Al2O3 Membranes Research Articles

Chemical vapor deposition of silicon carbide on alumina ultrafiltration membranes for filtration of microemulsions

Worldwide, a considerable amount of oily wastewater is generated, with oil droplets from 2 to 200 nm that are difficult to separate because of their size and colloidal stability. This study presents a novel approach for effectively separating microemulsions via cubic silicon carbide (3C-SiC)-coated alumina (Al2O3) membranes fabricated based on low pressure chemical vapor deposition (LPCVD). SiC was deposited at a relatively low temperature at 860 °C on 100 nm Al2O3 membranes using two precursors: SiH2Cl2 and C2H2. With the increase in deposition time, up to 25 min, the pore size decreased from 41 nm to 33 nm, which is a smaller pore size of a SiC membrane than previously used for oil/water separation. The polycrystalline 3C-SiC-coated membranes showed improved hydrophilicity (water contact angle of 15°) and highly negatively charged surfaces (−65 mV). Microemulsion filtration experiments were carried out at a constant permeate flux (80 Lm−2 h−1) for six cycles with varying deposition time, pH, surfactant types, and pore sizes. The fouling of the SiC-coated membrane was, compared to the Al2O3 membrane, effectively mitigated due to the enhanced electrostatic repulsion and hydrophilicity. Surfactant adsorption mainly occurred when the surface charge of the microemulsion and the membranes were opposite. Therefore, the surface charge of the alumina membrane changed from positive to negative when soaked in negatively charged microemulsions, whereas SiC-coated membranes remained negatively charged regardless of surfactant type. The membrane fouling was alleviated when the membrane and oil droplets had the same charge. Lastly, the 62 nm SiC-coated membrane with 20 min coating time was the best choice for the filtration of the microemulsion, because of the high rejection of the oil droplets and low fouling tendency.

Evaluation of the performance characteristics of aerostatic bearing with porous alumina (Al2O3) membrane using theoretical and experimental methods

Instruments with high levels of precision commonly use aerostatic bearings. Moreover, the use of porous (Al2O3 membrane) material validates that the pressure is spread uniformly throughout the air film region. The impression of applied load on the thickness of the air film of the aerostatic bearings was evaluated using a certain experimental technique. As the applied load rises, the thickness of the air film expands, and as the compressive stress rises, it contracts. The theoretical model parameters were set using the experimental stipulations. It was discovered that the theoretical model and the experimental data were consistent. The pressure gradient induced in the air film and the air bearings’ capacity for carrying loads were calculated using a theoretical simulation. The results of theoretical modeling and experimental comparison of the different characteristics of porous (Al2O3 membrane) aerostatic bearings based on stiffness and load-carrying capacity are graphically illustrated in this study. Porous aerostatic bearings with Al2O3 membranes have a number of potential applications, including high-speed spindles, precision instruments, microelectromechanical systems, vacuum pumps, cryogenic applications, etc.

<i>In Situ</i> ALD-TEM System to Study Atomic Nucleation Phenomena - Enabled by Ultrathin Large Aspect Ratio Free-Standing Shell Structures

Today, Atomic Layer Deposition (ALD) sets the limits for achieving nanometer precision of thin, yet almost dense films. However, the initial growth process, determining possible film thinness, is poorly understood. A better understanding can be obtained with the help of in-situ characterization during film growth with high spatial and chemical resolution. Transmission Electron microscopy (TEM) would be a suitable and widely available technique to accomplish this objective. However, standard instruments have differing vacuum requirements than those necessary for ALD. During ALD, TEM detectors could be damaged as they are being exposed to corrosive volatile chemical compounds. Here we present a dedicated TEM holder design, where ALD deposition occurs inside a microchip containing a large area cavity surrounded by thin film Al2O3 membranes. These membranes act as windows for TEM characterization while decoupling the ALD process from the TEM environment. The microchip consists of longitudinal large overhang shell structures, themselves made by ALD and etched in an HF vapor etch processes. The set-up, which includes controlled heating, was tailored to ALD requirements, and passed a vacuum-pressure test. Post-mortem inspection of film growth on a silicon sample chip demonstrates the successful formation of an ALD Al2O3 film with 40 nm thickness inside the cavity. These results demonstrate the potential of the system to enable a range of experiments on growth phenomena that may lead to even thinner films and better control of interfaces than previously possible.

