Separation Of Products Research Articles

Green synthesis and investigation of antioxidant and antibacterial activity of new derivatives of chromenoazepines employing CuO/TiO2@MWCNTs.

The synthesis of novel, high-yield derivatives of chromenoazepine was investigated in this work. CuO/TiO2@MWCNTs was used as a nanocatalyst in a multicomponent reaction involving 4-aminocumarine, activated acetylenic chemicals, and alkyl bromide in room temperature water to create these novel compounds. Using MCRs of 4-aminocumarine, isothiocyanate, and alkyl bromide in the presence of CuO/TiO2@MWCNTs as nanocatalysts in room-temperature water, chromenothiazepines were synthesized under comparable conditions. The freshly synthesized azepine exhibits antioxidant activity since its NH group has undergone two evaluation processes. Additionally, using two types of Gram-negative bacteria in a disk distribution procedure, the antibacterial activity of recently developed azepines was evaluated, and these compounds also inhibited the growth of Gram-positive bacteria. This method's benefits include quick reaction times, large product yields, and straightforward catalyst and product separation through easy steps.

Electric-field-assisted in situ separation of mandelic acid in an enzymatic milli-reactor improves the control of reaction conversion and enhances the enantiomeric ratio

Enantiopure or enantiomerically enriched chemicals are often used as active pharmaceutical ingredients (APIs). However, API synthesis and purification on a preparative scale is usually costly, time-consuming, and difficult to scale up in conventional batch reactors. To develop an alternative solution, we applied kinetic enantioselective synthesis with simultaneous product separation. More specifically, we constructed a continuously operated packed-bed milli-reactor (PBR) with an orthogonally applied electric field for in situ separation. We tested our concept in the enzymatic production of mandelic acid (MA) enantiomers from racemic methyl mandelate (rMM) by immobilised Aspergillus niger lipase. The electric field selectively extracted the product (mandelate anions) whilst leaving almost 100 % of the electroneutral substrate in the reaction mixture. Such selective product separation significantly enhanced MA formation by shifting the reaction toward product synthesis. The applied electric current efficiently controlled the overall rMM conversion, reaching more than 90 % compared to 30% without current. We identified the electric current providing the highest (R)-(-)-MA to (S)-(+)-MA enantiomeric ratio equals to 5.20. This ratio was above 3.86 achieved in an ordinary PBR, albeit subject to further optimization. Our PBR with in situ product separation provided superior process control and significantly enhanced enantiomerically enriched chemical synthesis.

Florisil as an efficient reagent for deprotection of tert-butyl carbamates, carbonates and esters

Florisil (magnesium polysilicate) is an efficient and eco-friendly reagent for the deprotection of tert-butyl carbamates, carbonates, and ethers. Moderate to excellent yields could be achieved in the presence of other acid-sensitive groups. The separation of products is easy, and Florisil can be recycled several times without observing a decrease in yields.

Self-Promoted Hydroxyl Radical Releasing Magnetic Zn@Fe Particles.

Semiconductor photocatalysts, such as TiO2 and ZnO, have garnered significant attention for their ability to generate hydroxyl radicals, offering various practical applications. However, the reliance on UV light to facilitate electron-hole separation for hydroxyl radical production poses limitations. In this study, a novel approach is presented utilizing Zn@Fe core/shell particles capable of generating hydroxyl radicals without external energy input. The generation process involves electron donation from Zn to O2, resulting in the formation of radical species .O2 -/H2O2, followed by Fe-catalyzed conversion of H2O2 into hydroxyl radicals through the Fenton reaction. The release of .OH imparts good antimicrobial and antiviral properties to the Zn@Fe particles. Furthermore, the inclusion of Fe confers magnetic properties to the material. This dual functionality holds promise for diverse potential applications for the Zn@Fe particles.

Rapid separation of MOFs particles with the aid of PVDF hollow fiber membrane

Metal-organic frameworks (MOFs) have been widely investigated due to their fascinating structures and properties. However, the time-cost synthetic process and the difficult separation from liquid phase hinder their practical application. In this study, a self-made automatic apparatus containing commercial poly(vinylidene fluoride) (PVDF) hollow fiber membranes was used to separate MOFs from large-volume suspension. Taking MIL-88A(Fe) synthesized with industrial-grade chemicals as an example, the investment cost, operation cost, human cost, time duration during separation process, and unit cost price of MIL-88A(Fe) were significantly reduced by 62%, 82%, 100%, 90%, and 36%, respectively, compared to those of centrifugation. More importantly, MIL-88A(Fe) powders that were separated and purified by the apparatus were easy to be removed from membrane surface by slight vibration, which displayed good morphology, crystallinity, as well as high degradation efficiency toward organic contaminants via photo-Fenton reaction. Meanwhile, the membrane can be reused instantly without any rinse. More encouragingly, this method is applicable to other MOFs’ separation, like ZIF-8 and ZIF-67. This study further confirmed the potential and prospective of high-throughput production and facile separation of MOFs for practical applications.

