A TiO2 modified whisker mullite hollow fiber ceramic membrane for high-efficiency oil/water emulsions separation

Design and preparation of membranes with ultrahigh separation performance and antifouling property for oil-in-water (O/W) emulsions remains challenging. In this study, a high flux mullite/TiO₂ ceramic composite membrane was prepared via multi-precipitation of TiO₂ on a whisker mullite hollow fiber support synthesized by combining phase inversion and high-temperature sintering techniques. The results showed that the generated whisker mullite structure improved the permeation flux, and the micro-nano structured TiO₂ functional layer endowed the membrane surface with superhydrophility and stability. The retention of the optimal composite membrane (M20T13) that was soaked in the titanium solution 20 times for 13 min each time for the O/W emulsions like n-hexane, toluene and engine oil maintained over 98 %, and the flux after 6 h filtration was 668.34 L·m⁻²·h⁻¹, 487.25 L·m⁻²·h⁻¹ and 258.66 L·m⁻²·h⁻¹, respectively, much higher than that of the optimal substrate (F3A1, mass ratio of fly ash: Al₂O₃ = 3:1). Moreover, the flux recovery rate of M20T13 was much higher than that of F3A1 after chemical backwashing. This work manifests great potential in O/W treatment fields.     

Nano-Modification of the Polyvinyl Alcohol/Organic Acid-Modified Polyvinylidene Fluoride Thin-Film Composite Membrane and Its Application in the Nanofiltration Process

In this study, a novel thin-film nanocomposite (TFN) membrane is developed consisting of a cross-linked nano-modified polyvinyl alcohol (PVA) selective layer on an organic acid-modified polyvinylidene fluoride (PVDF) membrane. The nano-modification of the PVA layer is performed via incorporating different amounts of the amine-functionalized multiwalled carbon nanotubes (MWCNTs-NH₂) into the PVA matrix. The effect of citric acid on the chemical structure and morphology of the PVDF support is also investigated. The performance of the resultant membranes in the nanofiltration (NF) of MgSO₄ and acid yellow-17 aqueous solutions is also studied. The results indicate that the modification of the support with 0.5 wt% of citric acid increased the water permeance from 1.59 L m⁻² h⁻¹ bar⁻¹ (LMH/bar) for PVA/PVDF to 4.49 LMH/bar for the PVA/modified PVDF membrane. Furthermore, the optimum value of MWCNT-NH₂ (0.6 wt%) increases the permeance of the resultant TFN membrane to 4.94 LMH/bar while maintaining a high rejection. Interestingly, the incorporation of MWCNT-NH₂ into the PVA layer and citric acid into the PVDF solution results in a membrane with the highest permeance of 6 LMH/bar.     

Preparation of microporous polyamide networks for carbon dioxide capture and nanofiltration

For the first time, microporous polyamide networks have been synthesized via the interfacial polymerization of piperazine and acyl chloride monomers containing tetrahedral carbon and silicon cores. These polyamides, with Brunauer–Emmett–Teller surface area between 488 and 584 m² g^?1, show a CO₂ uptake of up to 9.81 wt% and a CO₂/N₂ selectivity of up to 51 at 1 bar and 273 K, suggesting their great potential in the area of carbon capture and storage applications. We have developed the interfacial polymerization on the surface of the porous polyacrylonitrile substrate, resulting in the formation of ultrathin microporous membranes with thicknesses of about 100 nm. These nanofiltration (NF) membranes exhibited an attractive water flux of 82.8 L m^?2 h^?1 at 0.4 MPa and a high CaCl₂ (500 mg/L) rejection of 93.3%. These NF membranes follow the salt rejection sequence of CaCl₂ > NaCl > Na₂SO₄, demonstrating the positively charged character of these membranes.     

An Integrated Process for D-Sorbitol Production over NiO/TiO2 Supported Ru Nanocatalyst: A Greener Approach

