Preparation of waste face masks modified with MnO2/poly(m-phenylenediamine) as a novel adsorbent for hexavalent chromium removal: Comprehensive batch and column study

•Waste surgical face mask (SFM) was modified with Poly(m-phenylenediamine) using a novel method.•The synthesis method involves in-situ-surface polymerization of m-phenylenediamine.•The oxidant and monomer solutions were reused for 14 cycles.•The column study was performed to study the behavior of the adsorbent in a continuous flow.•The adsorbent was able to remove around 99% of Cr(VI) at the concentration of 100 mg L−1.