Enhanced separation of dual pollutants from wastewater containing Cr (Ⅵ) and oil via Fe-doped sludge derived membrane

One-step separation of multi-component contaminants in chemical separations by a single material is essential to simplify the separation process and enhance the separation efficiency. This work proposed an eco-friendly and effective "cation doping" strategy, utilizes waste river sludge (RS) as raw material, incorporates Fe to improve ion removal performance, and the Fe-doped RS/PVDF membrane was obtained for simultaneously removing Cr (Ⅵ) and oil from electroplating wastewater. The membrane exhibits outstanding rejection rates for oil (>98 %) and Cr (Ⅵ) (89.10 %), which was superior to Cr (Ⅵ) rejection rate of RS/PVDF membrane (22.04 %) without Fe doping under the combined action of electrostatic attraction, surface complexation, redox, and the superhydrophilic/underwater oleophobicity. Notably, protonation and low operating pressure contributed to Cr (Ⅵ) removal, and the membrane presents satisfactory acid-alkali resistance, anti-interference ions ability and chemical stability. Therefore, this work offers a novel development strategy for affordable and effective multifunctional separation membrane, and also promotes the realization of simultaneous and rapid removal of heavy metal ions and oil contaminants, which is encouraging in terms of potential industrial applications.