Mixed Esters Research Articles

Comparison of concentration and extraction workflows for qPCR quantification of intI1 and vanA in untreated wastewater

Quantitative polymerase chain reaction (qPCR) measurement of antibiotic resistance genes (ARGs) in untreated municipal wastewater may prove useful in combating the antimicrobial resistance crisis. However, harmonizing and optimizing qPCR-based workflows is essential to facilitate comparisons across studies, and includes achieving highly-effective ARG capture through efficient concentration and extraction procedures. In the current study, combinations of sample volume, membrane types and DNA extraction kits within filtration and centrifugation-based workflows were used to quantify 16S ribosomal RNA (16S rRNA), class 1 integron-integrase gene (intI1) and an ARG encoding resistance to vancomycin (vanA) in untreated wastewater sampled from three wastewater treatment plants (WWTPs). Highly abundant 16S rRNA and intI1 were detected in 100 % of samples from all three WWTPs using both 2 and 20 mL sample volumes, while lower prevalence vanA was only detected when using the 20 mL volume. When filtering 2 mL of wastewater, workflows with 0.20-/0.40-μm polycarbonate (PC) membranes generally yielded greater concentrations of the three targets than workflows with 0.22-/0.45-μm mixed cellulose ester (MCE) membranes. The improved performance was diminished when the sample volume was increased to 20 mL. Consistently greater concentrations of 16S rRNA, intI1 and vanA were yielded by filtration-based workflows using PC membranes combined with a DNeasy PowerWater (DPW) Kit, regardless of the sample volume used, and centrifugation-based workflows with DNeasy Blood & Tissue Kit for 2-mL wastewater extractions. Within the filtration-based workflows, the DPW kit yielded more detection and quantifiable results for less abundant vanA than the DNeasy PowerSoil Pro Kit and FastDNA™ SPIN Kit for Soil. These findings indicate that the performance of qPCR-based workflows for surveillance of ARGs in wastewater varies across targets, sample volumes, concentration methods and extraction kits. Workflows must be carefully considered and validated considering the target ARGs to be monitored.

Health risk assessment of exposure to various vapors and fumes in a factory of automobile manufacturing

This study aimed to comprehensively evaluate the health risk of exposure to various vapors and fumes in a factory of automobile manufacturing. This study was performed in 2021 on 115 workers. Vapors and fumes were gathered by the adsorbent tubes of activated charcoal and mixed cellulose esters (MCE) membrane filter, respectively. The flow rate for vapors and fumes were between 0.05 and 0.20 L per min and 1 to 4 L per min, respectively. After preparing, samples were analyzed. To assess the non-cancer and cancer risk of the pollutants, the method proposed environmental protection agency (EPA) was applied. The total concentration of copper (1.031 ppm), manganese (0.114), and 2-butoxyethanol (91.767 ppm) were found to be higher than The threshold limit values (TLVs). The values of non-cancer risk (HQ) due to exposure to vapors of benzene (6.583), toluene (1.396), ethyl benzene (1.212), xylene (31.148), 2-butoxyethanol (89.302), 2-propanol (4.695), 1,2,3-trimethylbenzene (1.923), copper (2.336), manganese (715.82), aluminum (3.772), and chromium (107.066) were higher than the acceptable limit. Moreover, the estimated LCR for benzene (2.15 × 10−4), ethyl benzene (3.97 × 10−4), vinyl chloride (1.25 × 10−4), and chromium (2.11 × 10−2) were higher than the threshold risk level set by EPA. It is emphasized that preventive measures are performed.

