Ceramic Membrane Supports Research Articles

Preparation, Characterization and Properties of New Low Cost Multi-Channel Ceramic Membrane Tube for Water Treatment

Multi-channel tubular macroporous ceramic membrane supports were successfully prepared via a plastic extrusion method, using α-Al2O3 with a purity of 94wt% and aluminum hydroxide as starting materials, the ash of burned rice hull as the pore-forming agent and a small amount of talc and kaolin as sintering aids. The effects of the kinds of sintering aids, content of aluminum hydroxide and ash of burned rice hull on the porosity, pore size and distribution, compressive strength, acid and alkali corrosion resistance and permeability of the new multi-channel ceramic membrane supports were investigated. The results showed that aluminum hydroxide effectively improved the mechanical strength, and the support sintered at 1450°C for 4h with the aluminum hydroxide content of 20wt% exhibited higher performance: average pore size diameter and porosity were nearly 5μm and 50% respectively, the compressive strength was around 7MPa, the pure water flux was 26m3/m2h at 0.1MPa and changed to nearly 20m3/m2h after the acid and alkali treatment at 90°C for 48h. The support possesses excellent corrosion resistance and can be used in the water treatment process with large range of pH value.

Preparation of Porous Ceramic Separation Membrane Supports

This study used alumina fine as main raw materials to prepare the porous ceramic separation membrane supports. The effects of different the sintering temperature and holding time on ceramic separation membrane supports are studied, and the TG/DSC curves of raw materials powder are analyzed by the preparation process. The results show that sintering temperature 1200°C, holding time 6 h, pore-forming agent more than 20%, prepared the uniform pore size distribution, porosity, accord with more than 50% of porous ceramics water demand separation membrane supports.

Performance characteristics of hydrothermal and sonication assisted electroless plating baths for nickel–ceramic composite membrane fabrication

This paper addresses the performance characteristics of nickel–ceramic composite membranes fabricated with hydrothermal mass transfer coupled electroless plating baths. Deposition of nickel on a ceramic membrane support with an average pore size of 275 nm was considered to study the effect of autogenous pressure under hydrothermal conditions and sonication coupled hydrothermal conditions on the process as well as membrane characteristics. Bath conversion, plating efficiency, average film thickness and percent pore densification (PPD) were studied. Parametric investigations were carried out for wide range of initial nickel sulfate concentration (0.04–0.16 mol/L) in the solution at a higher loading ratio (393 cm 2/L). An interesting observation from this study was that the autogenous pressure together with ultrasound provided the best performance characteristics of electroless plating. The optimal performance characteristics refer to 81.87% conversion, 84.19% plating efficiency, 99.92% PPD for a nickel composite membrane with film thickness of 37 μm prepared using 0.16 mol/L of nickel solution metal concentration. The microfiltration study on oil-in-water emulsions inferred that the membrane fabricated with HTSO coupling and C i = 0.04 mol/L gave a rejection of 90.13% and membrane permeability of 0.11 × 10 − 10 m 3.m − 2 .s − 1 .Pa − 1 .

Effect of TiO 2 addition on the fabrication of ceramic membrane supports: A study on the separation of oil droplets and bovine serum albumin (BSA) from its solution

