Aqueous Phase System Research Articles

Highly selective electrosynthesis of imines via electroreduction coupling of nitroarenes with aryl aldehydes on Co9S8 with positively charged sulfur vacancies

The electrocatalytic synthesis of imines through the reductive imination of nitroarenes with aldehydes is a facile, environmentally friendly, and valuable process. In this study, high selectivity electrosynthesis of imines was realized through the electrocatalytic C-N coupling reaction between nitroarenes and aryl aldehydes on Co9S8 nanoflowers with rich sulfur vacancies (Co9S8-Vs). Comparative experiments revealed that positively charged sulfur vacancies play a pivotal role in boosting catalytic selectivity towards imines. Electron-deficient sulfur vacancies intensified the adsorption of negatively charged Ph-NO2, thereby enhancing the conversion rate of the electrochemical nitrobenzene-reduction reaction (eNB-RR). Simultaneously, sulfur vacancies augmented the adsorption capability of negatively charged Ph-CHO, enriching Ph-CHO species at the electrode interface and expediting the Schiff base condensation reaction rate. The experimental results show that the reaction conditions can satisfy the different nitroarenes and aryl aldehydes in the electrocatalytic aqueous-phase system under mild conditions to obtain the corresponding imine products in high selectivity. This study provides a facile and environmentally friendly pathway for future electrocatalytic synthesis of imine.

Revealing protein aggregation behaviour and dispersion properties induced by molecular interactions between sucrose esters and myofibrillar protein in an aqueous phase system

The effects of sucrose esters (SE) with varying hydrophilic-lipophilic balance (HLB) values (SE 11, 13, 15) and different concentrations (0.01, 0.1, 1.0 mM) on the dispersion properties and structure of myofibrillar proteins (MPs) in the aqueous phase were investigated. The results demonstrated that the SE 11 and SE 13 reduced the particle size and enhanced the distribution uniformity of the MPs. All of the SE exhibited a slight reduction in the ζ-potential absolute values of the MPs. Meanwhile, the SE 11 significantly reduced the turbidity of the MPs, especially in the 0.1 mM group. Macroscopic and microscopic images showed that the optimum dispersion state was in the SE 11–0.1 group. Furthermore, the interactions between SE and MPs exerted a significant impact on the proteins structure. The SE 13 and SE 15 caused significant changes, which presented concentration correlation, in the tertiary and secondary spatial structures of the MPs. Nevertheless, slight structural changes were observed in MPs with different SE11 concentrations. The SE did not alter the molecular weight of the MPs, i.e. it did not induce irreversible aggregation, nor degradation of the proteins. These results were verified by the surface hydrophobicity, UV–Vis spectroscopy, intrinsic fluorescence, circular dichroism, and SDS-PAGE. Molecular docking simulation showed that hydrophobic interactions and hydrogen bonds were the main interaction force between SE 11 and MPs. Therefore, our findings provided meaningful insights into the dispersion state of the MPs aqueous containing SEs and contributed to the practical application of non-ionic surfactants in meat protein processing.

The critical role of electron donating rate of pyrogenic carbon in mediating the degradation of phenols in the aquatic environment

Phenols are the widely detected contaminants in the aquatic environment. Pyrogenic carbon (PyC) can mediate phenols degradation, but the specific properties of PyC or phenols influencing this reaction remain unknown. The present study investigated the kinetic process and mechanism of removal of various phenols by different PyC in aqueous phase system. To avoid the impact of the accumulated degradation byproducts on the overall reaction, we conducted a short-term experiment, quantified adsorption and degradation, and obtained reaction rate constants using a two-compartment first-order kinetics model. The adsorption rate constants (ka) of phenols by PyC were 10–220 times higher than degradation rate constants (kd), and they were positively correlated. Interestingly, no correlation was found between kd and common PyC properties, including functional groups, electron transfer capacities, and surface properties. Phenols were primarily attacked by •OH in the adsorbed phase. But neither the instantly trapped •OH, nor the accumulated •OH could explain phenol degradation. Chemical redox titration revealed that the electron transfer parameters, such as the electron donating rate constant (kED) of PyC, correlated well with kd (r>0.87, P < 0.05) of phenols. Analysis of 13 phenols showed that Egap and ELUMO negatively correlated with their kd, confirming the importance of the electronic properties of phenols to their degradation kinetics. This study highlights the importance of PyC electron transfer kinetics parameters for phenols degradation and manipulation of PyC electron transfer rate may accelerate organic pollutant removal, which contributes to a deeper understanding of the environmental behavior and application of PyC systems.