Identifying the features of surface roughness and H2 bubble production on the super-hydrophobic properties of Al2O3 and Mg membranes

This research investigates Alumina (Al2O3) and Magnesium nano membrane layers using hybrid technology. Hybrid is a concept of combining two or more materials/elements to achieve something better. Hybrid technology was developed because of the possibility of combining materials/elements which, if used simultaneously, has more advantages than if used independently. The problem to be solved is to find the best composition of Alumina and Magnesium hybrid membranes. Superhydrophobic properties of the membrane are achieved at a percentage of Mg: 50 %, Al2O3:50 %. At a composition below 50 % Mg, the small surface roughness has a low surface tension, while the H2 production reaction by Mg is also low, so the surface tension carrying capacity of the gas and the roughness of the droplets is not strong, which causes the hydrophobicity to be low. In compositions above 50 % Mg, H2 production by high Mg makes bubbles cover the roughness peaks so that the surface tension is lower and changes the superhydrophobic to hydrophobic properties. At a high Mg percentage, H2 production is very large, while surface roughness decreases due to minimal Al2O3. As a result, the roughness grooves are unable to accommodate H2 gas bubbles, the bubbles completely cover the roughness peaks which are the source of surface tension so that the hydrophobic properties become hydrophilic. The results of this best hybrid composition can be used as a guide in making superhydrophobic membranes on Alumina (Al2O3) and Magnesium alloys. This membrane application is used as a filtration membrane in the water purification process. Superhydrophobic membranes are widely applied in membrane distillation, membrane gas absorption and pervaporation

Synthesis and performance of ultrafiltration membranes incorporated with different oxide nanomaterials: experiments and modeling

Abstract In membrane filtration technology, membrane fouling is the primary obstacle to optimizing efficiency and results in a short membrane lifetime and high operating costs. By incorporating nanomaterials into the membrane synthesis process, a mixed-matrix membrane with significantly enhanced characteristics and performance may be obtained. Graphene oxide (GO), aluminum oxide (Al2O3), tin oxide (SnO2), and titanium oxide (TiO2) were incorporated into a polyethersulfone (PESU) membrane. The water permeability of the modified membranes showed improvements when compared with the pure membrane. It increased from 65 L/m2 h bar for the pristine membrane (PES-1) to 143.6, 83.68, 92.12, 75.43 L/m2 h bar for Al2O3 (PES-2), TiO2 (PES-3), SnO2 (PES-4), and GO (PES-5) membranes, respectively. It was discovered that the membrane's surface hydrophilicity was significantly and directly affected by the incorporation of nanoparticles. Fouling parameters include Rr (Reversible fouling ratio), Rir (irreversible fouling ratio), Rt (total fouling ratio), and Frr (flux recovery ratio) and were measured to determine the membrane's fouling tendency. The results showed that the membrane's propensity for fouling could be reduced when nanoparticles were incorporated into it. The experimental results are best explained by the cake layer and both standard and intermediate blocking mechanism models, as determined by the traditional single fouling models.

Modified ceramic membranes for the treatment of highly saline mixtures utilized in vacuum membrane distillation

Membrane Distillation processes could enable the treatment of highly saline solutions and facilitate minimal (MLD) or zero liquid discharge (ZLD) applications. Ceramic membranes can be a robust alternative to polymeric membranes if they are chemically modified to exhibit hydrophobic qualities to prevent wetting, particularly for vacuum membrane distillation (VMD). This study found that the thin top layer of asymmetrically structured ceramic membranes is robust enough for highly saline and abrasive suspensions and that TiO2 membranes outperform Al2O3 membranes in respect to the mass transport due to their larger support pore size and lower thermal conductivity. A maximum permeate flux of 35 kg/(m2 h) with exceptionally high rejections were measured in VMD using a saline brine with a concentration of 350 g NaCl per kg H2O. Furthermore, a VMD mass transfer model was successfully adopted (based on the Dusty Gas Model) to facilitate the calculation of the mass transfer through asymmetrically structured TiO2 membranes. Model deficiencies such as the underestimation of polarization effects were discussed, and correction factors integrated accordingly. This was done to establish a mass transfer modelling fundament for asymmetrical ceramic membranes used in MD that can be extended in future works and possibly serve as a tool for membrane optimization.

