Ceramic Filters Research Articles

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.

A Compact THz Photometer for Solar Flare Burst Studies from Space

Recent solar flare observations reveal the presence of THz components having a few orders of magnitude higher amplitude than the Radio Frequency (RF) and microwave radiations in the solar flare spectrum. This feature makes it remarkably beneficial for the detection of solar flares of low magnitudes such as Geostationary Operational Environmental Satellite (GOES) Class C, and M flares. Hence, space agencies including National Aeronautics and Space Administration (NASA) and European Space Agency (ESA) are gearing up with THz instruments for solar flare observations. In line with this, Laboratory for Electro-Optics Systems (LEOS) has completed the development of a photometer that operates in continuum THz band, from 1.5 to 15 THz. The entire electro-opto-mechanical design was carried out to realize a compact, light-weight and power-efficient photometer to meet the size, mass and power constraints posed by inherent resource limitations of experimental satellite platforms such as Nanosatellite, Microsatellite and Polar Satellite Launch Vehicle’s 4th Stage Orbital Platform (PS4-OP). A Cassegrain optical configuration was designed to collect the sun radiation with an aperture effective area of 0.0027 m2 with ceramic low pass filters and resonant mesh filter for selective perception of THz radiation, rejecting the huge background of visible and Near Infrared (NIR) with a spectral selectivity of 107:1. Sensitivity of the Photometer was estimated to be 41.5 K/mV in 1.5 to 15 THz band by calibration using a blackbody radiation source. The radiometric resolution of the payload is 125 Solar Flux Unit (SFU) (1 SFU=1×10-22 Wm-2Hz-1). The payload was successfully developed and space-qualified for its deployment in Nanosatellite or PS4-OP platform.

Evaluation of a novel nickel ceramic filter prepared by urea precipitation method for removal of tars from biomass syngas using naphthalene as tar model compound

Gasification has been shown to be an effective thermal conversion process for waste biomass in order to create fuel, specialty chemicals, and hydrogen. Gasification is likely to take on a major role in the near future in the burgeoning hydrogen economy. In order to improve the commercial viability of gasification, catalytic tar reforming has come to the forefront as one of the most promising methods of reducing the tar content that has been detrimental to downstream equipment in the process. The use of catalytic ceramic filters has presented promising potential for this application that can serve dual role of tar and particulate removal. In this study, a nickel-based ceramic filter has been prepared using urea vacuum impregnation technique and evaluated for tar removal efficiencies. The urea technique was more effective than traditional impregnation techniques at uniformly dispersing nickel across the surface of the ceramic filter, driving the nickel particles to penetrate the pores of the support, thus aiding in improved tar removal capabilities. Through steam reforming studies using a naphthalene simulant tar molecule, the 15 wt% nickel filter was able to reduce the naphthalene content by 97% at temperature of 750 °C over 2 h. An activation energy of 126.4 kJmol was achieved for steam reforming using the urea vacuum impregnated catalytic filter compared to 136.4 kJmol using the incipient wetness impregnated filter.

Mussel-Inspired Construction of Silica-Decorated Ceramic Membranes for Oil–Water Separation

In recent years, ceramic membranes have received widespread focus in the area of liquid separation because of their high permeability, strong hydrophilicity, and good chemical stability. However, in practical applications, the surface of ceramic membranes is prone to be contaminated, which degrades the permeation flux of ceramic membranes during the separation process. Inspired by mussels, we imitate the biomimetic mineralization process to prepare a ceramic membrane of nano–silica on the pre-modified zirconia surface by co-deposited polydopamine/polyethyleneimine. The modified ceramic membranes were utilized for the purpose of oil–water separation. Separation performance has been tested using a disc ceramic membrane dynamic filtration device. The outcomes revealed an enhanced permeability in the modified membrane, measuring as 159 L m−2 h−1 bar−1, surpassing the separation flux of the unmodified membrane, which was 104 L m−2 h−1 bar−1. The permeation performance of the modified membrane was increased to 1.5 times. Modified ceramic membranes are highly resistant to fouling. From the beginning to the end of separation process, the oil rejection rate of the modified ceramic membrane is always higher than 99%. After a 2 h oil–water separation test run, modified ceramic membrane permeate flux can be restored to 91% after cleaning. It has an enormous capacity for application in the area of oil–water separation.