Amphiphilic super-macroporous cryogel particles for the high-efficiency separation of bio-butanol using a fixed-bed method

Bio-butanol as a renewable energy can be produced through biomass fermentation. Among these, the adsorption-based technique is the most energy-efficient. However, the adsorption of small amounts of butanol from the aqueous phase remains a challenge. In this work, poly (methyl methacrylate)-based (PMMA) cryogel particles with tunable polarity and a super-macroporous structure were prepared by combining a simple dropping method and sulfolane freeze casting. The maximum adsorption capacities of the PMMA cryogel particles using the batch shaking and fixed-bed were 520.2 and 1442.2 mg/g, respectively. Adsorption rate constant of amphiphilic cryogel particles increased by approximately 9–40 times compared with PMMA cryogel particles. Adsorption capacity of the PMMA-based cryogel particles was maintained at 99 % of the initial adsorption capacity after 10 cycles. This study presented a strategy for the design of adsorbents with super-macroporous structures and hydrophilic modification to facilitate the adsorption of hydrophobic butanol from the aqueous phase system.

Distribution characteristics of sulfonamide antibiotics between water and extracellular polymeric substances in municipal sludge

The interaction between extracellular polymeric substances (EPS) in municipal sludge and antibiotics in wastewater is critical in wastewater treatment, resource recovery, and sludge management. Therefore, it is increasingly urgent to investigate the distribution coefficient (Log K) of sulfonamide antibiotics (SAs) in EPS, particularly in sludge-derived dissolved organic carbon (DOC) and aqueous phase systems. Herein, through balance experiments, the concentrations of SAs were determined using alkaline extraction EPS (AEPS) and alginate-like extracellular polymer (ALE) systems, and the Log KDOC values were determined. The results showed that the Log KDOC of AEPS was higher than that of ALE, which exhibited a negative KDOC value, indicating an inhibitory effect on dissolution. For the three SAs studied, the Log KDOC values were in the following order: sulfamethoxazole > sulfapyridine > sulfadiazine. This order can be attributed to the differing physicochemical properties, such as polarity, of the SAs. Three-dimensional excitation–emission matrix fluorescence spectra and fitting results indicated a lack of aromatic proteins dominated by tryptophan and humus-like substances in ALE. Meanwhile, the hydrophobic interaction of aromatic proteins dominated by tryptophan was the main driving force in the binding process between AEPS and SAs.

One-Step Preparation Method and Rapid Detection Implementation Scheme for Simple Magnetic Tagging Materials

With the widespread application of tagging materials, existing chemical tagging materials exhibit limitations in stability and detection under field conditions. This study introduces a novel magnetic detection scheme. Hydrophilic material-modified Fe3O4 nanoparticles (COOH-PEG@Fe3O4 NPs) were synthesized using the co-precipitation technique. The content of Fe3O4 nanoparticles in the magnetic tagging liquid can reach up to 10 wt% and remain stable in an aqueous phase system for seven days. This research details the preparation process, the characterization methods (IR, 1HNMR, EDX, XRD, SEM, TEM, VSM, DLS), and the performance effects of the materials in magnetic tagging. Experimental results indicate that COOH-PEG@Fe3O4 NPs exhibit high remanence intensity (Br = 1.75 emu/g) and considerable stability, making it possible to quickly detect tagged liquids in the field using portable flux meters and optical pump magnetometers. This study provides new insights into the design and application of magnetic tagging materials, making it particularly suitable for long-term tagging and convenient detection in field scenarios.

