Ceramic Filters Research Articles

Efficiency of Ceramic Candle Filters towards Purification of Drinking Water

Efficiency of Ceramic Candle Filters towards Purification of Drinking Water

Design of an Intermittent Biosand Filter Amended with Oyster Shell Powders for the Improvement of Household Water Quality in Sub-Saharan Africa and Madagascar

Access to safe drinking water and the wide spread of water-borne diseases are major challenges in Sub-Saharan Africa and Madagascar. Based on this, a water purification models has been developed which can use on a local scale. It consists of an intermittent biosand filter amended with oyster shell powders designed from local materials. The performance of the filter was evaluated through physicochemical and bacteriological analyses using standardized methods on raw polluted well water with previously determined initial D0 characteristics. The effectiveness of the designed filter was assessed and a filtration operation was carried out over a monitoring period of 13 days (D13) prior to 7 days of acclimatization of the system. With a filtration rate of 0.75l/h-1, there is a very strong reduction in turbidity from 35.59NTU to 0 NTU and in BOD5 from 125mg/l to 2mg/l. More so, bacteriological analyses reveal a progressive and complete decrease from D0 to D13 of fecal coliforms from 9000 CFU/100ml to 0 CFU/100ml; total coliforms from 6,000 CFU/100 ml to 0 CFU/100 ml and fecal streptococci from 10,800 CFU/100 ml to 0 CFU/100 ml. Compared to the classic ceramic filter, no significant difference in the Duncan test is reported for the highlighted parameters. This filter presents potential among other water treatment methods at the local scale for reducing the risks of water-borne diseases and achieving Sustainable Development Goal 6 in developing countries.

Preparation of β-SiAlON/SiC composite ceramic foam filters and their oxidation resistance

In this study, ceramic foam filters with high porosity, strength, and oxidation resistance are produced at low temperatures by preparing porous β-SiAlON/SiC composite ceramic foams using the foam impregnation method with Si, Si, α-Al2O3, AlN, and SiC as the raw materials. The presence of SiC inhibits the growth of β-SiAlON grains, which reduces the amount of β-SiAlON produced. As the proportion of β-SiAlON increases, the porosity of the β-SiAlON/SiC composite ceramic foam decreases, whereas the bulk density and compressive strength increase. Non-isothermal oxidation experiments show that β-SiAlON/SiC composite ceramic foams exhibit high oxidation resistance and their macroscopic morphology does not change significantly after oxidation. As the proportion of β-SiAlON increases, the smooth SiO2 oxide layer on the surface of the ceramic foam gradually changes to acicular and columnar mullite crystals, and the oxidation resistance increases. Therefore, β-SiAlON acts as a high-temperature binder when it is added to SiC. Hence, the prepared β-SiAlON/SiC composite ceramic foams can be used as ceramic filters in the field of molten metal filtration.

High‐Performance Ceramic Catalyst Filters with Textured Waveguides for Efficient Removal of Volatile Organic Compounds

AbstractThe cordierite‐based ceramic catalyst filter (CCF) has attracted considerable attention as a promising future air purification system due to its ability to filtrate particulate matter (PM), as well as decompose volatile organic compounds (VOCs) through ultraviolet (UV)‐activated photocatalytic reactions. Its performance, however, is strictly limited because majority of UV photons are absorbed near the entrance of the high‐aspect‐ratio air‐flow channels, thus, only a limited portion of photocatalysts is activated during the flow of polluted air. In this study, a high‐performance CCF is presented featuring textured waveguides (TWs) aligned with an array of UV light‐emitting diodes (LEDs) emitting at a peak wavelength of 365 nm, which are inserted into an array of high‐aspect‐ratio channels. TWs ensure the delivery of UV photons deep inside channels via total internal reflection and scattering, enabling the activation of majority of photocatalysts, resulting in remarkable improvement in VOCs removal efficiency. The proposed CCF system exhibits much higher formaldehyde (HCHO) removal efficiency by 70% compared to conventional CCF systems even subjected to much lower UV light power densities. It is strongly believed that it is possible to further improve the removal efficiency, while maintaining effective PM filtering and ultralow electrical power consumption, by optimization of the geometry of the CCF system with TWs.