Design optimization of ceramic membrane filters based on a response surface method

Ceramic membrane filters fabricated from local raw materials are excellent for municipal wastewater treatment. This paper studied the fabrication of ceramic membranes using Response Surface Methodology (RSM). It also looked at the influence of clay, palm kernel shell ash, kaolin, and starch on the properties of ceramic membrane filters. Optimal test conditions and procedures were determined by selecting a fitting model based on experimental data. The Box–Behnken design (BBD) was chosen for its ability to reduce the number of experimental trials, thus making it cost-effective. The BBD design was executed using Design-Expert 13 software (Stat-Ease, Inc., Minneapolis, MN, USA), requiring 29 experimental runs. According to the study, responses such as porosity, flow rate, thickness, and density were used in the model. The fabrication of the 29 ceramic membranes includes formulation, shaping (slip casting method), drying, and sintering. Based on RSM, an optimum ceramic membrane design was proposed: Kaolin = 413 g, Clay = 180 g, Starch 147 g, Palm Kernel shell ash = 13 g. Compared with the test results, this combination possesses favorable and reliable accuracy. The addition of kaolin played a role in creating a porous framework within the ceramic membrane. Clay serves as a binding agent, aiding the consolidation of ceramic particles within the membrane matrix. Starch served as a pore-forming agent during the fabrication process. From the study, the palm kernel shell ash served as a binder and a reinforcing agent, bolstering mechanical strength and structural robustness.

From drainage to resource: a practice approach to reuse greywater for household irrigation purposes

Abstract The United Nations indicates that available freshwater resources will decrease significantly due to pollution growth and urbanization; two-thirds of the world's population may face water shortages by 2030. Extended use of greywater is an alternative option for reducing potable water consumption in urban areas. Recently, the reuse of treated greywater for home gardens, peri-urban agriculture, and landscaping has become a widespread concern in many developing countries. This paper presents a study on a low-cost system that can perform greywater treatment for household use. This treatment system employed physical filtration by ceramic filters, quartz gravel, hollow fiber membrane, and UV disinfection. Three greywater samples collected from the kitchen, washing basins, and bathroom were investigated. The operation process determines the system's effectiveness by considering turbidity, coliform, Biochemical Oxygen Demand (BOD5), and Chemical Oxygen Demand (COD) concentration of the inlet and outlet water. As a result, high removal efficiency (i.e., >60%) could be obtained for each investigated parameter. Results also showed that grey water generated from washing basins has the highest potential for reuse since the water quality after treatment satisfies the water reuse standards for household irrigation. The findings encourage further exploration and implementation of greywater reuse practices.

Effect of flow velocity on the permeability of ceramic foam filters (CFFs)

The structural uniformity of commercial Al2O3-based Ceramic Foam Filters (CFF) of Grades 30, 50, 65 and 80 was investigated using the permeability of samples from five different locations of the CFF tiles/Blocks, specifically from the four corners and the centre. Statistical analysis at 95 % confidence interval revealed no significant variations in the permeability values among these locations. Additionally, the impact of different flow regimes within the CFF structure, namely laminar, transitional, and turbulent regimes, on the permeability was explored. It was demonstrated that permeability, as a parameter of fluid velocity, exhibited a notable increase with increasing pore diameter. In CFF samples with pore diameters greater than 0.5 mm, the deviation in permeability between turbulent flow and creeping flow was attributed to large eddies occupying a substantial portion of the pore volume. This phenomenon resulted in the narrowing of the flow channels and reduction in the viscous boundary layer. The correlation between filtration efficiency and velocity, as well as CFF pore diameter, is discussed in view of the influence of streamlining and the size of the eddies on the re-entrainment of captured particles.