The catalytic transformation of D-glucose towards D-sorbitol is a well-established process in the biorefinery industry. Normally, this batch-wise hydrogenation over metallic catalysts suffers from several troubles such as low yielding and facile catalyst deactivation. To address these challenges, we, hereby fabricated 5NiO/TiO₂-supported Ru nanocatalysts (Ru-5NiO/TiO₂, 1.0 and 5.0 wt% Ru) and examined their efficacy in the continuous-flow reduction of D-glucose aqueous solution (20 wt%) to produce D-sorbitol for the first time. In this study, D-glucose conversion and D-sorbitol yield were represented as a function of residence time, where the feeding rate of D-glucose was systematically controlled to maximize the outcome of D-sorbitol. Remarkably, D-glucose was fully converted to 99.0% selectivity of D-sorbitol under optimized reaction conditions (100 °C, 8 MPa H₂ with a flow rate of 100 L h^?1). The experimental results showed that the mean activity and specific rate of 1.0 wt% Ru-5NiO/TiO₂ were achieved as 731.3 mmol h^??1 g^??1 and 1030.7 mmol h^?1 g^?1, respectively, which surpassed those of monometallic Ru-based catalysts (1.0 wt% Ru/TiO₂, 1.0 wt% Ru/SiO_2, and 1.6 wt% Ru/C). Moreover, the stability of 1.0 wt% Ru-5NiO/TiO₂ nanocatalyst was sustained for long-term operation (>?360 h) and no leaching of ruthenium was highly acknowledged.

Graphical Abstract

     

Eco-friendly tape casting of borosilicate glass/Al2O3 sheets for LTCC applications

This work reports the innovative development of a borosilicate glass/Al₂O₃ tape for LTCC applications using an eco-friendly aqueous tape casting slurry. Polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) were the respective dispersants, while carboxymethyl cellulose (CMC) and styrene acrylic emulsion (SA) were the respective binders. The results showed that PVP was more suitable than PAA as the dispersant for the aqueous casting slurry, and that 1.5 wt% PVP would achieve well dispersion of CABS glass/Al₂O₃ powder in the aqueous slurry. Moreover, a small amount of 2.0 wt% CMC binder could yield smooth CABS glass/Al₂O₃ tapes crack free. A high-quality CABS glass/Al₂O₃ tape with a smooth surface was made from an aqueous slurry containing 1.5 wt% PVP dispersant, 2.0 wt% CMC binder, and 2.0 wt% PEG-400 plasticizer. The density, tensile strength, and surface roughness of the green tape were 2.05 g/cm³, 0.87 MPa, and 148 nm, respectively. The resulting CABS glass/Al₂O₃ composites sintered at 875 °C exhibited a bulk density of 3.14 g/cm³, a dielectric constant of 8.09, a dielectric loss of 1.0 × 10^?3, a flexural strength of 213 MPa, a thermal expansion coefficient of 5.30 ppm/^°C, and a thermal conductivity of 3.2 W m^?1 K^?1, thus demonstrating its broad prospects in LTCC applications.     

Reaction-bonded robust SiC ceramic membranes sintered at low temperature with coal gangue

Herein, we report an in-situ reaction-bonded SiC membrane sintered at low temperature using a solid waste (i.e. coal gangue) as the sintering aid to form strong neck connections. The effects of sintering temperature and coal gangue proportion on their properties regarding pore size, open porosity, bending strength and pure water permeability were investigated. The single-channel tubular SiC membrane sintered at 1300 °C with a coal gangue proportion of 12 wt% was optimal, exhibiting an average pore size of 2.78 μm, a open porosity of 47.08%, a bending strength of 34.01 ± 1.3 MPa and a high water permeability of 83967 L m⁻² h⁻¹ bar⁻¹. The membrane could completely reject D₅₀ = 0.87 μm SiC solids and presented a steady-state water permeability of 458 L m⁻² h⁻¹·bar⁻¹. The SiC membrane could be regenerated through ultrasonication and its steady-state water permeability was almost unchanged for 3 cycles, proving its mechanical robustness. This work may appeal to the practical low-cost production of high-performance SiC membranes.     

Asymmetric TiO2 hybrid photocatalytic ceramic membrane with porosity gradient: Effect of structure directing agent on the resulting membranes architecture and performances

Asymmetric TiO₂ hybrid photocatalytic ceramic membranes with porosity gradient have been fabricated via acid-catalyzed sol–gel method. Different structure directing agents (SDAs) i.e. Pluronic P-123, Triton X-100, Tween 20 and Tween 80 were incorporated in the preparation of TiO₂ sol to obtain a porous multilayered TiO₂ coated on the alumina ceramic support. Six different SDA-modified membrane specimens were fabricated. Four of which were coated with the TiO₂ sols prepared using only one type of SDA. The remaining two specimens were fabricated via multilayer coating of different TiO₂ sols prepared using different types of SDAs. Physico-chemical and morphological properties of different TiO₂ layers were thoroughly investigated. The membrane M1 which had the most porous TiO₂ sub-layers showed a high pure water permeability of 155 L m⁻² h⁻¹ bar⁻¹. The membrane showed a relatively high Rhodamine B (RhB) removal of 2997 mg m⁻² over 8 h treatment duration in the batch photoreactor, second only to the Pluronic-based TiO₂ membrane (specific RhB removal of 3050 mg m⁻²). All membrane specimens exhibited good performances while operated in the flow-through photocatalytic membrane reactor. Over 91% of RhB removal capability was retained after 4 treatment cycles. All membranes also showed self-cleaning property by retaining >90% of initial flux after 4 treatment cycles. The flexibility of optimizing membrane performances by fine-tuning the porosity gradient configuration of the photocatalytic layer has also been demonstrated.     

