Molecularly imprinted open porous membranes made from Pickering W/O HIPEs for selective adsorption and separation of methyl 4-hydroxybenzoate

In this study, novel molecularly imprinted open porous membranes (MIOPMs) were prepared using the Pickering HIPEs template method and molecular imprinting technology for selective adsorption and separation of methyl 4-hydroxybenzoate (M4HB). The template M4HB, functional monomers, crosslinker and plastifier 2-ethylhexyl acrylate (2-EHA) were contained in the oil phase. Hydrophobic silica nanoparticles (HNP-SiO₂) were employed as a stabilizer to establish stable W/O Pickering HIPEs with nonionic surfactant sorbitantrioleate (Span 85). The results of SEM and FTIR indicated that the optimal MIOPMs were prepared successfully and possessed open and interconnecting pores. Then, the MIOPMs were used as sorbents for M4HB. The correlation coefficient (R²) values for the Langmuir-Freundlich isotherm model and pseudo-second-order kineticmodel fitting to the adsorption equilibrium and kinetic data respectively were all higher than 0.95. The maximum adsorption capacity and the time of rapid adsorption for MIOPM4 were 4.146 mg g^-1 and 100 min, respectively. In addition, the permeability separation factor of MIOPMs for M4HB compared to a structurally related analog methyl2-hydroxybenzoate (M2HB) could reach 3.122.