Adsorptive removal performance and mechanism of cesium ion from aqueous solutions by a K/Zn/Sn/S metal sulfide
A nanosheet-like K/Zn/Sn/S metal sulfide(KZTS-NS)was synthesized by a hydrothermal method.The adsorption properties and mechanism of KZTS-NS towards Cs+was investigated.The results showed that fast adsorption of Cs+occurred by KZTS-NS with an equilibrium time of only 10 minutes and Cs+removal rate of 96.50％.The adsorption isotherms were well fitted with the Langmuir model,and the calculated maximum adsorption capacity reached 133.96 mg·g-1,which was higher than other reported adsorbents.The adsorption of Cs+by KZTS-NS was a spontaneous,endothermic,and entropy-increasing process.KZTS-NS had a good performance on Cs+adsorption in the pH range of 3-10.The inhibitory effect of coexisting ions on Cs+adsorption by KZTS-NS followed the sequence of Mg2+＞Ca2+＞Na+＞K+.The removal rates of Cs+by KZTS-NS in tap water,mineral water,lake water,and seawater were 42.14％,25.15％,14.14％,and 4.44％,respectively.The KZTS-NS before and after cesium ion(Cs+)adsorption was characterized using scanning electron microscopy(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS),etc.to reveal the Cs+adsorption mechanism.Results showed that the nanosheet-like morphology of KZTS-NS remained unchanged before and after adsorption of Cs+.K,Zn,Sn,and S elements were evenly distributed on the surface of KZTS-NS.The XRD characteristic peaks after Cs+adsorption shifted towards a lower 2θ value,corresponding to an increase in crystal plane spacing.The XPS spectra and quantitative analysis indicated that the adsorption mechanism of KZTS-NS for Cs+was ion exchange.In summary,KZTS-NS could rapidly and efficiently remove Cs+from wastewater and showed a great potential for further application.This study provides a technical reference and the basic data supports for the treatment of wastewater containing radioactive Cs+ions.
metal sulfideadsorbentcesiumradioactive contaminationion exchange
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