Boosting humoral and cellular immunity with enhanced STING activation by hierarchical mesoporous metal-organic framework adjuvants

Vaccination is essential for preventing and controlling infectious diseases, along with reducing mortality. Developing safe and versatile adjuvants to enhance humoral and cellular immune responses to vaccines remains a key challenge in vaccine development. Here, we designed hierarchical mesoporous MOF-801 (HM801) using a Cocamidopropyl betaine (CAPB) and a Pluronics F127 in an aqueous phase system. Meanwhile, we synthesized a novel SARS-CoV-2 nanovaccine (R@M@HM801) with a high loading capacity for both the STING agonist (MSA-2) and the Delta receptor binding domain (Delta-RBD) antigen. R@M@HM801 enhanced MSA-2 and RBD utilization and effectively co-delivered MSA-2 and RBD antigens to antigen-presenting cells in the draining lymph nodes, thereby promoting the activation of both T and B cells. Lymphocyte single-cell analysis showed that R@M@HM801 stimulated robust CD11b+CD4+ T cells, CXCR5+CD4+ T follicular helper (Tfh), and durable CD4+CD44+CD62L−, CD8+CD44+CD62L− effector memory T cell (TEM) immune responses, and promoted the proliferative activation of CD26+ B cells in vivo. Meanwhile, R@M@HM801 induced stronger specific antibodies and neutralization of pseudovirus against Delta compared to the RBD + MAS-2 and RBD + MAS-2 + Alum vaccines. Our study demonstrated the efficacy of a hierarchical mesoporous HM801 and its potential immune activation mechanism in enhancing adaptive immune responses against viruses and other diseases.

Interaction between chromite and Mn(II/IV) under anoxic, oxic and anoxic-oxic conditions: Dissolution, oxidation and pH dependence

Chromite oxidative dissolution has been recognized as an important process leading to elevated Cr(VI) in soil and groundwater. Under natural conditions, direct oxidation of Cr(III) by O2 is very unfavorable, and a critical determinant of Cr(VI) generation in soil and groundwater is the interaction between chromite and Mn(II) or Mn(III/IV) oxides. Here, the effects of Mn(II) or Mn(IV) on the oxidative dissolution of chromite were investigated at pH values of 5, 7 and 9 during anoxic, oxic and anoxic-oxic processes. The results showed that the direct oxidation of Cr(III) by O2 was slow in aqueous-phase system, while the Mn oxides in chromite could oxidize dissolved Cr(III). The added Mn(II) can be catalytically oxidized to MnOOH on the chromite surface only under alkaline oxidation conditions, and the catalytic efficiency is slow, which has less effect on chromite oxidative dissolution. Compared with the direct oxidation of O2 and catalytic oxidation of Mn(II), the synthesized biogenic Mn oxides drove the oxidative dissolution of chromite to release more Cr(VI) and were the main threat to the long-term stability of chromite in the environment. Overall, both acidic and alkaline environments are favorable to the catalytic oxidation of chromite by O2, Mn(II) and δ-MnO2, while neutral conditions are favorable to the long-term stability of chromite. These above processes may occur in soils and sediments with redox fluctuations (e.g., rice paddies, river floodplains, wetlands, and peatlands), and the presence of Mn(II) and Mn(III/IV) may play an important role in the oxidation and mobilization of Cr(III), leading to elevated Cr(VI) levels in soils and groundwater.

