Mixed Cellulose Ester Research Articles

Effects of filter structure, flow velocity, particle concentration and fouling on the retention efficiency of ultrafiltration for sub-20 nm gold nanoparticles

Ultrafiltration techniques with membranes of pore sizes under 100 nm have been widely applied in drinking water, wastewater, semiconductor and pharmaceutical process water treatments for nanoparticle (NP) and pathogen removal. The most direct way to evaluate the membrane performance is to experimentally obtain the size fractional retention efficiency. However, the real-life performance of the membrane in terms of fouling (or loading) characteristics and the effects of the concentration of challenging particles and rate of flux (or filtration velocities) on the filtration efficiency during fouling have not been well understood. In this study, systematic filtration experiments for filtration efficiency at clean and loaded conditions were conducted for three different 50 nm rated membrane filters, including PTFE (Polytetrafluoroethylene), PCTE (Polycarbonate Track-Etched) and MCE (Mixed Cellulose Ester) membranes, against 5, 10 and 20 nm Au NPs at different feed concentrations and fluxes. The results showed that the effects of feed concentration and flux are significant. This study provides important insights of retention mechanisms and efficiency for different ultrafiltration membrane structures at varied filtration velocities and fouling characteristics giving clear directions of future NP ultrafiltration research.

Терагерцевое поглощение в композитных пленках на основе металлоорганического перовскита и смешанного эфира целлюлозы

Composites based on the organometallic perovskite CH3NH3PbI3 and mixed cellulose ester were studied by terahertz time-domain spectroscopy. It is shown that the introduction of mixed cellulose esters into the precursor of organometallic perovskite CH3NH3PbI3 significantly modifies the parameters of perovskite in the terahertz region and also improves the stability of such composite films. It is found that the addition of mixed cellulose ester to the perovskite film leads to a significant weakening of the THz absorption bands in the frequency range of the order of 1 and 2 THz, which are caused by the excitation of low-frequency vibrational modes in CH3NH3PbI3 perovskite molecules. This can be explained by the fact that cellulose ester molecules enveloping perovskite molecules dampen low-frequency vibrations in them.

Diffusion studies of Diclofenac sodium topical gel using Different Synthetic Membranes

Diffusion of the drug from a formulation and across membranes simulating biological cell membranes is the major concern to be taken under consideration while formulating any dosage form. This brings on a major role in those which are to be applied along the skin, since drug needs to first release from the polymer matrix then enter systemic circulation via the skin. The purpose of the study was to compare the dispersion rate of diclofenac sodium from the gel formulation across five different synthetic membranes. In this work, we worked to measure the drug release profile using and using various kinetic models, found out the mechanism of diffusion through membranes on the drug release profile. The evaluation was done by an in vitro drug release system in the laboratory using Franz diffusion cell. Diclofenac sodium topical gel was formulated using carbopol 934 as the gel-forming agent(1). Diffusion studies showed that the highest release was given by mixed cellulose ester membrane (83.16%) in 71.5 hrs. Followed by cellulose acetate membrane (78.1%), cellulose acetate nitrate membrane (75.6), polyether sulphone membrane (70.8%) and sigma cellulose membrane (56.39%). Drug release followed first-order kinetics and Higuchi's model of diffusion from all the membranes with case II and super case II transport mechanisms

Droplet digital PCR assays for the quantification of brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus)from environmental DNA collected in the water of mountain lakes.

