Ultrasonic bidirectional regulation of chrysophanol and aurantio-obtusin self-assembly enhanced nanofiltration separated ethanol extract of cassia seed

Abstract

Anthraquinone components sublimate during heat treatment refining, causing equipment pipeline contamination and a drop in component output, which is a challenging technical problem for pharmaceutical manufacturers to resolve. Furthermore, the waste liquid generated during pipeline cleaning simultaneously increases production costs and pollutes the environment. Although nanofiltration has the technological advantage of traditional temperature refining, anthraquinone components are absorbed onto the membrane surface during the concentration of cassia seed ethanol extract, leading to membrane pollution and a significant decrease in separation efficiency. Based on the π-π stacking effect and ultrasonic cavitation effect of anthraquinone components, this study proposes the hypothesis of enhancing nanofiltration separation by ultrasonic regulation of the self-assembly of anthraquinone components. The effects of pH, ethanol concentration, ultrasonic power, and the molecular weight cut-off of nanofiltration membranes on the solute rejection and membrane flux were all systematically explored in this work. The separation processes of chrysophanol and aurantio-obtusin were clarified by combining the relationship between ultrasonic power and the existing state. It was discovered that the self-assembly behavior of chrysophanol and aurantio-obtusin was regulated bidirectionally by ultrasonic power. In the range of 100 W − 300 W, the proportion of molecular states of anthraquinone components drops as the particle size distribution of the solution increases. Ultrasound encouraged the π-π stacking effect among anthraquinones, resulting in self-assembly and reduced surface pollution under the cavitation effect, leading to efficient nanofiltration separation. Ultrasonic power showed a logarithmic correlation with the molecular proportion of anthraquinones components in 300 W − 700 W, and ultrasound promoted the breakage of hydrogen bonds between supramolecular structures, resulting in an increase in the molecular proportion and a decrease in solute rejection. The response surface method was used to optimize the separation parameters of ultrasonic-enhanced nanofiltration. Chrysophanol and aurantio-obtusin rejections in cassia seed extract with ethanol concentrations of 35 % − 65 % were both greater than 88 % and 91 %, respectively, as the separation volume increased from 2 L to 20 L. Based on the intermolecular forces of the anthraquinone components in various ethanol solutions, this study used an ultrasonic bidirectional self-assembly ratio to purify cassia seed extract at room temperature through ultrasonic-enhanced nanofiltration, thereby avoiding the problems of component sublimation and environmental contamination brought on by conventional concentration.