Design and synthesis of an efficient nanoporous adsorbent for Hg2+ and Pb2+ ions in water

Abstract

An efficient nanoporous adsorbent for Hg²⁺ and Pb²⁺ ions in water has been synthesized from the interaction of aqueous NaH₂C₃N₃S₃ and Na₃C₃N₃S₃ solutions. The Raman spectra of the sample indicate that the S–S bonds have been formed by this interaction, and N₂ sorption isotherms together with TEM images indicate the presence of hierarchical nanopores (mesopores/macropores). Interestingly, this nanoporous sample exhibits excellent adsorption behavior of heavy metal ions in water, giving the adsorption capacity of Hg²⁺ and Pb²⁺ at 735.3 and 375.9 mg g⁻¹, respectively. The Hg²⁺ and Pb²⁺ sorption isotherms are typical Langmuir and their kinetic model follows the pseudo-second-order. These results indicate that the adsorption behavior of the Hg²⁺ and Pb²⁺ ions on the sample is chemical. More importantly, this sample can be recycled 4 times without obvious loss of the adsorption ability in water, which is very important for its industrial applications in the future.