Materials and Applications for Low-Cost Ceramic Membranes

Application of physicochemical techniques to the removal of ammonia nitrogen from water: a systematic review

Ammonia nitrogen is a common pollutant in water and soil, known for its biological toxicity and complex removal process. Traditional biological methods for removing ammonia nitrogen are often inefficient, especially under varying temperature conditions. This study reviews physicochemical techniques for the treatment and recovery of ammonia nitrogen from water. Key methods analyzed include ion exchange, adsorption, membrane separation, struvite precipitation, and advanced oxidation processes (AOPs). Findings indicate that these methods not only remove ammonia nitrogen but also allow for nitrogen recovery. Ion exchange, adsorption, and membrane separation are effective in separating ammonia nitrogen, while AOPs generate reactive species for efficient degradation. Struvite precipitation offers dual benefits of removal and resource recovery. Despite their advantages, these methods face challenges such as secondary pollution and high energy consumption. This paper highlights the development principles, current challenges, and future prospects of physicochemical techniques, emphasizing the need for integrated approaches to enhance ammonia nitrogen removal efficiency.

Optimization of fractionation with membranes of antioxidant enzymatic hydrolysate of Californian red worm (Eisenia fetida) protein

Problem

Earthworm is a valuable source of biologically and pharmacologically active compounds, with applications in the treatment of various types of diseases; however, the main application they have been given is in the production of organic fertilizer. One of the alternatives for obtaining bioactive compounds is by means of enzymatic hydrolysis.

Aim

This study proposes the optimization of the fractionation of the antioxidant enzymatic hydrolysate from Californian red worm (Eisenia fetida) protein.

Methodology

For this purpose, the worms were separated and hydrolyzed using the enzyme Alcalase 2.4L for 4000s. The obtained hydrolysate was fractionated by means of a crossflow tangential ultrafiltration system, with a 3 kDa molecular weight cut-off ceramic membrane. A response surface design of the composite central factorial type was implemented to evaluate the effect of pH, transmembrane pressure, and flow factors on the response variables transmission, volume reduction factor (VRF) and permeate flow resistance. The transmissions focused on the antioxidant peptides, measured by three conventional methods such as TEAC, FRAP, ORAC, also known as TTEAC, TFRAP and TORAC, respectively. The evaluated resistances were the total resistance (Rtotal), fouling resistance (Rfouling), and gel resistance (Rgel).

Result

The results showed that the three factors evaluated affect all the response variables either in their linear or quadratic terms or by some interaction. For each response variable, a mathematical model was obtained, with statistical significance and a non-significant lack of adjustment. The models obtained were used for a multi-objective optimization process in which transfers were maximized, and resistances were minimized. The efficiency of the optimum ultrafiltration process was 25 %.

Conclusion

The neutral-alkaline pH is ideal for the ultrafiltration process of bioactive peptides, as it is where the highest transmissions of peptides with antioxidative capacity are found. Under optimal conditions, the 3 kDa membrane permeate was found to exhibit higher antioxidant capacity than the retentate and feed. Based on this, the fraction of less than 3 kDa emerges as a potential multifunctional ingredient, thanks to its antioxidant properties.

Low-Cost Antibacterial Ceramic Water Filters for Decentralized Water Treatment: Advances and Practical Applications

Access to clean water remains challenging for people living in underdeveloped regions, rural areas, and remote locations. In the absence of centralized water treatment systems, point-of-use (POU) solutions are necessary. Ceramic water filters (CWFs) have emerged as a practical and affordable option for decentralized water treatment. This review focuses on recent advances in antibacterial CWFs, including preparation methods, filtration performance, and applications. The review highlights the significance of preparation techniques, material choices, and additives in determining CWF properties and performance. Despite virus and chemical contaminant removal limitations, ongoing research on nanofillers and antibacterial additives shows promise for enhancing the CWF performance. The cost-effectiveness, ease of production, and low operational requirements of CWF make it a viable solution for decentralized drinking water systems, particularly in resource-limited areas. Studies have demonstrated the efficacy of CWFs in reducing water contaminants, but proper maintenance and user training are crucial to optimal performance.

Application of coal fly ash based ceramic membranes in wastewater treatment: A sustainable alternative to commercial materials

The continued increase in the global population has resulted in increased water demand for domestic, agricultural, and industrial purposes. These activities have led to the generation of high volumes of wastewater, which has an impact on water quality. Consequently, more practical solutions are needed to improve the current wastewater treatment systems. The use of improved ceramic membranes for wastewater treatment holds significant prospects for advancement in water treatment and sanitation. Hence, different studies have employed ceramic membranes in wastewater treatment and the search for low-cost and environmentally friendly starting materials has continued to engender research interests. This review focuses on the application of coal fly ash in membrane technology for wastewater treatment. The processes of membrane fabrication and the various limitations of the material. Several factors that influence the properties and performance of coal fly ash ceramic membranes in wastewater treatment are also presented. Some possible solutions to the limitations are also proposed, while cost analysis of coal fly ash-based membranes is explored to evaluate its potential for large-scale applications.