Controllable synthesis of 3D superhydrophilic Cd(II) ion-imprinted polymer microspheres based on OV-POSS and bifunctional monomers synergy with superior selectivity for Cd(II) adsorption

Novel 3D porous Cd(II) ion-imprinted polymer (Cd(II)-IIP) microspheres based on octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization technique combined with the synergistic effect of N-hydroxymethylacrylamide (NMA) and 1-vinylimidazole (1-VI) as bifunctional monomers. RAFT polymerization could achieve a controllable synthesis of polymer networks on OV-POSS. The structure, composition and properties of Cd(II)-IIP were systematically investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscope, water contact angle and thermogravimetric analysis. The results showed that the adsorbent, with a water contact angle of 0 ° and superhydrophilicity, has a high potential for application in aqueous phase systems. Different parameters influencing the sorption performance of Cd(II)-IIP, such as OV-POSS ratio, functional monomers ratio, adsorbent dosage, pH and adsorption time were optimized. Under optimal conditions, the maximum adsorption amount of Cd(II)-IIP for Cd(II) was 80.21 mg/g, and the adsorption equilibrium state could be reached within 40 min. The sorption kinetics proved that the sorption was chemisorption and the rate-limiting step was intraparticle diffusion. Thermodynamic studies showed that Cd(II) sorption was a spontaneous endothermic process. Importantly, XPS analysis, density functional theory (DFT) and frontier molecular orbital (FMO) theory calculations showed that the sorption of Cd(II)-IIP was attributed to the coordination of O and N atoms with Cd(II) on NMA and1-VI, respectively. Actual water sample analysis results indicated that Cd(II)-IIP was an adsorbent of great application potential.

Paper-assisted ratiometric fluorescent sensors for on-site sensing of sulfide based on the target-induced inner filter effect

Dissolved sulfide tends to species transformation and loss upon leaving the matrix, thus the development of a practical on-site determination of sulfide is crucial for environmental monitoring and human health. In this work, a novel paper-based ratiometric fluorescence sensor was developed for the field analysis of sulfide, which system was constructed by the inner filter effect (IFE) of CdS quantum dots (QDs) toward carbon dots (C-dots). Instead of an aqueous phase system, the conversion of sulfide to its hydride would induce the in-situ formation of CdS QDs on the paper, which acted as an energy acceptor to quench the emission of C-dots, leading to a variation of ratiometric fluorescence from blue to yellow with the increasing concentration of sulfide. Moreover, we proposed a smartphone-based fluorescence capture device integrated with a programmed Python program, accomplishing both color recognition and accurate detection of sulfide. Under the optimal condition, this ratiometric fluorescence sensor allowed for the on-site analysis of sulfide with a limit of detection of 0.05 μM. The accuracy of the sensor was validated via the successful field analysis of environmental water samples with satisfactory recoveries. Compared to other fluorescence methods used for sulfide analysis, this developed system retains the advantages of label-free, low-cost, ease of operation, and miniaturization, showing great potential for the measurement of sulfide on-site, as well as environmental monitoring.

Effects of the addition sequence of soybean protein isolate and cellulose nanofibers on the properties and in vitro digestion of emulsions

In this study, soybean protein isolate (SPI) and cellulose nanofibers (CNF) were used to prepare an oil-in-water emulsion. The effect of the sequence of adding SPI and CNF on the properties of the emulsion was examined by analyzing the emulsion index, microstructure, droplet size, zeta potential, rheological behavior, and in vitro gastrointestinal digestion characteristics of the emulsion. By using both SPI and CNF as emulsifiers, a better emulsification effect was obtained than using SPI or CNF alone. The particle size of the emulsion with SPI added first and CNF added later was smaller than that of the emulsion with CNF added first and SPI added later. And the emulsions with SPI added first had more cellulose nanofibers in the aqueous phase system. The emulsion with CNF added first and SPI added later was more likely to form a three-dimensional network structure; thus, it is more conducive to reducing the release of free fatty acids. When 50 mmol/L NaCl was added to the emulsion, the emulsion droplets gathered, and the viscosity increased, which was conducive to the formation of three-dimensional network gel structure of emulsion, but at the same time, the ability to release free fatty acids was improved.