Gasoline desulfurization by a TiO2‐filled ethyl cellulose pervaporation membrane

The TiO₂ nanoparticles were incorporated into an ethyl cellulose (EC) matrix to improve the pervaporation (PV) performance of the membrane for gasoline desulfurization. The microstructures of different EC membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray and transmission electron microscopy. The PV experiments showed that the hybrid membrane of EC/TiO₂ demonstrated an improved permeation flux (J ) of 7.58 kg m^?2 h^?1 and a sulfur enrichment factor (α) of 3.13 in comparison with the pure EC membrane, with a J of 3.73 kg m^?2 h^?1 and an α of 3.69. In addition, the effects of the operating conditions, including the operating temperature, layer thickness, crosslinking time, feed flow rate, and feed sulfur content level, on the PV performance of the EC/TiO₂ membrane were investigated. Under a 100 mL/min feed flow rate and a 85 μg/g sulfur content, J of the 10 μm thick membrane increased to 7.58 kg m^?2 h^?1 with α of 3.13 compared to the pure EC membrane (3.73 kg m^?2 h^?1, 3.69) at 80 °C with 30 min of crosslinking time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 : 134 , 43409.     

Effect of TiO2 doping on the characteristics of macroporous Al2O3/TiO2 membrane supports

A cost-effective tubular macroporous ceramic support consisting of alumina and titania was prepared by extrusion and subsequent heat treatment. An Al₂O₃/TiO₂ composite support with high porosity (41.4%), an average pore size of 6.8 μm and sufficient mechanical strength (32.7 MPa) was obtained after sintering at 1400 °C. The formation mechanism of this support as investigated with X-ray micromapping, SEM and XRD indicated that the appearance of Al₂TiO₅ plays a key role in the fabrication of high performance composite membrane supports at relatively low temperature. The amount of Al₂TiO₅ present in the composite has a strong impact on the properties of supports, especially with regard to the mechanical strength. A composite of 85 wt.% Al₂O₃/15 wt.% TiO₂ sintered at 1400 °C for 2 h exhibited both high permeability (pure water flux of 45 m³ m^?2 h^?1 bar^?1), together with an excellent corrosive resistance towards hot NaOH and HNO₃ solutions.     

Preparation and characterization of a novel hydrophilic PVDF/PVA UF membrane modified by carboxylated multiwalled carbon nanotubes

Polyvinylidene fluoride (PVDF)/polyvinyl alcohol (PVA) ultrafiltration (UF) membranes were prepared via a phase inversion method employing the modification of carboxylated multiwalled carbon nanotubes (MWCNTs‐COOH). Various contents of MWCNTs‐COOHs (0.00–0.15 wt%, weight of casting solution) were added into PVDF/PVA/dimethyl sulfoxide systems for the fabrication of the plate UF membrane. Fourier transform infrared spectroscopy spectra identified the successful introduction of carboxyl through the C?O peak at 1730 cm^?1. Scanning electron microscopy images exhibited the external surface and the asymmetric morphology with the appearance of a sponge‐like inner structure. Atomic force microscopy analysis determined the roughness values and rougher topography. The hydrophilicity of the composite membrane containing 0.09 wt% of MWCNTs‐COOHs improved the most. This sample has the highest pure water flux, approximately doubled (126.6 L·m^?2·h^?1) compared to the PVDF/PVA membrane (68.6 L·m^?2·h^?1), an enhanced bovine serum albumin flux recovery rate, showing an increase of 17%, and the best fouling resistance ability. Meanwhile, the porosity and dynamic contactangle also indicate the enhancement of membrane hydrophilicity. Dextran (DEX) 600k rejection reached 91.0%. Break strength, elongation at break, and Young's modulus also had improvements of 60%, 215.5%, and 56.7%, respectively, when the MWCNTs‐COOH content was 0.12 wt%. POLYM. ENG. SCI., 56:955–967, 2016. © 2016 Society of Plastics Engineers     