Ceramic Filters Coated with Green Ag-Nanoparticles for Drinking Water Treatment in Rural Households of Nigeria.

A ceramic water filter (CWF) coated with plant-based nanoparticles was used as household water purifier in a rural community. Silver nanoparticles (AgNPs) were produced from the stem bark of Bridelia ferruginea plant, and their efficacy to enhance the physical, chemical, and microbial quality of raw stream water sample was determined using analytical probes and pour-plate techniques, respectively. The pH of the filtered water sample ranged 7.6 to 8.1, which is within the WHO permissible limit for drinking water, and the electrical conductivity values were also reduced from 110 to 70 µS/cm. The CWF coated with AgNPs (CWF-AgNPs) removed Klebsiella pnuemoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Entamoeba histolytica from the stream water sample. The highest percentage of coliform reduction in the CWF and CWF-AgNPs were 93.18% and 99.64%, respectively. The raw data showed that the CWF-NPs enhanced the quality of the stream water. The surface and internal structure of the CWF-AgNPs can be modified by varying the concentration of the composite materials, so as to determine the most effective combination. The improved CWF-AgNPs will enhance achieving United Nations Sustainable Development Goal #6, which focuses on clean water and sanitation.

Solid–liquid separation of lignocellulosic sugars from biomass by rotating ceramic disc filtration

A simple, low energy, and productive filtration method to clarify biomass hydrolysate to enable biochemical and thermochemical pathways to biofuels and biochemicals.

WO3/Pt photocatalyst supported by a ceramic filter for indoor air purification under visible light irradiation

Household air pollution exposure can lead to various chronic health issues, photocatalytic air purification could improve the indoor air quality.

Development of ceramic filtering membranes based on Tunisian clay and phosphate sludge in wastewater treatment

In order to fully exploit the Tunisian clays of the El Haria formation (Paleocene), and the phosphate washing sludge in the Gafsa region of Tunisia, and to obtain finished products using less expensive materials such as ceramic filtration membranes, four samples were studied to evaluate their suitability for industrial use. Different methods of identification were used, including: X-ray diffraction; chemical analysis; Fourier Transform InfraRed Spectroscopy; determination of the specific surface; thermal analysis; particle size analysis; plasticity. The results of these analyses indicate that the clays contain smectites and kaolinites associated with quartz, gypsum, calcite, and dolomite. The phosphate sludge had a low density (1.88 g cm−3), was plastic (plasticity limit of 22.09) and was mainly composed of fluoroapatite (48 %), calcite (32 %) and clay. The present work aims at developing new porous and flat ceramic membranes based on clay and sludge in percentages that vary from 10 % to 30 %, and in the form of disk with a diameter of 40 mm and a thickness of 3–5 mm. These membranes heated at temperatures between 800 °C and 1100 °C, are characterized by their physical properties (water absorption, porosity), mechanical properties (resistance to compression) and morphology (scanning electron microscopy). The results show porous membranes with pore sizes ranging from a few microns to tens of microns (1–20 μm). They show a good elimination efficiency of pollutants from wastewater. The integration of sludge improves the properties of the ceramic membranes and the management of large quantities of phosphate waste and thus minimizes its harmful impact on the environment.