Classical methods for estimating the abundance of fish populations are often both expensive, time-consuming and destructive. Analyses of the environmental DNA (eDNA) present in water samples could alleviate such constraints. Here, we developed protocols to detect and quantify brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) populations by applying the droplet digital PCR (ddPCR) method to eDNA molecules extracted from water samples collected in 28 Swedish mountain lakes. Overall, contemporary fish CPUE (catch per unit effort) estimates from standardized survey gill nettings were not correlated to eDNA concentrations for either of the species. In addition, the measured environmental variables (e.g. dissolved organic carbon concentrations, temperature, and pH) appear to not influence water eDNA concentrations of the studied fish species. Detection probabilities via eDNA analysis showed moderate success (less than 70% for both species) while the presence of eDNA from Arctic char (in six lakes) and brown trout (in one lake) was also indicated in lakes where the species were not detected with the gillnetting method. Such findings highlight the limits of one or both methods to reliably detect fish species presence in natural systems. Additional analysis showed that the filtration of water samples through 1.2 μm glass fiber filters and 0.45 μm mixed cellulose ester filters was more efficient in recovering DNA than using 0.22 μm enclosed polyethersulfone filters, probably due to differential efficiencies of DNA extraction. Altogether, this work showed the potentials and limits of the approach for the detection and the quantification of fish abundance in natural systems while providing new insights in the application of the ddPCR method applied to environmental DNA.

Preparation and Characterization of Sulfated Cellulose Nanocrystalline and its Composite Membrane for Removal of Tetracycline Hydrochloride in Water

The removal of antibiotic pollutants remaining in the environmental media has been a big challenge nowadays. Herein, we report a facile and green approach to fabricate an eco‐friendly composite membrane without addition of any toxic polymers or chemical cross‐linking agents to effectively remove the tetracycline hydrochloride in Water. Firstly, the sulfated cellulose nanocrystalline (CNC) was obtained via hydrolysis of sulfuric acid by using microcrystalline cellulose (MCC) as raw material under ultrasonic condition. The as‐prepared CNC has a nanowhisker dimension with 200.2 ± 110.2 nm in length, 15.7 ± 9.3 nm in width, and 7.2 ± 3.1 nm in height. The obtained CNC is cellulose type I as determined by X‐ray diffraction (XRD), while its crystallinity index (CrI) can reach 82.3%. Then, the composite membrane derived from the obtained CNC and commercial mixed cellulose ester (MCE) membrane was facilely prepared through vacuum dewatering process, which is applied to remove tetracycline hydrochloride (Th) in solution. The results showed that the removal efficiency of Th through the neat MCE was only 28 ± 4%, while it could be improved to 58 ± 5% and 89 ± 1%, respectively, by filtering through composite membranes with different contents of CNC deposition. Such effect is derived from the combine factors based on both steric hindrance (sieving) and electrostatic interaction (Donnan) effect of the composite membranes. The development of related CNC materials and composite fabrication processes is in favor of cost‐effective and “green” polymer composites for the remediation of increasing antibiotic pollution and the purification of contaminated water nowadays.

Additive Printed All-Cellulose Membranes with Hierarchical Structure for Highly Efficient Separation of Oil/Water Nanoemulsions.

To expand the application of commercial membranes in oily wastewater separation, in this work, all-cellulose membranes were fabricated by depositing cellulose nanocrystals onto the surface of mixed-cellulose esters via a large-scale additive printing strategy. The thickness, pore size, surface wettability, and water flux of all-cellulose membranes can be well tuned by controlling the printing cycles of cellulose nanocrystal inks. Under optimal printing conditions, the resultant all-cellulose membranes with nanoporous architecture (76-91 nm) exhibit superhydrophilicity and underwater superoleophobicity, which benefits the separation of oil/water nanoemulsions with a high water flux (>1500 L m-2 h-1 bar-1) and an ultrahigh efficiency (>99%). Moreover, these all-cellulose membranes exhibit excellent stability and reusability for long-term separation and retains their inherent properties under various acidic, basic, and salty conditions, as well as mechanical abrasion. The presented scalable additive printing is a facile, economical, and sustainable strategy to construct all-cellulose membranes with excellent separation performance for oil/water nanoemulsions.

