The Research On ZnS Nanocrystal Sorbents For The Heavy Metal Ions Removal From Waste Water

With the development of economy,industry produced a large number of industrial wastewater containing heavy metal ions.Heavy metals have toxic properties and it can not be resolved,so the heavy metals can peresit in environment for a long time and then through the food chain into the human's organism,causing serious threat to the health of people and environment.All method of removing heavy metal ions,nanometer materials material removed the heavy metal ions in the industrial wastewater efficiently.The NCs sorbent was synthesized by direct coating ZnS NCs on the surface of the?-Al₂O₃.Morphology observation analysis of the samples were conducted with transmission electron microscopy?TEM?and X-ray diffraction?XRD?.The as-prepared ZnS NC sorbent can efficiently remove99.9%Hg²⁺,99.0%Cu²⁺,93.9%Pb²⁺,65.0%Cd²⁺.Through the XPS and XRD characterization method,the mechanism of heavy metals removal by ZnS NCs sorbent was investigated.It is found that the adsorption reaction process belong to ion exchange process.The influence of pH value,ZnS NC layer thickness and ZnS NCs size on heavy metal removal by ZnS NCs sorbents were investigated.The experiment result showed that size-dependent and thickness play an important role in heavy metal removal.The lay thickness was 35-40 nm and size was 4-5nm,the ZnS NCs sorbent had a better adsorption performance.Additionally,Heat treatment method promoted the copper removal performance of sorbent greatly.Finally,concentration of the Cu²⁺was from238.5 mg/L to 170.0 mg/L,247.8 mg/L to 165.7 mg/L?Based on the adsorption experiment,the NCs sorbent can remove Hg²⁺,Cu²⁺,Pb²⁺,Cd²⁺quickly and efficiency.The competition adsorption of various heavy metas on sorbent was also investigated.It was found that the solubility product?Ksp?of heavy metal sulfides played an important role in the adsorption process.That adsorption characteristic was utilized for the simultaneous removal and separation the heavy metals from water accordingly.The Ksp of sulfides was more smaller and the more easier removal by ZnS NCs...