Ceramic Support Research Articles

Carbon-Doped TiO2 Nanofiltration Membranes Prepared by Interfacial Reaction of Glycerol with TiCl4 Vapor

In the pursuit of developing advanced nanofiltration membranes with high permeation flux for organic solvents, a TiO2 nanofilm was synthesized via a vapor–liquid interfacial reaction on a flat-sheet α-Al2O3 ceramic support. This process involves the reaction of glycerol, an organic precursor with a structure featuring 1,2-diol and 1,3-diol groups, with TiCl4 vapor to form organometallic hybrid films. Subsequent calcination in air at 250 °C transforms these hybrid films into carbon-doped titanium oxide nanofilms. The unique structure of glycerol plays a crucial role in determining the properties of the resulting nanopores, which exhibit high solvent permeance and effective solute rejection. The synthesized carbon-doped TiO2 nanofiltration membranes demonstrated impressive performance, achieving a pure methanol permeability as high as 90.9 L·m−2·h −1·bar−1. Moreover, these membranes exhibited a rejection rate of 93.2% for Congo Red in a methanol solution, underscoring their efficacy in separating solutes from solvents. The rigidity of the nanopores within these nanofilms, when supported on ceramic materials, confers high chemical stability even in the presence of polar solvents. This robustness makes the carbon-doped TiO2 nanofilms suitable for applications in the purification and recovery of organic solvents.

Preparation of high flux low‐cost ceramics membrane supports with oil‐based drilling cutting pyrolysis residues (ODPRs) as raw material

AbstractLow‐cost ceramic membrane support is important for the filtration performance of a asymmetry filtration membrane. In this study, the oil‐based drilling cutting pyrolysis residues (ODPRs) were used as raw materials incorporating with fly ash, and carbon particles were used as pore‐forming agents to prepare high‐flux low‐cost ceramic membrane supports. Besides the strength of the supports was decreased with increased carbon particles addition and size, the porosity, pore size and consequently the Darcey permeability k1 and pure water permeability of the support were increased with the increased carbon particle addition and size. The chemical stability of the support was deteriorated with the increased carbon particles addition. A leaching test on the support with 10% 12 µm carbon particle addition indicates that the support obtained by using the ODPRs incorporating with fly ash as raw materials is safe for aqueous filtration. This study showcased the utilization of ODPRs as a primary resource to manufacture a high‐permeability support for water filtration. This approach aligns with the principles of sustainable development, following a waste‐to‐product‐to‐environment pathway.

Advancing greener LNG-fueled vessels: Compact simultaneous reduction system for CH4, NOX and CO2 emissions

Stringent ship regulations necessitate simultaneous emission reductions, challenged by cargo loss and energy constraints. This study proposes a compact reduction system that simultaneously mitigate CH4, NOX, and CO2 emissions onboard LNG-fueled vessels. The proposed system integrates two pivotal technologies: a metal support-based compact methane oxidation catalyst (MOC)-selective catalytic reduction (SCR) system to capture CH4 and NOX, and a cryogenic CO2 capture (CCC) system to capture and store CO2 in its solid phase utilizing LNG's cold energy. This innovative approach addresses two challenges. First, the compact MOC-SCR system employs metal support with an enhanced surface area-to-volume ratio surpassing the capabilities of ceramic support materials, achieving a volume reduction of 80.02% and 79.82% respectively. Secondly, the CCC system significantly lowers specific energy consumption by 61.54% by harnessing LNG's cold energy compared to the absorption-based CO2 capture system. As a result, the proposed system not only reduces CH4, NOX, and CO2 emissions simultaneously with a high capture rate but also reduces volume and weight. Furthermore, it achieves a high CO2 capture rate of 92.12%, while diminishing cargo losses by 25.30%. These findings provide valuable guidance for developing environmentally sustainable vessels, aligning with the continuously increasing stringency of regulations.

