(449ch) Sulfur-Based Copolymer Nanofiber Prepared Via Inverse Vulcanization for Heavy Metal Sequestration

Recent progress on inverse vulcanization has opened various opportunities to develop advanced materials for environmental remediation and energy storage applications. Herein, the development of a nanofiber adsorbent with extremely high capacity for various heavy metals, especially mercury (Hg²⁺), is presented.

Processable sulfur copolymer was synthesized via facile inverse vulcanization of elemental sulfur with 2-carboxyethyl acrylate (CEA). Diradical chain ends of elemental sulfur produced from ring opening polymerization was stabilized by direct addition of CEA copolymer. Rheology of resulting sulfur-CEA copolymer (poly(S-r-CEA)) dope solution was manipulated by adjusting the molar ratio of the components. Poly(S-r-CEA) products were viscoelastic (i.e. 0< phase angle (δ) <90°). Temperature-dependence of viscosity was analyzed via oscillatory rheology in order to determine appropriate temperature for the dope solution which can be processed into a nanofiber via electrospinning.

The prepared poly(S-r-CEA) nanofiber was tested for removal of heavy metals and was found out to have very high affinity towards Hg²⁺. Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy was employed in order to elucidate poly(S-r-CEA)-Hg²⁺ complex. Adsorption isotherm data revealed that Hg²⁺ sequestration of poly(S-r-CEA) follows monolayer Langmuir-type and that the calculated maximum adsorption capacity could reach up to 1000 mg g^-1. This adsorption capacity of poly(S-r-CEA) nanofiber is comparable to current Hg²⁺ benchmark adsorbent but features significant advantages such as cost and availability of main raw material, ease of preparation, and effectiveness of treatment process. This work therefore presents a new promising materials for the removal of Hg²⁺and other heavy metal ions from contaminated water for environmental remediation.

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and future Planning (2015R1A2A1A15055407) and 2015 Research Fund of Myongji University.