Low cost porous ceramic membrane support was prepared using kaolin, pyrophyllite, feldspar, ball clay, quartz and calcium carbonate mixture along with PVA as a binder. The main intention of this work is to study the changes in the properties of the membrane supports (pore size, porosity, mechanical strength and pure water permeability) by the addition of titanium dioxide (TiO 2). Three membrane supports, namely, support-I, 3G and 6G supports (naming is based on the loading of TiO 2) were prepared by uniaxial compaction method. All the membrane supports were sintered at 950 °C and systematically analyzed using thermogravimetric (TG), particle size distribution (PSD), X-ray diffraction (XRD), N 2 adsorption–desorption and scanning electron micrograph (SEM) analysis. The porosity of the support-I, 3G and 6G supports was found to be 44, 38 and 36% with an average pore diameter of 0.98, 0.93 and 0.83 μm, respectively. The flexural strength of the membrane supports was increased with the addition of TiO 2 and ranges between 28 and 33 MPa. Solvent permeation studies through these membrane supports revealed that the non polar solvents were more permeable than the polar solvents and the transport mechanism was mainly controlled by viscosity of the solvents. Performance of the membrane supports was investigated for oil-in-water emulsion separation by varying the feed concentration and applied pressure. A maximum rejection of 99% was obtained with 6G support for an oil concentration of 200 ppm. Also, an attempt has been made for the separation of bovine serum albumin (BSA) from its solution using these membrane supports and a reasonable rejection of 40% was obtained for 100 ppm of BSA solution. Research highlights ► Effect of addition of TiO 2 on the properties of the porous ceramic membrane supports was investigated. ► Potential of the supports was tested for oil and BSA separation from its solution. ► Higher rejection for oil (99%) and moderate rejection for BSA (40%) were obtained. ► Pore fouling mechanisms were also investigated for the oil-in-water emulsion system.

Study of ceramic ultrafiltration membrane support based on phosphate industry subproduct: Application for the cuttlefish conditioning effluents treatment

The development and the characterisation of a new support for ultrafiltration membranes prepared from the mud of the hydro cyclone laundries of phosphate are presented. The choice of this material is based mostly on its low cost (considering its abundance in the Tunisian ores). Indeed, the use of this material for membrane preparation allows a good management of this subproduct which represents a major problem in phosphate transformation industry due to the resulting environmental pollution. Paste from the mud of the hydro cyclone laundries of phosphate was extruded and heated at 900 °C to produce a porous tubular support having an average pore diameter and a porosity of about 1.05 μm and 39%, respectively. The properties regarding to mechanical and chemical resistances are very interesting. The deposition of the ultrafiltration layer from zirconium material was performed by slip-casting method. The heating treatment at 700 °C leads to an average pore size of 5 nm. The determination of the water permeability shows a value of 86 l/h m 2 bar. This membrane can be used for crossflow ultrafiltration. The application of the cuttlefish effluent treatment shows an important decrease of turbidity, inferior to 1.5 NTU and chemical organic demand (COD), retention rate of about 60%. So, it seems that this membrane is suitable to use for wastewater treatment.

Fabrication and Catalytic Properties of Palladium Nanoparticles Deposited on a Silanized Asymmetric Ceramic Support

We developed an improved fabrication technique for the deposition of palladium nanoparticles on a ceramic membrane support in which the support surface was silanized with amino-functional silane. I...

Corrosion resistance characterization of porous alumina membrane supports

Tubular porous alumina ceramic membrane supports were fabricated by an extrusion–drying–sintering process and then characterized in detail in terms of corrosion resistance in both H 2SO 4 and NaOH aqueous solutions. Variations in the properties of the alumina supports such as mass loss percent, mechanical strength, open porosity and pore size distribution were studied before and after corrosion under different conditions. In addition, the microstructures were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction before and after corrosion. The fabricated porous alumina supports offer possibilities for some potential applications as micro-filtration or ultra-filtration membrane supports, as well as in the pre-treatment of strongly acidic industrial waste-liquids.