Arsenic leaching from ceramic water filters: Effects of firing temperature and influent conditions

Ceramic water filters (CWFs), fabricated using local sourced clay, have been widely acknowledged as sustainable and effective point-of-use (POU) drinking water treatment approach. However, arsenic leaching from CWFs poses a potential risk of arsenic exposure, thereby limiting their safe application. In this study, CWFs were made from red clay to investigate the critical roles of firing temperatures (900–––1050 °C), solution chemistry conditions (i.e., pH, Na+, Ca2+), as well as operational conditions on arsenic leaching. Overall, arsenic leaching from CWFs followed a flushing-out pattern, with up to 61 % of total leachable arsenic released during initial first 100-pore-volume filtration. Specially, higher firing temperature led to lower initial arsenic leaching but higher cumulative leaching from resulting CWFs over long-term filtration. Feed solutions at circumneutral pH, with low Na+ or high Ca2+ resulted in less cumulative arsenic leaching, while POU operational conditions (intermittent operation and fluctuating flow rate) had negligible effects. Mechanism investigation found that firing process enhanced arsenic mobility, i.e., the exchangeable arsenic fraction was only 5.34 % in unfired clay but 26.7 % − 37.3 % in CWFs. The enhanced arsenic mobility was mainly caused by the thermal transformation of source clay, especially the thermal alteration in the hematite lattice. Our findings provide not only new insights into the process controlling arsenic leaching from CWFs but also shed light on ways to mitigate leaching, thereby improving the safety of CWFs application.

Electricity-driven rapid regeneration of ceramic paper-based soot filters with conductive potassium-supported antimony-doped tin oxide catalyst

To address short-term emission of massive particulate matter (PM) from diesel engines, rapid regeneration of catalyzed diesel particulate filters (CDPF) based on soot combustion is a considerable challenge. Herein, we employed an aluminosilicate fiber-weaved ceramic paper (CP) as a filter matrix, on which highly active potassium-supported antimony-doped tin oxides (K/ATO) were coated to fabricate a CDPF. The K/ATO/CP monolith preserves the 3D-network structure of CP while incorporating the mesopores of K/ATO, providing potential for trapping soot particles effectively. Furthermore, electricity pulses are designed to pass through the conductive K/ATO coating on the monolith for CDPF regeneration, achieving nearly complete soot conversion within less than half a minute using 1400 J of energy input. Both the reaction rate and the energy efficiency surpass previously reported those of other methods for soot combustion. Mechanism studies revealed that the electricity pulse can stimulate the release of tremendous lattice oxygen from the catalyst and in turn trigger rapid soot combustion, and boost surface sulfate decomposition to alleviate SO2 poisoning. This work presents an electrification strategy to realize rapid regeneration of CDPF for effective PM elimination utilizing onboard electricity system for hybrid powers.

Effect of Sodium Tripolyphosphate on The Morphology and Thermal Properties of Anorthite-Based Ceramic Foam Filters for Aluminum Alloy Castings

Effect of Sodium Tripolyphosphate on The Morphology and Thermal Properties of Anorthite-Based Ceramic Foam Filters for Aluminum Alloy Castings

Effect of different materials of filter holder on sensory profile of coffee beverages

AbstractCoffee beverages are renowned for their complex chemical composition and sensory attributes. The Koar® filter holder, developed in Brazil, is an extraction method which utilizes percolation and is available in acrylic, stainless steel, ceramic, and porcelain variations. Thus, this study aimed to investigate how the manufacturing materials of Koar® filter holders impact the sensory profile of coffee beverages, as perceived by consumers. A group of 100 consumers were used, and the methods of check all that apply (CATA), and acceptance testing were applied. The results revealed significant variations in eight sensory attributes assessed by consumers. The beverages prepared with ceramic and porcelain filter holders exhibited similar sensory profiles, contrasting with those produced using acrylic and stainless steel. These sensory findings emphasize the impact of the Koar® filter holder material on the coffee beverage's sensory attributes and underscore the importance of understanding the specific perceptions and needs of the target audience.Practical applicationsConsidering the importance of the studies with consumers, this research presents findings that are very important for industries in the equipment production segment for the coffee beverage extraction process. Based on the results presented in this study, industries can develop products with specific materials that can enhance the sensorial attributes of the coffee beverage according to consumer preference.

Fabrication of high-permeance SiC filters reinforced with in situ-grown mullite whiskers for gas/solid filtration

The pursuit of cost-efficiency, superior strength, and excellent gas permeance has driven the development of silicon carbide (SiC) membranes or filters for gas/solid filtration. In this study, SiC filters with high gas permeance reinforced with in situ-grown mullite whiskers were successfully prepared through reaction bonding. Low-cost kaolin and bauxite were used as sintering aids and raw materials for mullite whisker formation, and MoO3 was used as an additive to promote mullite whisker growth. The effects of different sintering temperatures and the addition of kaolin, bauxite, and MoO3 on filter performance were systematically investigated. When the sintering aid and MoO3 content additions were 6 and 1.5 wt%, respectively, and the sintering temperature was 1450 °C, the resulting ceramic filter exhibited a porosity of 45.5 %, a bending strength of 17.9 MPa, and an average pore size of 47.7 µm. Moreover, the filter exhibited a high Darcy’s permeability coefficient of 2.42 × 10−11 m2, satisfactory chemical stability, and thermal shock resistance. The addition of MoO3 facilitated the consumption of the molten phases and increased the anisotropic growth rate of the mullite whiskers, which contributed to the fabrication of the high-permeance filters. Finally, the ceramic filters demonstrated good performance for the filtration of dusty gases loaded with fly ash particles with a mean size of 15.3 µm at room temperature and 300 °C, and the removal rate reached > 99.9 %. The pressure drop was a little lower than that of our commercially available SiC filters. The SiC filters showed good prospects in the field of gas/solid filtration.

