Long-Chain Branched Bio-Based Poly(butylene dodecanedioate) Copolyester Using Pentaerythritol as Branching Agent: Synthesis, Thermo-Mechanical, and Rheological Properties.

The introduction of long-chain branched structures into biodegradable polyesters can effectively improve the melt strength and blow-molding properties of polyesters. In this study, pentaerythritol (PER) was used as a branching agent to synthesize branched poly(butylene dodecanedioate) (PBD), and the resulting polymers were characterized by Nuclear Magnetic Resonance Proton Spectra (1H NMR) and Fourier Transform Infrared spectroscopy (FT-IR). It was found that the introduction of a small amount of PER (0.25-0.5 mol%) can generate branching and even crosslinking structures. Both impact strength and tensile modulus can be greatly improved by the introduction of a branching agent. With the introduction of 1 mol% PER content in PBD, the notched impact strength of PBD has been increased by 85%, and the tensile modulus has been increased by 206%. Wide-angle X-ray diffraction and differential scanning calorimetry results showed that PER-branched PBDs exhibited improved crystallization ability compared with linear PBDs. Dynamic viscoelastics revealed that shear-thickening behaviors can be found for all branched PBD under low shear rates.

Demulsifier-Inspired Superhydrophilic/Underwater Superoleophobic Membrane Modified with Polyoxypropylene Polyoxyethylene Block Polymer for Enhanced Oil/Water Separation Properties.

Demulsifiers are considered the key materials for oil/water separation. Various works in recent years have shown that demulsifiers with polyoxypropylen epolyoxyethylene branched structures possess better demulsification effects. In this work, inspired by the chemical structure of demulsifiers, a novel superhydrophilic/underwater superoleophobic membrane modified with a polyoxypropylene polyoxyethylene block polymer was fabricated for enhanced separation of O/W emulsion. First, a typical polyoxypropylene polyoxyethylene triblock polymer (Pluronic F127) was grafted onto the poly styrene-maleic anhydride (SMA). Then, the Pluronic F127-grafted SMA (abbreviated as F127@SMA) was blended with polyvinylidene fluoride (PVDF) for the preparation of the F127@SMA/PVDF ultrafiltration membrane. The obtained F127@SMA/PVDF ultrafiltration membrane displayed superhydrophilic/underwater superoleophobic properties, with a water contact angle of 0° and an underwater oil contact angle (UOCA) higher than 150° for various oils. Moreover, it had excellent separation efficiency for SDS-stabilized emulsions, even when the oil being emulsified was crude oil. The oil removal efficiency was greater than 99.1%, and the flux was up to 272.4 L·m-2·h-1. Most importantly, the proposed F127@SMA/PVDF membrane also exhibited outstanding reusability and long-term stability. Its UOCA remained higher than 150° in harsh acidic, alkaline, and high-salt circumstances. Overall, the present work proposed an environmentally friendly and convenient approach for the development of practical oil/water separation membranes.

Preparation of Small-Pore Ultrafiltration Membranes with High Surface Porosity by In Situ CO2 Nanobubble-Assisted NIPS.

The fabrication of ultrafiltration (UF) membranes with a small pore size (<20 nm) and high surface porosity is still a great challenge. In this work, a nanobubble-assisted nonsolvent-induced phase separation (BNIPS) technique was developed to prepare high-performance UF membranes by adding a tiny amount of CaCO3 nanoparticles into the casting solution. The phase inversion occurred in a dilute-acid coagulation bath to simultaneously generate CO2 nanobubbles, which regulated the membrane structure. The effects of the nano-CaCO3 content in the casting solution on the structure and performance of poly(ethersulfone)/sulfonated polysulfone (PES/SPSf) UF membranes were studied. The UF membrane prepared from a casting solution with 0.3% nano-CaCO3 achieved a surface porosity of 12%, a pore diameter of 10.2 nm, and a skin-layer thickness of 80.3 nm. The superior structure of the UF membrane was mainly attributed to the in situ generation of CO2 nanobubbles because the CO2 nanobubbles were amphiphobic to water and solvents to delay the phase inversion time and acted as nanosize porogens. The produced membrane showed an unprecedented separation performance, achieving a pure water permeance of up to 1128 L·m-2·h-1·bar-1, 2.5 fold that of the control membrane. Similarly, a high bovine serum albumin rejection of above 99.0% was obtained. The overall permeability and selectivity were better than those of commercial and other previously reported UF membranes. This work provides insight toward a simple and cost-effective technique to address the trade-off between pure water permeance and solute rejection of UF membranes.

