Adsorption kinetics and isotherms of berberine by ZSM-5 molecular sieves from Cortex Phellodendron

In this paper, a porous material (ZSM-5 molecular sieves) with remarkable structure is select to apply for berberine adsorption from the extracts of the Cortex Phellodendron. The batch experiments show that the optimum adsorbent dosage was 2.0 g and pH   8 is favorable for the berberine adsorption. The adsorption of berberine by ZSM-5 molecular sieve is more in consistence with the pseudo-second-order kinetic model and chemical adsorption plays a major role. There exist three diffusion stages during the adsorption of berberine, indicating that intraparticle diffusion is not the only rate-controlling step. Isothermal adsorption data is more in consistence with the Langmuir model, indicating that adsorption occurs at the monolayer interface. Thermodynamic results show that the adsorption is a spontaneous and exothermic process with entropy decrease. Under the conditions of pH  2 and concentration of eluents of 80%, the elution rate is 98.73%. The purity of berberine increased from 31.4 to 73.1%. After repeating adsorption for 15 times, the adsorption capacity of ZSM-5 molecular sieve for berberine remains well, which indicates that ZSM-5 has great purification capacity and reusability. These results confirm that ZSM-5 has potential superior properties for the purification and isolation of active ingredients from medicinal herbs.