Recycling of fly ash for preparing porous mullite membrane supports with titania addition

In order to effectively utilize industrial waste fly ash, porous mullite ceramic membrane supports were prepared from fly ash and calcined bauxite with chemically pure titania as sintering additive. The effects of TiO 2 on the sintering behaviors and main properties of porous mullite were studied in detail. Due to the addition of titania, the sintering of the flyash-based mullite was inhibited at low temperatures, but effectively improved at high temperatures, the latter is suitable for preparing porous mullite membrane supports by incomplete sintering. Titania entered into liquid glassy phase with low high-temperature viscosity during sintering, resulting in the improvement of sintering activity, as well as the lowering of secondary mullitization temperature (where 2.0% titania). Between 1300 and 1500 °C, with increasing titania content, the samples exhibit increased trends in both linear shrinkage percent and bulk density, but a slightly decreased trend in open porosity, at all sintering temperatures. At 1300–1500 °C, the samples sintered at 1450 °C for 2 h exhibit the lowest shrinkage and bulk density, as well as the highest open porosities in the investigated titania content range of 0–6.0 wt.%. Also, with increasing titania content, the pore size decreases slightly but the three-point flexural strength increases gradually at 1450 °C.

A morphological study of ceramic hollow fibre membranes: A perspective on multifunctional catalytic membrane reactors

Asymmetric ceramic hollow fibre membranes and membrane supports have been prepared using a combined phase inversion and sintering technique for use in a multifunctional catalytic membrane reactor. The asymmetric structure is such that the fibre may simultaneously function either as a porous membrane and a matrix for catalyst deposition, or as a porous support for the coating of a gas separation layer and a matrix for catalyst deposition. The effectiveness of catalyst deposition depends strongly on the pore size distribution of the membrane or membrane support, which is bimodal in nature and is affected by the calcination temperature and the fibre preparation parameters. The effect of the calcination temperature and preparation parameters on the pore size distribution and fibre morphology have been studied systematically with regard to catalyst deposition and fibre mechanical strength and a route to optimizing the fibre structure has been suggested.

Preparation and characterization of macroporous ceramic supports for membranes

The objectives of this work were to prepare the ceramic supports from clays. These raw materials have been dictated by their natural abundance (low price) and their beneficial properties. The powders mixed with certain organic additives have been extruded to fabricate a porous tubular configuration with highly uniform porous structures. Subsequently, the influence of the sintering temperature on the total porosity, average pore size, pore size distribution and strength of supports is investigated.

Preparation and characterization of tubular membrane supports using centrifugal casting

In this paper, the manufacture of a tubular supports ceramics membrane is described. The main objective of this work consists of the preparation and characterization of adequate and less expensive membrane supports, using abundant local raw materials. A porous raw materials tube of 20mm in diameters and 170mm in length were successfully fabricated by centrifugal casting technique. Moreover, the obtained samples were characterized, using different techniques. The structure was analyzed by X-ray diffraction (XRD) and mercury porosimetry techniques. The pore size and the presence of possible defects in the supports were determined by Scanning Electron Microscopy (SEM). It has been found that tubular ceramic membrane supports had a highly homogeneous product and a smooth inside-surface. The influence of the sintering temperature on the total porosity, average pore size and pore size distribution of supports is taken into account. The obtained results enabled to conclude that clay supports can be used alone (without any additions), successfully, in tangential microfiltration or as a support for ultrafiltration membranes. Finally, this investigation demonstrates that centrifugal casting may be also considered as a promising technique in order to fabricate tubes for membrane application.

Manufacture of tubular ceramic membrane supports using gelcasting

Ceramic membrane porous supports were manufactured using α-Al2O3 via gelcasting where acrylic acid was used as a base monomer. X-ray diffraction, N2 adsorption isotherms (BET, Longmuir and BJH method), mercury porosimetry and SEM were used to identify the characteristics and morphologies of the supports. The characteristics of the membrane were analysed in terms of the effect of particle size and sintering temperature on porosity, pore size and microstructure. The porosity and pore size decreased as the sintering temperature increased. With increasing particle diameter, pore size and porosity increased. Broad non-Gaussian pore distribution in the ceramic matrix was turned into a narrow Gaussian distribution when the particle size was reduced. It showed that finer particles result in a very smooth outer surface of the support system. The porous support was further characterised in terms of permeability of water at specified condition where an experimental set-up was developed to perform the permeability studies.