Constructed wetlands with recycled concrete for wastewater treatment in cold climate: Performance and life cycle assessment

This study investigated the technical, environmental, and economic feasibility of using recycled construction material (concrete) as substrate in constructed wetlands for cold climate decentralized domestic wastewater treatment. The wastewater treatment efficiency was examined, and life cycle assessment (LCA) and cost benefit analysis were performed. The technical feasibility was assessed in lab-scale two-stage wetland systems with recycled concrete or lava stone as substrates, which were operated at 22 °C and 5 °C with local wild plants and vegetables. The wetlands removed ∼85 % and ∼51 % of organics and ∼67 % and ∼34 % TN at 22 °C and 5 °C, respectively; no significant difference was found between concrete and lava stone. The heavy metal contents in the cultivated vegetables met WHO standards for human consumption, showing the feasibility of nutrient recovery from the treated wastewater. A comparative LCA of septic tank standalone, septic tank + constructed wetland (with recycled concrete), and gravity-driven ceramic membrane (GDCM) system was performed. This aims to illustrate the benefits of intensifying the existing treatment process (i.e., septic tank) with the constructed wetland, with an alternative membrane-based treatment technique as benchmark. The LCA results revealed that using waste materials as the substrate in constructed wetlands could reduce the environmental impact of wetlands. Installation of the wetland as posttreatment of the septic tank (1) could reduce ∼50 % of eutrophication potential without increasing global warming impact compared to the septic tank alone; (2) had ∼90 % higher global warming impact and ∼40 % lower eutrophication impact compared to GDCM. Economic analysis revealed that the total cost of septic tank + constructed wetland (0.143 €/m3) was comparable to the septic tank alone (merely 3.5 % difference), and 49 % lower than that of GDCM (with recycled membranes). Therefore, the septic tank + constructed wetland scenario could be favorable for sensitive areas with eutrophication potential regarding its technical, economical, and environmental feasibility.

A Comparative Study of the Self-Cleaning and Filtration Performance of Suspension Plasma-Sprayed TiO2 Ultrafiltration and Microfiltration Membranes

This study investigated the performance of photocatalytic titanium dioxide microfiltration membranes with an average pore size of approximately 180 nm and ultrafiltration membranes with an average pore size of around 40 nm fabricated with the suspension plasma spray process. The membranes were evaluated for their filtration performance using SiO2 particles of different sizes and polyethylene oxide with molecular weights of 20 kDa to 1000 kDa, and the fouling parameters were characterized. The rejection rate was enhanced by increasing the thickness of the membranes. This effect was more pronounced with the ultrafiltration membranes. The rejection rate of the ultrafiltration membrane was improved significantly after filling the larger pores on the surface with agglomerates of titanium dioxide nanoparticles. The self-cleaning performance of the membranes was assessed under visible light. Both ultrafiltration and microfiltration membranes showed a flux recovery under visible light illumination due to the photocatalytic activity of titanium dioxide. The membranes also show a flux recovery of more than 90%.

Graphene-Oxide-Grafted Natural Phosphate Support as a Low-Cost Ceramic Membrane for the Removal of Anionic Dyes from Simulated Textile Effluent

A novel natural phosphate/graphene oxide (GO) composite membrane was successfully fabricated using two steps: (i) silane chemical grafting and (ii) dip-coating of a GO solution. First, the low-cost disk ceramic support used in this work was fabricated out of Moroccan natural phosphate, and its properties were thoroughly characterized. The optimized ceramic support was sintered at 1100 °C following a specific heat treatment based on thermogravimetric analysis (TGA) and differential thermal analysis (DTA); it exhibited a permeability of 953.33 L/h·m²·bar, a porosity of 24.55%, an average pore size of 2.45 μm and a flexural strength of 22.46 MPa. The morphology analysis using SEM showed that the GO layer was homogenously coated on the crack-free Moroccan phosphate support with a thickness of 2.8 μm. The Fourier transform infrared spectrometer (FT-IR) results showed that modification with silane could improve the interfacial adhesion between the GO membrane and the ceramic support. After coating with GO on the surface, the water permeability was reduced to 31.93 L/h·m²·bar (i.e., by a factor of 142). The prepared GO/ceramic composite membrane exhibited good efficiency in the rejection of a toxic azo dye Congo Red (CR) (95.2%) and for a simulated dye effluent (87.6%) under industrial conditions. The multi-cycle filtration tests showed that the rejection rate of CR dye remained almost the same for four cycles. Finally, the flux recovery was also studied. After 1 h of water cleaning, the permeate flux recovered, increased significantly, and then remained stable.