Nano (metal oxide)-based catalytic membranes for refining of petroleum lubricating oil feedstock

Worldwide, the refining of lubricating oils feedstock is basically carried out either by solvent or hydrotretment refining. Both methodologies can provide integrated processes; hence oils of good quality can be gained. Nevertheless, these processes are always escorted with environmentally harmful emissions and long-operational time as well as high energy ingesting. Thus, implementation of green chemistry trend in such field could particularly help in the reduction of both hazardous emissions and extensive use of energy. In proportion to this route, current research study provides a new platform for the refining of lube oils base-stocks via combining both membrane separation and nanotechnology concept. Four different freshly-prepared nano-structured metals oxides (MgO, Al2O3, BaO and SrO) membranes were used during this study. Reasonable removal of aromatics as well as reduction of the pour point values in the products, compared to the original feedstock, could be obtained by all membranes. However, the best performance (among the four types) could be detected for both MgO and Al2O3 membranes. Particularly, they showed fluid total permeability of ca 95% with a flux equal 1.793 × 10−8 (L/m2.h.bar) and selectivity of aromatics over saturates came up to nearly 420. Those values were attained at low operating conditions of time (10 min), temperature (50 °C) and pressure of 100 mbar.

Topological Defects Created by Gamma Rays in a Carbon Nanotube Bilayer.

Graphene sheets are a highly radiation-resistant material for prospective nuclear applications and nanoscale defect engineering. However, the precise mechanism of graphene radiation hardness has remained elusive. In this paper, we study the origin and nature of defects induced by gamma radiation in a graphene rolled-up plane. In order to reduce the environmental influence on graphene and reveal the small effects of gamma rays, we have synthesized a novel graphene-based nanocomposite material containing a bilayer of highly aligned carbon nanotube assemblies that have been decorated by organometallic compounds and suspended on nanoporous Al2O3 membranes. The bilayer samples were irradiated by gamma rays from a 137Cs source with a fluence rate of the order of 105 m-2s-1. The interaction between the samples and gamma quanta results in the appearance of three characteristic photon escape peaks in the radiation spectra. We explain the mechanism of interaction between the graphene sheets and gamma radiation using a pseudo-Majorana fermion graphene model, which is a quasi-relativistic N=3-flavor graphene model with a Majorana-like mass term. This model admits the existence of giant charge carrier currents that are sufficient to neutralize the impact of ionizing radiation. Experimental evidence is provided for the prediction that the 661.7-keV gamma quanta transfer enough energy to the electron subsystem of graphene to bring about the deconfinement of the bound pseudo-Majorana modes and involve C atoms in a vortical motion of the electron density flows in the graphene plane. We explain the radiation hardness of graphene by the topological non-triviality of the pseudo-Majorana fermion configurations comprising the graphene charge carriers.

Performance of Composite Glass-Diarylethene Crystal Photomechanical Actuator Membranes.

Hybrid organic-inorganic composites based on organic photochromic crystals embedded in inorganic templates provide a new approach to photomechanical materials. Diarylethene (DAE) nanowire crystals grown in Al2O3 membranes have exhibited reversible photoinduced bending and lifting [Dong, X., Chem. Mater. 2019, 31, 1016-1022]. In this paper, the hybrid approach is extended to porous SiO2 membranes. Despite the different template material (SiO2 instead of Al2O3) and much larger channels (5 μm diameter instead of 0.2 μm diameter), similar photomechanical behavior is observed for this new class of organic-inorganic hybrid actuators. The ability to reuse individual glass templates across different DAE filling cycles allows us to show that the DAE filling step is crucial for determining the mechanical work done by the bending template. The bending curvature also depends quadratically on the template thickness, in good agreement with theory. The light-induced bending can be repeated for up to 150 cycles without loss of performance, suggesting good fatigue resistance. The results in this paper demonstrate that the hybrid organic-inorganic approach can be extended to other host materials and template geometries. They also suggest that optimizing the organic filling and template thickness could improve the work output by an order of magnitude.