Synthetic bacterial consortia enhanced the degradation of mixed priority phthalate ester pollutants

Dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DOP) are hazardous chemicals listed as priority pollutants that disrupt endocrine systems. According to available reports, these six priority phthalate esters (PAEs) are considered the most polluting; however, no studies have been conducted on the efficient remediation of these PAEs. We therefore designed and constructed a synthetic bacterial consortium capable of the simultaneous and efficient degradation of six priority PAEs in minimal inorganic salt medium (MSM) and soil. The consortium comprised Glutamicibacter sp. ZJUTW, which demonstrates priority for degrading short-chain PAEs; Cupriavidus sp. LH1, which degrades phthalic acid (PA) and protocatechuic acid (PCA), intermediates of the PAE biodegradation process; and Gordonia sp. GZ-YC7, which efficiently degrades long-chain priority PAEs, including DEHP and DOP. In MSM containing the six mixed PAEs (250 mg/L each), the ZJUTW + YC + LH1 consortium completely degraded the four short-chain PAEs within 48 h, and DEHP (100%) and DOP (62.5%) within 72 h. In soil containing the six mixed PAEs (DMP, DEP, BBP, and DOP, 400 mg/kg each; DBP and DEHP, 500 mg/kg, each), the ZJUTW + YC + LH1 consortium completely degraded DMP, DEP, BBP, and DBP within 6 days, and 70.84% of DEHP and 66.24% of DOP within 2 weeks. The consortium efficiently degraded the six mixed PAEs in both MSM and soil. We thus believe that this synthetic microbial consortium is a strong candidate for the bioremediation of environments contaminated with mixed PAE pollutants.

Microbial communities in aerosol generated from cyanobacterial bloom-affected freshwater bodies: an exploratory study in Nakdong River, South Korea.

Toxic blooms of cyanobacteria, which can produce cyanotoxins, are prevalent in freshwater, especially in South Korea. Exposure to cyanotoxins via ingestion, inhalation, and dermal contact may cause severe diseases. Particularly, toxic cyanobacteria and their cyanotoxins can be aerosolized by a bubble-bursting process associated with a wind-driven wave mechanism. A fundamental question remains regarding the aerosolization of toxic cyanobacteria and cyanotoxins emitted from freshwater bodies during bloom seasons. To evaluate the potential health risk of the aerosolization of toxic cyanobacteria and cyanotoxins, the objectives of this study were as follows: 1) to quantify levels of microcystin in the water and air samples, and 2) to monitor microbial communities, including toxic cyanobacteria in the water and air samples. Water samples were collected from five sites in the Nakdong River, South Korea, from August to September 2022. Air samples were collected using an air pump with a mixed cellulose ester membrane filter. Concentrations of total microcystins were measured using enzyme-linked immunosorbent assay. Shotgun metagenomic sequencing was used to investigate microbial communities, including toxic cyanobacteria. Mean concentrations of microcystins were 960 μg/L ranging from 0.73 to 5,337 μg/L in the water samples and 2.48 ng/m3 ranging from 0.1 to 6.8 ng/m3 in the air samples. In addition, in both the water and air samples, predominant bacteria were Microcystis (PCC7914), which has a microcystin-producing gene, and Cyanobium. Particularly, abundance of Microcystis (PCC7914) comprised more than 1.5% of all bacteria in the air samples. This study demonstrates microbial communities with genes related with microcystin synthesis, antibiotic resistance gene, and virulence factors in aerosols generated from cyanobacterial bloom-affected freshwater body. In summary, aerosolization of toxic cyanobacteria and cyanotoxins is a critical concern as an emerging exposure route for potential risk to environmental and human health.

Polyethersulfone (PES) Filters Improve the Recovery of Legionella spp. and Enhance Selectivity against Interfering Microorganisms in Water Samples.

In the analysis of water samples, the type of filtration membrane material can influence the recovery of Legionella species, although this issue has been poorly investigated. Filtration membranes (0.45 µm) from different materials and manufacturers (numbered as 1, 2, 3, 4, and 5) were compared: mixed cellulose esters (MCEs), nitrocellulose (NC), and polyethersulfone (PES). After membrane filtration of samples, filters were placed directly onto GVPC agar and incubated at 36 ± 2 °C. The highest mean counts of colony-forming units and colony sizes for Legionella pneumophila and Legionella anisa were obtained with PES filters (p < 0.001). All membranes placed on GVPC agar totally inhibited Escherichia coli and Enterococcus faecalis ATCC 19443 and ATCC 29212, whereas only the PES filter from manufacturer 3 (3-PES) totally inhibited Pseudomonas aeruginosa. PES membrane performance also differed according to the manufacturer, with 3-PES providing the best productivity and selectivity. In real water samples, 3-PES also produced a higher Legionella recovery and better inhibition of interfering microorganisms. These results support the use of PES membranes in methods where the filter is placed directly on the culture media and not only in procedures where membrane filtration is followed by a washing step (according to ISO 11731:2017).