Cost-effective macro-porous mullite-corundum ceramic membrane supports derived from the industrial grade powder

In order to develop cost-effective macro-porous ceramic membrane supports, the porous supports with large pore size were prepared from the coarse industrial mullite-corundum powder (M) with the mixture of kaolin and basic carbonate magnesium (KM) as sintering additive. Crystalline phase transition mechanism of the sintering additive and the supports was studied respectively by TG/DTA and XRD. The results confirm that at 1200–1400 °C α-cordierite formed from the sintering additive, and that above 1400 °C α-cordierite decomposed into mullite and liquid glassy phase. Sintering characteristic of the coarse mullite-corundum compacts was revealed as a function of KM/M mass ratio. The result indicates that the sintering ability of coarse mullite-corundum improved because of the produced liquid silica-rich glassy phase via the decomposition of KM-derived α-cordierite. In addition, the open porosity of the macro-porous mullite-corundum could be effectively tailored by choosing the KM/M mass ratio, the pore-former/M mass ratio and sintering temperature. The fabricated mullite-based macro-porous supports showed an average pore size of 26.21 μm and nitrogen flux of 2.375 × 10 4 m 3/(m 2 h), as well as good mechanical and thermal properties.

Synthesis and characterization of nanocomposite MCM-41 (‘LUS’) ceramic membranes

A new type of nanocomposite membranes, MCM-41 (‘LUS’)-based material networks grown into porous ceramic membrane support walls (alumina and zirconia), were prepared. Physical characterization (low-angle XRD, TPD, SEM–EDX) confirm the sole presence of the LUS mesostructure (BJH pore size ≈3.2nm), and in a high enough amount to plug the pores of the tubular supports. Single gas hydrodynamic characterization shows that the contribution of defects (i.e. viscous flux) is negligible or comparable to reference mesoporous commercial membranes (5nm pore size γ-alumina), but with a considerably enhanced permeance for gases and water, as well as, a single pore size. When compared to literature results on similar organized mesoporous membranes, this work shows even greater improvements.

Preparation and Sintering of Macroporous Ceramic Membrane Support from Titania Sol‐Coated Alumina Powder

The preparation of ceramic support at relatively low sintering temperature of 1350°–1500°C was investigated with a powder processing route, namely, titania sol coated on coarse alumina powder (median particle size d50, 27.5 μm). The sintering kinetics analysis indicates that the microstructure control of support is closely related to the sol coating and the sintering conditions. The mechanisms of sintering process were discussed in detail with the corresponding kinetics parameter, i.e., activation energy Ea and exponent n as well as the microstructure characterization. The prepared support provides practical applications with tunable pore size and desired mechanical strength.

Elaboration and chemical corrosion resistance of tubular macro-porous cordierite ceramic membrane supports

Tubular macro-porous supports for ceramic micro-filtration membranes were prepared by extrusion followed by sintering from low cost commercial grade cordierite powder. The effects of sintering temperature on the micro-structure, fracture strength, LTEC (linear thermal expansion coefficient), pore size distribution and permeation flux were studied. Our results indicate that the optimized sintering temperature was in the vicinity of 1380 °C. The fabricated cordierite supports showed an average pore diameter of 8.66 μm, open porosity of 36.20%, nitrogen gas flux of 1.45 × 10 4 m 3 m −2 h −1 and LTEC of 4.34 × 10 −6 °C −1 (between 25 and 1000 °C). To verify the practicability in the strong corrosive environment, the chemical resistance tests were carried out in the sodium hydroxide and sulfuric acid solutions under the boiling condition, respectively. Compared with the as-used alumina supports, the cordierite supports exhibited better thermal alkali resistance but poorer acid resistance according to the mass loss results. In addition, the corroded cordierite supports were characterized by fracture strength, open porosity and pore size distribution. The fabricated macro-porous supports are expected to have potential applications in the pre-treatment of strong alkali media and dust-containing hot gas.