Enhanced quality factor (∼336,800 GHz) of MgTiO3 ceramic by Hf substitution for Ti-site

Mg(Ti1–xHfx)O3 (0 ≤ x ≤ 0.1) microwave dielectric ceramics were synthesized by solid-state reaction method. The effects of Hf substitution for the Ti-site on the phase composition, structure, and microwave dielectric properties of MgTiO3 ceramic were systematically investigated. The study demonstrated that Hf substitution significantly improved the quality factor of MgTiO3 ceramic. A single phase was confirmed at x = 0.002 and 0.005 by XRD and SEM, while secondary phases were observed at x ≥ 0.02. The Rietveld refinement of XRD data implied that the distortion of [Ti(Hf)O6] octahedron started with alleviation and then gradually deteriorated with an increase in Hf content. Raman spectra displayed that the frequencies of the vibrational modes were high when there was low distortion in [Ti(Hf)O6] octahedron, manifesting that the low distortion weakened the effect of non-harmonic vibration. The quality factor of the samples with x ≤ 0.05 was far higher than that of undoped MgTiO3, which may be related to low distortion in [Ti(Hf)O6] octahedron and high relative density. Notably, the excellent microwave dielectric properties of Q × f ∼336,829 GHz, εr ∼17.2 and τf ∼ -49.7 ppm/°C were achieved for the Mg(Ti0.995Hf0.005)O3 ceramic. The greatly improved quality factor of MgTiO3-based microwave ceramics through Hf substitution makes it a suitable candidate material for ceramic filters.

Foamy ceramic filters and new possibilities of their applications

Peculiarities of sintering of foamy ceramic filters based on submicron aluminum oxide powders with additions of titanium oxide and manganese dioxide nanopowders are considered. The processes of removal of polymeric and binder paraffin material during sintering have been studied. The physical and mechanical properties of the obtained porous permeable filters with a foamy structure were analyzed in details. At a sintering temperature in an air atmosphere of 1350 °C, sufficiently high physical and mechanical properties were obtained, which made it possible to use the developed filters as catalyst carriers for vehicle exhaust gases. Bench comparative tests have shown that ceramic filters with a foamed structure are promising catalysts for afterburning car exhaust gases instead of ceramic honeycomb blocks of catalyst carriers. The developed technology allows reducing the sintering temperature of porous foam ceramic filters to 1350 °C and replacing expensive high-temperature ceramic heaters with cheaper nickel-chromium ones.

Preparation and enhanced mechanical properties of novel Al2O3‐C ceramic filter reinforced by microporous powder and SiC whiskers

AbstractIn present work, the novel Al2O3‐C ceramic filter fabricated by using microporous corundum‐spinel powder instead of dense Al2O3 powder and reinforced by SiC whiskers is proposed. The effects of Si powder content (0, 3, 6, and 9 wt. %) on the microstructures and mechanical properties of the filters were studied. After replacing the α‐Al2O3 micro‐powder with microporous corundum‐spinel powder, the in situ spinel whiskers were formed inside the filter skeleton under the reducing atmosphere. The rough surface structure of the microporous powder increased the interface contact area with the small‐sized carbon particles, resulting in a compact interface bonding in the filter skeleton and a higher cold compressive strength of the filter. When the Si powder content increased to 6–9 wt. %, the in‐situ SiC whiskers were formed not only between the microporous powder, but also inside the pores near the surface of it by vapor‐solid reaction mechanism in the filter skeleton. The SiC whiskers synergized with the microporous powder to form a more compact interface structure, thus remarkably enhancing their cold compressive strength and thermal shock resistance. Overall, the mechanical properties of the filters were significantly improved by the addition of 9 wt. % Si powder. The filter skeleton had an apparent porosity of 36.2% and a bulk density of 1.93 g/cm3. The filter also exhibited a high cold compressive strength of 1.59 MPa and a superior thermal shock resistance. It has the potential for better purification efficiency on molten steel in the future due to a rougher skeleton surface structure compared to existing Al2O3‐C filters.