Deployment of Superhydrophilic and Super-antifouling Cr-soc-MOF-1-Based Membrane for Ultrafast Separation of Stabilized Oil-in-Water Emulsions.

In spite of massive progress in oil-water separation, attributable to the use of advanced materials, the separation process faces challenges such as low permeance and fouling problems. Therefore, superwettable materials used in several fields are considered potential candidates for oily wastewater treatment. Metal-organic frameworks (MOFs) are receiving more and more interest in various separation applications due to their wide potential applications. Nevertheless, MOFs have been rarely explored for separating stabilized oil-in-water emulsions due to the difficulty in finding highly hydrolytic stable MOF candidates for this application. Furthermore, oil can clog water-stable materials owing to its high density, causing the degradation of MOF particles. As a result, there is a need to develop better MOF materials that can fulfill these requirements. Herein, we have explored Cr-soc-MOF-1 as a candidate for this application and deployed it as a membrane, which exhibited superhydrophilicity and underwater superoleophobicity for separating stabilized oil-in-water emulsions. The Cr-soc-MOF-1 membranes were synthesized by assembling the as-prepared MOF particles on a mixed cellulose ester substrate using a vacuum-assisted self-assembly technique. The Cr-soc-MOF-1 membrane exhibited ultrahigh water permeance (7465.9 L·m-2·h-1·bar-1), very high oil rejection (99.9%), and excellent anti-oil-fouling properties. The Cr-soc-MOF-1 membranes also exhibited excellent recyclability over 10 continuous separation cycles. Further, they exhibited an outstanding performance in separating various surfactant-stabilized oil-in-water emulsions. Thus, the Cr-soc-MOF-1 membranes exhibit a high potential in treating oily wastewater.

CO2 electroreduction to multicarbon products from carbonate capture liquid

CO2 electroreduction to multicarbon products from carbonate capture liquid

Single-Piece Membrane Supercapacitor with Exceptional Areal/Volumetric Capacitance via Double-Face Print of Electrode/Electrolyte Active Ink.

Single-piece flexible supercapacitors (FSCs) have light and ultrathin superiorities, thereby having great potential in portable/wearable electronics. However, all the available single-piece FSCs are fabricated by in situ growth routes, which are incompatible with large-scale technology. This work designs a carboxymethyl cellulose/phytic acid/polyaniline ink, incorporating electrode with electrolyte active compositions. Based on the electrode/electrolyte active ink, a double-face print technique on mixed cellulose ester and nylon membranes to fabricate single-piece membrane-FSCs, where both sides of membranes can be utilized well, is proposed. Consequently, one FSC is measured to be only ≈0.785 cm2 in area, ≈0.021g in weight, and ≈200µm in thickness, while it has exceptional areal and volumetric capacitances up to 757 mF cm-2 and 37.8 F cm-3 , respectively, based on the entire device. It also exhibits high flexibility with a capacitance retention of 98% after 2000 bend cycles from 0° to 180°. The state-of-the-art FSCs are expected to have exciting prospects in portable/wearable electronics, smart reading, and flexible displays. The preparation strategy renders the massive production of large-area and mini-size arrayed FSCs, and also the "do-it-yourself" or homemade preparation, which adds more interest and designability for general users.

Single particle ICP-MS combined with filtration membrane for accurate determination of silver nanoparticles in the real aqueous environment.