Solar to hydrogen conversion by a 25 cm2-photoelectrochemical cell with upscaled components

An innovative tandem photoelectrochemical cell with a scaled-up active area from 0.25 to 25 cm2 based on low-cost and non-critical raw materials was employed to produce green hydrogen by water splitting. It uses a photoanode/membrane/photocathode tandem cell configuration in which a hematite-based photoanode is layered on a fluorine-doped tin oxide glass for the oxygen evolution reaction, CuO is deposited on a hydrophobic gas diffusion layer as the photocathode for the hydrogen evolution reaction and an anion exchange membrane is used as the electrolyte and gas separator. The solid membrane's low hydrogen and oxygen crossover guarantees the operational stability of the tandem photoelectrochemical cell and the efficient separation of water-splitting products. Significant efforts have been focused on scaling up the cell. It has allowed obtaining, for the first time, a 25 cm2 unit cell prototype. Appropriate design approaches have been considered to optimise water/gas management, current collection, gas-tightness and clamping. The adopted architecture allowed for the reduction of the bias-potential from −1.23 V, generally employed to investigate PEC cells, up to −0.6/-0.4 V 20 h-durability tests demonstrated good resistance to corrosion, showing a constant photocurrent. Efficiency at −0.6 V was about 0.2%. Selective hydrogen production was demonstrated by mass spectrometric analysis.

Production and radiochemical separation of 68Ge from irradiated Ga–Ni alloy target in 30 MeV cyclotron

Abstract Gallium-68 [t 1/2: 67.7 min, β+ (89 %)] has application in PET imaging mainly for prostate cancer and neuroendocrine tumours. Gallium-68 is generally obtained from a 68Ge/68Ga generator. It is therefore an important task to prepare 68Ge (t 1/2 = 271 days) radiochemical for the manufacture of 68Ge/68Ga generator to cater for the needs of various nuclear medicine centres. Germanium-68 has been produced successfully after irradiation of indigenously developed Ga–Ni targets in a 30 MeV cyclotron and chemical processing of the irradiated targets using an indigenous semi-automated module. The Ga–Ni targets were prepared by an electroplating method. The 68Ge has been radiochemically separated from irradiated Ga–Ni targets using Sephadex G-25 column chromatography. The chemical separation yield and radionuclidic purity of 68Ge were about 70 % (n = 3) and about 98.3 % (n = 3), respectively.

Photocatalytic and Superhydrophobic Nanoporous Membranes for Emulsion Separation and Removal of Pesticides and Pharmaceutical Products

Photocatalytic and Superhydrophobic Nanoporous Membranes for Emulsion Separation and Removal of Pesticides and Pharmaceutical Products

One-pot Tandem Synthesis and Spontaneous Product Separation of N-heterocycles based on Bifunctional Small-molecule Photocatalyst.

Homogeneous and heterogeneous reactions wherein the resulting products remain dissolved in solvents generally require complicated separation and purification process, despite the advantage of heterogeneous systems allowing retrieval of catalysts. Herein, we have developed an efficient approach for the one-pot tandem synthesis of quinazolines, quinazolinones and benzothiadiazine 1,1-dioxides from alcohols and amines utilizing a bifunctional bipyridinium photocatalyst with redox and Lewis acid sites using air as an oxidant. Through solvent-modulation strategy, the photocatalytic system exhibits high performance and enables most products to separate spontaneously. Consequently, the homogeneous catalyst can be reused by direct centrifugation isolation of the products. Notably, the method is also applicable to the less active substrates, such as heterocyclic alcohols and aliphatic alcohols, and thus provides an efficient and environmentally friendly photocatalytic route with spontaneous separation of N-heterocycles to reduce production costs and meet the needs of atomic economy and green chemistry.

Zr-Based MOF-Stabilized CO2-Responsive Pickering Emulsions for Efficient Reduction of Nitroarenes.