Symmetric and asymmetric ceramic-supported polyelectrolyte multilayer nanofiltration membranes

Polyelectrolyte multilayer based nanofiltration membranes can remove organic micropollutants from water. Such polyelectrolyte multilayer membranes (PEMMs) are often assembled on polymeric supports, but less research focuses on inorganic (ceramic) supports. In this work, we assembled symmetric and asymmetric, coatings of poly(allylamine (PAH) and poly(styrene sulfonate) (PSS) on ceramic supports. Symmetric membranes are assembled with the same salt concentration in the coating solution for each layer. Asymmetric membranes use very permeable layers (high salt concentration in coating solution) as base layers and dense top layers with lower permeability (low salt concentration in coating solution) as filtration layers. By reversing the coating order – first salt-free and after that high salt concentration, we obtained reverse asymmetric membranes. They consistently outperformed the symmetric and standard asymmetric design in removing organic micropollutants, reaching an average retention of 85 ± 13 % compared to 77 ± 14 % for the standard asymmetric membranes. We attribute this higher retention to a more efficient pore overcoating for the reverse asymmetric membranes. This work demonstrates that ceramic supports combined with reverse asymmetric PEMMs can be efficiently used for micropollutant removal from water.

Development and characterization of an asymmetrical flat microfiltration membrane based on natural phengite clay: Application as a pretreatment for raw seawater reverse osmosis desalination

The work focuses on developing a new asymmetric flat microfiltration membrane using an inexpensive geological material, natural Moroccan phengite clay. The optimal porous ceramic support was prepared by applying the paste casting method and sintering at a low temperature of 1050 °C for 2 h. Secondly, the microfiltration layer was developed by the spin coating method. The layer was then dried and sintered at 850 °C/2h. SEM analysis revealed that the morphological structure of the layer is homogeneous and free from cracks. Furthermore, the microfiltration layer has an average pore size of 1.23 μm, a thickness ranging from 30.3 μm to 31.3 μm, a water permeability of 258.1 L/h.m2.bar, and good chemical stability against corrosion. The performance of the manufactured membrane was evaluated by filtering raw seawater (RSW1 and RSW2) as a potential application for seawater pretreatment before desalination by reverse osmosis. The prepared membrane significantly reduced turbidity concentrations by 98.7 % for RSW1 and 96.8 % for RSW2. The fouling and antifouling mechanisms were also examined. Finally, the preparation cost of the phengite membrane was estimated to be 125 $/m2.

From single tube to multi-channel configuration: Constructing nanofiltration membranes with superior adhesion strength on the ceramic support by interfacial polymerization

Ceramic membranes with multi-channel configurations exhibit superior mechanical strength, high packing density, and high separation efficiency, making them more suitable for industrial applications than single tube and hollow fiber membranes. However, the preparation of thin-film composite (TFC) membranes on multi-channel ceramic supports remains a challenge because of the poor compatibility between organic and inorganic materials and their special configuration. In this study, nanofiltration membranes with a stabilized structure supported by 19-channel ceramic membranes were successfully prepared with improved adhesion strength and dynamic interfacial polymerization. TFC membranes with different channels exhibited uniform microstructure and stable performance. Specifically, polyethyleneimine, which served as a polymerization reactant, can be tightly wound on the surface of ceramic membranes via hydrogen bonding and van der Waals forces during interfacial polymerization. Owing to the enhanced cross-linked network interactions between the support and separation layers, the adhesion strength was significantly improved. Consequently, the optimized membranes maintained excellent rejection to MgCl2 of ∼94 % after the back-flush test under the pressure of 4 bar. Additionally, the multi-channel TFC membranes exhibited stable performance, with a pure water permeance of ∼14.9 LMH/bar and a molecular weight cut-off of 450 Da. When filtering sunset yellow for 10 h, the prepared membranes exhibited stable permeance and excellent rejection performance.

Unveiling the potential of ultra-low load Co on porous carbon-rich SiCN(O) fibre mats towards oxygen electrocatalysis in alkaline medium

The development of efficient and cost-effective catalysts for the oxygen electrocatalysis is crucial for advancing renewable energy technologies, such as fuel cells, electrolyzers and metal-air batteries. Herein, we report the high efficiency of Co nanoclusters generated on porous silicon oxycarbonitride (SiCN(O)) fibre mats towards Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) in alkaline medium. Porous SiCN(O) ceramic fibrous supports were synthesized via electrospinning of a blend of oligosilazane Durazane 1800, polyacrylonitrile and polystyrene followed by an appropriate heat-treatment. Co nanoparticles with a remarkably low mass loading (4 wt%) were immobilized on the SiCN(O) fibres for efficient bifunctional catalytic activity towards OER/ORR. The catalysts exhibited ORR activity (onset potential (E0) of 0.83 V vs. RHE) and excellent stability (80 h) in alkaline medium. Concomitantly, the catalyst required only 1.67 V to drive a current density of 10 mA cm−2 in 1 M KOH for OER.