Hydrolysis of cellulose to glucose in aqueous phase with phosphate group modified hydroxy-rich carbon-based catalyst

By catalytically converting cellulose using a phosphate-modified hydroxyl-rich carbon-based catalyst (P@HRCBC), which was made by hydrothermal carbonization, glucose was successfully hydrolyzed from cellulose in an aqueous phase system (HTC). The glycosidic bond breaking catalyzed by the -PO3H2 and the cellulose matrix lamellar exfoliation are both enhanced by the excellent adsorption capacity of the exceptionally rich –OH. The activity of cellulase is perfectly imitated. Within 120 min, the glucose output and the conversion of cellulose achieved 96.3% and 47.1%, respectively. The numerous ways that P@HRCBC adsorbs cellulose and cellobiose alter its catalytic ability and make separating glucose easier. After numerous cycles, the conversion of cellulose was maintained at 90.3%, thanks to the remarkable stability of –OH and -PO3H2. P@HRCBC shows an actual "enzymatic" catalytic function that provides a new solution for the efficient green hydrolysis of cellulose into glucose.

Lignin-First Biorefinery for Converting Lignocellulosic Biomass into Fuels and Chemicals

Driven by the excessive consumption of fossil resources and environmental pollution concerns, a large amount of biorefinery research efforts have been made for converting lignocellulosic biomass into fuels and chemicals. Recently, a strategy termed “lignin-first,” which allows for realizing high-yield and high-selectivity aromatic monomers, is regarded as one of the best prospective strategies. This review summarizes recent research advances in lignin-first biorefinery, starting from the raw lignocellulose through lignin-first processing and moving to downstream processing pathways for intermediate compounds. In particular, for the core purpose of producing liquid fuels, the corresponding downstream processing strategies are discussed in detail. These are based on the structural properties of the intermediates derived from lignin-first biorefinery, including the catalytic conversion of lignin and its derivatives (aqueous phase system and pyrolysis system) and the cascade utilization of carbohydrate residues (fermentation, pyrolysis, and hydrothermal liquefaction). We conclude with current problems and potential solutions, as well as future perspectives on lignin-first biorefinery, which may provide the basis and reference for the efficient utilization of lignocellulosic biomass.

Recent Advances of the Confinement Effects Boosting Electrochemical CO2 Reduction.

Powered by clean and renewable energy, electrocatalytic CO2 reduction reaction (CO2 RR) to chemical feedstocks is an effective way to mitigate the greenhouse effect and artificially close the carbon cycle. However, the performance of electrocatalytic CO2 RR was impeded by the strong thermodynamic stability of CO2 molecules and the high susceptibility to hydrogen evolution reaction (HER) in aqueous phase systems. Moreover, the numerous reaction intermediates formed at very near potentials lead to poor selectivity of reaction products, further preventing the industrialization of CO2 RR. Catalysis in confined space can enrich the reaction intermediates to improve their coverage at the active site, increase local pH to inhibit HER, and accelerate the mass transfer rate of reactants/products and subsequently facilitate CO2 RR performance. Therefore, we summarize the research progress on the application of the confinement effects in the direction of CO2 RR in theoretical and experimental directions. We first analyzed the mechanism of the confinement effect. Subsequently, the confinement effect was discussed in various forms, which can be characterized as an abnormal catalytic phenomenon due to the relative limitation of the reaction region. In specific, based on the physical structure of the catalyst, the confinement effect was divided in four categories: pore structure confinement, cavity structure confinement, active center confinement, and other confinement methods. Based on these discussions, we also have summarized the prospects and challenges in this field. This review aims to stimulate greater interests for the development of more efficient confined strategy for CO2 RR in the future.

A Universal Eluent System for Method Scouting and Separation of Biotherapeutic Proteins by Ion-Exchange, Size-Exclusion, and Hydrophobic Interaction Chromatography.

