmuir model (R² = 0.974). The mechanisms primarily involved ion exchange, chemisorption and cation-π coordination. This work may provide theoretical guidance for the application of insoluble modifying agents in materials preparation and open up a new method for preparing high-performance metal-supported adsorbents, and have potential application in the treatment of cadmium ions-containing wastewater.

中文翻译：

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双层硫化钙-碳酸钙负载海带生物炭高效捕获镉离子的合成、吸附及机理

负载金属纳米颗粒的生物炭已成为有前途的去除重金属的吸附剂。然而，目前的制备方法主要依赖于可溶性改性剂，主要是由于不溶性改性剂引起的大金属颗粒聚集的挑战，导致吸附能力差。亟需克服不溶性改性剂的应用瓶颈，制备高性能的金属负载吸附剂。在这里，我们巧妙地将富含海藻酸钠且效果稳定的海带与不溶性亚硫酸钙相结合，成功制备了均匀负载在生物炭表面的纳米氧化钙和硫化钙。通过自然老化和人工老化，在吸附剂表面构建碳酸钙保护层，以保护硫化钙的稳定性。所制备的镉离子吸附剂的最大吸附容量高达 386.4 mg/g，是原始生物炭的 23 倍。吸附行为与 Elovich 模型 （R ² = 0.983） 和 Langmuir 模型 （R ² = 0.974） 一致。机制主要涉及离子交换、化学吸附和阳离子-π 配位。该工作可为不溶性改性剂在材料制备中的应用提供理论指导，为制备高性能金属负载吸附剂开辟新方法，在含镉离子废水处理中具有潜在应用价值。