A study on ceramic composite filters utilizing rice husk for enhancing groundwater quality

Summary: This study addresses the persistent reliance of certain communities on groundwater for drinking purposes, despite its failure to meet quality standards due to the presence of harmful coliform bacteria. To meet these standards, a cost-effective and environmentally friendly filtration method is proposed, utilizing clay and rice husk as formative elements. The research focuses on creating a ceramic composite filter by blending rice husk with clay in varying compositions (30 %, 40 %, and 50 %). The mixture is processed into a paste, shaped into a green body, air-dried, and fired at different temperatures (875 °C, 900 °C, and 925 °C). Compression, porosity, and flow tests are conducted to evaluate the filter's performance. An increase in rice husk composition leads to higher flow rates, indicating improved water flow through the filter, suggests a positive influence of rice husk on the hydraulic characteristics of the filter material. The ceramic composite filter effectively filters coliform bacteria, achieving a 93 % reduction, although it falls short of meeting drinking water quality standards. The optimal sintering temperature is identified at 900 °C with a forming pressure of 30 MPa. This study emphasizes the potential of clay and rice husk-based ceramic filters as a viable option for improving groundwater quality, acknowledging their positive impact on porosity and flow characteristics. However, further refinement is required to fully align with established drinking water quality standards, suggesting avenues for future research and development in this critical field. This research explores the potential development of technology ceramic composite filter with the hope of making a positive contribution to advancing clean and sustainable energy solutions in the future

Mullite fiber porous ceramic with high quality factor for high-temperature PM filtration

Porous ceramic filters with high porosity and high filtration are in urgent need of high-temperature gas filtration. Here a lightweight and low thermal conductivity mullite fiber porous ceramic filter was prepared through vacuum filtration method using solution blow spun mullite fiber as the matrix material and silica sol as the high-temperature binder. Mullite fiber porous ceramic with a mass ratio of 10:1 has uniform pore structure, low density (0.58 g cm−3), high porosity (78.11%), high compressive strength (1.79 MPa), as well as low thermal conductivity (0.095 W m−1 K−1) at a sintering temperature of 1300 ℃. When the air flow is 6 L min−1, the pressure drop is 180 Pa, the filtration efficiency of PM2.5 and PM10–2.5 is 98.85% and 99.61%, respectively, and the filtration quality factor is 0.025 Pa−1. The mullite fiber porous ceramic filter have outstanding quality factor, which has broad application prospects in high-temperature gas filtration.

Evaluation of the adsorption behavior and divalent metal ions removal efficiency of ceramic point-of-use water filter materials

Ceramic water filters (CWFs) are point-of-use devices mostly used in developing countries as a result of their effectiveness in the treatment of household water. However, there is a dearth of knowledge on the metal ions adsorption behavior of the filter materials. Therefore, this study investigates the adsorption behavior of the divalent metal ions using commercially available ceramic water filters as adsorbents, in a batch experiment and compared the data, to the extent of metal ion removal during filtration. The ceramic water filters were characterized with x-ray fluorescence spectrometer, x-ray powder diffractometer and fourier-transform infrared spectrophotometer. An adsorption batch experiment was conducted and filtration experiments were performed to determine the extent of divalent metal ions removed. The results of the study showed that divalent metal ions were adsorbed efficiently by ceramic water filters. The pseudo-second-order kinetic model best described the kinetic behavior of metal ion removal process. The extent of adsorption of ceramic water filters was in the range: 7.015–335.77 mgg−1. The adsorption patterns fitted the Freundlich isotherm model while the entropy, enthalpy, and Gibbs free energy, indicate that the processes for all CWF-adsorbents are endothermic, feasible and spontaneous. The kinetic and thermodynamic behavior of CWF-adsorbents indicate that the mechanism of the sorption process is chemisorption. There was a significant difference in the amount of divalent metal ions adsorbed in batch experiments compared to filtration experiments for ceramic water filter materials (Pot filter and candle filter). The metal ions adsorption potentials of ceramic water filters are found to be rate dependent; hence the rate of filtration must be of concern to manufacturers.

