Engineering and optimization of nano- and mesoporous silica fibers using sol–gel and electrospinning techniques for sorption of heavy metal ions

In this paper, we report on a novel design strategy of an efficient sorbent for removal of trace contaminants from water. This kind of sorbent is composed of a nonporous core of SiO2 nanofiber and a mesoporous shell (denoted as nSiO2@mSiO2 (“n” means “nonporous” and “m” means “mesoporous”)). The nSiO2@mSiO2 fiber possesses a continuously long fibrous shape and mesoporous micromorphology, thus, showing both high sorption capacity and separability. The flexible nonporous SiO2 nanofiber was prepared with electrospinning first, followed by covering a mesoporous SiO2 shell based on a modified Stöber method using CTAB (cetyltrimethylammonium bromide) as the directing agent for formation of the mesopores. Also, functional thiol groups were grafted on the nSiO2@mSiO2 to enhance its performance. With a large specific surface area and long fibrous morphology, the nSiO2@mSiO2 fiber and its thiol-functionalized counterpart exhibit impressive performance on removal of Pb2+ and Cd2+ from water. Furthermore, the flexible texture and fibrous morphology of the nSiO2@mSiO2 fiber also made the removal of metal ions and the separation process more convenient and efficient, implying that the nSiO2@mSiO2 fiber could have great potential for industrial applications.

Graphical abstractnSiO2@mSiO2 and its thiol-functionalized counterpart can be conveniently patterned into films acting as filter for water purification; thus, removal of heavy metal ions can be achieved simply through percolation.Figure optionsDownload full-size imageDownload high-quality image (61 K)Download as PowerPoint slideHighlights► A new method was designed to prepare core–shell structured continuously long mesoporous SiO2 microfiber. ► Core–shell structured mesoporous SiO2 fiber acts as adsorbent for removal of heavy metal ions from water, making the recycling process simpler. ► Entangling of long fiber increases the sorption possibility of heavy metal ions. ► Sorption capacity and efficiency of heavy metal ions are greatly enhanced through grafting of thiol groups. ► Film patterned from mesoporous SiO2 fiber makes water purification much easier.