A Pickering emulsion is a natural microreactor for interfacial catalysis in which an emulsifier is critical. Recently, a metal-organic framework (MOF) has attracted attention to emulsify water-organic mixtures for constructing a Pickering emulsion. However, a few stimuli-responsive Pickering emulsions based on MOFs have been reported, and the MOF emulsifiers cannot be regenerated at room temperature. Herein, the Zr-MOF with a rodlike morphology is synthesized using ionic liquid as a modulator and then modified with n-(trimethoxysilylpropyl)imidazole (C3im) to prepare a series of functionalized Zr-MOFs (MOF-C3im). It is found that MOF-C3im is an excellent emulsifier to construct stable and CO2-responsive Pickering emulsions even at low content (>0.20 wt %). Notably, the emulsification and demulsification of the emulsions can be easily and reversibly switched by bubbling of CO2 and N2 alternatively at room temperature because CO2 and imidazole molecules anchored on the Zr-MOF underwent a reversible acid-base reaction, resulting in an obvious change in the wettability of the emulsifier. As a proof of concept, the reduction reactions of nitrobenzene have been successfully carried out in these Pickering emulsions, demonstrating the efficient integration as a microreactor for chemical reaction, product separation, and emulsifier recycling under ambient conditions. This strategy provides an innovative option to develop stimulus-responsive Pickering emulsions for sustainable chemical processes.

Hydrodynamic studies of innovative membrane reactor for enzymatic hydrolysis of lignocellulosic waste.

This paper presents the study concerning the impact of the basic operational parameters on the performance of an innovative microfiltration membrane reactor applied for enzymatic hydrolysis of lignocellulosic biomass. The concept and basic hydrodynamics of the reactor with tubular ceramic membranes and a propeller agitator were shown. Besides, the efficiency of enzymatic hydrolysis of corn straw was studied to check reactor functionality. It has been proven that the proposed reactor construction can improve the microfiltration of lignocellulosic suspension by reducing the cake layer on the membrane surface. Increasing the rotational speed of the propeller agitator also improved the filtration efficiency. The permeate flux during the microfiltration experiments was lower for smaller lignocellulose biomass fraction (D<425 μm) when compared to the less fragmented corn straw (425<D<900 μm). For larger solid fractions, a stirring speed increase enhanced the separation efficiency regardless of the differences in biomass concentration. In contrast, this trend for the finer biomass fraction was only noticeable for the highest used biomass concentration (C=2.0%). Considering the enzymatic hydrolysis of corn straw, membrane separation of reaction products positively influenced the process yield, and the results depended on the applied operational parameters.

Manipulating Microbial Cell Morphology for the Sustainable Production of Biopolymers.

The total rate of plastic production is anticipated to surpass 1.1 billion tons per year by 2050. Plastic waste is non-biodegradable and accumulates in natural ecosystems. In 2020, the total amount of plastic waste was estimated to be 367 million metric tons, leading to unmanageable waste disposal and environmental pollution issues. Plastics are produced from petroleum and natural gases. Given the limited fossil fuel reserves and the need to circumvent pollution problems, the focus has shifted to biodegradable biopolymers, such as polyhydroxyalkanoates (PHAs), polylactic acid, and polycaprolactone. PHAs are gaining importance because diverse bacteria can produce them as intracellular inclusion bodies using biowastes as feed. A critical component in PHA production is the downstream processing procedures of recovery and purification. In this review, different bioengineering approaches targeted at modifying the cell morphology and synchronizing cell lysis with the biosynthetic cycle are presented for product separation and extraction. Complementing genetic engineering strategies with conventional downstream processes, these approaches are expected to produce PHA sustainably.

Direct Photoreforming of Real-World Polylactic Acid Plastics into Highly Selective Value-Added Pyruvic Acid under Visible Light.

Although polylactic acid (PLA) represents a pivotal biodegradable polymer, its biodegradability has inadvertently overshadowed the development of effective recycling techniques, leading to the potential wastage of carbon resources. The photoreforming-recycling approach for PLA exhibits significant potential in terms of concepts and methods. However, the reaction faces enormous challenges due to the limited selectivity of organic oxidation products as well as the increased costs and challenging separation of organic products associated with alkali-solution-assisted prehydrolysis. Herein, we report an alkali-free direct-photoreforming pathway for real-world PLA plastics utilizing the Pd-CdS photocatalyst under visible-light illumination, obviating the need for chemical pretreatment of PLA. The devised pathway successfully produces H2 at a rate of 49.8 μmol gcat.-1 h-1, sustained over 100 h, and exhibits remarkable selectivity toward pyruvic acid (95.9% in liquid products). Additionally, experimental findings elucidate that Pd sites not only function as a typical cocatalyst for enhancing the photocatalytic evolution of H2 but also suppress competitive side reactions (e.g., lactic acid coupling or decarboxylation), consequently augmenting the yield and selectivity of pyruvic acid and H2. This investigation provides a straightforward and sustainable direct-photoreforming route capable of simultaneously mitigating and repurposing plastic waste into valuable chemicals, thus offering a promising solution to the current environmental challenges.