Microwaves induced epitaxial growth of urchin like MIL-53(Al) crystals on ceramic supports

Shaping Metal–Organic Frameworks (MOFs) poses a significant challenge for their widespread application on a large scale. In particular, a precise control over crystal orientation and arrangement on substrates are expected to provide exiting opportunities for novel materials with customized characteristics and enhanced performance in catalysis, gas storage, sensing, optics and electronics. Here we demonstrated for the first time that microwave irradiation can induce well controlled epitaxial growth of urchin-like MIL-53(Al) crystals via the hydrothermal conversion of Atomic Layer Deposition alumina layers on SiC foams. The resulting large, ordered crystals feature specific size, homogeneity, dispersion, and quantity that strongly correlate with the nature of the ceramic support and its ability to absorb microwaves. Furthermore, the supported MIL-53(Al) urchins were considered as templates for generating nanostructured alumina fibers on SiC foams, providing attractive catalyst carriers with high specific surface areas.

Titania and zirconia ceramic nanofiltration membrane fabrication by coating method on mullite and mullite-alumina microfiltration supports for industrial wastewater treatment

Industrial wastewater treatment increasingly relies on membrane separation, with ceramic membranes offering many advantages such as thermal stability and pH resistance. The resistance of ceramic membranes to extreme pH conditions indicates their ability to maintain structure and performance when exposed to highly acidic or alkaline environments. A high-permeability ceramic nanofiltration membrane was developed, boasting excellent rejection rates through a multilayer asymmetric design. Initially, two tubular porous supports, mullite and mullite-alumina, with a weight percent of 50, were fabricated using the extrusion method. Subsequently, a colloidal sol of titania (TiO2) and titania-zirconia (TiO2- ZrO2) was prepared via the sol–gel method and coated on the ceramic supports using the dip-coating method. After analyzing the membrane microstructure using SEM, XRD, and BET, the efficiency of the membranes in treating synthetic oily wastewater was evaluated. The results underscore the significant impact of the Donnan exclusion mechanism on the rejection of nanofiltration (NF) membranes. An increase in pressure led to a rise in rejection rates up to 7 bars. The Chemical Oxygen Demand (COD) rejection for mullite-titania zirconia (MTZ) and mullite-alumina-titania zirconia (MATZ) membranes was 98.65 % and 98 %, respectively. The pure water permeability test results for mullite and mullite-alumina supports, as well as MTZ and MATZ membranes, were recorded as 254, 382, 70, and 89 L bar-1m-2h−1, respectively.

Preparation of ultra-high permeability dual-layer Al2O3 hollow fiber supports for zeolite membrane fabrication

Four-channel dual-layer Al2O3 hollow fiber with ultra-high permeability and mechanical strength was prepared by co-extrusion and co-sintering technique for the first time and used as support for NaA zeolite membranes fabrication. The macroporous inner layer of the Al2O3 hollow fiber, composed by large Al2O3 particle, gives supports the high permeability and mechanical strength, while the thin out layer, composed by small particles, provides an even and smooth surface for zeolite membrane growth. By using SiO2 as the sintering aid, the sintering temperature of the inner layer was reduced and match with that of the outer layer. The effects of SiO2 adding amount, sintering temperature, Al2O3 particle size and their content on the structure and properties of the prepared hollow fiber were investigated systematically. At a sintering temperature of 1520 °C, a dual-layer hollow fiber with surface pore size of 0.38 μm and fracture load of 24.52 N, exhibits pure water flux as high as 22.23 m3 m 2 h−1 bar−1. The NaA membrane prepared on this support achieved a flux of 14.14 kg m−2 h−1 and a separation factor >10,000 in pervaporation separation of EtOH/H2O solution (90 wt%, 75 °C). This work provides an efficient and low-cost way to prepare ceramic hollow fiber support for high-performance zeolite membrane fabrication.

