Micro-wrinkled graphene oxide-supported surface molecularly imprinted polymers for selective menthol enrichment from peppermint hydrosol

Menthol is the principal aroma-active constituent of peppermint essential oil. During industrial steam distillation, large volumes of peppermint hydrosol are generated, and menthol remains in this aqueous byproduct at a relatively high proportion. Selective recovery is difficult because menthol coexists with small molecules of similar structure and polarity. Herein, a surface molecularly imprinted polymer supported on micro-wrinkled graphene oxide (WGO) was developed for selective menthol enrichment and pH-responsive release in peppermint hydrosol-related systems. Molecular docking identified 3-aminophenylboronic acid (APBA) as the optimal functional monomer and showed that APBA, menthol, and PTEOS could form a stable ternary pre-assembly complex. WGO was then used as the support for APBA grafting, followed by TMOS/PTEOS-based sol-gel surface imprinting. The wrinkled interface pre-regulated the spatial distribution of surface reaction sites, reduced local steric hindrance and grafting competition, and promoted more uniform monomer anchoring and imprinting-layer growth. Consequently, compared with the flat GO-based material (G-M), W-M showed a higher maximum adsorption capacity (226 vs 178 mg g⁻¹), a much larger specific surface area (611.72 vs 31.05 m² g⁻¹), and superior competitive adsorption toward menthol (36.28 mg g⁻¹; Kd = 14.28 L g⁻¹; IF = 2.21). W-M also exhibited pronounced pH-responsive release, with cumulative menthol release approaching 90% under acidic conditions. This work demonstrates an effective support-morphology engineering strategy for selective enrichment and controlled release of aroma-active molecules from complex aqueous matrices.