Impact of Physical and Chemical Modification of the Surface of Porous Al2O3 Ceramic Membranes on the Quality of Transferred HSMG® and CVD Graphene

Graphene transfer onto ceramics, like Si/SiO₂, is well-developed and described in the literature. However, it is problematic for other ceramic materials (e.g., Al₂O₃ and ZrO₂), especially porous ones. In this case, it is mainly due to poor adhesion to the substrate, resulting in strong degradation of the graphene. For these reasons, the research topic of this study was undertaken. This article presents research on the development of the methodology of graphene transfer onto ceramic Al₂O₃ surfaces. Polycrystalline graphene chemical vapour deposition (CVD) monolayer and quasimonocrystalline high-strength metallurgical graphene (HSMG^®) synthesised on liquid copper were used. When developing the transfer methodology, the focus was on solving the problem of graphene adhesion to the surface of this type of ceramic, and thus reducing the degree of graphene deterioration at the stage of producing a ceramic-graphene composite, which stands in the way of its practical use. Plasma and chemical ceramic surface modification were applied to change its hydrophobicity, and thus to improve the adhesion between the graphene and ceramic. The modification included the use of dielectric barrier discharge (DBD) plasma, oxygen plasma (RF PACVD method - Radio Frequency Plasma Assisted Chemical Vapour Deposition), and hydrofluoric acid treatment. Changes in surface properties caused by the modifications were determined by measuring the contact angle and (in the case of chemical modification) measuring the degree of surface development. The effectiveness of the applied surface preparation methodology was evaluated based on the damage degree of CVD and HSMG^® graphene layer transferred onto modified Al₂O₃ using optical microscopy and Raman spectroscopy. The best average I_D/I_G ratio for the transferred HSMG^® graphene was obtained after oxygen plasma modification (0.63 ± 0.18) and for CVD, graphene DBD plasma was the most appropriate method (0.17 ± 0.09). The total area of graphene defects after transfer to Al₂O₃ was the smallest for HSMG^® graphene after modification with O₂ plasma (0.251 mm²/cm²), and for CVD graphene after surface modification with DBD plasma (0.083 mm²/cm²).

Ag-CuO-Decorated Ceramic Membranes for Effective Treatment of Oily Wastewater

Although ultrafiltration is a reliable method for separating oily wastewater, the process is limited by problems of low flux and membrane fouling. In this study, for the first time, commercial TiO₂/ZrO₂ ceramic membranes modified with silver-functionalized copper oxide (Ag-CuO) nanoparticles are reported for the improved separation performance of emulsified oil. Ag-CuO nanoparticles were synthesized via hydrothermal technique and dip-coated onto commercial membranes at varying concentrations (0.1, 0.5, and 1.0 wt.%). The prepared membranes were further examined to understand the improvements in oil-water separation due to Ag-CuO coating. All modified ceramic membranes exhibited higher hydrophilicity and decreased porosity. Additionally, the permeate flux, oil rejection, and antifouling performance of the Ag-CuO-coated membranes were more significantly improved than the pristine commercial membrane. The 0.5 wt.% modified membrane exhibited a 30% higher water flux (303.63 L m^-2 h^-1) and better oil rejection efficiency (97.8%) for oil/water separation among the modified membranes. After several separation cycles, the 0.5 wt.% Ag-CuO-modified membranes showed a constant permeate flux with an excellent oil rejection of >95% compared with the unmodified membrane. Moreover, the corrosion resistance of the coated membrane against acid, alkali, actual seawater, and oily wastewater was remarkable. Thus, the Ag-CuO-modified ceramic membranes are promising for oil separation applications due to their high flux, enhanced oil rejection, better antifouling characteristics, and good stability.

Art Design Teaching Based on the Multidata Fusion Algorithm and Virtual Simulation Technology

Virtual Reality (VR) technologies are widely applied to teaching art design. VR has been created with high-level techniques that create the artificial environment to support virtual aesthetics. Especially ceramics art design requires technical advancement to enhance business individuals. However, the user requires the virtual reality experience to improve the art design teaching performance. During the teaching process, reality learning patterns, experiences, and fusion ceramic product design are required to enhance art design teaching. So, in this research, modern art design has been optimized using virtual reality with a deep learning architecture for craftsmanship, style, ideals, creative aesthetics, cultural ramifications, and inherited designers to create an effective model. The deep learning-assisted gate array algorithm (GAA) is used to optimize the modern art structure in system design. Therefore, this approach reveals some experimental findings that produce better performance benefits than saving time and resources in traditional manual detection systems.