Short-stage synthesis of metal–ceramics composites as precursors for high performance catalytic applications

NiAl, NiCoAl, and CoCuAl intermetallics on ceramic TiC and TiCrC supports were produced by self-propagating high-temperature synthesis (SHS) from granular mixtures and used as precursors for preparation of catalysts for CO and propane deep oxidation and CO2 hydrogenation. The precursors were converted into catalysts by aluminum leaching and stabilization with hydrogen peroxide solution. Prepared supported catalysts were characterized by XRD, SEM/EDS, and BET methods and tested in the processes of deep oxidation of CO and propane and methanation of CO2. It was revealed that 100 % CO conversion is observed in TiC-supported catalysts at 250 °C. Catalysts containing NiCo active phase on both ceramic supports were shown to be the most active in propane oxidation. In CO2 methanation, Ni/TiCrC sample showed the highest CO2 conversion (58.9 % at 350 °C) with 100 % methane selectivity.

In-situ grown columnar mullite reinforced SiC porous ceramic membrane support with excellent mechanical performance and corrosion resistance: Using TiO2 as the key to form columnar mullite

In this study, in-situ growth of columnar mullite reinforced silicon carbide porous membrane supports were prepared, and the addition of TiO2 helped to reduce the sintering temperature for the anisotropic growth of necked columnar mullite crystals. The synthesis of in situ columnar mullite makes reasonable use of the oxidized silica of silicon carbide, and in turn reduces the loss of the silicon carbide porous membrane support under strong corrosive conditions. The material showed a flexural strength of up to 72.95 MPa, and a water flux of 31612.83 L·m−2·h−1·bar−1 when sintered for 2 h in an air environment at 1250 °C. The flexural strength after corrosion in 20 vol% H2SO4 and 1 wt% NaOH solution (90 °C) exceeded 93 %. This shows that this porous silicon carbide ceramic membrane scaffold has potential applications in the field of water treatment under harsh environments.

Digital light processing of high-purity SiC ceramic membrane support modified by SiC whisker

High-purity SiC ceramic membrane has gained tremendous attention in the treatment of various corrosive wastewaters. Additive manufacturing technique makes it possible to fabricate high-purity SiC ceramic membrane with complex configurations. Here, we proposed a route for the preparation of high-purity SiC ceramic membrane support using digital light processing and SiC whisker reinforcement. With the increase of whisker content, the viscosity of SiCw/SiC photosensitive slurry increased due to the formation of whiskers agglomerations; the average pore size shifted from 3.15 μm to 1.35 μm with the occupation of large pores by SiC whiskers. In addition, the compressive strength of the ceramic support increased from 10.7 MPa to 16.7 MPa because of the decline in pore size and the toughening effects by SiC whiskers. So, the introduced SiC whiskers enhanced the pore connectivity and mechanical strength of the porous ceramics. This work provides a feasible path to manufacture high-purity SiC ceramic membrane support with complex configuration, high pore-connectivity and excellent mechanical properties.

A reverse particle grading strategy for design and fabrication of porous SiC ceramic supports with improved strength

A reverse particle grading strategy for design and fabrication of porous SiC ceramic supports with improved strength

Thin polyamide layer cross-linked graphene-oxide based ceramic membranes for efficient separation of the surfactant stabilized oil-in-water emulsions