Characterization and quality control of biotherapeutic proteins commonly require the application of several orthogonal separation techniques in order to establish product identity and purity. Many of the techniques used rely on a buffered aqueous mobile phase system to maintain the native conformation of the protein and its variants. Optimal pH, buffer substance(s), and chromatography methods vary with each protein of interest and result in tedious method development for each new drug product. Linear controlled pH gradient systems from pH 5.6 to pH 10.2 has been shown to provide a global method for the separation of charge variants of monoclonal antibodies. This can be realized using two balanced zwitterionic buffer blends. The pH linearity of the resulting system, with a cation ion exchange column in place, can generate any pH value in this accessible pH range. This study expands the scope of this buffer system and demonstrates its application in conjunction with a quaternary HPLC pump for several analytical techniques: the pH optimization of salt gradient-based anion and cation exchange during method development, as well as performing pH gradient elution. In addition, the same universal buffers are used for hydrophobic interaction and size exclusion chromatography. This eluent system omits the need to prepare different buffers for each method and flushing of the HPLC system between method changes. The implementation of this concept is further demonstrated to allow an automated method scouting approach and selection of different methods that requires minimal manual intervention.

Deep eutectic solvent-based three-liquid-phase-extraction system for one-step separation of Cu, Mg and Zn in water samples

A novel and environmentally friendly three-liquid-phase extraction (TLPE) approach was developed for simultaneous separation of copper (Cu), magnesium (Mg) and zinc (Zn) from water samples. The proposed organic/two aqueous phase system consists of di(2-ethylhexyl)phosphoric acid (D2EHPA), Choline Chloride:urea (deep eutectic solvent (DES)), and salt (K2HPO4). The effects of various factors including amount of DES and K2HPO4, pH, D2EHPA concentration, phase-mixing time, and diluent on the preconcentration/separation of Cu, Mg and Zn were evaluated. The results showed that 96.6% of Zn was concentrated in the D2EHPA-rich top phase, whereas 97.8% of Cu and 98.1% of Mg were quantitatively extracted into the DES-rich middle phase and salt-rich bottom phase, respectively. Excellent recovery (>97%) of Cu, Mg and Zn was obtained by using 20% (v/v) D2EHPA in hexane, and 1.72 g DES and 3.12 g K2HPO4 in two lower aqueous phases at pH= 4. The limits of detection were 1.58, 1.55 and 2.37 mg/L for Cu, Mg and Zn, respectively. Relative standard deviations (RSDs) for 0.5 mg/L and 1.0 mg/L of Cu, Mg and Zn in water samples were < 6%. The accuracy of the procedure was confirmed by analyzing a certified reference material of water and tea (NIST SRM 1640a, GBW 07605). Under optimized conditions, excellent agreement was observed between the TLPE-flame atomic absorption spectrometry (FAAS) results and certified values using the student’s t-test (P = 0.05). TLPE procedure was successfully applied for the determination of Cu, Mg and Zn in water samples.

Ultrasensitive molecularly imprinted electrochemiluminescence sensor based on highly-conductive rGO-COOH synergically amplify TCPP luminophor signal in aqueous phase system for “switches-controlled” detection of tryptamine

An efficient and innovative molecularly imprinted electrochemiluminescence sensor (MIECLS) based on the reduced carboxylated graphene oxide (rGO-COOH) amplifying aqueous phase meso-tetra(4-carboxyphenyl)porphyrin (TCPP) signal was constructed for “switches-controlled” detection of tryptamine (Tryp). The conductive rGO-COOH uninterruptedly accelerated the high-energy electrons injection into the aqueous co-reaction system of green metal-free TCPP, and more excited state molecules (TCPP*) were generated to obtain excellent ECL signal. Benefiting from the large specific surface area provided by rGO-COOH, molecularly imprinted polymer (MIP) with specific recognition cavities can be firmly electropolymerized on the surface of rGO-COOH/glassy carbon electrode (GCE), which regulated electrons transfer rate to realize “switches-controlled” detection by elution and recombination of Tryp. Under optimal conditions, the MIECLS exhibited a favorable linear relationship with Tryp in the concentration range of 1 × 10−9–1 × 10−4 mol L−1 and the limit of detection (LOD) was 0.25 × 10−9 mol L−1. The MIECLS was used for Tryp detection in actual samples with the satisfactory results (recovery rate, 83.19–91.32%) and consistent with that of HPLC. The dual application of TCPP and MIP/rGO-COOH/GCE can create nicely synergistic effect for the Tryp detection, making a novel avenue to the rapid analysis of other food hazards.