Desorbent swing adsorption process using ethylene to separate propane and propylene under isobaric conditions

The separation of olefin and paraffin using adsorption technology remains a significant challenge. This study proposes a novel desorbent swing adsorption (DSA) process using an olefin desorbent with a weaker adsorption affinity (C2: ethylene) to separate a paraffin/olefin mixture with a higher adsorption affinity (C3s: propane and propylene) under isobaric conditions, which is the reverse concept of using a desorbent with a stronger affinity in conventional DSA systems. The proposed DSA process effectively separates the C3 mixture because the deteriorating effects caused by the desorbent is minimized. Based on sequential breakthrough experiments with zeolite 13X DSA using ethylene, the efficient separation of a propylene dehydrogenation product (propane:propylene = 60:40 vol%) to produce polymer-grade propylene is achieved. It is confirmed that ethylene desorbent stream pushes out the adsorbed propylene and regenerates the adsorption bed without changing the pressure. The desorption step plays a key role in the separation performance of the proposed DSA process because the regenerated bed offers favorable conditions when filled with the weaker desorbent after the desorption step. The flowrate of the desorbent strongly affects the efficiency of propylene desorption. After validating the dynamic mathematical model using the experimental results, a two-bed DSA process using a six-step sequence that includes rinse export/import and idle steps is shown to achieve a propylene purity above 99.999 % (desorbent-free basis) with a recovery of 99.39 %, a productivity of 4.21 mol∙kg−1∙hr−1, and an ethylene usage of 7.59 mol∙kg−1∙hr−1. This study offers important insights into the development of adsorptive separation designs for olefin/paraffin separation.

Extraction and Separation of Natural Products from Microalgae and Other Natural Sources Using Liquefied Dimethyl Ether, a Green Solvent: A Review.

Microalgae are a sustainable source for the production of biofuels and bioactive compounds. This review discusses significant research on innovative extraction techniques using dimethyl ether (DME) as a green subcritical fluid. DME, which is characterized by its low boiling point and safety as an organic solvent, exhibits remarkable properties that enable high extraction rates of various active compounds, including lipids and bioactive compounds, from high-water-content microalgae without the need for drying. In this review, the superiority of liquefied DME extraction technology for microalgae over conventional methods is discussed in detail. In addition, we elucidate the extraction mechanism of this technology and address its safety for human health and the environment. This review also covers aspects related to extraction equipment, various applications of different extraction processes, and the estimation and trend analysis of the Hansen solubility parameters. In addition, we anticipate a promising trajectory for the expansion of this technology for the extraction of various resources.

Engineering flower-shaped hierarchical micromotors on a sustainable biotemplate by teamed boronate affinity-based surface imprinting for effective separation of shikimic acid

Self-propelled nano/micromotors are the frontier of separation materials because they are capable of converting external energy in the surrounding environment into kinetic energy for their autonomous movement. In this work, a bioinspired flower-shaped hierarchical teamed boronate affinity (TBA)-imprinted Pt-free micromotor is introduced based on waste rape pollen as a biotemplate due to its merits of sustainability, rich source and low price. Such micromotor, composed of MnO2 nanosheets as a catalytic medium, Mg-Al layered double hydroxides (LDH) nanosheets as large surface area substrate and functional surface imprinted polymers as identification subject, exhibits autonomic motor behavior powdered by oxygen bubbles generated by the decomposition of H2O2 and selective recognition and separation for shikimic acid (SA). The hierarchical flower-shaped structure affords more accessible recognition sites for SA, which thus facilitates the separation process. Moreover, in combination with the TBA strategy, the micromotor can precisely recognize the target via boronate affinity between boronic acids and cis-diols from SA while showing strong binding capacity under neutral conditions. Benefiting from the pluripotent role of pioneering boronate affinity-covalent imprinted technique, hydrogen bonds interaction and nanoconfinement effect, the resulting affinity towards SA is evidently enhanced with maximal adsorption capacity of 129.51 mg g−1 at neutral pH in the presence of H2O2. After five capture/release cycles, the adsorption capacity remains above 85 %. This proposed flower-shaped hierarchical micromotor expands the scope of potential materials for the adsorption of SA and provides a new and promising direction for fabricating adsorbents applied in the separation and purification of natural products.

