Abstract

Pollution with the heavy metal cadmium (Cd²⁺) is a global problem. Cadmium adversely affects living organisms, highlighting the need to develop new methods for removal of this pollutant from the environment. In this study, we used a novel biomaterial based on calcium-crosslinked alginate-encapsulated bacteria to precipitate Cd²⁺ in polluted water. Our results show that calcium-crosslinked alginate-encapsulated bacteria effectively removed Cd²⁺ ions from cadmium-polluted water. Approximately 100% of Cd²⁺ ions were removed by 10 g (wet weight) of this biomaterial when the loading concentration of Cd²⁺ reached 1 mM in a volume of 50 ml water. During this process, a CdS nanoparticle, showing good crystallinity in the quantum range, was simultaneously produced. To validate the activity and stability of this biomaterial, we measured cysteine desulfhydrase activity in the stored biomaterial and whether this biomaterial could be recycled. The encapsulated bacteria maintained catalytic activity for at least 2 weeks. The capsules were easily regenerated and possessed good recyclability. Our results indicated that calcium-crosslinked alginate-encapsulated bacteria are suitable for depletion of Cd²⁺ in polluted water and for production of CdS nanoparticles. These calcium-crosslinked alginate-encapsulated bacteria are safe for biological manipulation and can be widely used to produce CdS nanoparticles during bioremediation of Cd²⁺-polluted water.

Key points

• Calcium-crosslinked alginate-encapsulated bacteria can effectively precipitate Cd ²⁺ in water coupled with production of CdS quantum dots.

• The encapsulated bacteria maintained catalytic activity for at least 2 weeks.

• The capsules were easily regenerated and possessed good recyclability.

中文翻译：

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钙交联的藻酸盐包埋细菌用于修复镉污染的水和生产CdS纳米颗粒

摘要

重金属镉（Cd ²⁺）的污染是一个全球性问题。镉对生物体有不利影响，突出了开发新方法从环境中去除这种污染物的需要。在这项研究中，我们使用了一种基于钙交联的藻酸盐包埋细菌的新型生物材料，使Cd ²⁺沉淀在污水中。我们的结果表明，钙交联的藻酸盐包埋细菌可以有效地从镉污染的水中去除Cd ²⁺离子。当Cd ²⁺的负载浓度达到10 g（湿重）时，大约100％的Cd ²⁺离子被去除。在50 ml的水中达到1 mM。在此过程中，同时生产了在量子范围内显示出良好结晶度的CdS纳米颗粒。为了验证这种生物材料的活性和稳定性，我们测量了存储的生物材料中的半胱氨酸脱硫酶活性以及该生物材料是否可以回收。包封的细菌保持催化活性至少2周。胶囊易于再生并且具有良好的可回收性。我们的结果表明，钙交联的藻酸盐包埋细菌适合去除Cd ²⁺在污水中和用于生产CdS纳米粒子。这些钙交联的藻酸盐包埋的细菌对于生物处理是安全的，并且可以在对Cd ²⁺污染的水进行生物修复期间广泛用于生产CdS纳米颗粒。

关键点

•钙交联的藻酸盐包埋细菌可有效地 在水中沉淀Cd ²⁺ ，并产生CdS量子点。

•封装的细菌保持催化活性至少2周。

•胶囊易于再生，具有良好的可回收性。