**4. Conclusions**

In this study, the Mxene–CS composite was successfully prepared by the simple solution method and applied in the removal of Cr(VI) from the aqueous solution. The following conclusions can be drawn from the batch experiment.

(1) In the prepared Mxene–CS, the layered structure of Mxene does not completely disappear, with the irregular compact particles detected, indicating that CS was successfully loaded on the Mxene.

(2) The effects of parameters, including Mxene–CS dosage and pH, on the removal of Cr(VI) from the aqueous solution were investigated. With the Mxene–CS dosage ranging from 0.02 to 0.12 g/L, the removal efficiency of Cr(VI) was increased from 12.9% to 40.5%. The influence of pH on the removal of Cr(VI) by the Mxene–CS was mainly controlled by the varying potential at different pH.

(3) The removal of Cr(VI) by Mxene–CS is more prone to the pseudo–second–order kinetic model, indicating the removal process should be controlled by the chemical adsorption. The Langmuir isotherm was more suitable to describe the adsorption behaviors of Cr(VI) by Mxene–CS, with the maximum adsorption capacity of 43.1 mg/g.

This experiment should provide a reliable theoretical basis for Mxene–CS adsorption of Cr(VI), and further expand the application prospect of inorganic–organic composites in wastewater.

**Author Contributions:** H.W.: Writing—Original draft preparation; L.N.: Investigation; H.G.: Investigation; W.Z.: Writing—Reviewing and Editing; H.S.: Supervision. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Natural Sciences Foundation of China [52000163], the Natural Science Foundation of Henan Province [202300410423], and the China Postdoctoral Science Foundation [2020M682354].

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The author would also thank the support from the Modern Analytical Computing Center of Zhengzhou University.

**Conflicts of Interest:** The authors declare no conflict of interest.