Two-dimensional (2D) graphene oxide (GO) membranes (GOM) have great potential in separation applications. However, GOMs face two distinct challenges: low flux arising from their tight stacking and instability arising from re-exfoliation of GO sheets in solution. To address these challenges, herein, we report the functionalization of basal planes of GO layers with 2-[2-(3-Trimethoxysilylpropylamino)ethylamino]ethylamine (TSE), followed by transforming them into membranes through a two-step process. In the first step, the functionalized GO sheets were assembled onto the porous ceramic support. At this stage, the interlayer distance between GO sheets was modulated via TSE’s long hydrocarbon chain. Afterward, the free amines of TSE on functionalized GO membranes (fGOM) surface were cross-linked with trimesoyl chloride (TMC) to prepare a hydrophilic thin-layer on top of fGOM (TL-fGOM), further enhancing their stability. Further, TL-fGOMs were tested for oil-in-water-emulsion separation. The increased interlayer distance and the increased surface hydrophilic nature of TL-fGOM offered ultra-high water permeance, 4860 % higher compared to the non-functionalized GOM. Moreover, the separation efficiency of TL-fGOM improved from 37 % of that of ceramic membranes to 99.5 %. Additionally, they showed excellent anti-fouling properties. After exposing the membranes to 500 ppm emulsion for 10 hours in batches, the flux recovery ratio exceeded 90 %. The TL-fGOM in our work demonstrated outstanding performance in purifying oily emulsions containing diesel/toluene/heptane-in-water. All these results revealed that the appropriate functionalization of graphene oxide could assist in forming a thin layer of graphene oxide on the support membranes, offering high separation efficiency and fouling resistance. This approach can be extended further to utilize the graphene oxide membranes for practical applications.

Fabrication of Tailored Membranes with Special Surface Wettability Features for Highly Efficient Crude Oil-in-Water Emulsion Separation.

Treating oily wastewater streams such as produced water has a huge potential to resolve the issue of wastewater disposal and generate useful water for reuse. Among different techniques employed for oily wastewater (oil-in-water; O/W emulsion) treatment, membrane-based separation is advantageous owing to its lower energy consumption, recycling, ease of operation, and wider scope of tuning the active layer chemistry for enhanced performance. In line with the possibilities of enhancing the performance of the membranes for efficient O/W emulsion separation, the current work is designed to yield five different variants of polyaniline (PANI) active layers with special surface wettability features (superhyrophilic and underwater superoleophobic) on a ceramic alumina support. To achieve variants of PANI on ceramic alumina supports, emulsion polymerization was carried out, and different concentrations of initiator ammonium persulfate (APS) were applied to lead to PANI-A@Aluminum Oxide membrane, PANI-B@Aluminum Oxide membrane, PANI-C@Aluminum Oxide membrane, PANI-D@Aluminum Oxide membrane, and PANI-E@Aluminum Oxide membrane corresponding to 0.15, 0.25, 0.35, 0.5, and 1.0 M concentrations of initiator. The variation in initiator concentration resulted in different PANI growth patterns; hence, the resultant membranes showed different structural, physical, and performance features. Different characterization techniques including 1H NMR, SEM, FE-TEM, AFM, water contact angle, XRD, EDX, and ATR-FTIR confirmed a more uniform and continuous growth of PANI (PANI-B) using a 0.25 M initiator concentration. The resultant PANI-B@Aluminum Oxide membrane showed an excellent surfactant stabilized crude O/W emulsion separation reaching >99% with a permeate flux of 2154 L m-2 h-1 (LMH) at 4 bar using a 100 ppm surfactant stabilized crude oil-in-water emulsion. The fouling and cleaning cycles revealed that the membrane can be reused with a 70% recovery of the initial permeate flux.

A new ceramic microfiltration membrane based on olive seeds: development and characterization

ABSTRACT The development of low-cost methods for wastewater treatment and the separation of oil-in-water emulsions is of considerable significance. Recently, natural material-based, inexpensive membranes have become a hot area of research. In this work, natural olive seeds were used to develop a novel ceramic membrane support. With the oil filtration process in place, the choice was reached to utilize the olive kernels’ beneficial qualities best. The process involved blending plastic paste with water and organic ingredients, followed by extruding the resulting paste into a porous tubular. After firing at 200 °C/2 h, the membrane's water permeability and porosity were 1,852 L/h m2 bar and 45%, respectively, and its average pore width varied from 2 to 15 μm. The efficiency of the microfiltration membrane in separating oil-in-water emulsions was assessed using two test solutions containing oil concentrations of 500 and 1,000 mg/L. Under a transmembrane pressure of 1 bar, the membrane exhibited exceptional permeate flux exceeding 200 L/m2 h, along with a high oil rejection rate of over 96% across all feed concentrations.