Design of microstructure for hollow fiber loose nanofiltration separation layer and its compactness-tailoring mechanism.

In order to promote the application of membrane technology in the treatment of textile wastewater containing small molecule dye, fabricating a hollow fiber loose nanofiltration (LNF) with a thin and compact separation layer and deepening the understanding of compactness-tailoring mechanism in chemical crosslinking are essential. Firstly, the mechanisms of synergistic crosslinking of PEI-70K and PEI-10K, along with a weakening of the PEI hydration by ethanol, were expounded in primary crosslinking. Then, some LNF separation layers with different compactness were prepared through crosslinking with different crosslinkers to further reduce pore size, which resulted in the efficient removal (~100%) of a small molecular dye (methyl orange (MO), M = 327 g mol-1). The removal of methyl orange is mainly caused by size sieving. The relationship among the pore size, the Mw of the secondary crosslinkers, and the pore size reduction rate was interpreted by comparing the pore size reduction rate of three secondary crosslinkers with different molecular weights. In addition, the as-prepared separation layer exhibited excellent dimensional stability and solvent resistance. This paper not only provides a reference for fabricating hollow fiber LNF with better purification performance, but also shows their potential in developing solvent resistant nanofiltration.

Multi-ionic electrolytes and E.coli removal from wastewater using chitosan-based in-situ mediated thin film composite nanofiltration membrane.

This work presents the experimental investigation of flat sheet composite nanofiltration membrane synthesized with chitosan nanoparticles through interfacial polymerization of piperazine with trimesoyl chloride on polyethersulfone/sulfonated polysulfone substrates. The synthesized membrane was tested in wastewater treatment containing inorganic salts and E.Coli. Single binary electrolyte solution of KCl, MgCl2, MgSO4, and Na2SO4, ternary electrolyte solution, containing a combination of MgCl2 and MgSO4, KCl and MgCl2 and quaternary electrolyte solution of KCl, MgCl2, and MgSO4 as feed were treated in crossflow membrane cell for the water flux and species rejection in the permeate under operating pressure up to 0.5 MPa. The rejection of Na1+, K1+, Mg2+, Cl1-, and SO42- was observed to be 81, 28, 87, 96, and 98%, respectively with an average water flux up to 214 ± 10 L m⁻2.hr⁻1 in the permeate for the binary electrolyte solution. Similarly, the rejection for K1+, Mg2+, Cl1- and SO42- was noted to be 33, 94, 97, and 99%, respectively, for ternary electrolyte solution with an average water flux up to 211 ± 10 L m-2.hr-1. The quaternary ion system in the feed resulted in an average water flux up to 198 ± 12 L m⁻2.hr⁻1 with the rejection of K+, Mg+2, Cl- and SO4-2 as 35, 87, 96, and 99%, respectively. The model feed solution of E. coli after passing through the membrane achieved an E. coli rejection (99%) with water flux up to 220 L m-2.hr-1.

High-Efficiency Separation of Mg2+/Sr2+ through a NF Membrane under Electric Field.

