Jie Fu

Adsorption of alkaloids on ordered mesoporous carbon

An ordered mesoporous carbon (OMC) adsorbent was synthesized, characterized, and evaluated for effective separation and purification of alkaloid compounds from aqueous solutions. The OMC adsorbent has a large BET specific surface area (1532.2m(2)/g), large pore volume (2.13cm(3)/g), and narrow pore diameter distribution with a median pore diameter of 4.21nm. Berberine hydrochloride, colchicine, and matrine were selected as the model compounds for evaluating the adsorption properties of the OMC adsorbent for alkaloid purification. Batch adsorption experiments of pure components in water were carried out to measure both adsorption equilibria and kinetics, and column breakthrough and desorption experiments were performed to validate the separation and regeneration efficacy of the OMC adsorbent. The adsorption equilibrium capacities of berberine hydrochloride, colchicine, and matrine on the OMC adsorbent at 0.100mg/L and 298K are 450, 600, and 480mg/g, respectively, which are more than double the adsorption capacities of these compounds on two commonly used commercial resins (HPD300 and HPD100B) at similar conditions. Adsorption equilibrium of all three alkaloids could be obtained within 120min at 298K. The dynamic adsorption capacities determined from the breakthrough experiments are within 12% of the estimated equilibrium capacities from the Langmuir isotherms; and 74.3-92.8% of the adsorbed amounts could be recovered by desorbing with a 70% alcohol solution. The adsorption isotherms are analyzed with both Langmuir and Freundlich models, the adsorption kinetic data with the pseudo-first-order and pseudo-second-order models, and the breakthrough curves with four breakthrough models. The large adsorption capacity, fast adsorption rate, and easy regeneration make the ordered mesoporous carbon a promising adsorbent for adsorption and purification of alkaloid compounds from the extracts of herbal plants.

Optimization of mesoporous carbons for efficient adsorption of berberine hydrochloride from aqueous solutions.

Sixteen mesoporous carbon adsorbents were synthesized by varying the ratio of soft to hard templates in order to optimize the pore textural properties of these adsorbents. The mesoporous carbon adsorbents have a high BET specific surface area (1590.3-2193.5 m(2)/g), large pore volume (1.72-2.56 cm(3)/g), and uniform pore size distribution with a median pore diameter ranging from 3.51 nm to 4.52 nm. It was observed that pore textural properties of the carbon adsorbents critically depend on the molar ratio of carbon sources to templates, and the hard template plays a more important role than the soft template in manipulating the pore textures. Adsorption isotherms of berberine hydrochloride at 303 K were measured to evaluate the adsorption efficacy of these adsorbents. The adsorption of berberine hydrochloride from aqueous solutions on the sixteen mesoporous carbon adsorbents synthesized in this work is very efficient, and the adsorption equilibrium capacities on all samples are more than double the adsorption capacities of berberine hydrochloride of the benchmark adsorbents (polymer resins and spherical activated carbons) at similar conditions. It was observed from the adsorption experiments that the equilibrium adsorption amounts of berberine hydrochloride are strongly correlated with the BET specific surface area and pore volume of the adsorbents. The adsorbent with the highest BET of 2193.5 m(2)/g displayed the largest adsorption capacity of 574 mg/g at an equilibrium concentration of 0.10mg/mL of berberine hydrochloride in an aqueous solution.