Silicalite-1/PDMS Hybrid Membranes on Porous PVDF Supports: Preparation, Structure and Pervaporation Separation of Dichlorobenzene Isomers.

Separation of dichlorobenzene (DCB) isomers with high purity by time− and energy−saving methods from their mixtures is still a great challenge in the fine chemical industry. Herein, silicalite-1 zeolites/polydimethylsiloxane (PDMS) hybrid membranes (silicalite-1/PDMS) have been successfully fabricated on the porous polyvinylidene fluoride (PVDF) supports to first investigate the pervaporation separation properties of DCB isomers. The morphology and structure of the silicalite-1 zeolites and the silicalite-1/PDMS/PVDF hybrid membranes were characterized by XRD, FTIR, SEM and BET. The results showed that the active silicalite-1/PDMS layers were dense and continuous without any longitudinal cracks and other defects with the silicalite-1 zeolites content no more than 10%. When the silicalite-1 zeolites content exceeded 10%, the surfaces of the active silicalite-1/PDMS layers became rougher, and silicalite-1 zeolites aggregated to form pile pores. The pervaporation experiments both in single-isomer and binary−isomer systems for the separation of DCB isomers was further carried out at 60 °C. The results showed that the silicalite-1/PDMS/PVDF hybrid membranes with 10% silicalite-1 zeolites content had better DCB selective separation performance than the silicalite-1/α−Al2O3 membranes prepared by template method. The permeate fluxes of the DCB isomers increased in the order of m−DCB < o−DCB < p−DCB both in single-isomer and binary-isomers solutions for the silicalite-1/PDMS/PVDF hybrid membranes. The separation factor of the silicalite-1/PDMS/PVDF hybrid membranes for p/o−DCB was 2.9 and for p/m−DCB was 4.6 in binary system. The permeate fluxes of the silicalite-1/PDMS/PVDF hybrid membranes for p−DCB in p/o−DCB and p/m−DCB binary−isomers solutions were 126.2 g∙m−2∙h−1 and 104.3 g∙m−2∙h−1, respectively. The thickness−normalized pervaporation separation index in p/o−DCB binary−isomers solutions was 4.20 μm∙kg∙m−2∙h−1 and in p/m−DCB binary−isomers solutions was 6.57 μm∙kg∙m−2∙h−1. The results demonstrated that the silicalite-1/PDMS/PVDF hybrid membranes had great potential for pervaporation separation of DCB from their mixtures.

Comparison of ZnO, Al2O3, AlZnO, and Al2O3-Doped ZnO Sensing Membrane Applied in Electrolyte-Insulator-Semiconductor Structures.

In this study, ZnO, AlZnO, Al2O3, and Al2O3-doped ZnO-sensing membranes were fabricated in electrolyte–insulator–semiconductor (EIS) structures. Multiple material analyses indicate that annealing at an appropriate temperature of 500 °C could enhance crystallizations, passivate defects, and facilitate grainizations. Owing to their material properties, both the pH-sensing capability and overall reliability were optimized for these four types of membranes. The results also revealed that higher Al amounts increased the surface roughness values and enhanced larger crystals and grains. Higher Al compositions resulted in higher sensitivity, linearity, and stability in the membrane.

Narrow Segment Driven Multistep Magnetization Reversal Process in Sharp Diameter Modulated Fe67Co33 Nanowires.