The efficient separation of Sr2+/Mg2+ through nanofiltration (NF) technology is a great challenge because Sr2+ and Mg2+ ions are congeners with the same valence and chemical properties. In this work, an NF membrane under an electric field (EF) was successfully employed to separate Mg2+ and Sr2+ ions for the first time. The effects of current densities, Mg2+/Sr2+ mass ratios, pH of the feed, and coexisting cations on separation performance were investigated. Dehydration of Sr2+ or Mg2+ ions under EF was proved by molecular dynamics simulation. The results showed that a high-efficient separation of Mg2+/Sr2+ was achieved: Mg2+ removal of above 99% and increase in Sr2+ permeation with increasing EF. A separation factor reached 928 under optimal conditions, far higher than that without EF. The efficient separation of Mg2+/Sr2+ ions was mainly due to rejection of most Mg2+ ions by NF membrane and in situ precipitation of partly permeated Mg2+ ions by OH- generated on the cathode under EF. Meanwhile, preferential dehydration of Sr2+ ions under EF due to lower hydration energy of Sr2+ compared with Mg2+ resulted in an increase of permeation of Sr2+ ions. This work provided a new idea for separation of congener ions with similar valence and chemical properties.

Enhanced anodic oxidation and energy saving for dye removal by integrating O2-reducing biocathode into electrocatalytic reactor.

Simultaneous enhancement of dye removal and reduction of energy consumption is critical for electrochemical oxidation in treating dyeing wastewater. To address this issue, this work presented a novel process termed biocathode-electrocatalytic reactor (BECR). The dual-chamber BECR employed O2-reducing biocathode instead of normal stainless steel (SS) cathode and MnOx/Ti anode to reduce O2 in the cathode chamber and treat methylene blue (MB) in the anode chamber, respectively. BECR successfully started up at 0.7 and 1 V and substantially improved MB and total organic carbon (TOC) removal compared with the electrocatalytic reactor with SS cathode (ECR-SS), e.g., removal of MB (150 mg L-1) increased from 27.0 ± 0.2% to 78.1 ± 0.4% at 1 V. To achieve the same TOC removal, BECR reduced the energy consumption by approximately 45.7% compared with ECR-SS (19.5 and 35.9 kWh (kg TOC) -1 for BECR and ECR, respectively). To explain the above merits of BECR, M(·OH) (·OH adsorbed on the anode surface) generation, potential of MnOx/Ti anode (Ea), and their correlation were investigated. When coupled with O2-reducing biocathode, MnOx/Ti anode considerably accelerated M(·OH) generation because Ea increased. The increased Ea in BECR was due to the fact that its cathodic reaction was converted to the four-electron O2 reduction, which exhibited a higher cathodic potential than hydrogen evolution reaction on SS cathode in ECR-SS. Thereby, BECR simultaneously promoted dye removal and reduced energy consumption, showing promise in treating dyeing wastewater.

Multifunctional PVDF/CNT/GO mixed matrix membranes for ultrafiltration and fouling detection.

Membrane fouling can be effectively addressed by modifying the membrane to realize anti-fouling capability together with real-time fouling detection. Here, we present the synthesis and water treatment testing of a promising candidate for this application, a composite membrane of polyvinylidene fluoride (PVDF) and functionalized carbon nano-materials prepared by a facile phase inversion method. The synergistic effect of oxidized multi-walled carbon nanotubes (OMWCNTs) and graphene oxide (GO) enabled better surface pore structures, higher surface roughness, hydrophilicity, and better antifouling property as compared with that of pristine PVDF membranes. The PVDF/OMWCNT/GO mixed matrix membranes (MMMs) achieved a high water flux of 125.6 L m-2 h-1 with high pollutant rejection rate, and their electrical conductivity of 2.11 × 10-4 S cm-1 at 100 kHz was sensitive to the amount of pollutant uptake. By using hybrid MMMs, we demonstrate simultaneous pollutant filtering and uptake monitoring, which is an important step in revolutionizing the water treatment industry.