Study of pervaporation for dehydration of caprolactam through PVA/nano silica composite membranes

We investigated nano silica/PVA composite membranes to propose an improved caprolactam pervaporation (PV) dehydration process. The membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and contact angle measurement. Compared with the pure PVA membranes, the nano silica/PVA composite membranes showed different surface morphologies with enhanced hydrophilicity because of their unique formation. To evaluate PV performance and mechanism, we assessed the permeation flux, separation factor, diffusivity/sorptivity selectivity, and activation energy of the composite membranes. The evaluated results indicate that the nano silica/PVA composite membranes induced a breakthrough in the dehydration of a caprolactam-water mixture with a maximum flux of 3.8 kg m^? 2 h^? 1 and an acceptable separation factor of 150.     

High-performance composite photocatalytic membrane based on titanium dioxide nanowire/graphene oxide for water treatment

In this study, a novel dopamine-modified TiO₂ nanowire (NW)-intercalated graphene-oxide-based photocatalytic (NWC) membrane was prepared by vacuum-assisted filtration using a commercial cellulose acetate membrane as a support layer. At the same time, compared with the synthesized reduced graphene-oxide/polydopamine/TiO₂ nanoparticle composite (NPC) membrane, it was found that the NWC membrane has high water flux (273 L m⁻² h⁻¹) and removal rate (above 98%) on the dye-oil emulsion. After 5 cycles of experiments, the NWC membrane maintained a relatively stable permeation flux and removal rate, which was significantly better than the NPC membrane. The results showed that the NWC membrane had a more uniform distribution of TiO₂ NW, and had better antifouling ability, recyclability, and photocatalytic performance than NPC membrane. In summary, the NWC photocatalytic membrane of this study shows excellent water purification potential and provides a new path for photocatalytic water treatment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48488.     

Ordered mesoporous carbon–TiO2 materials for improved electrochemical performance of lithium ion battery

A series of ordered mesoporous carbon–TiO₂ (OMCT) materials with various weight percentages of TiO₂ (50–75 wt%) were synthesized by evaporation-induced self-assembly and in-situ crystallization at various calcination temperatures (600–1200 °C) to evaluate the Li-ion storage performance. The OMCT has ordered 2D hexagonal mesoporous structures and the TiO₂ nanocrystals with different phases are embedded into the frameworks of carbonaceous matrix. The reversible capacity of OMCT is highly dependent on the phase and content of TiO₂, and the anatase TiO₂ is a superior crystalline phase to rutile and TiN for Li-ion insertion. The OMCT₆₅ which contains 35 wt% carbon and 65 wt% TiO₂ shows a high capacity of 500 mAh g^?1 at 0.1C after 80 cycles. In addition, OMCT₆₅ exhibits a good cyclability and rate capability. The reversible capacity remains at 98 mAh g^?1 at a high rate of 5C, and then recoveries to 520 mAh g^?1 at 0.1C after 105 cycles. The excellent reversible capacity and rate capability of OMCT₆₅ are attributed to the embedment of well-dispersed anatase TiO₂ nanocrystals into the specific porous structure of OMCT, which can not only facilitate the fast Li-ion charge transport but can also strengthen the carbon–TiO₂ co-constructing channels for lithiated reactions.     

Multifunctionality of poly(vinyl alcohol) nanofiber webs containing titanium dioxide

We prepared titanium dioxide/PVA nanocomposite fiber webs for application in multifunctional textiles by electrospinning. The morphological properties of the TiO₂/PVA nanocomposite fibers were characterized using scanning electron microscopy and transmission electron microscopy. Layered fabric systems with electrospun TiO₂ nanocomposite fiber webs were developed using various concentrations of TiO₂ and a range of web area densities, and then the UV‐protective properties, antibacterial functions, formaldehyde decomposition ability, and ammonia deodorization efficiency of the fabric systems were assessed. Layered fabric systems with TiO₂ nanocomposite fiber webs containing 2 wt% TiO₂ nanoparticles at 3.0 g m^?2 web area density exhibited an ultraviolet protection factor of greater than 50, indicating excellent UV protection. The same system showed a 99.3% reduction in Staphylococcus aureus. Layered fabric systems with TiO₂ nanocomposite fiber webs containing 3 wt % TiO₂ nanoparticles at 3.0 g m^?2 web area density exhibited a 85.3% reduction in Klebsiella pneumoniae. Titanium dioxide nanocomposite fiber webs containing 3 wt % TiO₂ nanoparticles at 3.0 g m^?2 web area density exhibited a formaldehyde decomposition efficiency of 40% after 2 h, 60% after 4 h, and 80% after 15 h under UV irradiation. The same system showed an ammonia deodorization efficiency of 32.2% under UV irradiation for 2 h. These results demonstrate that TiO₂ nanocomposite fibers can be used to produce advanced textile materials with multifunctional properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of renewable porous TiO<Subscript>2</Subscript>/PVA composite sphere as photocatalyst for methyl orange degradation