Magnetic nanomaterials are of great interest due to their potential use in data storage, biotechnology, or spintronic based devices, among others. The control of magnetism at such scale entails complexing the nanostructures by tuning their composition, shape, sizes, or even several of these properties at the same time, in order to search for new phenomena or optimize their performance. An interesting pathway to affect the dynamics of the magnetization reversal in ferromagnetic nanostructures is to introduce geometrical modulations to act as nucleation or pinning centers for the magnetic domain walls. Considering the case of 3D magnetic nanowires, the modulation of the diameter across their length can produce such effect as long as the segment diameter transition is sharp enough. In this work, diameter modulated Fe67Co33 ferromagnetic nanowires have been grown into the prepatterned diameter modulated nanopores of anodized Al2O3 membranes. Their morphological and compositional characterization was carried out by electron-based microscopy, while their magnetic behavior has been measured on both the nanowire array as well as for individual bisegmented nanowires after being released from the alumina template. The magnetic hysteresis loops, together with the evaluation of First Order Reversal Curve diagrams, point out that the magnetization reversal of the bisegmented FeCo nanowires is carried out in two steps. These two stages are interpreted by micromagnetic modeling, where a shell of the wide segment reverses its magnetization first, followed by the reversal of its core together with the narrow segment of the nanowire at once.

Синтез и изучение композиционного материала на основе пористого анодного оксида алюминия, модифицированного нанонитями серебра

The paper presents the results of an experimental study of the deposition of modified silver into the pores of ceramic Ag&amp;Al2O3 membranes, laboratory samples of thin nanocomposite membranes were obtained based on the developed technological methods of silver deposition, and their composition and surface morphology were studied.

Atomic Layer Deposition for Gradient Surface Modification and Controlled Hydrophilization of Ultrafiltration Polymer Membranes.

In recent years, atomic layer deposition (ALD) has emerged as a powerful technique for polymeric membrane surface modification. In this research, we study Al2O3 growth via ALD on two polymeric phase-inverted membranes: polyacrylonitrile (PAN) and polyetherimide (PEI). We demonstrate that Al2O3 can easily be grown on both membranes with as little as 10 ALD cycles. We investigate the formation of Al2O3 layer gradient through the depth of the membranes using high-resolution transmission electron microscopy and elemental analysis, showing that at short exposure times, Al2O3 accumulates at the top of the membrane, reducing pore size and creating a strong growth gradient, while at long exposure time, more homogeneous growth occurs. This detailed characterization creates the knowledge necessary for controlling the deposition gradient and achieving an efficient growth with minimum pore clogging. By tuning the Al2O3 exposure time and cycles, we demonstrate control over the Al2O3 depth gradient and membranes' pore size, hydrophilicity, and permeability. The oil antifouling performance of membranes is investigated using in situ confocal imaging during flow. This characterization technique reveals that Al2O3 surface modification reduces oil droplet surface coverage.

Gravity-Driven Separation of Oil/Water Mixture by Porous Ceramic Membranes with Desired Surface Wettability.

Porous Al2O3 membranes were prepared through a phase-inversion tape casting/sintering method. The alumina membranes were embedded with finger-like pores perpendicular to the membrane surface. Bare alumina membranes are naturally hydrophilic and underwater oleophobic, while fluoroalkylsilane (FAS)-grafted membranes are hydrophobic and oleophilic. The coupling of FAS molecules on alumina surfaces was confirmed by Thermogravimetric Analysis and X-ray Photoelectron Spectroscopy measurements. The hydrophobic membranes exhibited desired thermal stability and were super durable when exposed to air. Both membranes can be used for gravity-driven oil/water separation, which is highly cost-effective. The as-calculated separation efficiency (R) was above 99% for the FAS-grafted alumina membrane. Due to the excellent oil/water separation performance and good chemical stability, the porous ceramic membranes display potential for practical applications.