Bifunctional semi-closed YF3-doped 1D carbon nanofibers with 3D porous network structure including fluorinating interphases and polysulfide confinement for lithium-sulfur batteries.

In this study, semi-closed YF3-doped 1D carbon nanofibers with 3D porous networks (SC-YF3-doped 3D in 1D CNFs) are fabricated for the first time via electro-blown spinning technology. The internal 3D porous networks not only offer a stable 3D electrode structure to accommodate the volume expansion, but also enable a high sulfur loading (80%). More importantly, the external semi-enclosed carbon layer maintains outstanding conductivity and further blocks polysulfide diffusion, which significantly breaks the limitation of a traditional carbon matrix. On the other hand, the YF3 nanoparticles are beneficial for forming more uniform fluorinating electrode interphases, achieving the excellent synergistic effect of chemical and physical adsorption to polysulfide. Therefore, the assembled Li-S batteries exhibit a high reversible discharge capacity of 954.2 mA h g-1 with a decay of merely 0.043% per cycle after 600 cycles at 1C rate. Moreover, the discharge capacity decay can be as low as 0.029% per cycle during 800 cycles at a high current density of 2C rate. Even at a high rate of 5C, the cells still possess a favorable capacity of 636.5 mA h g-1 while steadily operating for 700 cycles with a capacity decay rate of merely 0.056%, implying the great potential of this stable semi-closed cathode structure for industrialization.

Polysulfone-graft-4'- aminobenzo-15-crown-5-ether based tandem membrane chromatography for efficient adsorptive separation of lithium isotopes.

Adsorptive membrane-based chromatography can provide the high separation efficiency common to column chromatography but at a lower working pressure. Herein, a novel membrane chromatography system for lithium isotope adsorptive separation is reported. It uses polysulfone-graft-4'-aminobenzo-15-crown-5-ether (PSf-g-AB15C5) porous membranes (0.52 mmol/g of immobilization crown ether, average pore size of 62.7 nm, porosity of 80.4%) as a stationary phase packed in a chromatography column (Ø 25 × 100 mm). Furthermore, a four-stage tandem membrane chromatography system was designed to enhance lithium isotope separation performance. The partial eluate from the former column was used as the feed solution for the next stage. Results show that the flow rate of the eluent could reach 18 mL/h owing to the lower internal diffusion resistance of membranes. Meanwhile, adsorption isotherms and adsorption kinetics show that Li+ adsorption was an exothermic and spontaneous process. The surface diffusion, multilayer adsorption and ion-pore electrostatic interaction between Li+ and the crown ether groups on the membranes played a key role in the separation of 7Li+ and 6Li+ by membrane chromatography. The separation factor obtained from the single-stage membrane chromatography was up to 1.0232. The abundances of 7Li+ and 6Li+ gradually increased with an increase in the elution stages. The relative abundances of 7Li+ and 6Li+ obtained from the four-stage tandem membrane chromatography increased by 0.26% (from 92.40 to 92.66%) and 0.2% (from 7.60 to 7.80%), respectively. In conclusion, our current research opens a new avenue for the simultaneous enrichment of 7Li+ and 6Li+ during lithium isotope adsorptive separation.

Ultra-low graphene oxide loading for water permeability, antifouling and antibacterial improvement of polyethersulfone/sulfonated polysulfone ultrafiltration membranes.