Effect of Rare‐Earth Oxides Containing Refractories on the Cleanliness of Al‐Killed Steels

Refractories have a significant impact on the cleanliness of molten steel, especially when utilized as ceramic filters. To explore the feasibility of applying rare‐earth oxides in ceramic filters, the interactions between CeO2/CeAlO3 functional refractories and steels with different Al contents are explored, and compared with the microporous magnesia refractory. In the test of CeO2 refractory, the total oxygen (T.O) content significantly increases, while the dissolved Al content obviously decreases in 38CrMoAl steel (0.876 wt% [Al]). Furthermore, the T.O contents in 38CrMoAl and X70 steel (0.040 wt% [Al]) in the test of CeAlO3 refractory are 22.9% and 70.9% of that in the test of microporous magnesia refractory, respectively. Meanwhile, the loss of dissolved Al in steel caused by the interaction between CeAlO3 refractory and steel is relatively small. Therefore, CeAlO3 is relatively stable after contact with molten steel and promising to be applicated in the ceramic filter for improving the cleanliness of molten steel.

A Nanostructured Protein Filtration Device for Possible Use in the Treatment of Alzheimer's Disease-Concept and Feasibility after In Vivo Tests.

Alzheimer's disease (AD), along with other neurodegenerative disorders, remains a challenge for clinicians, mainly because of the incomplete knowledge surrounding its etiology and inefficient therapeutic options. Considering the central role of amyloid beta (Aβ) in the onset and evolution of AD, Aβ-targeted therapies are among the most promising research directions. In the context of decreased Aβ elimination from the central nervous system in the AD patient, the authors propose a novel therapeutic approach based on the "Cerebrospinal Fluid Sink Therapeutic Strategy" presented in previous works. This article aims to demonstrate the laborious process of the development and testing of an effective nanoporous ceramic filter, which is the main component of an experimental device capable of filtrating Aβ from the cerebrospinal fluid in an AD mouse model. First, the authors present the main steps needed to create a functional filtrating nanoporous ceramic filter, which represents the central part of the experimental filtration device. This process included synthesis, functionalization, and quality control of the functionalization, which were performed via various spectroscopy methods and thermal analysis, selectivity measurements, and a biocompatibility assessment. Subsequently, the prototype was implanted in APP/PS1 mice for four weeks, then removed, and the nanoporous ceramic filter was tested for its filtration capacity and potential structural damages. In applying the multi-step protocol, the authors developed a functional Aβ-selective filtration nanoporous ceramic filter that was used within the prototype. All animal models survived the implantation procedure and had no significant adverse effects during the 4-week trial period. Post-treatment analysis of the nanoporous ceramic filter showed significant protein loading, but no complete clogging of the pores. We demonstrated that a nanoporous ceramic filter-based system that filtrates Aβ from the cerebrospinal fluid is a feasible and safe treatment modality in the AD mouse model. The presented prototype has a functional lifespan of around four weeks, highlighting the need to develop advanced nanoporous ceramic filters with anti-biofouling properties to ensure the long-term action of this therapy.

Ceramic Filters for the Efficient Removal of Azo Dyes and Pathogens in Water

Overcoming the scarcity of safe and sustainable drinking water, particularly in low-income countries, is one of the key challenges of the 21st century. In these countries, the cost of centralized water treatment facilities is prohibitive. This work examines the application of low-cost ceramic filters as point-of-use (POU) devices for the removal of methylene blue, o-toluidine blue, Staphylococcus aureus, and Staphylococcus typhi from contaminated water. The ceramic filters had typical kaolinite functional groups, making them suitable for the removal of dyes and pathogens. Surface charge measurements indicated strongly anionic filters, while thermal properties confirmed the carbonization of the biowaste additive leaving behind a porous kaolinite structure which subsequently dehydroxylated into meta kaolinite. In addition, morphological data showed heterogeneous filter surfaces. Increased biomass content improved the permeability, water adsorption, flow rate, and apparent porosity of the filter. The ceramic filter removed methylene blue (42.99–59.74%), o-toluidine (79.95–92.71%), Staphylococcus aureus (98–100%), and Staphylococcus typhi (75–100%). Overall, the study demonstrated the effectiveness of POU ceramic filters in removing organic pollutants in contaminated water while serving as disinfectants.