Reversible phase separation of CO2 responsive microemulsion: Judgment on whether and how regulated by ratio of ion to responsive surfactant concentration

CO2 responsive microemulsion is a promising solvent with diverse applications in various fields including oil exploitation, material synthesis, and metal recovery. The implementation of reversible phase separation becomes important in enabling the reuses of CO2 responsive microemulsion and facilitating the separation of products in these applications. Earlier reports have established that changes in ion concentration within CO2 responsive microemulsion result in reversible phase separation. Ion in CO2 responsive microemulsion is derived from protonation of CO2 responsive substance which is commonly used as surfactant. An increase in ion concentration leads to a decrease in surfactant concentration. In microemulsion, adsorption of surfactants and ions at the oil–water interface is correlated with interface performance, which influence the ability to achieve efficient phase separation. Interfacial tension (IFT) is an important parameter for interface performance. In this work, ratio of ion to CO2 responsive surfactant concentration was defined as ∮. The relationship between IFT and ∮ was investigated through a combination of experiments and molecular dynamic simulation to explore mechanism of reversible phase separation. The results of present study indicated that ∮ was found to play a vital role in either inhibiting or promoting the formation of hydrogen bond network by hydrophilic groups in surfactants. The changes of hydrogen bond network resulted in increase or decrease in IFT, leading to reversible phase separation. This relationship between IFT and ∮ was used as a theoretical guidance to optimize N2/CO2 bubbling time to achieve reversible phase separation. The optimization improved the efficiency of CO2 responsive microemulsion in extracting active components from Rehmannia glutinosa Libosch. leaves, and enhanced sustainability of the microemulsion. The findings of this study could be used to advance the scientific understanding of reversible phase separation, offering theoretical guidance for green and efficient utilization of CO2 responsive microemulsion in extraction of natural products. Ultimately these results could encourage the broader applications of CO2 responsive microemulsion across diverse fields.

Innovative vanillin yielding from lignin: process modelling and assessment

In this work, we present the modelling of a novel process to promote vanillin production from lignin using PODIC®. The model includes the PODIC© production, lignin depolymerisation and final product separation. Furthermore, a complete assessment of the proposed process in terms of economic and environmental performance was performed. Regarding the economic evaluation, a comprehensive study was done leading to high investment (13.76 €/kgLignin) and operational (5.16 €/kgLignin) costs. The main reasons for the elevated costs were identified and further alternative process configuration were evaluated too. Despite this, the main result was that the proposed process is challenging to commercialize. Since it is complex to obtain profits even at larger scales, improvement of the process design to improve the economics are considered. An environmental analysis of the environmental impacts generated by the overall production process of vanillin and phenolic compounds was carried out considering energy consumption, human health, greenhouse gas emissions, water consumption and human toxicity. Electricity consumption of the PODIC® reactor was identified as the hotspot of the system. The CO2 emissions were also compared with the Borregaard process and found to be similar.

Cu(II)-Mediated direct 18F-dehydrofluorination of phosphine oxides in high molar activity

BackgroundThe 18F/19F-isotope exchange method employing P(V)-centered prosthetic groups demonstrates advantages in addressing mild one-step aqueous 18F-labeling of peptides and proteins. However, the molar activity (Am) achieved through isotope exchange remains relatively low, unless employing a high initial activity of [18F]F−. To overcome this drawback, our work introduces a novel approach through a Cu-mediated direct 18F-dehydrofluorination of phosphine oxides. This method leverages the straightforward separation of the 18F-labeled product from the phosphine oxide precursors, aiming to primarily increase Am.ResultsThrough a 19F-dehydrofluorination efficiency test, Cu(OAc)2 was identified as the optimal oxidative metal salt, exhibiting a remarkable 100% conversion within one hour. Leveraging the straightforward separation of phosphine oxide precursors and phosphinic fluoride products, the Am of an activated ester, [18F]4, sees an impressive nearly 15-fold increase compared to the 18F/19F-isotope exchange, with the same initial activity of [18F]F−. Furthermore, this Cu(II)-mediated 18F-dehydrofluorination approach demonstrates tolerance up to 20% solvent water content, which enables the practical radiosynthesis of 18F-labeled water-soluble molecules under non-drying conditions.ConclusionsThe direct 18F-dehydrofluorination of phosphine oxide prosthetic groups has been successfully accomplished, achieving a high Am via Cu(II)-mediated oxidative addition and reductive elimination.

Solvent processing for improved separation of hydrothermal liquefaction products

Solvent extraction and separation of HTL products using naphtha range hydrocarbons was studied with the aim of decreasing operational hazards while improving scalability, reliability, and yields.