The removal of radioactive Co²⁺ from aqueous solutions is a critical issue because it is highly toxic and hazardous to humans. Metal sulfides are promising materials for the removal of toxic ions; however, studies on the adsorption of Co²⁺ by this class of adsorbents as well as their adsorption mechanisms and practical application in complex natural water matrixes are limited. To fill this knowledge gap, in this study, a layered K/Zn/Sn/S metal sulfide nanosheet (KZTS-NS) was employed as an adsorbent for Co²⁺ removal from aqueous solutions. Besides ion exchange, the mechanism of surface adsorption by forming a Zn_0.76Co_0.24S composite was found when initial Co²⁺ concentration was higher than 20 mg/L, which was reported for the first time in layered metal sulfides. The Co²⁺ adsorption performance of KZTS-NS was systematically studied using batch methods in deionized water, including isotherms, kinetics, influential factors, and selectivity. The results indicated that KZTS-NS exhibited a high adsorption capacity, rapid kinetics, and strong selectivity in a wide pH range. Furthermore, tap water was used as a complex natural water matrix, and the practical application of KZTS-NS in a bench-scale countercurrent two-stage adsorption-flocculation-microfiltration (CTA-F-MF) process for Co²⁺ removal from tap water matrix was demonstrated. The CTA-F-MF process significantly enhanced the performance of the adsorbent, thereby achieving ultrahigh Co²⁺ removal (decontamination factor of up to 1176). This study not only provides a new insight into the adsorption of Co²⁺ by layered metal sulfides, but also forms the basis to enable the practical application of metal sulfides in the field of radioactive wastewater treatment.

从水溶液中去除放射性Co ²⁺是一个关键问题，因为它对人类有剧毒并且有害。金属硫化物是去除有毒离子的有前途的材料。然而，这类吸附剂对Co ²⁺的吸附及其吸附机理的研究以及在复杂天然水基质中的实际应用受到了限制。为了填补这一知识空白，在本研究中，采用层状K / Zn / Sn / S金属硫化物纳米片（KZTS-NS）作为吸附剂，用于从水溶液中去除Co ²⁺。除离子交换外，当初始Co ²⁺形成时发现了通过形成Zn _0.76 Co _0.24 S复合材料的表面吸附机理。浓度高于20 mg / L，这是在层状金属硫化物中的首次报道。使用间歇法在去离子水中系统研究了KZTS-NS的Co ²⁺吸附性能，包括等温线，动力学，影响因素和选择性。结果表明，KZTS-NS在宽pH范围内显示出高吸附能力，快速动力学和强选择性。此外，自来水被用作复杂的天然水基质，并且KZTS-NS在台式规模的逆流两级吸附-絮凝-微滤（CTA-F-MF）工艺中用于去除自来水中的Co ²⁺的实际应用。演示了水基质。CTA-F-MF工艺显着提高了吸附剂的性能，从而获得了超高的Co²⁺去除（向上的去污因子至1176）。该研究不仅为层状金属硫化物对Co ²⁺的吸附提供了新的见解，而且为使金属硫化物在放射性废水处理领域中的实际应用奠定了基础。