Natural and recycled materials for sustainable membrane modification: Recent trends and prospects

Despite water being critical for human survival, its uneven distribution, and exposure to countless sources of pollution make water shortages increasingly urgent. Membrane technology offers an efficient solution for alleviating the water shortage impact. The selectivity and permeability of membranes can be improved by incorporating additives of different nature and size scales. However, with the vast debate about the environmental and economic feasibility of the common nanoscale materials in water treatment applications, we can infer that there is a long way before the first industrial nanocomposite membrane is commercialized. This stumbling block has motivated the scientific community to search for alternative modification routes and/or materials with sustainable features. Herein, we present a pragmatic review merging the concept of sustainability, nanotechnology, and membrane technology through the application of natural additives (e.g., Clays, Arabic Gum, zeolite, lignin, Aquaporin), recycled additives (e.g., Biochar, fly ash), and recycled waste (e.g., Polyethylene Terephthalate, recycled polystyrene) for polymeric membrane synthesis and modification. Imparted features on polymeric membranes, induced by the presence of sustainable natural and waste-based materials, are scrutinized. In addition, the strategies harnessed to eliminate the hurdles associated with the application of these nano and micro size additives for composite membranes modification are elaborated. The expanding research efforts devoted recently to membrane sustainability and the prospects for these materials are discussed. The findings of the investigations reported in this work indicate that the application of natural and waste-based additives for composite membrane fabrication/modification is a nascent research area that deserves the attention of both research and industry.

Preparation and Characterization of Low-Cost Ceramic Membrane Coated with Chitosan: Application to the Ultrafine Filtration of Cr(VI)

In this work, low-cost ceramic membranes (CMs) were prepared from ultrafine starting powders such as kaolin, clay, and starch by a dry compaction method. The ceramic membranes were sintered at different temperatures and times and were characterized by XRD, XRF, TG-DTA, SEM-EDS, N₂-BET, water absorption, compressive strength, and pure water flux. The optimal membrane, sintered at 1000 °C for 3 h, possessed water absorption of 27.27%, a compressive strength of 31.05 MPa, and pure water flux of 20.74 L/h m². Furthermore, chitosan crosslinked with glutaraldehyde was coated on the surface of the ceramic membrane by the dip coating method, and the pore size of the chitosan-coated ceramic membrane (CCCM) was 16.24 nm. Eventually, the separation performance of this membrane was assessed for the removal of chromium(VI) from aqueous solution. The ultrafine filtration of Cr(VI) was studied in the pH range of 2-7. The maximum removal of Cr(VI) was observed to be 71.25% with a pH of 3. The prepared CCCM showed good membrane properties such as mechanical stability and ultrafine structure, which have important applications for the treatment of wastewater including such heavy metals.

Cost and efficiency perspectives of ceramic membranes for water treatment

More robust ceramic membranes with tailorable structures and functions are increasingly employed for water treatment, particularly in some harsh applications for their ultra-long service lifespan due to their high mechanical, structural, chemical and thermal stability and anti-fouling properties. Decreasing cost and enhancing efficiency are two key but quite challenging application-oriented issues for broader and larger-scale engineering application of current ceramic membranes, and are required to make ceramic membranes a highly efficient and economic water treatment technique. In this review, we critically discuss these two significant concerns of both cost and efficiency for water treatment ceramic membranes, focusing on an overview of various advanced strategies and mechanism insights. A brief up-to-date discussion is first introduced about recent developments of ceramic membranes covering the major advances of novel membranes and applications. Then some promising strategies for decreasing the cost of ceramic membranes are discussed, including membrane material cost and processing cost. To fully address the issue of moderate efficiency with single separation function, valuable and considerable insights are provided into recent major progress and mechanism understandings in application with other unit processes, such as advanced oxidation and electrochemistry techniques, to significantly enhance treatment efficiency. Subsequently, a review of recent ceramic membrane applications emphasizing harsh operating environments is presented, such as oil-water separation, saline water, refractory organic and emerging contaminant wastewater treatment. Finally, engineering application, conclusions, and future perspectives of ceramic membrane for water treatment applications are critically discussed offering new insight based on understanding the issues of cost and efficiency.