Direct deposition of two-dimensional MXene nanosheets on commercially available filter for fast and efficient dye removal

Generally, the efficiency of water purification can be greatly increased by a high-flux membrane separation technology. One major challenge in the application of this technology is to achieve high removal efficacy of target pollutants with elevated water flux. Here we report a novel self-assembled composite by depositing two-dimensional MXene nanosheets on a commercialized mixed cellulose ester filter (as designated as MCM). Morphology study reveals that MCM exhibits an ultrathin flaked structure with uniform nanochannels which is stapled on a porous support. The tailored membrane has been successfully applied in the methylene blue solution treatment and 100% ± 0.1% removal rate is achieved while the feed concentration of dye solution is up to 90 mg·L−1. Concurrently, stable and comparatively elevated water flux was achieved, i.e., 28.94 ± 0.74 L·m-2·h−1, which is 1.88-fold of that of the commercialized UTC60 membrane. Further investigations on the separation mechanism are performed to get more insights into separation performance exhibited by MCM. It is found that the size-selective sieving, electrostatic repulsion of MXene and the high porosity of substrate play the synergistic effect on the fast and efficient dye removal behavior. Taken together, the composite membrane fabricated in present work provides an alternatively high-efficiency approach for dye treatment, and unflagging efforts will be further invested on the development and large-scale application of MXene-based membrane.

Process development of [64Cu]Cu-ATSM: efficient stabilization and sterilization for therapeutic applications

Hypoxia plays an important role in tumor prognosis. [64Cu]Cu-ATSM, a hypoxia-targeted radioactive agent, reportedly shows antitumor effect in vivo. For clinical application, [64Cu]Cu-ATSM must be manufactured at high concentrations to allow the administration of a therapeutic dose with safe intravenous bolus injection. Fifteen radical scavengers were tested to stabilize [64Cu]Cu-ATSM against radiolysis, and sodium l-ascorbate was selected. The optimal sterilization membrane filter was evaluated from polyvinylidene fluoride (PVDF), polyether sulfone, and mixed cellulose esters; PVDF showed the most efficient radiochemical yield after filtration. The proposed procedures can be used for the practical manufacturing of [64Cu]Cu-ATSM for therapeutic use.

Passage and community changes of filterable bacteria during microfiltration of a surface water supply

The omnipresence of filterable bacteria that can pass through 0.22-μm membrane filters demands a change in the sterile filtration practice. In this study, we identified that filterable bacteria enriched from a surface water are members of the Bacteroidetes, Proteobacteria, Spirochaetae, Firmicutes, and Actinobacteria. Filterable bacteria displayed superior filterability during the entire bacterial growth phase, especially at the exponential phase. Maximal passage percentages were comparable at different cell densities, and achieved earlier at high cell density. Furthermore, filter retention for the investigated bacteria is independent of liquid temperature. However, cultivation temperature could affect the growth of some specific filterable bacteria and lead to variability in the passage percentage. Additionally, membrane materials, pore size and filtering flux greatly affected the passage of filterable bacteria. The majority of filterable Hylemonella and SAR324 could pass through 0.1-μm polyvinylidene fluoride and polyethersulfone filters but could not pass through 0.1-μm polycarbonate and mixed cellulose esters filters. Taken together, our results demonstrated that the ultra-small size of filterable bacteria, membrane characteristics and filtration operational conditions could challenge the validity of the 0.22/0.1-μm sterilizing grade filters in providing bio-safety barriers.

Implications of Chemical Reduction Using Hydriodic Acid on the Antimicrobial Properties of Graphene Oxide and Reduced Graphene Oxide Membranes.