This work presents the role of commercial microfiltration membranes combined with single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) in removing environmental matrix interference for model silver nanoparticles (AgNPs) determination. The filters with different pore sizes (0.22μm, 0.45μm, 0.8μm) and materials (mixed cellulose ester, polyether sulfone, and nylon) were investigated to acquire the recovery of particle concentration and size of AgNPs spiked into different real aqueous solutions, including ultrapure water, tap water, surface water, and sewage effluent. The maximum recovery of nanoparticle concentration was 70.2% through the 0.8μm polyether sulfone membrane. The heated filters were able to improve the recovery of AgNPs particle concentration in the real aqueous environment. Hence, the pretreatment method by SP-ICP-MS combined with filtration membrane was simple, fast, and low-cost to quantify AgNPs in natural water environments.

Design of hybrid g-C3N4/GO/MCE photocatalytic membranes with enhanced separation performance under visible-light irradiation

Photocatalytic membranes with concurrent catalytic oxidation and separating functions possess promising potentials for the degradation of organic pollutants in wastewater treatment. Herein, we designed a hybrid photocatalytic membrane (viz., g-C3N4/GO/MCE) by vacuum-filtration-assisted assembling method, consisting of graphitic carbon nitride (g-C3N4) nanosheets as a top layer, graphene oxide (GO) nanosheets as an interlayer, and commercial mixed cellulose ester (MCE) as a substrate layer. The microstructures, chemical compositions, and physicochemical properties of the designed g-C3N4/GO/MCE membranes were systematically characterized by a series of characterization techniques. Particularly, photocatalysis-filtration reactor cells were designed for the evaluation of the simultaneous separation and photocatalytic degradation performance in a single unit using both organic dyes and antibiotics as modeling pollutants in wastewater. Four parameters were adopted to represent the integrated photocatalysis-filtration performance of our designed photocatalytic membranes, including permeance (P), rejection (R’, filtration alone), removal (R, combined photocatalysis-filtration under light-irradiation), and degradation rate (D). The hybrid membranes showed superior permeance and solute removal under visible-light irradiation (300 W, λ > 420 nm), in which the permeance was 20% higher than that of no-irradiation conditions. In addition, 10 consecutive cycling tests and light-on/off cycles of the as-prepared g-C3N4/GO/MCE membrane toward RhB showed quite stable permeance in the range of 268.9 to 352.9 L h−1 m−2 bar−1, and the removal was maintained in the range of 88.4% to 95.4%, indicating excellent long-term stability. Remarkably, it also exhibited good removal performance of antibiotics (e.g., ofloxacin, norfloxacin, sulfamethoxazole, erythromycin, and roxithromycin). Accordingly, the designed hybrid g-C3N4/GO/MCE photocatalytic membranes with excellent photocatalytic activity and photocatalysis-filtration performance are promising for wastewater treatment and water purification applications.

A comparative study on environmental surveillance of enterovirus: Using a two-phase separation method and a filtration method with a mixed cellulose ester (MCE) membrane

This study aimed to compare the sensitivity of two-phase separation and the filtration method using a mixed cellulose ester (MCE) membrane to detect enteroviruses in sewage samples. From December 2015 to July 2016, four domestic sewage samples (1 L/sample) were collected monthly from the Guangzhou Liede Sewage Treatment Plant, and each sewage sample was divided into two aliquots (500 mL). The sewage sample was concentrated using the two-phase separation and the filtration method using an MCE membrane, and the treated solutions were inoculated into cells for enterovirus isolation. Polymerase chain reaction amplification, VP1 sequencing, and enterovirus molecular typing were performed on the positive isolates. The detection rates of poliovirus (PV) and non-polio enterovirus (NPEV) obtained using the filtration method using an MCE membrane were higher than those using the two-phase separation method. McNemar's test showed that the detection rates of PV, NPEV, type 1 Sabin-like (SL1), type 2 Sabin-like (SL2), and type 3 Sabin-like (SL3) strain were not statistically significant (P > 0.05). In Guangdong Province, China, the detection rates for PV and NPEV were 53.13% and 62.50% (20/32), respectively. Twenty-seven PVs were isolated, three highly variable strains of the type 1 vaccine, with seven nucleotide substitutions in the VP1 region, compared with the type 1 Sabin strains. Eighty-seven strains of NPEV were isolated and nine serotypes were identified, among which coxsackievirus B3 (CVB3), echovirus 6(E6), and echovirus 11(E11) were the dominant strains. The filtration method using an MCE membrane is more sensitive than two-phase separation and can be used as a robust, sensitive, and cost-effective method to isolate enteroviruses from sewage.

