With rapid development of ocean transportation, frequent oil spills and nuclear reactor accidents cause severe damage to the environment and ecosystems for it produces pollution which is very difficult to clear up.

To cope with this problem, scientists from Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences (ASIPP) developed multifunctional flexible free-standing membrane which can be applied in radioactive ions Sr²⁺ and Cs⁺ tainted water treatment and oil uptake when coated with a thin layer of hydrophobic molecules. These findings might open up a simple, low-cost route toward water treatment and separation technologies.

To treat the tainted water, scientists in ASIPP constructed a shape-moldable and nanoporous membrane based on the layer-by-layer (LbL) which takes titanate nanobelt (TNB) and polyethylenimine (PEI) as raw material. This new-synthesized membrane was found exceptionally capable of preconcentration and removal of radioactive ions Sr²⁺ and Cs⁺. The result showed that the exchange of Cs⁺ and Sr²⁺ ions occurs within the (003) planes of titanate nanobelts.

Furthermore, the membrane is coated with a thin layer of hydrophobic molecules (volatile silicone), resulting in a superhydrophobic surface, as evidenced by its high water contact angle (150.58^o). The engineered multilayer membrane is exceptionally capable of selectively and rapidly adsorbing oils up to 23 times the adsorbent weight.

This research was published in Scientific Reports with title Multifunctional flexible free-standing titanate nanobelt membranes as efficient sorbents for the removal of radioactive 90Sr2+ and 137Cs+ ions and oils. 

Characterization of sodium titanate nanobelt (Na-TNB) membrane. (Image by WEN Tao) 

Absorption efficiency of modified TNB membrane for oils and organic liquids. The gasoline was labeled with Rhodamine B for clear presentation. (Image by WEN Tao)