Anisotropic emulsion constructed boronate affinity imprinted Janus nanosheets for stir bar sorptive extraction of cis-diol-containing catechol

Molecularly imprinted stir bar sorptive extraction (MI-SBSE) is a powerful method for synchronously achieving rapid mixing and selective enrichment. Herein, boronate affinity imprinted Janus nanosheets for stir bar sorptive extraction of cis-diol-containing catechol is reported. In this work, Janus nanosheets (NS-2) with amino groups on one side and vinyl groups on the other side are firstly prepared by self-organized interfacial sol-gel process from O/W anisotropic emulsion templates. Then, boronate affinity imprinted polymer layer is grafted onto the vinyl groups of NS-2 by initiating a precipitation polymerization (NS-2-MIPs). Finally, NS-2-MIPs are attached to the aldehyde functionalized glass tube with the magnetic inner core. Finally, MI-SBSE was used for selective enrichment of catechol, which is a typical endocrine disrupting chemical. The effects of solution pH, adsorption kinetics, isotherms, selectivity as well as the regeneration on the catechol adsorption onto the NS-2-MIPs are investigated in detail. NS-2-MIPs show largely enhanced adsorption capacity and good selectivity toward catechol than non-imprinted nanosheets (NS-2-NIPs). The maximum adsorption capacities achieve 286.3 μmol g−1 at 308 K and 263.0 μmol g−1 at 298 K, and the quick adsorption equilibrium reach within 30 min by accomplishing 98% of removal ratio. Moreover, chemical adsorption via boronate affinity mainly dominate the binding process and catechol is homogenously captured onto the binding sites with uniform distribution by a monolayer adsorption. Furthermore, 87.97% of catechol is captured after the effective mixing and selective enrichment by MI-SBSE by accelerating mass transfer. The findings of the present work not only provides insights to develop nanosheet-based stir bar using imprinted Janus nanosheets, but also presents a new method for catechol separation.