Silica Filter Membrane by Utilizing Palm Oil Empty Bunches Waste

Keramasan Gas and Steam Power Plant uses river water as raw material after going through treatment in the WTP system. To overcome the problem of high silica value in demin water, a ceramic filter membrane device was developed from empty palm oil bunch waste that reduced silica content to standards. This research aims to improve water treatment efficiency to meet the established water quality standards. Keramasan Gas and Steam Power Plant uses river water sources as raw materials, which are processed through the WTP (Water Treatment Plant) system to produce demineralized water as the main supply in the HRSG water filler system. However, the water treatment process has not been optimal because the silica content in demin water is still high (>20 PPB), violating the established quality standards (<20 PPB). Therefore, this study proposes an innovation in the form of a ceramic filter membrane from empty palm oil bunch waste to reduce silica content. Tests show a decrease in silica values to standard. These innovations have had a positive impact, including chemical savings, water treatment optimisation, and wastewater reduction. In addition, the use of empty palm oil waste also contributes to efforts to reduce environmental pollution.

Research on Online Monitoring Technology and Filtration Process of Inclusions in Aluminum Melt.

Online monitoring and real-time feedback on inclusions in molten metal are essential for metal quality control. However, existing methods for detecting aluminum melt inclusions face challenges, including interference, prolonged processing times, and latency. This paper presents the design and development of an online monitoring system for molten metal inclusions. Initially, the system facilitates real-time adjustment of signal acquisition parameters through a multiplexer. Subsequently, it employs a detection algorithm capable of swiftly extracting pulse peaks, with this task integrated into our proprietary host computer software to ensure timely detection and data visualization. Ultimately, we developed a monitoring device integrated with this online monitoring system, enabling the online monitoring of the aluminum alloy filtration process. Our findings indicate that the system can accurately measure the size and concentration of inclusions during the filtration process in real time, offering enhanced detection speed and stability compared to the industrial LiMCA CM (liquid metal cleanliness analyzer continuous monitoring) standard. Furthermore, our evaluation of the filtration process demonstrates that the effectiveness of filtration significantly improves with the increase in inclusion sizes, and the synergistic effect of combining CFF (ceramic foam filter) and MCF (metallics cartridge filter) filtration methods exceeds the performance of the CFF method alone. This system thus provides valuable technical support for optimizing filtration processes and controlling inclusion quality.

Impact of functional coatings on microstructure and properties of periclase-magnesium aluminate spinel ceramic filter and its purification capacity on molten steel

Reticulated ceramic filters play an important role in the reduction of non-metallic inclusions in molten steel, which can improve the quality of steel products. In this work, periclase-magnesium aluminate spinel ceramic filters with Al2O3 and TiO2 functional coatings were fabricated by using microporous MgO powder, respectively. The effects of the functional coatings on their microstructure, properties and purification capacity on molten steel were studied. The filter with Al2O3 functional coating exhibited the best mechanical properties owing to the good rheological properties of the coating slurry, as well as the formation of in-situ spinel layer connection between the Al2O3 functional coating and the microporous MgO layer of the filter substrate. Compared with the filters without functional coating or with TiO2 functional coating, the filter with Al2O3 functional coating made more Al2O3 inclusions deposit on the filter surface by physical adsorption due to the same chemical composition between the functional coating and inclusions, which significantly improved the adsorption capacity of filter for Al2O3 inclusions in molten steel. Overall, the filter with Al2O3 functional coating had the highest cold compressive strength of 1.4 MPa, a residual retention of cold compressive strength after thermal shock of 65.71 % and an efficiency of 36.56 % in reducing the total oxygen content of the steel.