Enhancing stability and performance of graphene oxide membrane grafted on low-cost rich-silica support: A comparative study of two activation approaches

Although graphene oxide has shown encouraging results in membrane field, it has a major stability issue when coated on ceramic supports, particularly those formed of geomaterials. This work aims to prepare stable graphene oxide layer deposited on a low-cost rich-silica support. The graphene oxide membrane was prepared using grafting method, which included surface activation and modification followed by the graphene oxide layer coating. Siloxane functional groups were activated using either hydrochloric acid or piranha solution to determine which of them provided the highest membrane stability. The support surface was chemically modified using 3-glycidoxypropyltrimethoxysilan followed by the deposition of graphene oxide nanosheets using evaporation-assisted assembly. According to Fourier-transform infrared spectroscopy, the support activated with piranha solution has more silanol functional groups than the support activated with hydrochloric acid while the appearance of 3-glycidoxypropyltrimethoxysilan band on the modified support, proves the accomplishment of grafting. The stability test of the membrane demonstrated a highly stable deposited layer for the graphene oxide membrane activated with piranha solution in different pH contrary to the non-grafted graphene oxide membrane and the graphene oxide membrane activated with hydrochloric acid that peeled off from the support. On the support activated with piranha solution, 3-glycidoxypropyltrimethoxysilan concentration was investigated and an optimal value of 0.1 mol L−1 was determined. The filtration performance of the membrane was assessed by the removal of anionic and cationic dyes. For anionic dyes, the membrane rejection reached a value of 90 % for direct red 80 and 87 % for methyl orange. For the rhodamine B considered as cationic dye, the membrane rejection reached a value of 81 %. The membrane may be considered sustainable since it is inexpensive and emits at least 9.76 kg CO2eq m−2 less than other ceramic membranes during its preparation.

EFFECT OF RICE STARCH CONTENT ON TUBULAR ALUMINA MEMBRANE SUPPORT FABRICATED BY AGAR GELCASTING

This study addresses the challenge of fabricating cost-effective tubular ceramic membranes through agar gelcasting. The addition of rice starch as the pore-forming agent in the ceramic membrane support layer, with varying contents from 0 to 6 wt%, was focused on improving the permeability of the tubular ceramic membrane. Scanning electron microscopy (SEM) revealed the co-existence of large pores from starch decomposition and small pores in the form of interparticle voids. When the rice starch was enhanced, the firing shrinkage and apparent porosity increased, and the bulk density decreased. Notably, the tubular ceramic membranes with 6 wt% of the rice starch addition exhibited a permeability of 0.17 Lh⁻¹m⁻²bar⁻¹ under a pressure of 2.5 bar.

Combining dip-coating and rotate-drying to preparation of PDMS on SiC tubular support with macropore for high pervaporation performance

High-performance polydimethylsiloxane (PDMS)/ceramic tubular pervaporation membranes have potential in industrial separation applications, but realizing the preparation of PDMS layer on the ceramic supports with micrometer-scale pore size (0.8 μm or 4.3 μm) for improving performance remains a challenge. We report a strategy (combined dip-coating and rotate-drying, DCRD) to preparation of PDMS on silicon carbide (SiC) tubular support with macropore. Response surface methodology was employed to optimize the dip-coating process, and the influence of friction velocity on tubular composite membranes was investigated. The results indicate that pulling speed, casting solution viscosity, and their interaction have significant effects on the pervaporation performance of PDMS/SiC tubular composite membranes. Moreover, increasing friction velocity results in uneven PDMS layer thickness, which in turn impacts the pervaporation performance of the composite membrane. Furthermore, the rigid structure of SiC restricts the movement of PDMS polymer chains, enabling the composite membrane to maintain stable pervaporation performance at higher isobutanol feed concentrations (3 wt%) or elevated feed temperatures (60 °C). After continuous operation for 200 h, the developed PDMS/SiC tubular composite membrane consistently maintained the total flux of 650 g m−2 h−1 and the separation factor of 39 for isobutanol/water. Eventually, this novel fabrication method offers new insights into the preparation of various other organic-inorganic tubular composite membranes.