The antimicrobial properties of graphene-based membranes such as single-layer graphene oxide (GO) and modified graphene oxide (rGO) on top of cellulose ester membrane are reported in this study. rGO membranes are made from GO by hydriodic acid (HI) vapor treatment. The antibacterial properties are tested after 3 h contact time with selected model bacteria. Complete bacterial cell inactivation is found only after contact with rGO membranes, while no significant bacterial inactivation is found for the control i) GO membrane, ii) the mixed cellulose ester support, and the iii) rGO membrane after additional washing that removes the remaining HI. This indicates that the antimicrobial effect is neither caused by the graphene nor the membrane support. The antimicrobial effect is found to be conclusively linked to the HI eliminating microbial growth, at concentrations from 0.005%. These findings emphasize the importance of caution in the reporting of antimicrobial properties of graphene-based surfaces.

Synthesis and application of sugarcane bagasse cellulose mixed esters. Part II: Removal of Co2+ and Ni2+ from single spiked aqueous solutions in batch and continuous mode

Sugarcane bagasse cellulose succinate trimellitate (SBST) was prepared by a one-pot synthesis method. The synthesis of this novel mixed ester was investigated by a 23-factorial design. The parameters investigated were time, temperature, and succinic anhydride mole fraction (χSA). The responses evaluated were the adsorption capacity (qCo2+ and qNi2+), weight gain (wg), and number of carboxylic acid groups (nT,COOH). 13C Multiple Cross-Polarization solid-state NMR spectroscopy, 1H NMR relaxometry, and Fourier-transform infrared spectroscopy were used to elucidate the SBST structure. The best SBST reaction conditions were 100 °C, 660 min, and χSA of 0.2, which yielded SBST with a wg of 57.1%, nT,COOH of 4.48 mmol g−1, and qCo2+ and qNi2+ of 0.900 and 0.963 mmol g−1, respectively. The maximum adsorption capacities (Qmax) (pH 5.75, 25 °C) estimated by the Redlich-Peterson model for Co2+ and Ni2+ were 1.16 and 1.29 mmol g−1. The ΔadsH° values for Co2+ and Ni2+ adsorption obtained by isothermal titration calorimetry were 8.03 and 6.94 kJ mol−1. Regeneration and reuse of SBST were investigated and the best conditions applied for fixed-bed column adsorption in five consecutive cycles. SBST was fully desorbed and Qmax values for Co2+ (0.95 mmol g−1) and Ni2+ (1.02 mmol g−1) were estimated using the Bohart-Adams model.

Regioselectively substituted cellulose mixed esters synthesized by two-steps route to understand chiral recognition mechanism and fabricate high-performance chiral stationary phases

It is challenging to design and fabricate new and high-performance cellulose-based chiral stationary phases (CSPs), due to the indistinct chiral recognition mechanism and the inherent difficulty to control the structure of cellulose derivatives. Herein, taking advantage of the high regioselective benzoylation of cellulose in 1-allyl-3-methylimidazolium chloride, a series of regioselectively substituted cellulose mixed esters, cellulose 6-benzoate-2,3-phenylcarbamate, are directly obtained by a facile two-steps route without protecting and deprotecting process. The resultant cellulose mixed esters exhibit high chiral recognition capability. In particular, when the benzoate group has an electron-donating substituent on phenyl ring, such as 4-tert-butyl group, the corresponding regioselectively substituted cellulose mixed esters have much better enantioseparation capability than cellulose tri(3,5-dimethylphenylcarbamate), which is commercially available as Chiralcel OD column, one of the most powerful CSPs. More importantly, via adjusting the chemical structure of cellulose derivatives and adding a post-treatment process to optimize their chiral recognition properties, the chiral recognition mechanism is clearly revealed. The synergy of the hydrophobic helical conformation, weak hydrogen-bond donating ability and appropriate distribution of substituents of cellulose derivatives is essential to fabricate high-performance CSPs.

