RESUMEN
Based on the molecular sieving and solution-diffusion effect in nanofiltration separation, the correlation between initial concentration and mass transfer coefficient of three typical phenolic acids from Salvia miltiorrhiza was fitted to analyze the relationship among mass transfer coefficient, molecular weight and concentration. The experiment showed a linear relationship between operation pressure and membrane flux. Meanwhile, the membrane flux was gradually decayed with the increase of solute concentration. On the basis of the molecular sieving and solution-diffusion effect, the mass transfer coefficient and initial concentration of three phenolic acids showed a power function relationship, and the regression coefficients were all greater than 0.9. The mass transfer coefficient and molecular weight of three phenolic acids were negatively correlated with each other, and the order from high to low is protocatechualdehyde >rosmarinic acid> salvianolic acid B. The separation mechanism of nanofiltration for phenolic acids was further clarified through the analysis of the correlation of molecular weight and nanofiltration mass transfer coefficient. The findings provide references for nanofiltration separation, especially for traditional Chinese medicine with phenolic acids.
RESUMEN
Based on the nanofiltration mass transfer model, the enhanced separation behavior of ephedrine in organic solution was studied. In the experiment, the sensitive region of ethanol concentration and pH on the rejection of ephedrine was screened out by Box-Behnken central composite experiment design. Furthermore, to analyze the separation regularity of ephedrine and organic solution, the correlation between mass transfer coefficient and concentration of organic solvent was fitted with the changed organic solution by nanofiltration mass transfer mathematical model. Experiments showed the enhanced separation behavior, the decrease in the mass transfer coefficient while the increase in ethanol concentration from 20% to 40%, MWCO at 450 and pH 6.0. Under the same conditions, the enhanced separation behavior was appeared as the solvent changed into methanol and acetonitrile, the enhanced effect was positively correlated with the concentration of the three common organic solvents, and the effect order was acetonitrile>ethanol>methanol. This study took ephedrine as an example, and explored the mechanism of nanofiltration separation in the environment of organic solution, so as to provide references for nanofiltration separation for heat-sensitive traditional Chinese medicine of alkaloid.
Asunto(s)
Efedrina , Química , Etanol , Metanol , Peso Molecular , SolventesRESUMEN
To optimize the concentrate process of alkaloid from Leonurus japonicus by nanofiltration-ultrafiltration coupling technology with response surface methodology. The experiment showed that after ultrafiltration pre-treatment, the total protein removal rate was 94.38% in aqueous extract from L. japonicus, and the nanofiltration technology had obvious advantages over the conventional concentrate process. The optimal concentrate conditions were as follows：molecular weight cut-off 450, pH 3.07, concentration of stachydrine hydrochloride 80.15 mg•L⁻¹, and concentration of the total alkaloid 285.73 mg•L⁻¹. The cut-off rate was 93.37% and 95.85% respectively for stachydrine hydrochloride and the total alkaloid under the optimum conditions, with a relative error of 0.79% and 1.16% respectively. The combination of Box-Behnken design and response surface analysis can well optimize the concentrate process of L. japonicus by nanofiltration, and the results provide the basis for nanofiltration concentrate for heat-sensitive traditional Chinese medicine.