Operation of Hybrid Membranes for the Removal of Pharmaceuticals and Pollutants from Water and Wastewater

Hybrid ceramic membranes (i.e., membranes with a layer-by-layer (LbL) coating) are an emerging technology to remove diverse kinds of micropollutants from water. Hybrid ceramic membranes were tested under laboratory conditions as single-channel (filter area = 0.00754 m2) and multi-channel (0.35 m2) variants for the removal of pharmaceuticals (sulfamethoxazole, diclofenac, clofibric acid, and ibuprofen) and typical wastewater pollutants (i.e., COD, TOC, PO4-P, and TN) from drinking water and treated wastewater. The tests were conducted with two low transmembrane pressures (TMP) of 2 and 4 bar and constant temperatures and flow velocities, which showed rejections above 80% for all the tested pharmaceuticals as well for organic pollutants and phosphorous in the treated wastewater. Tests regarding sufficient cleaning regimes also showed that the LbL coating is stable and resistant to pHs between 2 and 10 with the use of typical cleaning agents (citric acid and NaOH) but not to higher pHs, a commercially available enzymatic solution, or backwashing. The hybrid membranes can contribute to the advanced treatment of water and wastewater with low operational costs, and their application at a larger scale is viable. However, the cleaning of the membranes must be further investigated to assure the stability and durability of the LbL coating.

A Comprehensive Study on the Applications of Clays into Advanced Technologies, with a Particular Attention on Biomedicine and Environmental Remediation

In recent years, a great interest has arisen around the integration of naturally occurring clays into a plethora of advanced technological applications, quite far from the typical fabrication of traditional ceramics. This “second (technological) life” of clays into fields of emerging interest is mainly due to clays’ peculiar properties, in particular their ability to exchange (capture) ions, their layered structure, surface area and reactivity, and their biocompatibility. Since the maximization of clay performances/exploitations passes through the comprehension of the mechanisms involved, this review aims at providing a useful text that analyzes the main goals reached by clays in different fields coupled with the analysis of the structure-property correlations. After providing an introduction mainly focused on the economic analysis of clays global trading, clays are classified basing on their structural/chemical composition. The main relevant physicochemical properties are discussed (particular attention has been dedicated to the influence of interlayer composition on clay properties). Lastly, a deep analysis of the main relevant nonconventional applications of clays is presented. Several case studies describing the use of clays in biomedicine, environmental remediation, membrane technology, additive manufacturing, and sol-gel processes are presented, and results critically discussed.

Process intensification through waste fly ash conversion and application as ceramic membranes: A review

Improper disposal of huge quantities of fly ash generated by thermal power plants and few other industries contributes to both air and water pollution, and therefore, recent advancements in research are focused toward utilizing this waste material in fabricating useful membranes. This article presents an overview of various methods used to fabricate fly ash-based membranes and critical parameters affecting the same. Fly ash-based membranes also act as the support for fabricating composite membranes and therefore, different means of coating the support membranes are discussed in this paper. Among various methods of membrane fabrication, extrusion method can be considered for bulk production of membranes, which is a pre-requisite for industrial implementation. The article also throws light on a wide range of wastewater that have been successfully treated using these fly ash-based ceramic membranes. However, the use of these membranes should be avoided in acidic solutions as it may cause leaching of heavy metals present in fly ash, causing health hazards. Most of these membranes function on the basis of size exclusion principle, whereas membranes with charge-based separation are also well known. Both of these types of membranes are discussed in this work. Utilization of fly ash-based membranes in separation processes not only reduce the cost associated with the process, but will also intensify the process through various other means such as reduced energy consumption, environmental safety and so on. Thus, the main focus of this review is to present the readers with development and important future directions in this research topic.

A Materials Science Perspective of Midstream Challenges in the Utilization of Heavy Crude Oil

