Size-dependent nanocrystal sorbent for copper removal from water

• ZnS nanocrystals (NCs) sorbent was developed for Cu(II) removal from water.
• ZnS NCs layer thickness played an important role in Cu(II) removal.
• The adsorption capacity of ZnS NCs on Cu(II) is about 650 mg/g.
• The reaction mechanism of Cu(II) removal by ZnS NCs sorbent was investigated.

In this study, ZnS nanocrystals (NCs) was synthesized and investigated as a novel sorbent for the copper removal from waste water. According to the adsorption experiments, the copper removal efficiency is over 99.0% in one minute. The saturated adsorption capacity of ZnS NCs sorbent on copper is about 650 mg/g which is closed to the theoretic adsorption capacity. The influence of pH value, other metal ions and NCs sorbent size on copper removal efficiency were investigated, respectively. The ZnS NCs sorbent was characterized by TEM and XPS to reveal the reaction mechanism. It was found that the NCs layer thickness played an important role in copper removal by ZnS NCs sorbent. It is more difficult to remove the copper from water for the sorbents with thicker NCs layer. Heat treatment method promoted the copper removal performance of sorbent greatly. Additionally, the sorbent and the copper removed by sorbent could be reclaimed easily. Therefore, it is a promising method to remove the copper from water by ZnS NCs sorbent.

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