The aqueous dispersion of graphene oxide (GO) was employed as additive to fabricate antifouling and antibacterial polyethersulfone (PES)/sulfonated polysulfone (SPSf)/GO mixed matrix membranes (MMMs) by the non-solvent induced phase separation (NIPS). The effect of different amounts of GO on the morphology and performance of MMMs were studied. The results showed that the casting solution exhibited an increasing trend in viscosity with increment in GO concentration (from 0 to 0.016 wt%) owing to the hydrogen bonding (H-bonding) interaction among GO, H2O and SPSf. Raman and molecular dynamic (MD) simulations analyses confirmed that there existed H-bonding interaction among SPSf, GO and H2O. Specifically, the agglomeration of GO was inhibited and stable homogeneous casting solution was obtained. Meanwhile, the H-bonding interaction also played a key role in the MMMs structure and improved properties. It was found that GO nanosheets were uniformly embedded to form many cellular-like voids in the asymmetric PES/SPSf/GO MMMs with a sponge-like structure. The pure water flux of the MMMs with a very low GO content of 0.012 wt% was up to 816.9 L/m2h and the rejection of bovine serum albumin (BSA) was more than 99.2% under a pressure of 0.1 MPa. Additionally, the mechanical properties of MMMs was also improved with the increase of GO content. Importantly, the MMMs displayed excellent antifouling and antibacterial performance. A high fouling recovery (94.2%) and antibacterial rate (90.0%) against Escherichia coli (E. coli) obtained were attributed to improved hydrophilicity, enhanced negative charge and GO nano-size effect. In summary, our study provides a simple approach to tailor MMMs with the enhancement of permeation, antifouling and antibacterial properties at a very low content of GO.

Antibacterial and environmentally friendly chitosan/polyvinyl alcohol blend membranes for air filtration.

An antibacterial and environmentally friendly chitosan (CS) /polyvinyl alcohol (PVA) blend membrane for air filtration was prepared via nonsolvent induced phase separation (NIPS) method. The chemical structure, thermal behavior, morphology, mechanical property and surface charge of the resultant CS/PVA membranes were characterized. Results showed that CS and PVA were miscible due to the intermolecular hydrogen bond between them. The blend membrane obtained from over 20 wt.% CS concentration exhibited a gradient interconnected porous structure without skin layer. The air filtration efficiency and pressure drop obtained from CS/PVA membrane with 30 wt.% CS concentration and the thickness of 37 µm under a face velocity of 5.3 cm s-1 were 95.59% and 633.5 Pa, respectively. The performance of air filtration obtained is mainly attributed to the direct interception of membrane surface. Further, the antibacterial rate of the blend membrane was up to 94.8% for E. coli and 91.3% for S. aureus.

Chitosan-graft-benzo-15-crown-5-ether/PVA Blend Membrane with Sponge-Like Pores for Lithium Isotope Adsorptive Separation.

Crown ether exhibits a high separation coefficient for lithium isotope separation owing to its precise size selectivity to cations. A crown ether-based solid-liquid extraction method for the lithium isotope separation with a high extraction efficiency is regarded as a valid alternative to the classic liquid-liquid method. A chitosan-graft-benzo-15-crown-5-ether (CTS-g-B15C5)/polyvinyl alcohol (PVA) porous blend membrane for lithium isotope adsorptive separation was fabricated by immersion-precipitation-phase inversion. Results indicated that the finger-like structure of the blend membrane was replaced gradually by a sponge-like structure with the increase of the CTS-g-B15C5 concentration from 20 to 50 wt %. Meanwhile, the porosity and mechanical strength of the blend membrane slightly decreased from 76.9% and 2.68 MPa to 72.5% and 2.02 MPa, respectively, whereas the average pore size increased from 0.33 to 0.73 µm. The obtained CTS-g-B15C5/PVA (50/50 wt/wt) blend membrane exhibited a sponge-like asymmetrical gradient structure and good mechanical strength and used for the solid-liquid extraction experiment. It is found that the distribution coefficient increased from 13.50 to 49.33, and the single-stage separation factor increased from 1.008 to 1.046 with the immobilization amount of crown ether from 1.07 to 2.60 mmol·g-1. It also meets the acceptable separation factor of 1.03 in a large scale of lithium isotope separation. In addition, 6Li and 7Li were enriched in the solid or membrane phase and the aqueous phase, respectively. In summary, the blend membrane has great potential applications in the development of green and highly efficient membrane chromatography for lithium isotope separation.