An increasing global population and a sharply upward trajectory of per capita energy consumption continue to drive the demand for fossil fuels, which remain integral to energy grids and the global transportation infrastructure. The oil and gas industry is increasingly reliant on unconventional deposits such as heavy crude oil and bitumen for reasons of accessibility, scale, and geopolitics. Unconventional deposits such as the Canadian Oil Sands in Northern Alberta contain more than one-third of the world's viscous oil reserves and are vital linchpins to meet the energy needs of rapidly industrializing populations. Heavy oil is typically recovered from subsurface deposits using thermal recovery approaches such as steam-assisted gravity drainage (SAGD). In this perspective article, we discuss several aspects of materials science challenges in the utilization of heavy crude oil with an emphasis on the needs of the Canadian Oil Sands. In particular, we discuss surface modification and materials' design approaches essential to operations under extreme environments of high temperatures and pressures and the presence of corrosive species. The demanding conditions for materials and surfaces are directly traceable to the high viscosity, low surface tension, and substantial sulfur content of heavy crude oil, which necessitates extensive energy-intensive thermal processes, warrants dilution/emulsification to ease the flow of rheologically challenging fluids, and engenders the need to protect corrodible components. Geopolitical reasons have further led to a considerable geographic separation between extraction sites and advanced refineries capable of processing heavy oils to a diverse slate of products, thus necessitating a massive midstream infrastructure for transportation of these rheologically challenging fluids. Innovations in fluid handling, bitumen processing, and midstream transportation are critical to the economic viability of heavy oil. Here, we discuss foundational principles, recent technological advancements, and unmet needs emphasizing candidate solutions for thermal insulation, membrane-assisted separations, corrosion protection, and midstream bitumen transportation. This perspective seeks to highlight illustrative materials' technology developments spanning the range from nanocomposite coatings and cement sheaths for thermal insulation to the utilization of orthogonal wettability to engender separation of water-oil emulsions stabilized by endogenous surfactants extracted during SAGD, size-exclusion membranes for fractionation of bitumen, omniphobic coatings for drag reduction in pipelines and to ease oil handling in containers, solid prills obtained from partial bitumen solidification to enable solid-state transport with reduced risk of damage from spills, and nanocomposite coatings incorporating multiple modes of corrosion inhibition. Future outlooks for onsite partial upgradation are also described, which could potentially bypass the use of refineries for some fractions, enable access to a broader cross-section of refineries, and enable a new distributed chemical manufacturing paradigm.

A readily synthesized bismuth oxyiodide/attapulgite for the photodegradation of tetracycline under visible light irradiation

Bismuth oxyiodide and attapulgite have proven to be potential materials for the removal of emerging contaminants in wastewater.

The Effect of Ceramic Membranes' Structure on the Oil and Ions Removal in Pre-Treatment of the Desalter Unit Wastewater

Salts, organic materials, and hazardous materials can be found regularly in the effluent from a desalter unit of crude oil. These materials should be separated from the wastewater. Four kinds of inexpensive and innovative ceramic microfiltration membranes (mullite, mullite-alumina (MA 50%), mullite-alumina-zeolite (MAZ 20%), and mullite-zeolite (MZ 40%)) were synthesized in this research using locally available inexpensive raw materials such as kaolin clay, natural zeolite, and alpha-alumina powders. Analyses carried out on the membranes include XRD, SEM, void fraction, the average diameter of the pores, and the ability to withstand mechanical stress. Effluent from the desalter unit was synthesized in the laboratory using the salts most present in the desalter wastewater (NaCl, MgCl₂, and CaCl₂) and crude oil. This synthesized wastewater was treated with prepared ceramic membranes. It was discovered that different salt concentrations (0, 5000, 25,000, 50,000, 75,000, and 100,000 mg L⁻¹) affected the permeate flux (PF), oil rejection, and ion rejection by the membrane. Results showed that in a lower concentration of salts (5000 and 25,000 mg L⁻¹), PF of all types of ceramic membranes was increased significantly, while in the higher concentration, PF declined due to polarization concentration and high fouling effects. Oil and ion rejection was increased slightly by increasing salt dosage in wastewater due to higher ionic strength. Monovalent (Na⁺) and multivalent (Ca²⁺ and Mg²⁺) ion rejection was reported about 5 to 13%, and 23 to 40% respectively. Oil rejection varied from 96.2 to 99.2%.

Synthesis and Evaluation of Asymmetric Mesoporous PTFE/Clay Composite Membranes for Textile Wastewater Treatment

Asymmetric mesoporous composite PTFE membranes wit 40, 50, and 85 wt.% of a clay (kaolin) were fabricated and characterized using a scanning electron microscope equipped with EDX for morphology and elemental analysis. The surface chemistry of the membranes was checked using Fourier transform infrared spectroscopy. The effect of incorporating the clay on the hydrophilicity, permeability, morphology, and antifouling properties of the fabricated membranes was investigated. It was observed that incorporating kaolin particles improved the mechanical properties but decreased the contact angle of the membranes, thereby resulting in an improvement in the membrane permeability. The performance of the three composite UF membranes was evaluated through the treatment of a real textile effluent sample containing indigo dye. The results confirmed that these membranes are effective in the removal of COD, color, and turbidity. Indeed, at a transmembrane pressure of 2.5 bar, almost total removal of the turbidity, COD removal > 85%, and color removal > 97% were attained. Furthermore, membrane A85 (with 85% clay) showed the best performance, with a water flux of 659.1 L·h^-1·m^-2·bar^-1. This study highlights the potential of incorporating low-cost clay material for the enhancement of the performance of mixed organic/inorganic matrix membranes, which can be applied to textile wastewater treatment.