Mixed cellulose ester membrane as an ion redistributor to stabilize zinc anode in aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZBs) with high energy density, low cost and environmental characteristics, have become the promising device for energy storage. However, uncontrolled zinc dendrite growth remains an impediment to the popularization of AZBs. The unrestricted two-dimensional (2D) ions diffusion is the main cause of the above defect. In this work, mixed cellulose ester (MCE) membrane is proposed as the separator. A dense homogeneous pore structure can achieve a physical shunting effect on ion diffusion, which can control and homogenize the ion motion. Further, the mechanism of this physical pore effect is confirmed by comparing the behavior of Zn deposition in MCE systems with different pore sizes but the same composition. As conjectured, a membrane with a smaller pore size is more favorable. In addition, the MCE contains many polar oxygen-containing functional groups that can facilitate and modulate ion diffusion through coordination. This chemical ion guiding effect, together with the above physical pore effect, gives the separator the ability to suppress dendrite formation. Zn/Zn symmetric cells with this membrane exhibit ultralong cycle life exceeding 1250 h at 0.5 mA cm−2 and 1000 h at 5 mA cm−2. And the Zn//MnO2 battery presents excellent cycle stability for more than 500 cycles with a capacity retention of 90.67%. This work proposes MCE separators and reveals their coordinated regulation of physical and chemical effects on metal-based anodes. This will shed light on the development of high-performance separators and AZBs.

Tunable nanostructured stainless-steel coating for high-selective and high-permeable separation membranes for oil/water emulsions

This paper demonstrates a stainless-steel (SS) nano-pyramid structure (diameter of ~20–50 nm and pore size of 156.1 nm) sputter-coated on mixed cellulose ester (MCE) membrane for the use in separation of oil/water emulsions. SS-coated MCE membrane presented a superhydrophilic, antifouling surface as well as underwater superoleophobicity. The coated membrane achieved excellent separation efficiency of >99% when applied to light oil-water emulsions with a range of viscosities and densities. The highest permeation flux measured was 1,555 L m−2 h−1 when applied to toluene-in-water emulsions. The membrane also presented outstanding recyclability, as evidenced by oil rejection rate retaining at >99% through four separation cycles. The coated membrane was also shown to work well under harsh conditions including salty water, extreme pH values (1–14), and high temperatures (60 °C). In addition, our fabrication route of SS-coated MCE employs low process temperature while being highly scalable, which is favorable for industrial-scale applications.

How different microfilters affect the recovery of eleven EU-regulated mycotoxins.

Microfiltration is a common step in liquid chromatography - tandem mass spectrometry (LC-MS), a method of choice in determining several mycotoxins in a solution at once. However, microfiltration may entail filter-analyte interactions that can affect the accuracy of the procedure, and underestimate exposure. The aim of our study was to assess how five different membrane materials for syringe filters (nylon, polytetrafluoroethylene, polyethersulphone, mixed cellulose ester, and cellulose acetate) affect microfiltration and recovery of EU-regulated mycotoxins, including aflatoxins B1, B2, G1, and G2, deoxynivalenol, fumonisins B1 and B2, zearalenone, T-2 and HT-2 toxins, and ochratoxin A. Polytetrafluoroethylene filters turned out to least affect microfiltration through mycotoxin loss, followed by more commonly used nylon filters, whereas the remaining three filter membrane materials had such a negative effect on recoveries that we found them incompatible with the procedure. Our findings clearly suggest that it is important to select a proper filter type that suits analyte properties and solution composition and to discard the first few filtrate drops to ensure the accuracy of the analytical procedure.

