Deep-Eutectic-Solvent-Based Mesoporous Molecularly Imprinted Polymers for Purification of Gallic Acid from Camellia spp. Fruit Shells

Abstract

To produce antioxidant substances from agricultural waste Camellia spp. fruit shells before their further utilization, gallic acid from five kinds of Camellia spp. fruit shells was separated on specific recognition by deep eutectic solvent molecularly imprinted polymers (DES@MIPs), which were prepared by bulk polymerization using gallic acid as the template and deep eutectic solvents (α-methylacrylic acid and choline chloride) as functional monomers. The optimized DES@MIPs were characterized by scanning electron microscopy, particle size analysis, nitrogen sorption porosimetry, elemental analysis, Fourier transform infrared spectroscopy, and thermal gravimetric analysis. The adsorptive behavior of gallic acid on DES@MIPs was also investigated. The results indicated that DES@MIPs were successfully prepared as mesoporous materials with average pore diameter of 9.65 nm and total pore volume of 0.315 cm3 g−1, and the adsorption behavior was multilayer adsorption and pseudo-second-order kinetics with the saturation adsorptive capacity of gallic acid reaching 0.7110 mmol g−1. Although the content of gallic acid in five fruit shells was quite different, the purification recovery of gallic acid was high, ranging from 87.85–96.75% with a purity over 80%. Thus, the purification of gallic acid from Camellia spp. fruit shells could be realized feasibly using DES@MIPs with favorable economic and environmental benefits.

Preparation and Application Progress of Imprinted Polymers

“…In addition, the imprinted materials showed a high imprinted factor of 4.77, which presented outstanding recognition specificity. Gallic acid MIPs were synthesized with bulk polymerization using DESs as functional monomers ( Figure 8 ) [ 99 ], the obtained MIPs has a mesoporous structure with an average pore diameter of 9.65 nm. The adsorption behavior followed pseudo-second-order kinetic model, with a maximum adsorption capacity of 0.711 mmol/g.…”

“…However, there is limited research on the nanoscale cavity, which can not reveal the influence of intrinsic cavities inside imprinted materials on selectivity. Therefore, it is necessary to optimize the physical selectivity by utilizing PALS, which is sensitive to the determination of the nanoscale [ 60 , 64 , 99 , 146 , 147 , 148 ].…”

“… Illustration of the preparation of DESs ( A ) and MIPs ( B ) [ 99 ]. (MMA: methylacrylic acid, ChCl: choline chloride, GA: gallic acid, EGDMA: ethylene glycol dimethacrylate).…”

Synthesis of molecularly imprinted polymer based on cooperative imprinting for enrichment of gallic acid in Puer tea

“…Rwo and Deng teams have prepared the MIPs with deep eutectic solvents (DESs) as the functional monomers for the enrichment of GA in red ginseng tea leave and Camellia spp. fruit shells 20,21 . The DESs contain a wealth of functional groups by changing the hydrogen‐bond donor or hydrogen‐bond acceptor, which could further increase the adsorption capacity of MIPs.…”

“…fruit shells. 20,21 The DESs contain a wealth of functional groups by changing the hydrogen-bond donor or hydrogen-bond acceptor, which could further increase the adsorption capacity of MIPs. Hao et al formulated a novel hollow double imprinting surfaces MIP based on magnetic Fe 3 O 4 and mesoporous SiO 2 layer, for specific adsorption of GA from green tea.…”