Selective recognition of bisphenol a using molecularly imprinted polymer based on choline chloride-methacrylic acid deep eutectic solvent monomer: Synthesis characterization and adsorption study

Abstract

A deep eutectic solvent molecularly imprinted polymer (DES-MIP) was synthesized via bulk polymerization using bisphenol A (BPA) as the template, DES as the monomer, ethylene glycol dimethyl acrylate (EGDMA) as the cross-linker, and benzoyl peroxide (BPO) as the initiator. The DES-MIP was then compared with a conventional molecularly imprinted polymer (MIP) as a reference, which was synthesized using methacrylic acid (MAA) as a functional monomer. Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) were used to characterize the synthesized polymers. The DES-MIP has a higher selectivity for BPA (17.72 mg/g) g) as compared to the structurally similar compounds including bisphenol AP (9.78 mg/g), 2-naphthol (8.25 mg/g), and 4-tertiary butyl-phenol (6.98 mg/g). The investigation focused on optimizing various parameters such as pH, adsorption kinetics, isotherms, and thermodynamics. The DES-MIP exhibited the highest binding capacity at pH 7. Kinetic and isotherm analyses revealed that the data corresponded well with pseudo-second-order kinetic and Langmuir isotherm models. Thermodynamic analysis indicated that the adsorption of BPA on DES-MIP was exothermic and spontaneous with ΔH0 (−23.734 kJ/mol) and ΔG0 (−2.929 kJ/mol−). These results demonstrate the efficacy of DES as a functional monomer alternative for MIP synthesis, which significantly enhances the recognition of BPA adsorption. According to reusability tests, the polymer could be recycled five times without losing significant adsorption capacity. DES-MIP is an interesting adsorbent with a good adsorption capability and remarkable selectivity for BPA capture.