Converting solution viscosity to distance-readout on paper substrates based on enzyme-mediated alginate hydrogelation: Quantitative determination of organophosphorus pesticides

Quantitatively paper-based senor is performed with simple distance-readout on mixed cellulose ester (MCE) filter paper based on acetylcholinesterase (AChE)-mediated alginate hydrogel. The method is accomplished with the aid of the inhibition effect of target samples on the AChE enzyme-catalyzed hydrolysis of acetylcholine, which changes the pH value of the solution to release Ca2+ and trigger alginate hydrogelation. The viscosity of the solution is thus regulated with the presence of target samples in the reaction mixture, leading to a significant change in the diffusion diameter of the solution spotted on the filter paper. The concentration in the sample is quantitatively determined by ruler-measureable diffusion diameter of the spot on the paper. With successfully application for quantitatively sensing of organophosphorus pesticides (OPs), we show that the method exhibits excellent reproducibility with RSD (n = 5) as low as 0.09% and good selectivity for detection of OPs. The dynamic range of the method is up to 66.7 ng/mL with the limit-of-detection (LOD) of 3.3 ng/mL. The present study provides a new approach for developing paper-based sensors with quantitative distance-readout, by utilizing enzymatic inhibition to modulate liquid viscosity, which would be of value for target detection in complex samples.

Persistence of Bacteroidales and other fecal indicator bacteria on inanimated materials, melon and tomato at various storage conditions

In order to determine the microbial safety of produce, conventional fecal indicator bacteria (CFIB) such as Escherichia coli and Enterococcus are quantified as a standard practice. Bacteroidales are also fecal indicators mostly used for water samples; however, their use and persistence in foods has been rarely studied. In this study, persistence of both CFIB and genetic markers of host-specific Bacteroidales was determined in artificially contaminated materials and vegetables with different textured surfaces under different storage conditions. Sterile feces were contaminated with E. coli, E. faecalis, Bacteroidesthetaiotaomicron (human origin), and Bacteroidales from porcine and bovine origin. Feces were applied to filters of mixed cellulose esters and tomatoes (smooth surface) and flat cork coupons and melons (rough surface) and stored at 10 °C/95% relative humidity (RH) and 25 °C/65%RH for up to 25 days. Bacteroidales markers were analyzed by real-time polymerase chain reaction (qPCR), whereas CFIB were plated onto selective agars. CFIB detection on filters and cork surfaces declined over time. E. coli decreased 2.9 log CFU and 1.2 log CFU per filter and cork, respectively, at 10 °C/95%RH and 5.8 log CFU and 1.8 log CFU per filter and cork, respectively, at 25 °C/65%RH. E. faecalis decreased 1.9 log CFU on filters and 1.3 log CFU on cork at 10 °C/95%RH and 2.6 log CFU/filter and cork under both storage conditions. Although E. coli levels in tomatoes slightly increased during storage, the levels decreased by the end of the assays. However, CFIB levels in melons stored at 10 °C/95%RH increased after 20 days; when stored at 25 °C/65%RH, these levels increased after five days.Bacteroidales levels (universal and host-specific markers) in inanimated material and produce did not show significant differences (P ≤ 0.01) over time. Stability and persistence of Bacteroidales genetic markers make them superior to CFIB as markers and are alternatives for determining the risk of exposure to feces-contaminated produce.

Inactivation of bacterial and fungal spores by UV irradiation and gaseous iodine treatment applied to air handling filters

