The solution-diffusion with imperfections model as a method to understand organic solvent nanofiltration of multicomponent systems

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

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.

How far do we still need to go with antibiotics in aquatic environments? Antibiotic occurrence, chemical-free or chemical-limited strategies, key challenges, and future perspectives

Global consumption and progressive migration of antibiotics through aquatic systems have contributed to their rapid spread, posing significant threats to environmental and human health, and antibiotics have been recognized as emerging pollutants. Hence, extensive approaches have been proposed for antibiotic treatment in water, yielding great achievements. This review systematically summarized current knowledge from contamination characteristics to treatment strategies. First, the prevalence and characteristics of antibiotics in aquatic environments were discussed and chemical-free or chemical-limited strategies were subsequently reviewed, i.e. adsorption, membrane separation, electrochemistry, and photocatalysis. Thereafter, gaps were identified between conditions for treatment in aquatic environments and lab-scale experiments, emphasizing that simulated antibiotic concentrations in laboratory studies were often hundreds of times higher than those found in natural settings and lack consideration of complex water matrices. Additionally, concerns regarding health risks arose due to unexpectedly low mineralization rates. For future advancements, hybrid or combined technologies were recommended, along with the integration of smart tools such as machine learning for deeper insights into degradation processes and cross-risk assessments. This review offers valuable guidance for establishing effective strategies to control antibiotics in aquatic environments.

Ultrasonic-assisted activated carbon separation removing bacterial endotoxin from salvia miltiorrhizae injection

Ultrasonic-assisted activated carbon separation (UACS) was first employed to improve product quality by regulating adsorption rate and removing bacterial endotoxin from salvia miltiorrhizae injection. The adsorption rate was related to three variables: activated carbon dosage, ultrasonic power, and pH. With the increase of activated carbon dosage from 0.05 % to 1.0 %, the adsorption rates of salvianolic acids and bacterial endotoxin increased simultaneously. The adsorption rates at which bacteria endotoxins increased from 52.52 % to 97.16 % were much higher than salvianolic acids. As the ultrasonic power increased from 0 to 700 W, the adsorption rates of salvianolic acids on activated carbon declined to less than 10 %, but bacterial endotoxin increased to more than 87 %. As the pH increased from 2.00 to 8.00, the adsorption rate of salvianolic acid dropped whereas bacterial endotoxin remained relatively stable. On the basis of response surface methodology (RSM), the optimal separation conditions were established to be activated carbon dose of 0.70 %, ultrasonic power of 600 W, and pH of 7.90. The experimental adsorption rates of bacterial endotoxin were 94.15 %, which satisfied the salvia miltiorrhizae injection quality criterion. Meanwhile, salvianolic acids' adsorption rates were 1.92 % for tanshinol, 4.05 % for protocatechualdehyde, 2.21 % for rosmarinic acid, and 3.77 % for salvianolic acid B, all of which were much lower than conventional activated carbon adsorption (CACA). Salvianolic acids' adsorption mechanism on activated carbon is dependent on the component's molecular state. Under ideal separation conditions, the molecular states of the four salvianolic acids fall between 1.13 % and 6.60 %. The quality of salvia miltiorrhizae injection can be improved while maintaining injection safety by reducing the adsorption rates of salvianolic acids to less than 5 % by the use of ultrasound to accelerate the desorption mass transfer rate on the activated carbon surface. When activated carbon adsorption was used in the process of producing salvia miltiorrhizae injection, the pH of the solution was around 5.00, and the proportion of each component's molecular state was tanshinol 7.05 %, protocatechualdehyde 48.93 %, rosmarinic acid 13.79 %, and salvianolic acid B 10.28 %, respectively. The loss of useful components was evident, and the corresponding activated carbon adsorption rate ranged from 20.74 % to 41.05 %. The average variation rate in plasma His and IgE was significant (P < 0.05) following injection of 0.01 % activated carbon, however the average variation rate of salvia miltiorrhizae injection was dramatically decreased with the use of UACS and CACA (P > 0.05). The ultrasonic at a power intensity of 60 W/L and the power density of 1.20 W/cm2 may resolve the separation contradiction between salvianolic acids and bacterial endotoxin, according to experiments conducted with UACS at different power intensities. According to this study, UACS has a lot of potential applications in the pharmaceutical manufacturing industry and may represent a breakthrough in the field of ultrasonic separation.

Theory and simulation developments of confined mass transport through graphene-based separation membranes

The perspectives of graphene-based membranes based on confined mass transport from simulations and experiments for water desalination.

Green preparation of d-tryptophan imprinted self-supported membrane for ultrahigh enantioseparation of racemic tryptophan

Green and clean preparation of molecularly imprinted membrane for ultrahigh enantioseparation of racemic tryptophan.

Separation of binary solvent mixtures with solvent resistant nanofiltration membranes part B: process modeling

This part B of a two paper series develops an improved model derived from the classical solution-diffusion model, specifically for solvent separation process in SRNF.

Separation of cis-fatty acids from saturated and trans-fatty acids by nanoporous polydicyclopentadiene membranes

This article describes the separation of mixtures of fatty acid salts using a new organic solvent nanofiltration membrane based on polydicyclopentadiene (PDCPD). Mixtures of free fatty acids could not be separated by the membranes because they permeated at similar rates. When triisobutylamine was added to the fatty acids, the cis-fatty acid salts (oleic, petroselinic, vaccenic, linoleic, and linolenic acid) had slower permeation though the membranes than saturated (stearic acid) and trans-fatty acid (elaidic acid) salts. The reason for the difference in permeation was due to the formation of stable salt pairs between the amine and fatty acids that increased their cross-sectional areas. The fatty acid salts derived from saturated and trans-fatty acids were smaller than the critical area cutoff for the PDCPD membranes, so they readily permeated. In contrast, the fatty acid salts derived from the cis-fatty acids had critical areas larger than critical area cutoff of the PDPCD membranes and had slowed permeation. The partitioning coefficients of fatty acids and fatty acid salts were investigated to demonstrate that they were not responsible for the difference in permeation. The use of pressure was investigated to greatly accelerate the permeation through the membranes. For a solvent mixture of 35/65 (v/v) toluene/hexanes, the permeation of solvent was approximately 39 L m(-2) h(-1). This value is similar to values reported for permeation through membranes used in industry. The separation of a mixture of fatty acids based on the composition of soybean oil was investigated using pressure. The saturated fatty acid salts were almost completely removed from the cis-fatty acid salts when iBu(3)N was used as the amine to form the salt pairs. The separation of the cis-fatty acids found in soybean oil was investigated with Pr(3)N as the amine. The oleic acid salt (oleic acid has one cis double bond) preferentially permeated the membrane while the linoleic (two cis double bonds) and linolenic (three cis double bonds) salts were partly retained. The separation of fatty acids using membranes may have real applications in industry to purify fatty acids on a large scale.