Continuous production of cellulose mixed esters via homogeneous reactive twin-screw extrusion catalyzed by ionic liquid

Cellulose mixed esters (CMEs) substituted with two different types of acyl groups are promising polymeric materials with various tunable properties but are arduous to produce. This is because of the insolubility of cellulose in common solvents, and thus, the industrial production of CMEs with desired degrees of substitution (DSs) requires a costly multistep process. To accomplish their facile production, homogeneous reactions have been performed using ionic liquids (ILs) as solvents for cellulose. However, the high viscosity of the cellulose-IL solutions causes insufficient mixing in batch reactors; thereby, favoring low cellulose concentrations with long reaction times (typically hours). Herein, we demonstrate a rapid and scalable production of CMEs by exploiting the excellent shear mixing of a twin-screw extruder as a flow reactor. A co-solvent system comprising an IL, 1-ethyl-3-methylimidazolium acetate, and dimethyl sulfoxide was applied to dissolve cellulose at a high concentration (15 wt.%) via twin-screw extrusion. During continuous extrusion at 80 °C, cellulose reacted with two acyl reagents, isopropenyl acetate (IPAc) and vinyl propionate (VPr) (2.5:0.5, mol/mol), to yield cellulose acetate propionate (CAP) within minutes. The CAP was stably produced during the operation time of 50 min with an average isolated yield of 71%. The DSs of the acetyl and propionyl groups of CAP were 1.77 and 0.50, respectively, corresponding to sufficiently high conversion rates of 70% for IPAc and 100% for VPr.

High-performance copper nanowire electrode for efficient flexible organic light-emitting diode

Highly conductive and robust polyvinyl alcohol/copper nanowire (PVA/CuNW) flexible transparent conductive electrode (FTCE) is fabricated via a simple and low-cost process at room temperature. The CuNW film is formed on a mixed cellulose ester (MCE) membrane by vacuum filtration. Subsequently, the flowing glacial acetic acid (GAA)-toluene solution passes through them to remove the oxide layer without damaging nanowires. The final PVA/CuNW FTCE is constructed by embedding the treated CuNWs into a pre-prepared PVA binding layer on the polyethylene terephthalate (PET) substrate, which presents excellent conductivity with a low sheet resistance of 46.2 Ω / s q and a high transparency of 90.5% at 550 nm. Meanwhile, the chemical and mechanical stability have been significantly enhanced compared with the bare CuNW FTCE attributed to the protective effect of the PVA binding layer. A flexible phosphorescent OLED device using such PVA/CuNW FTCE as the anode exhibits a current efficiency of 26.4 cd/A at 1000 cd/m 2 , which is comparable to that of the reference device (27.1 cd/A) based on indium tin oxide anode on glass, indicating its high potential for application in flexible optoelectronics. • Highly conductive PVA/CuNW electrodes are fabricated at room temperature. • The electrode shows excellent optoelectronic properties. • Low roughness as well as significantly enhanced chemical and mechanical stability has been achieved. • The flexible OLED device using PVA/CuNW exhibits high luminance and efficiency.

Niosomes for Topical Application of Antioxidant Molecules: Design and In Vitro Behavior

In the present study, gels based on xanthan gum and poloxamer 407 have been developed and characterized in order to convey natural antioxidant molecules included in niosomes. Specifically, the studies were conducted to evaluate how the vesicular systems affect the release of the active ingredient and which formulation is most suitable for cutaneous application. Niosomes, composed of Span 20 or Tween 20, were produced through the direct hydration method, and therefore, borate buffer or a micellar solution of poloxamer 188 was used as the aqueous phase. The niosomes were firstly characterized in terms of morphology, dimensional and encapsulation stability. Afterwards, gels based on poloxamer 407 or xanthan gum were compared in terms of spreadability and adhesiveness. It was found to have greater spreadability for gels based on poloxamer 407 and 100% adhesiveness for those based on xanthan gum. The in vitro diffusion of drugs studied using Franz cells associated with membranes of mixed cellulose esters showed that the use of a poloxamer micellar hydration phase determined a lower release as well as the use of Span 20. The thickened niosomes ensured controlled diffusion of the antioxidant molecules. Lastly, the in vivo irritation test confirmed the safeness of niosomal gels after cutaneous application.