Tailoring asymmetric Al2O3 membranes by combining tape casting and phase inversion

This study aimed to combine the techniques of tape casting and phase inversion to produce highly permeable ceramic membranes suitable for microfiltration in a single sintering step. The morphological, mechanical and textural characterization was performed using SEM, flexural strength measurement, mercury porosimetry and X-ray micro-computed tomography. Alumina membranes were produced using different slurry formulations and solidified via phase inversion, followed by sintering at 1400 or 1500 °C. Additionally, a co-casting strategy was successfully used for some membranes aiming to reduce the flux resistance caused by the dense layer usually formed at the bottom of ceramic membranes produced by phase inversion while the thin skin layer is preserved. Ceramic membranes with large pore sizes of the skin layer (0.30–0.42 μm) and high total porosity (46–75%) were obtained, and a clear increase of the mechanical resistance is observed when increasing alumina loading. Pure water flux of 52.4 and 26.60 m3 m-2 h-1 at 1 bar, and 27.60 and 41.11 MPa maximum flexural strength were achieved for membranes produced from slurries containing 45 and 50 wt% alumina, respectively. Simulations of permeability carried out from X-ray micro-computed tomography images in three axes proved a preferential fluid flow in the z-axis (from top to bottom) for different membrane regions and demonstrated that permeability is mainly influenced by the top skin and bottom layer morphology, which is in agreement with the experimental results.

Molecular Decoration of Ceramic Supports for Highly Effective Enzyme Immobilization-Material Approach.

A highly effective method was developed to functionalize ceramic supports (Al2O3 powders and membranes) using newly synthesized spacer molecules. The functionalized materials were subsequently utilized for Candida antarctica lipase B enzyme immobilization. The objective is to systematically evaluate the impact of various spacer molecules grafted onto the alumina materials will affect both the immobilization of the enzymes and specific material surface properties, critical to enzymatic reactors performance. The enzyme loading was significantly improved for the supports modified with shorter spacer molecules, which possessed higher grafting effectiveness on the order of 90%. The specific enzyme activity was found to be much higher for samples functionalized with longer modifiers yielding excellent enantioselectivity >97%. However, the enantiomeric ratio of the immobilized lipase was slightly lower in the case of shorter spacer molecules.

Anodic Oxidation of Bismuth Towards Various Nanostructures

The synthesis of highly-ordered nanostructures of valve metal oxides has recently attracted huge scientific and technological interest motivated by their possible use in many applications. The two most established members of this group of materials are nanoporous Al2O3 and TiO2 nanotubes [1,2]. While Al2O3 membranes have been since than widely used as template material of choice for a range of materials [3-5] due to the flexibility of the pore diameter/length and the relative ease of the Al2O3 dissolution, TiO2 nanotubes received high attention because of their applications in e.g. photocatalysis, water splitting, solar cells and biomedical uses [6]. Bismuth oxide is another interesting material and its nanostructures show an enhanced photoelectrochemical performance [7,8]. However, the formation of bismuth nanostructures, such as bismuth oxide nanopores [7, 8] or bismuth phosphate nanorods [9], by anodization is not well explored by now. Similar to the formation of nanoporous Al2O3, nanostructured Bi2O3 can be produced in acidic, F--free electrolytes [10]. In this presentation, we will demonstrate the anodization of bismuth in various electrolytes towards morphologically very interesting Bi2O3 nanostructures with many potential applications. References H. Masuda, K. Fukuda, Science, 268 (1995) 1466. J.M. Macak et al., Curr. Opin. Solid State Mater. Sci. 1-2 (2007) 3.K. Nielsch, F. Müller, A.-P. Li, U. Gösele, Adv. Mater. 12 (2000) 582. H. Asoh et al., J. Electrochem. Soc. 148 (2001) B152.J. Kolar, J. M. Macak, K. Terabe, T. Wagner, J. Mater. Chem. C, 2 (2014) 349.K. Lee, A. Mazare, P. Schmuki, Chem. Rev. 114 (2014) 9385.X. Lv, J. Zhao, X. Wang, X. Xu, L. Bai, B. Wang, J. Solid. Stat Electrochem. 17 (2013) 1215.K.C. Chitrada, K. S. Raja, R. Gakhar, D. Chidambaram, J. Electrochem. Soc. 162 (2015) H380.M. Yang, N. K. Shrestha, R. Hahn, P. Schmuki, Electrochem. Solid-State Lett. 13 (2010) C5. H. Sopha, V. Podzemna, L. Hromadko, J. M. Macak, Electrochem. Commun. 84 (2017) 6-9.