Exposure to viable bacterial and fungal spores re-aerosolized from air handling filters may create a major health risk. Assessing and controlling this exposure have been of interest to the bio-defense and indoor air quality communities. Methods are being developed for inactivating stress-resistant viable microorganisms collected on ventilation filters. Here we investigated the inactivation of spores of Bacillus thuringiensis var. kurstaki (Btk), a recognized simulant for B. antracis, and Aspergillus fumigatus, a common opportunistic pathogen used as an indicator for indoor air quality. The viability change was measured on filters treated with ultraviolet (UV) irradiation and gaseous iodine. The spores were collected on high-efficiency particulate air (HEPA) and non-HEPA filters, both flattened for testing purposes to represent “surface” filters. A mixed cellulose ester (MCE) membrane filter was also tested as a reference. Additionally, a commercial HEPA unit with a deep-bed (non-flattened) filter was tested. Combined treatments of Btk spores with UV and iodine on MCE filter produced a synergistic inactivation effect. No similar synergy was observed for A. fumigatus. For spores collected on an MCE filter, the inactivation effect was about an order of magnitude greater for Btk compared to A. fumigatus. The filter type was found to be an important factor affecting the inactivation of Btk spores while it was not as influential for A. fumigatus. Overall, the combined effect of UV irradiation and gaseous iodine on viable bacterial and fungal spores collected on flat filters was found to be potent. The benefit of either simultaneous or sequential treatment was much lower for Btk spores embedded inside the deep-bed (non-flattened) HEPA filter, but for A. fumigatus the inactivation on flattened and non-flattened HEPA filters was comparable. For both species, applying UV first and gaseous iodine second produced significantly higher inactivation than when applying them simultaneously or in an opposite sequence.

Sample preparation method for visualization of nanoparticulate captured on mixed cellulose ester filter media by enhanced darkfield microscopy and hyperspectral imaging

A significant hurdle in conducting effective health and safety hazard analysis and risk assessment for the nanotechnology workforce is the lack of a rapid method for the direct visualization and analysis of filter media used to sample nanomaterials from work environments that represent potential worker exposure. Current best-known methods include transmission electron microscopy (TEM) coupled with energy dispersive x-ray spectroscopy (EDS) for elemental identification. TEM-EDS is considerably time-, cost-, and resource-intensive, which may prevent timely health and safety recommendations and corrective actions. A rapid screening method is currently being explored using enhanced darkfield microscopy with hyperspectral imaging (EDFM-HSI). For this approach to be effective, rapid, and easy, sample preparation that is amenable to the analytical technique is needed. Here, we compare the sample preparation steps for mixed cellulose ester (MCE) filter media specified in NIOSH Method 7400-Asbestos and Other Fibers by Phase Contrast Microscopy (PCM)-against a new method, which involves saturation of the filter media with acetone. NIOSH Method 7400 was chosen as a starting point since it is an established technique for preparing transparent MCE filters for optical microscopy. Limitations in this method led to the development and comparison of a new method. The new method was faster, easier, and rendered filters more transparent, resulting in improved visualization and analysis of nanomaterials via EDFM-HSI. This new method is suitable for a rapid screening protocol due to its speed, ease of use, and the improvement in image acquisition and analysis.

A comparison of air sampling methods for Clostridium difficile endospore aerosol

The airborne dissemination of Clostridium difficile (C. difficile) endospores (spores) in healthcare environments is documented in multiple studies. Once airborne, spores have the potential for transport on air currents to other areas. This study compared the methods in the collection of C. difficile spore aerosol. This study determined the relative efficiency of commonly used bioaerosol air sampling methods when characterizing airborne C. difficile spore concentrations. Air samplers evaluated in this study were the AirTrace slit-to-agar impactor, AGI-30 impinger, SKC BioSampler impinger, and a 47-mm mixed cellulose ester (MCE) filter cassette. Non-toxigenic C. difficile spores were nebulized into an enclosure contained in a biological safety cabinet. Side-by-side air samples were drawn from the enclosure. The slit-to-agar impactor, successfully used in previous studies to collect airborne spores, served as the reference method. Relative efficiency for the 47-mm MCE filter cartridge was higher than the slit-to-agar impactor (mean 136.6%, 95% CI 124.7–148.5%). Efficiencies of the impingers were similar and were low (mean 4.13%, 95% CI 2.27–5.99%). Impingers failed to maintain culturability of C. difficile spores during sampling. This study is the first to compare the efficiencies of commonly used bioaerosol sampling methods to collect airborne C. difficile spores. Filter air sampling provided the greatest collection of airborne spores. Slit-to-agar air sampling may underestimate the number of airborne spores present. Impinger air sampling could significantly underestimate the actual number of airborne C. difficile spores present or fail to detect airborne spores.

