Ferrocene (pictured left) can be used to absorb metal ions or cationic dyes due to electrostatic attraction. This property could allow ferrocene to be used for water treatment.

Hongzhi Liu and Xiaoru Yang, Shandong University, Jinan, China, have developed a ferrocene-linked hybrid porous polymer through a one-pot Friedel–Crafts reaction of octavinylsilsesquioxane (OVS, pictured right) with ferrocene. This hybrid porous polymer has a high surface area of 1015 m²/g and a hierarchical pore structure. The obtained porous material has excellent absorption properties for dyes and heavy metal ions. The material has absorption capacities as high as 1683 mg/g for Congo red, 1083 mg/g for crystal violet, 1003 mg/g for rhodamine B, 441 mg/g for methylene blue, 191 mg/g for Hg²⁺, and 328 mg/g for Pb²⁺.

The prepared hybrid porous polymer could be easily regenerated and the removal efficiency for different absorbed compounds remained constant. According to the researchers, these results demonstrate the suitability of the porous polymer for wastewater treatment.

• Ferrocene-Functionalized Silsesquioxane-Based Porous Polymer for Efficient Removal of Dyes and Heavy Metal Ions,
  Xiaoru Yang, Hongzhi Liu,
  Chem. Eur. J. 2018.
  https://doi.org/10.1002/chem.201801765