Firstly, preparation of porous polyvinyl alcohol (PVA) spheres were investigated in detail by phase inversion method using N,N-dimethylacetamide (DMAc) and polyvinylpyrrolidone (PVP) as pore-forming additives. The morphology and pore structure of PVA spheres were characterized by SEM and BET measurements. It was found that the addition of DMAc and PVP increased the pore volume and the surface pore size of PVA sphere respectively. The maximum surface area of the porous PVA sphere reached 220 m²/g. Secondly; the synthesis of photoactive TiO₂ NPs (anatase type) at the low temperature was developed by controlling the aging process of the TiO₂ precursors. The crystallinity and photoactivity of TiO₂ NPs increased with the aging time. Finally, TiO₂ NPs/PVA composite spheres were prepared by immersing PVA sphere into TiO₂ precursor solution. Their structures were characterized by XRD pattern, TEM and TGA measurement. It was found that TiO₂ NPs were successfully immobilized into PVA spheres. The photodegradation of methyl orange (MO) under UV light by TiO₂/PVA spheres showed a good photocatalytic efficiency. Moreover, TiO₂/PVA spheres can be easily regenerated by the repeated immersion process. Overall, the porous TiO₂/PVA sphere displays a good photoactive property and an advantage of easier recovery, which facilitates its application in large-scale wastewater treatment.     

Preparation and characterization of a poly(vinyl alcohol)/tetraethoxysilane ultrafiltration membrane by a sol–gel method

Using poly(vinyl alcohol) (PVA) with highly hydrophilic properties as membrane material and poly(ethylene glycol) (PEG) as an additive, we prepared PVA/tetraethoxysilane (TEOS) ultrafiltration (UF) membranes with good antifouling properties by a sol–gel method. The PVA/TEOS UF membranes were characterized by X‐ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electron microscopy, and static contact angle of measurement of water. The hybridization of TEOS to PVA for preparing the PVA/TEOS UF membranes achieved the required permeation performance and good antifouling behaviors. The morphology and permeation performance of the PVA/TEOS membranes varied with the different TEOS loadings and PEG contents. The pure water fluxes (J_W) increased and the rejections (Rs) decreased with increasing TEOS loading and PEG content. The PVA/TEOS UF membrane with a PVA/TEOS/PEG/H₂O composition mass ratio of 10/3/4/83 in the dope solution had a J_W of 66.5 L m^?2 h^?1 and an R of 60.3% when we filtered it with 300 ppm of bovine serum albumin aqueous solution at an operational pressure difference of 0.1 MPa. In addition, the filtration and backwashing experiment proved that the PVA/TEOS membranes possessed good long‐term antifouling abilities. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4066–4074, 2013     

Asymmetric alumina-based ultrathin composite ceramic membranes with interfacial modification of black talc nanosheets

In this work, ultrathin planar alumina-based ceramic membranes with asymmetric structure and thickness less than 0.85 mm were successfully prepared by one-step molding phase transformation/sintering method using low-cost black talc (BT) nanosheets for the first time. The microstructure, pore structure, mechanical strength and permeability of novel ceramic membranes were systematically investigated with different BT amount and sintering temperatures. The doping of BT nanosheets effectively modulated the interfacial bonding area and strength between the grains, achieving significant increase in flexural strength through the evolution of the dense layer structure. The asymmetric structural features formed by the phase transformation/sintering process in combination with polymer substrate significantly reduced the thickness of effective separation layer, thus weakening the loss of flux caused by the densification of the film layer due to the interfacial modification process. Moreover, the organic carbon layers between BT layers were oxidized during the sintering process, forming fine pores and increasing the porosity, which showed to be unique characteristic different from other clay mineral materials. The prepared composite membrane had the pure water flux up to 16335 L m⁻² h⁻¹/bar at 1350 °C sintering, which achieved stable permeation of ∼5200 L m⁻² h⁻¹/bar and high retention over 90% for O/W emulsions.     

