Effective separation of nicotine from tobacco extract by silica gel

The high nicotine content in tobacco extract restricts its application in low-nicotine products. This study presents an economical and efficient methodology for the separation of nicotine using silica gel. The performances of static adsorption, dynamic separation, and regeneration were systematically evaluated. The results indicated that silica gel attained a maximum nicotine adsorption capacity of 73.23 mg/g and reached equilibrium within 30 minutes. Thermodynamic analysis indicated that the process was spontaneous and exothermic. When the water content of silica gel was 20.03 %, its adsorption capacity decreased by approximately 50 %. However, solvent elution and regeneration restored the adsorption capacity to over 95.7 % of that in the anhydrous state. EDS, FTIR, and XPS analyses revealed that the adsorption of nicotine by silica gel mainly depends on hydrogen bonding between surface hydroxyl groups and the pyridine nitrogen of nicotine, with a preferential interaction with the pyridine nitrogen, followed by the pyrrole nitrogen. The nicotine content in the eluted product exceeded 97.79 %, and the recovery rate reached 98.95 % when the silica gel column treatment volume was 6 mL/g. After five reuse cycles, the nicotine recovery rate slightly decreased to 92.15 %. This study provides a scalable and low-cost strategy for efficient nicotine separation, which has significant potential for industrial applications.