A nanoscale ferroferric oxide coated biochar derived from mushroom waste to rapidly remove Cr(VI) and mechanism study

Abstract We developed a magnetic nano-material from spent Lentinula edodes substrate (LES), which was coated with nano-magnet after carbonization to remove Cr(VI). LES was given polyporous and crinkly surface structure after carbonization and the iron modification, which significantly improved its Cr affinity. X-ray diffraction analysis verified nano-Fe 3 O 4 crystal formation on LES biochar (LBC) surface and the possible existence of grimaldiite. X-ray photoelectron spectroscopy analysis manifested the reduction of Cr(VI) to Cr(III). The maximum removal rate of Cr(VI) by LBC-Fe 3 O 4 reached 99.44%. Taguchi experiment indicated the removal rate was mainly determined by Cr(VI) concentration, dosage, and pH. Furthermore, LBC-Fe 3 O 4 maintained 78.56% of its initial Cr(VI) removal efficiency after seven regenerations, indicating its fabulous stability. LBC-Fe 3 O 4 also presented efficient removal of multi-pollutants including Cu, Ni, Pb, COD, NH 4 -N, etc. in practice. This research proved that LBC-Fe 3 O 4 could be applied for the treatment of Cr(VI) influenced liquid and recycling of agricultural waste.