Anodic Oxidation of Bismuth Towards Various Nanostructures

The synthesis of highly-ordered nanostructures of valve metal oxides has recently attracted huge scientific and technological interest motivated by their possible use in many applications. The two most established members of this group of materials are nanoporous Al2O3 and TiO2 nanotubes [1,2]. While Al2O3 membranes have been since than widely used as template material of choice for a range of materials [3-5] due to the flexibility of the pore diameter/length and the relative ease of the Al2O3 dissolution, TiO2 nanotubes received high attention because of their applications in e.g. photocatalysis, water splitting, solar cells and biomedical uses [6]. Bismuth oxide is another interesting material and its nanostructures show an enhanced photoelectrochemical performance [7,8]. However, the formation of bismuth nanostructures, such as bismuth oxide nanopores [7, 8] or bismuth phosphate nanorods [9], by anodization is not well explored by now. Similar to the formation of nanoporous Al2O3, nanostructured Bi2O3 can be produced in acidic, F--free electrolytes [10]. In this presentation, we will demonstrate the anodization of bismuth in various electrolytes towards morphologically very interesting Bi2O3 nanostructures with many potential applications. References H. Masuda, K. Fukuda, Science, 268 (1995) 1466.J.M. Macak et al., Curr. Opin. Solid State Mater. Sci. 1-2 (2007) 3.K. Nielsch, F. Müller, A.-P. Li, U. Gösele, Adv. Mater. 12 (2000) 582.H. Asoh et al., J. Electrochem. Soc. 148 (2001) B152.J. Kolar, J. M. Macak, K. Terabe, T. Wagner, J. Mater. Chem. C, 2 (2014) 349.K. Lee, A. Mazare, P. Schmuki, Chem. Rev. 114 (2014) 9385.X. Lv, J. Zhao, X. Wang, X. Xu, L. Bai, B. Wang, J. Solid. Stat Electrochem. 17 (2013) 1215.K.C. Chitrada, K. S. Raja, R. Gakhar, D. Chidambaram, J. Electrochem. Soc. 162 (2015) H380.M. Yang, N. K. Shrestha, R. Hahn, P. Schmuki, Electrochem. Solid-State Lett. 13 (2010) C5.H. Sopha, V. Podzemna, L. Hromadko, J. M. Macak, Electrochem. Commun. 84 (2017) 6-9.

N-Doped TiO₂-Coated Ceramic Membrane for Carbamazepine Degradation in Different Water Qualities.

The photocatalytic degradation of the model pollutant carbamazepine (CBZ) was investigated under simulated solar irradiation with an N-doped TiO2-coated Al2O3 photocatalytic membrane, using different water types. The photocatalytic membrane combines photocatalysis and membrane filtration in a single step. The impact of each individual constituent such as acidity, alkalinity, dissolved organic matter (DOM), divalent cations (Mg2+ and Ca2+), and Cl− on the degradation of CBZ was examined. CBZ in water was efficiently degraded by an N-doped TiO2-coated Al2O3 membrane. However, elements added to the water, which simulate the constituents of natural water, had an impact on the CBZ degradation. Water alkalinity inhibited CBZ degradation mostly due to increase in pH while radical scavenging by carbonate was more dominant at higher values (>200 mg/L as CaCO3). A negative effect of Ca2+ addition on photocatalytic degradation was found only in combination with phosphate buffer, probably caused by deposition of CaHPO4 or CaHPO4·2H2O on the catalyst surface. The presence of Cl− and Mg2+ ions had no effect on CBZ degradation. DOM significantly inhibited CBZ degradation for all tested background organic compounds. The photocatalytic activity of N-doped TiO2-coated Al2O3 membranes gradually decreased after continuous use; however, it was successfully regenerated by 0.1% HCl chemical cleaning. Nevertheless, dissolution of metals like Al and Ti should be monitored following acid cleaning.