Nanocellulose Based Filtration Membrane in Industrial Waste Water Treatment: A Review

In the field of industrial wastewater treatment, membrane separation technology, as an emerging separation technology, compared with traditional separation technology such as precipitation, adsorption, and ion exchange, has advantages in separation efficiency, low energy consumption, low cost, simple operation, and no secondary pollution. The application has been expanding in recent years, but membrane fouling and other problems have seriously restricted the development of membrane technology. Natural cellulose is one of the most abundant resources in nature. In addition, nanocellulose has characteristics of high strength and specific surface area, surface activity groups, as well as being pollution-free and renewable, giving it a very wide development prospect in many fields, including membrane separation technology. This paper reviews the current status of nanocellulose filtration membrane, combs the widespread types of nanocellulose and its derivatives, and summarizes the current application of cellulose in membrane separation. In addition, for the purpose of nanocellulose filtration membrane in wastewater treatment, nanocellulose membranes are divided into two categories according to the role in filtration membrane: the application of nanocellulose as membrane matrix material and as a modified additive in composite membrane in wastewater treatment. Finally, the advantages and disadvantages of inorganic ceramic filtrations and nanocellulose filtrations are compared, and the application trend of nanocellulose in the filtration membrane direction is summarized and discussed.

Enhanced Performance of Fly Ash-Based Supports for Low-Cost Ceramic Membranes with the Addition of Bauxite

Support is a necessary foundation for ceramic membranes to achieve high performance. Finding the optimum balance between high performance and low cost is still a significant challenge in the fabrication of ceramic supports. In this study, low-cost fly ash-based ceramic supports with enhanced performance were prepared by the addition of bauxite. The pore structure, mechanical strength, and shrinkage of fly ash/bauxite supports could be tuned by optimizing the bauxite content and sintering temperature. When the sintering temperature and bauxite content were controlled at 1300 °C and 40 wt%, respectively, the obtained membrane supports exhibited a high pure water permeance of approximately 5.36 m³·m^-2·h^-1·bar^-1 and a high bending strength of approximately 69.6 MPa. At the same time, the optimized ceramic supports presented a typical mullite phase and excellent resistance to acid and alkali. This work provides a potential route for the preparation of ceramic membrane supports with characteristics of low cost and high performance.

Improvement of the fabricated and application of aluminosilicate-based microfiltration membrane

Aluminosilicate composite materials are characterized by their low cost, nontoxicity and facilely shaped. Membrane prepared using aluminosilicate composites have the following disadvantages: large mean pore size and low mechanical strength. To address these limitations, flat microfiltration membranes were fabricated using SiO₂ powder and aluminosilicate composite as raw materials. The membrane performance was optimized by regulating the particle size of SiO₂, the ratio of SiO₂ to aluminosilicate composite (s/a), and the type of chemical admixture. The X-ray diffraction results indicated that the crystalline SiO₂ particles were favorable for the preparation of membranes with higher bending strengths. The decreasing particle sizes of SiO₂ (1.33-0.15 μm) decreased the pore size distribution. The bending strength of the membrane reduced with an increase in s/a, while was effectively enhanced by adding dissolved Na₂SiO₃. The optimized inorganic microfiltration membrane could also catalyze ozone to remove 100% of benzophenone-4 with an initial concentration of 10 mg L^-1 within 15 min, and TOC removal by 52.67%. This paper presents a revised method for preparing an inorganic microfiltration membrane, which is an increasingly promising material for water treatment because of its low cost, low energy consumption, and high catalytic performance.

Preparation of a Zirconia-Based Ceramic Membrane and Its Application for Drinking Water Treatment

This work concerns the preparation of a mineral membrane by the slip casting method based on zirconium oxide (ZrO2) and kaolin. The membrane support is produced from a mixture of clay (kaolin) and calcium carbonate (calcite) powders using heat treatment (sintering). Membrane and support characterization were performed by Scanning Electron Microscopy (SEM), X-ray Fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Raman Spectroscopy. The prepared mineral membrane was tested to treat drinking water obtained from different zones of the El Athmania (Algeria) water station (raw, coagulated, decanted, and bio filtered water). Experimental parameters such as permeate flux, turbidity, and total coliforms were monitored. The results showed that the mineral membrane was mainly composed of SiO2 and Al2O3 and the outer surface, which represented the membrane support, was much more porous than the inner surface where the membrane was deposited. The permeate flux of the raw water decreased with filtration time, due to a rejection of the organic matters contained in the raw water. Moreover, the absence of total coliforms in the filtrate and the increase in concentration in the concentrate indicate that the prepared mineral membrane can be used for drinking water treatment.

