Recent advances of nanofiltration separation in pharmaceutical field from water to organic solution

Abstract

The pharmaceutical industry has grown rapidly, leading to significant improvements in drug quality and pharmaceutical technology. However, there is still an inevitable problem with the appropriate disposal of pharmaceutical wastewater. Pharmaceutical wastewater contains water, organic solvent, proteins, peptides, polyphenols, and other heat-sensitive ingredients. Because nanofiltration separation has technological advantages in room temperature, it is hard for alternative separation technologies to replace it. However, the separation model designed for aqueous solutions has significant disadvantages in organic solutions. To improve the applicability of the nanofiltration in the pharmaceutical industry, this paper reviewed the nanofiltration separation mechanism, application characteristics, and defects of active ingredients in organic solutions, combined with the actual states and interfacial mass transfer behaviors of components in complex solution systems based on the relationship among solute, solvent and nanofiltration membrane. The physicochemical characteristics of the nanofiltration membrane separation layer (effective separation pore size, membrane fouling, membrane material) and the solute's state change in conjunction with a transition in the solvent from water to organic in pharmaceutical wastewater. The differences in the diffusion behavior of solutes in various existing states at the nanofiltration membrane interface under the charge effect complete nanofiltration separation according to the effect of effective filtration pore size. It is found that models of nanofiltration separation are constructed based on solution separation parameters, the charge effect of the nanofiltration membrane, and effective separation pore size. It additionally suggested research strategies for the separation mechanism of active ingredients in organic solution: first, clarify the solute molecular state and nanofiltration membrane potential in organic solution; second, analyze the solute distribution curve in the interface layer with different existing states; third, calculate the effective filtration pore size of nanofiltration; fourth, according to the quantitative cutting model of the interface layer by effective filtration pore size, the nanofiltration separation mechanism was investigated. This paper provides a systematic review of the current state of application for nanofiltration technology in the pharmaceutical industry and suggests solutions appropriate for various solvent systems. These will help to increase the technology's applicability in the pharmaceutical industry, increase the effectiveness of using heat-sensitive ingredients, and lessen environmental pollution from organic wastewater.