Manufacture and optimization of tubular ceramic membrane supports

The manufacturing and optimization of centrifugally casted ceramic membrane supports is presented. For the optimization, the effect of three different powder sizes (0.25, 0.31 and 0.61 μm) and a sintering temperature range between 1050 and 1400 °C was investigated. The ceramic tubes were characterized according to tube dimensions, mercury porosimetry, water permeability, SEM and mechanical strength. It was shown that the centrifugal casting technique delivers highly reproducible support properties. A novel strength testing apparatus was developed to determine the mechanical strength of the ceramic tubes. It was found that the strength varied between 3300 MPa and 300 MPa, depending on the porosity of the supports. With increased sintering temperature, water permeability and porosity decreased, while strength and linear shrinkage increased. The pore diameter of the supports produced by the 0.31 and 0.61 μm powders decreased, while that of the 0.25 μm powders remained constant (72 nm) with increasing sintering temperature. The 0.61 μm powder sintered at the lowest sintering temperature resulted in the support with the highest porosity, pore diameter and porosity, but the lowest mechanical strength and linear shrinkage. An overall improvement concerning pure water permeability was seen when the support in this study was compared to our own previous studies and similar studies in literature.

Microstructure control of ceramic membrane support from corundum-rutile powder mixture

The reaction sintering of porous alumina ceramic membrane support was realized at 1300 °C using commercial titanium white powder (rutile) as sintering aids. The microstructures of sintered body were significantly affected by the amount of rutile, organic pore-forming agents and sintering techniques. The results indicated that the porosity dramatically decreased and the pore radius decreased from 1.6 μm to 0.8 μm with less than 10.0 wt.% rutile addition. Correspondingly, their permeations to nitrogen depending on the pore structure parameters of the support were in the range of 11.8–26.1 km 3 m − 2 h − 1 bar − 1 at 1400 °C. Organic additives up to 25.0 wt.% is appropriate, otherwise the excessive organic additives would lead to poor sintering of green support. Sintering experiments showed that the microcracks formed once the sintering temperature was over 1600 °C. To prepare porous alumina support with > 40% open porosity and 50 MPa mechanical strength along with better resistance to alkaline corrosion, the optimum sintering conditions are the sintering temperature of 1400 °C and 2–4 h holding time at this temperature.

Porous ceramic supports for membranes prepared from kaolin and doloma mixtures

The present paper reports the in situ synthesis of porous ceramic supports from local kaolin and kaolin–doloma mixtures. These raw materials have been dictated by their natural abundance (low price) and their beneficial properties. In this work, four different processing routes have been presented. In addition, two support shapes are of particular interest: tubular and flat configurations, which are currently the most used supports in membrane research. Tubular configurations have been produced by extrusion method whereas flat configurations have been produced by both dry-pressing and roll pressing. The doloma addition to kaolin has a positive effect on the porosity ratio of supports compared to those prepared from kaolin alone. Moreover, the influence of the sintering temperature on the total porosity, average pore size, pore size distribution and strength of supports has been investigated. It has been found that higher sintering temperatures (1250 °C) were needed to obtain a uniform pore size distribution within total porosity ratios of 43 and, 51% when processes 3 and 2 were applied, respectively.

Initial sintering stage pore growth mechanism applied to the manufacture of ceramic membrane supports

Initial sintering stage pore growth mechanism has been applied to the manufacture of alumina and zircon membrane supports formed by uniaxial compaction. The effect of sintering temperature (1200–1500 °C) on density, porosity, surface area, permeability, mean flow pore size, mesopores mean radius (<7 nm) and tortuosity has been investigated. A transition zone has been determined at the end of which permeability reaches a maximal value. Alumina and zircon samples possessed a reasonable flexural strength at the latter point. The transition zone is accompanied with a decrease in tortuosity for both materials. The trend of tortuosity change after the transition zone strongly depended on the shrinkage behavior of the samples.