One-step recovery of noble metal ions from oil/water emulsions by chitin nanofibrous membrane for further recycling utilization.

A multifunctional membrane, prepared by filtration of partial deacetylated chitin nanofibers, was reported to realize one-step green recovery of noble metal ions from surfactant-stabilized oil/water emulsions. The chitin nanofibrous membrane (CNFM) has nanoporous structure with superhydrophilic and underwater superoleophobic surface and could effectively separate oil/water emulsion. Combining with the chelation ability/reduction of amino groups of chitin, CNFM could simultaneously extract noble metal ions from oily wastewater. Furthermore, the noble metal ions adsorbed on the CNFM could be in situ reduced into metal nanoparticles (NPs) by amino groups on chitin without adding extra reducing agents, to yield NPs-loaded CNFM. Surprisingly, the recovered NPs-loaded CNFM maintained excellent catalytic activities and even displayed peroxidase mimic behavior, showing high potentials in biosensing, green catalysis and related fields. Hence, this work provides a simple and sustainable way to realize directly recovery of noble metal ions from oil/water emulsion.