Preparation of P(EGDMA-co-VPBA) Adsorbent and Its Application in the Separation of Steviol Glycosides

The poly (ethylene glycol dimethacrylate- co -vinylphenylboronic acid) P(EGDMA- co -VPBA) adsorbents are prepared via reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization with 4-vinylphenylboronic acid (VPBA) as the functional monomer, and used for selective adsorption of steviol glycosides (SGs). The boron content and pore structure of the P(EGDMA- co -VPBA) adsorbent are adjusted by changing the polymerization conditions. The adsorption results show that the pore structure of the P(EGDMA- co -VPBA) affects the adsorption capacity to SGs, the presence of boric acid functional groups shows favorable adsorption selectivity for stevioside (STV), and the adsorption selectivity is proportional to the content of boric acid in P(EGDMA- co -VPBA) adsorbents. The adsorption performance of P(EGDMA- co -VPBA) toward SGs is the best when the ratio of monomer to cross-linker is 1:50 and the solvent is acetonitrile. In the SG solution (6.0 mg mL −1 , C STV / C RA = 1:1), the adsorption capacities and adsorption selectivity ( α STV/RA ) of P(EGDMA- co -VPBA) to SGs are 113.20 mg g –1 and 4.99, respectively. The adsorption kinetics and isotherm data obey pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The boric acid copolymers with VPBA as the monomer prepared by the one-step method can become a promising material for efficient separation and purification of SGs.