Concentration of betanin from model beetroot extracts by using nanofiltration: parameter estimation and sensitivity analysis

BACKGROUND Nowadays, research focusing on natural compounds is getting more importance across the globe. Recently, natural bioactive compounds have gained the attention of researchers as a consequence of their exemplary physicochemical properties and exceptional utility in the food and pharma industries. However, separating and concentrating these bioactive compounds from their origin sources still poses a considerable challenge to their profitable commercial usage. The current study focuses on the application of a facile nanofiltration method for recovering betanin from model beetroot extract solutions using a polyamide nanofiltration membrane. Furthermore, the three‐parameter Spiegler–Kedem model was used to determine the transport parameters of the membrane and theoretically predict the performance of the membrane. Additionally, variance‐based sensitivity analysis methods were deployed to study the sensitivity of different operating and membrane transport parameters. RESULT The results indicate that the membrane exhibited the highest rejection of 99% and permeate flux of 3.14 ⨯ 10 −5 m 3 m −2 s −1 at 0.6 MPa pressure and 600 mL min −1 flow rate. The data obtained through the Spiegler–Kedem model were coherent with the experimental observations. Simulations on sensitivity analysis revealed that specific hydraulic permeability and cross‐membrane pressure majorly influence permeate flux and rejection. CONCLUSION This study showed that nanofiltration with 150 Da cut‐off membranes effectively concentrated betanin with 99% rejection. Higher cross‐membrane pressure and higher feed flow rates were preferable operating conditions for higher rejections. Variance‐based sensitivity analysis showed that cross‐membrane pressure and hydraulic permeability are the most influential parameters affecting permeate flux and rejection.