Microfiltration of raw soy sauce: membrane fouling mechanisms and characterization of physicochemical, aroma and shelf-life properties.

Refinement to remove fermented mash residue is essential for obtaining clarified, stable and high-quality soy sauce. In this study, raw soy sauce microfiltration was investigated. Four widely-used microfiltration membranes were employed: ceramic, polyethersulfone (PES), polyvinylidene fluoride (PVDF) and mixed cellulose ester (MCE). Membrane fouling mechanisms were identified based on the blocking filtration model, indicating that the dominant fouling mechanism during soy sauce microfiltration was cake formation on the membrane surface. Microfiltration delivered highly dispersed soy sauce having superior clarity and a light color, with satisfactory sterilization quality, and preserved well the NaCl, reducing sugar, total acid and amino nitrogen content, leading to a product having a longer shelf life as compared to pasteurization. The loss of volatile compounds after refinement (microfiltration and pasteurization) was not neglected, particularly the ester groups (total loss of 76.3% to 96.4%), which affected the aroma profile of the soy sauce; all the samples from microfiltration seemed to lack the floral aroma. Ceramic membrane filtration and pasteurization exhibited relatively good preservation of the aroma of soy sauce, which then obtained the best scores in sensory analysis.

Fouling-Resistant and Self-Cleaning Aliphatic Polyketone Membrane for Sustainable Oil-Water Emulsion Separation.

The cost-effective treatment of emulsified oily wastewater discharged by many industries and human societies is a great challenge. Herein, based on an aliphatic polyketone (PK) polymer with a good membrane formation ability and an intrinsic intermediate hydrophilicity, a new class of reduced PK (rPK) membranes combining an all hydrophilic and electrically neutral surface chemistry comprising ketone and hydroxyl groups, and a fibril-like morphology featuring re-entrant structure, was facilely prepared by phase separation and following fast surface reduction. The synergetic cooperation of surface chemistry and surface geometry endowed the prepared membranes with excellent superhydrophilicity, underwater superoleophobicity, and underoil superhydrophilicity, in addition to antiprotein-adhesion property. Thus, fouling-resistant and self-cleaning filtrations of challenging oil-in-water emulsions containing adhesive oil, surfactant, high salinity, and proteins were effortlessly realized with high flux (up to ∼50 000 L m-2 h-1 bar-1), slow and reversible flux decline, and low oil permeate (<20 ppm). In contrast, a commercial superhydrophilic microporous membrane made of mixed cellulose ester suffered severe fouling gradually or immediately when carrying out the emulsion filtrations due to its less than ideal surface properties. It is believed that this class of membranes with desirable superwettability, high flux, and preparation simplicity can be a potential new benchmark for high performance and large-scale oil-water separation in complex environments.

Homogeneous acylation of Cellulose diacetate: Towards bioplastics with tuneable thermal and water transport properties

In this study, we report a simple, non-degrading and efficient homogeneous acylation of cellulose diacetate (CDA) by using a large panel of commercially available acylating aliphatic moieties, differing in their structure (fatty, ramified, bulky, cycloaliphatic, aromatic, more or less spaced from the cellulose backbone), in view of generating a library of well-defined cellulose mixed esters with enhanced thermoplasticity. As reflected by a lowering of the glass temperature (Tg), the covalent grafting confers an improved mobility to the cellulose chains, by disrupting the initial H-bonds. In particular, it appears that the gain in free volume is tailored by the substituent structure and that acylating reagents consisting in a terminal bulky moieties spaced from CDA chains by a linear chain efficiently separate macromolecular chains without generating detrimental stiffening interactions (low Tg around 125 °C). Moreover, free-standing films easily prepared by solvent casting exhibit relevant water transport properties, which are closely dictated and tuned by the water solubility of the cellulose mixed ester.