The Effect of Diluent Mixture with Upper Critical Solution Temperature on Membrane Formation Process, Microstructure, and Performance of PVDF Hollow Fiber Membrane by TIPS Process.

Thermally induced phase separation (TIPS) is a technique to prepare commercial membrane. However, the quick polymer crystallization during the quenching process will bring about a dense and thick skin layer and thus decrease permeability markedly. In this paper, a diluent mixture with upper critical solution temperature (UCST) was used to prepare polyvinylidene fluoride (PVDF) hollow fiber membrane. That is, the separation between diluent (propylene carbonate (PC)) and non-diluent (dioctyl terephthalate (DOTP)) occurred during the quenching process when the temperature of the dope was lower than 110 °C. The effects of separation between PC and DOTP and the resulting coalescence of DOTP on the PVDF crystallization process, microstructure, and the permeability of the membranes were analyzed. The results showed that the suitable PC/DOTP weight ratio reduced the thickness of the skin layer near the outer surface markedly and resulted in a porous outer surface, and the microstructure evolution process was proposed. The maximum pure water flux for the prepared membrane is up to 128.5 L·m-2·h-1 even in a dry mode without using a hydrophilizing agent. The rejection rate of the carbonic particle is nearly 100%. This study presents a novel and simple way to fabricate the microporous membrane with the interconnected pore structure.

Engineering Interface with One-Dimensional Co3O4 Nanostructure in Catalytic Membrane Electrode: Toward an Advanced Electrocatalyst for Alcohol Oxidation.

Electrochemical oxidation has attracted vast interest as a promising alternative to traditional chemical processes in fine chemical synthesis owing to its fast and sustainable features. An electrocatalytic membrane reactor (ECMR) with a three-dimensional (3D) electrode has been successfully designed for the selective oxidation of alcohols with high current efficiency to the corresponding acids or ketones. The anode electrode was fabricated by the in situ loading of one-dimensional (1D) Co3O4 nanowires (NWs) on the conductive porous Ti membrane (Co3O4 NWs/Ti) via the combination of a facile hydrothermal synthesis and subsequent thermal treatment. The electrocatalytic oxidation (ECO) results of alcohols exhibited superior catalytic performance with a higher current efficiency on the Co3O4 NWs/Ti membrane compared with those of Co3O4 nanoparticles on the Ti membrane (Co3O4 NPs/Ti). Even under low reaction temperatures such as 0 °C, it still displayed a very high ECO activity for alcohol oxidation in the ECMR. For example, >99% conversion and 92% selectivity toward benzoic acid were obtained for the benzyl alcohol electrooxidation. The electrode is particularly effective for the cyclohexanol oxidation, and a selectivity of >99% to cyclohexanone was achieved at 0 °C, higher than most reported noble-metal catalysts under the aerobic reaction conditions. The extraordinary electrocatalytic performance of the 3D Co3O4 NWs/Ti membrane electrode demonstrates the significant influence of morphology effect and engineering interfaces in membrane electrodes on the electrocatalytic activity and charge transfer process of nanocatalysts. Our results propose that similar membrane electrodes serve as versatile platforms for the applications of 1D nanomaterials, porous electrodes, and ECMRs.

Biodiesel production from waste chicken fat with low free fatty acids by an integrated catalytic process of composite membrane and sodium methoxide.

An integrated process of catalytic composite membranes (CCMs) and sodium methoxide was developed to produce biodiesel from waste chicken fat. The free fatty acids (FFAs) in the chicken oil were converted to methyl esters by esterification with methanol using a novel sulfonated polyethersulfone (SPES)/PES/non-woven fabric (NWF) CCMs in a flow-through catalytic membrane reactor. The CCM is that the NWF fibers were fully embedded in SPES/PES with a homogeneous and microporous structure. The oil obtained after esterification was carried out by transesterification of sodium methoxide. The results showed that the FFAs conversion obtained by CCMs with the acid capacity of 25.28 mmol (H(+)) was 92.8% at the residence time 258s. The CCMs present a good stability during the continuous running of 500 h. The conversion of transesterification was 98.1% under the optimum conditions. The quality of the biodiesel met the international standards.