Optimization of TiO2 paste concentration employed as electron transport layers in fully ambient air processed perovskite solar cells with a low-cost architecture

The optimization of thickness and surface roughness of the TiO₂ layer as an efficient electron transporting layer (ETL) plays a significant role on the performance improvement of perovskite solar cells (PSCs). In the present investigation, TiO₂ pastes synthesized with various concentrations under hydrothermal conditions were utilized to deposit the TiO₂ films of tunable porosities as the ETLs of PSCs. Also, the PSCs were fabricated with a structure of FTO/block-TiO₂ (b-TiO₂)/m-TiO₂/CH₃NH₃PbI₃ (MAPbI₃)/CuInS₂ (CIS)/carbon as a low-cost architecture. Moreover, the effect of the TiO₂ paste concentration was studied on the performances of PSCs under fully ambient conditions. The optimal TiO₂ layer was constructed with 20 wt% TiO₂ paste concentration, which resulted in the formation of a hole‐free, smooth, and compact ETL layer. The champion perovskite solar cell fabricated with the 20 wt% TiO₂ paste concentration showed the highest power conversion efficiency (PCE) of 13.09% (J_SC = 20.80 mA cm^?2, V_OC = 0.98 V and FF = 0.64) but the champion PSC device made with the 10 wt% TiO₂ paste exhibited the lowest PCE = 8.05% (J_SC = 19.83 mA cm^?2, V_OC = 0.91 V and FF = 0.45). These results illustrated that the optimal 20 wt% TiO₂ paste caused ～163% enhancement in the PCE of the device. Consequently, it could be suggested for application in fabrication of cost-effective and large scale PSCs.     

Chitosan/TiO2 nanocomposite pervaporation membranes for ethanol dehydration

Novel chitosan/titanium dioxide (CS/TiO₂) nanocomposite membranes were prepared using tetrabutyl titanate (TBT) as precursor and acetyl acetone as chelating agent by in situ sol-gel process, and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetry (TG). The characterization results demonstrated that nano-sized TiO₂ particles dispersed homogeneously within the CS matrix, which could be assigned to the hydrogen and titanoxane bonds formed between CS and TiO₂. Moreover, the pervaporation performance of these membranes was investigated using the separation of ethanol-water mixture as model system. Compared with CS/TiO₂ hybrid membranes prepared by blending method, most of CS/TiO₂ nanocomposite membranes prepared by in situ sol-gel process exhibited higher permeation flux and separation factor under the identical conditions. Among all the prepared membranes, CS/TiO₂ nanocomposite membrane containing 6 wt% TiO₂ exhibited the best pervaporation performance, whose averaged permeation flux and separation factor were 0.340 kg m⁻² h⁻¹ and 196 for 90 wt% aqueous solution of ethanol at 80 °C, respectively.     

Role of the effective electrical conductivity of nanosuspensions in the generation of TiO2 agglomerates with electrospray

Suspensions with varying volume fraction of TiO₂ nanoparticles and ionic strength were electrosprayed to obtain agglomerates of different characteristics, which were then deposited to produce films with tailored morphology, thickness, and porosity. The role of the nanoparticle volume fraction in both the effective electrical conductivity of TiO₂ nanosuspensions and the control of the size of agglomerates produced by electrospray was investigated. A simple modified equation for the effective electrical conductivity of TiO₂ nanoparticle suspensions was derived. The equation, which accounted for nanoparticles' diffuse ionic layer and their agglomeration in a liquid, showed that the effective electrical conductivity is not only a function of the liquid and particle conductivities, and the particle volume fraction but also a function of both the thickness of the adsorbed ionic layer on the particles and the particle size. Gradual increase of particle volume fraction resulted in an increase in the suspension's effective electrical conductivity, when the initial liquid conductivity was in the range of 10^?4–10^?3 S m^?1. When the liquid conductivity was in the range of 10^?3–10^?2 S m^?1; however, addition of particles did not have any significant effect on the effective electrical conductivity. Control over the size of the TiO₂ nanoparticle agglomerates was achieved by electrospraying suspensions with liquid electrical conductivity of the order of 10^?3 S m^?1 and by varying the particle volume fraction. Electrospray deposition of suspensions with TiO₂ volume fraction=0.04% resulted in a more compact film with lower porosity and showed better water-splitting performance.