Catalytic Enantioselective Allylboration and Related Reactions of Isatins Promoted by Chiral BINOLs: Scope and Mechanistic Studies.

An improvement in the catalytic enantioselective allylboration of isatins with 2-allyl-1,3,2-dioxaborolane in the presence of chiral BINOL derivatives is reported, offering an efficient one-step access to enantioenriched N-unprotected 3-allyl-3-hydroxy-2-oxindoles. This catalytic process is also effective for the crotylboration reaction with enantiomeric ratios (er) up to 97:3, as well as for the asymmetric synthesis of homopropargylic alcohols via an allenyl addition to indoline-2,3-diones. Origins of the high enantioselectivity in chiral BINOL-catalyzed allylboration of isatins were examined by DFT calculations. A hypothetical scenario suggested a crucial internal hydrogen bonding between the amide group (C═O···H-O) and the ethylene hydroxyl of the transient chiral mixed boronate ester, generating a rigid and stabilized system that favors the addition of the allylboron species to the Re face of the ketone function. The key role of the alcohol additive (t-BuOH or t-AmOH) in the enantioselective allylboration reaction of isatins has also been shown on the basis of a kinetics study and computational calculations by favoring the transesterification of the 2-allyl-1,3,2-dioxaborolane with BINOL via proton transfer processes.

Core-shell structured, mixed cellulose ester-alumina composite membranes for air filters with improved environmental resistance

In this study, a composite membrane was developed by conformally coating an ultrathin Al2O3 layer through low-temperature (90 °C) atomic layer deposition (ALD) on a hydrophilic mixed cellulose ester (MCE) membrane with a 3D networked microporous structure. The thickness of the deposited Al2O3 layer, without clogging the pores of the membrane, was precisely controlled by varying the number of ALD cycles from 100 to 300. The ultrathin (∼33 nm) Al2O3 layer greatly enhanced the resistance to various environmental stimuli and contributed to the improved removal efficiency of airborne particulate matter (PM), owing to the reduced pore size. The resulting composite membrane installed on an insect screen exhibited excellent removal efficiency (>99%) for PM of various sizes (PM1.0, PM2.5, and PM10) at a controlled flow rate of 1 L/min. In particular, unlike polypropylene-based commercial PM filters that strongly rely on electrostatic adsorption for PM filtration, the reduction in the PM removal efficiency caused by water or ethanol was negligible in the developed composite membrane, enabling long-term use even in extreme environments.

Concurrent production and purification of glycolic acid from mixed esters via selective hydrolysis reactions catalyzed and thermodynamically promoted by MgO

Methyl glycolate (MG) in the presence of methyl levulinate (MLE) was selectively converted into magnesium glycolate via MgO-mediated hydrolysis reactions under mild conditions. The conversion of MG reached 95.2% while that of MLE was 15.1%, with reaction selectivity of 100%. After facile isolation procedures, the magnesium glycolate was readily transformed into glycolic acid, monomer of biodegradable plastic, with recovery rate of 90.2%. The basic sites with medium strength on MgO dominated the catalytic activity. The precipitation of magnesium glycolate led to the shift of chemical equilibrium for MG hydrolysis. DFT calculation results showed that the energy barriers for MG hydrolysis were smaller than those for MLE hydrolysis by 46–47 kJ/mol. Both the shift of chemical equilibrium and lower energy barriers contributed to the much higher reactivity of MG compared to MLE. This paper sheds light on the selective hydrolysis of esters and complete hydrolysis of an ester.