Preparation, Characterization, and Evaluation of Pyraclostrobin Nanocapsules by In Situ Polymerization.

In this study, pyraclostrobin nanocapsules were prepared by in situ polymerization with urea–formaldehyde resin as a wall material. The effects of different emulsifiers, emulsifier concentrations, and solvents on the physicochemical properties of pyraclostrobin nanocapsules were investigated. Solvesso™ 100 was selected as the solvent, and Emulsifier 600# was used as the emulsifier, which accounted for 5% of the aqueous phase system, to prepare pyraclostrobin nanocapsules with excellent physical and chemical properties. The particle size, ζ potential, and morphology of the nanocapsules were characterized by a particle size analyzer and transmission electron microscope. The nanocapsules were analyzed by Fourier-transform infrared spectroscopy, and the loading content and sustained release properties of the nanocapsules were measured. The results show that the size of the prepared nanocapsules was 261.87 nm, and the polydispersity index (PDI) was 0.12, presenting a uniform spherical appearance. The loading content of the pyraclostrobin nanocapsules was 14.3%, and their cumulative release rate was 70.99% at 250 h, providing better efficacy and sustainability compared with the pyraclostrobin commercial formulation.

A novel isopropanol salt aqueous two-phase system and its applications for 2, 3-butanediol extraction

At present, the hydrophilic alcohol and inorganic salt combined with the two-phase system have been widely used in the extraction of biological fermentation products. However, the residual salt in the extraction solution of the existing system caused the loss of salt and increased the energy consumption of subsequent product separation. Therefore, how to achieve organic phase without salt, water phase without extractant is particularly important. This paper studies the ternary liquid-liquid equilibrium of four highly soluble inorganic salts (K4P2O7, K2HPO4, K3PO4, K2CO3) + isopropanol + water at 298.15 K and their applications. By comparison, the extraction system with no salt and low water content in the organic phase and no extractant in the aqueous-rich phase was selected, with the K4P2O7/isopropanol aqueous phase system being the best system. Moreover, the screened system avoided the overuse of extraction solvent. The results showed that the isopropanol content had little effect on the water content in the extract phase. The salting-out extraction recovery rate of 2,3-butanediol is 100%, and the concentration coefficient is 5.74, which is much larger than other systems. More importantly, no salt was in the extract phase and no isopropanol was in the water-rich phase. Biofuel recovery from fermentation broth by K4P2O7/isopropanol aqueous two-phase system has the advantages of high selectivity and can effectively reduce energy demand.

Aqueous polymeric phase system as low-cost downstream processing technique for extraction of D-glucuronic acid

The large-scale availability of glucuronic acid for industrial sectors is limited due to involving costly conventional purification strategies. Here, aqueous two-phase system (ATPS) was used as potent economical platform for selective recovery of D-glucuronic acid. Paenibacillus apiarus MTCC 2192 produced extracellular D-glucuronic acid with maximum yield (0.657 mg/ml) during late log phase. D-glucuronic acid was extracted after treating cell free extract with ATPS system consisting 10% PEG and 15% Potassium hydrogen phosphate (PHP) salt. It showed maximum recovery (82.97%) with lower concentration (5%) of high molecular weight of PEG 6000. The increased concentration of PHP-salt from 10 to 25% (w/w) and variation of pH (4–9) favours high recovery of D-glucuronic acid in top phase due to removal of majority of inhibitory protein component. ATPS with 5% PEG 6000 and 25% PHP-salt showed higher recovery of D-glucuronic acid (84.20%) at pH-4 and could be used as low-cost bio-separation tool to fulfil its great demand.