Electrocatalytic oxidation of n-propanol to produce propionic acid using an electrocatalytic membrane reactor.

An electrocatalytic membrane reactor assembled using a nano-MnO2 loading microporous Ti membrane as an anode and a tubular stainless steel as a cathode was used to oxidize n-propanol to produce propionic acid. The high efficiency and selectivity obtained is related to the synergistic effect between the reaction and separation in the reactor.

Continuous esterification to produce biodiesel by SPES/PES/NWF composite catalytic membrane in flow-through membrane reactor: experimental and kinetic studies.

A novel composite catalytic membrane (CCM) was prepared from sulfonated polyethersulfone (SPES) and polyethersulfone (PES) blend supported by non-woven fabrics, as a heterogeneous catalyst to produce biodiesel from continuous esterification of oleic acid with methanol in a flow-through mode. A kinetic model of esterification was established based on a plug-flow assumption. The effects of the CCM structure (thickness, area, porosity, etc.), reaction temperature and the external and internal mass transfer resistances on esterification were investigated. The results showed that the CCM structure had a significant effect on the acid conversion. The external mass transfer resistance could be neglected when the flow rate was over 1.2 ml min(-1). The internal mass transfer resistance impacted on the conversion when membrane thickness was over 1.779 mm. An oleic acid conversion kept over 98.0% for 500 h of continuous running. The conversions obtained from the model are in good agreement with the experimental data.

Novel functionalized nano-TiO2 loading electrocatalytic membrane for oily wastewater treatment.

Membrane fouling is a critical problem in membrane filtration processes for water purification. Electrocatalytic membrane reactor (ECMR) was an effective method to avoid membrane fouling and improve water quality. This study focuses on the preparation and characterization of a novel functionalized nano-TiO(2) loading electrocatalytic membrane for oily wastewater treatment. A TiO(2)/carbon membrane used in the reactor is prepared by coating TiO(2) as an electrocatalyst via a sol-gel process on a conductive microporous carbon membrane. In order to immobilize TiO(2) on the carbon membrane, the carbon membrane is first pretreated with HNO(3) to generate the oxygen-containing functional groups on its surface. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) analyses are used to evaluate the morphology and microstructure of the membranes. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements are employed to illustrate the eletrochemical activity of the TiO(2)/carbon membrane. The membrane performance is investigated by treating oily wastewater. The oil removal rate increases with a decrease in the liquid hourly space velocity (LHSV) through the ECMR. The COD removal rate was 100% with a LHSV of 7.2 h(-1) and 87.4% with a LHSV of 21.6 h(-1) during the treatment of 200 mg/L oily water. It suggests that the synergistic effect of electrocatalytic oxidation and membrane separation in the ECMR plays a key role.

Comprehensive kinetic studies of acidic oil continuous esterification by cation-exchange resin in fixed bed reactors.

Biodiesel produced by esterification from molar ratio of methanol to free fatty acid (FFA) as 25:1 in presence of triglyceride was carried out with cation-exchange resin as a heterogeneous catalyst in three different scales of fixed bed reactors from minireactor (6.8 mm × 110 mm) to pilot scale reactor (70 mm × 1260 mm) at 338 K. The kinetic study of esterification was undertaken in terms of pseudo-homogeneous mechanism and performed as a first order reaction with elimination of the solid-liquid internal and external mass transfer resistances. Moreover, a kinetic model of FFA esterification was developed to illustrate the relationship between the FFA conversion and the catalyst bed height of fixed bed reactor. The model was also suitable for various resins in fixed bed reactor. The theoretical predictions were in agreement with the experimental data with root mean square (RMS) errors <10.