Synthesis and characterization of magnetic molecularly imprinted polymers for enrichment of sanguinarine from the extraction wastewater of M. cordata

A novel and efficient pretreatment method is proposed for the enrichment of sanguinarine (SA) from the extraction wastewater of Macleaya cordata (Willd) R. Br. using magnetic molecularly imprinted polymers (MMIPs) as solid phase adsorbent. The obtained MMIPs were synthesized by molecular imprinted technology and were well characterized with TEM, FT-IR, XRD, TGA, and VSM. The adsorption capacity and selectivity of MMIPs were also investigated. The results showed that the obtained MMIPs were core-shell spherical morphologies with an average diameter of 300 nm. The adsorption experiments showed that the MMIPs exhibited an almost three times higher adsorption capacity towards SA (Qmax = 12.24 mg/g) than magnetic molecularly non-imprinted polymers (MNIPs) (Qmax = 4.15 mg/g). The calculated parameters of adsorption isotherms and kinetics suggested that the adsorption process matched the Langmuir adsorption isotherm and pseudo-second-order kinetics model. The thermodynamic parameters were calculated, indicating that the adsorption process was spontaneous (ΔG298K = −3.24 kJ/mol). The selectivity experiment showed that the MMIPs displayed higher selective adsorption capacity for SA compared to its reference compounds. Moreover, the MMIPs were applied to enrich SA from the extraction wastewater of M. cordata. The proposed method could provide an effective, simple and environmentally friendly way to identify and enrich SA from the extraction wastewater of M. cordata.