Mesoporous Polymer-Derived Ceramic Membranes for Water Purification via a Self-Sacrificed Template

Membrane separation has been widely used in water purification, and mesoporous ceramic membranes show a high potential in the future because of their high stability and resistance to harsh environments. In the current study, a novel polymer-derived ceramic silicon oxycarbide (SiOC) membrane was developed via a preceramic reactive self-sacrificed method and was further applied in a homemade dead-end system for water purification. A cyclosiloxane hybrid polymer was selected as the precursor and polydimethylsiloxane (PDMS) was used as the sacrificial template. Membrane pores were formed because of template removal during the sintering process, creating channels for water transportation. The pore size and porosity could be readily adjusted by changing the amounts and types of PDMS used in the fabrication process. The as-prepared SiOC membrane showed a high water permeability (140 LMH@2.5 bar) and high removal rate of rhodamine B (RhB), demonstrating its potential applications in water treatment. This work would provide an easy and scalable method to prepare ceramic membranes with a controlled pore size, which could be used for different water treatment applications.

Fabrication and Characterization of Ice Templated Membrane Supports from Portland Cement

Porous ceramic membranes for aqueous microfiltration and ultrafiltration processes suffer from the high-costs of material and processing. The latter is mainly due to the high-temperature sintering step. In this work, cement-based membrane supports from ultrafine Portland cement are studied as a low-cost alternative to traditional oxidic ceramic supports. An environmentally friendly freeze-casting fabrication route is applied for the fabrication of porous membrane supports. Cement membrane supports are becoming mechanically stabile after hydration reaction of cement with water, which does not require any high-temperature sintering step as in a conventional ceramic membrane fabrication process. This fabrication route, which is sintering-free, decreases the cost and environmental impact of the membrane fabrication process by eliminating extra energy consumption step during sintering. The Archimedes method, scanning electron microscopy (SEM), micro-computed tomographic (µCT), and mercury porosimetry characterize the membrane supports in respect to open porosity, pore size distribution, morphology, and connectivity. The flexural strength of the 3 mm thick membranes is in the range from 1 to 6 MPa, as obtained by the ring-on-ring tests. The obtained membrane supports possess porosity in the range between 48 and 73% depending on fabrication conditions (cooling rate and the solid content, as determined by Archimedes method enabling water flux in the range between 79 and 180 L/(h·m²) at 0.5 bar transmembrane pressure difference and 3 mm membrane thickness.

The Investigation of Organic Binder Effect on Morphological Structure of Ceramic Membrane Support

In this study, we investigated the effect of different organic binders on the morphologic structure of ceramic membrane support. Natural raw clay material (kaolin) was used as the main mineral for ceramic membrane support. The physical and chemical properties of kaolin powder and the supports were identified by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), particle size and zeta potential distribution. Based on the XRF test, the main composition of kaolin powder was SiO2 (47.41%) and Al2O3 (38.91%), while the rest were impurities. The FTIR spectra showed the functional groups of Si-O and Al-O. The XRD diffractogram of natural raw clay powder identified kaolinite and nacrite were the main mineral phase whereas muscovite and quartz were detected in small quantities in the sample. After prepared the ceramic membrane supports, XRD diffractogram showed that anorthite and gehlenite were detected as the main mineral phases for ethylene glycol (EG), gelatin, methocel and for polyethylene glycol (PEG), respectively. According to BET analyses, the maximum and the minimum pore width were obtained for PEG and gelatin organic binders.

Influence of the Natural Zeolite Particle Size Toward the Ammonia Adsorption Activity in Ceramic Hollow Fiber Membrane

Natural zeolite is widely used in removing ammonia via adsorption process because of its superior ion-exchange properties. Ceramic particle size affects the adsorptivity of particles toward ammonia. In this study, hollow fiber ceramic membrane (HFCM) was fabricated from natural zeolite via phase inversion. The effect of natural zeolite particle size toward the properties and performance of HFCM was evaluated. The results show that the HFCM with smaller particle sizes exhibited a more compact morphological structure with better mechanical strength. The adsorption performance of HFCM was significantly improved with smaller particle sizes because of longer residence time, as proven by the lower water permeability. A high adsorption performance of 96.67% was achieved for HFCM with the smallest particle size (36 μm). These findings provide a new perspective on the promising properties of the natural zeolite-derived HFCM for ammonia removal.