A DFT study of the adsorption of fouling molecules (metal sulfides and hydroxides) onto TiZrO4 ceramic membranes

Ceramic membrane fouling is a constraint in the treatment of acid mine drainage (AMD), leading to a decrease in efficiency over time. Here, it is described via first-principles calculations the physical and chemical phenomena occurring on the surface of TiZrO4 filtration membranes due to the adsorption of eight potential fouling compounds [CuS, FeS, Fe2S3, CaS, Al(OH)3, Fe(OH)3, Fe(OH)2, and Cu(OH)2]. The interaction of these fouling molecules was performed onto nanostructured TiZrO4 surfaces with several pores representing the filtration membranes employed in the treatment of AMD. The adsorption energies reveal that the adsorption is feasible with all the fouling molecules studied, and it is strongly related to the molecular polarity of the adsorbate. Consequently, the adsorption of metal sulfides is more feasible than hydroxides with adsorption orders of CaS>FeS>CuS>Fe2S3, and Al(OH)3>Fe-hydroxides>Cu(OH)2. The outcomes suggest that the metal sulfide adsorption depends on the adsorbate intrinsic polarity, solvent effects, adsorbate van der Waals radius, and membrane surface topology, while the adsorption of hydroxides is less influenced by the last two factors. Density-based binding and energy decomposition analyses indicate strong electrostatic attractions and covalent bonds at the adsorbate-membrane interface supporting the chemical fouling onto ceramic filtration membranes. According to our theoretical results and the elevated concentration of Cu and Fe in AMD, we propose that FeS and CuS are mainly responsible for the fouling onto TiZrO4 membrane surfaces. These results offer valuable information on the adsorption phenomena at TiZrO4 membrane surfaces, which can be useful for metallurgy, industrial water treatment, food industry, biotechnology, and pharmaceutical applications.

Promoting the potabilization of drinking water at home using local materials as an alternative solution for combating waterborne diseases: Socioeconomic feasibility study in Dschang, West Cameroon

AbstractThis study aimed to assess the socioeconomic feasibility of promoting locally produced water filters to promote their local production. It appears that 69.8% of participants did not know that water filters were produced locally and 92.3% were ready to buy them with efficiency as the main motivation (39.8%). In addition, being aged [46–60 years old] (OR = 19.17; IC = 3.13–37.81; p = 0.008), being female (OR = 1.67; IC = 1.02–2.77; p = 0.041), student/pupil (OR = 2.32; IC = 1.13–4.78; p = 0.021), employed in the private sector (OR = 3.68; IC = 1.32–11.16; p = 0.015), and civil servant (OR = 3.28; IC = 1.09–10.99; p = 0.041) significantly increased the odds of having ever used a water filter in their household. In addition, we found that 71.7% of participants had ever used an imported ceramic water filter in their households and the main reason given by these participants for abandoning or renewing these filters within their households was that they felt that they had already become old and inefficient. The valorization of locally manufactured filters could therefore constitute a logical alternative that can contribute to solving a certain number of socioeconomic and health problems in our country.

Investigation of the feasibility of alternative burnout material (maize cob) versus the traditional material (sawdust) for point-of-use ceramic water filter production

Ceramic water filters, are a promising household water treatment technology. Filters were produced using clay as the base material and two locally available burnout materials (sawdust and maize cob). The clay which was classified as an Inorganic clay of low to medium plasticity has a liquid limit of 41.1% and plasticity index of 37.4%. The sizes of the combustible materials are 5,10, 22 microns mixed in proportions of 1:1 and 1:2 by proportions of clay and burnout materials respectively, moulded and fired to a temperature of 1000℃. In the end, ten filters were produced from various particles sizes and proportions of the sawdust and maize cob. The bulk density of the filters ranged from 1.67 to 3.5 g/cm3 with a typical value of 2.63±0.57 g/cm3 . Apparent porosity ranged from 94.94 to 99.87% with a typical value of 99.10±1.13%; while water absorption varied from 28.6 to 59.71 % with a mean of 40.02±9.49 %. Flow rate ranged from very slow rate of 0.051 to 0.92 L/h with a typical value of 0.354±0.226 L/h. Based on type of burnout material, filters made with sawdust had higher flow rates (0.433 L/hr) than those made from maize cob (0.291 L/hr). The percent turbidity removal ranged from 9.1% - 43.7% on the first week to 30.6 – 70.4% on the fifth week of the test for filters made from maize cob; whereas the percent turbidity removal ranged from 5.7 – 35.3% on the first week to 44.9 – 75.6% on the fifth day for sawdust. Filters made from sawdust performed significantly better than those made from maize cob (p = 0.044) at 95% confidence level. In terms of particle size, there was an increase in efficiency of Coliform removal efficiency from 99.6 to 99.8% as the particle size of burnout materials increased from 5 μm to 22 μm. Filters made with lower proportion (1:1) of burnout materials exhibited higher Coliform removal (99.76%) than those made with higher (2:1) proportion (99.63%). However, the proportion of burnout materials within the range used in this study did not significantly affect percentage Coliform removal (p = 0.247). Filters made from sawdust generally performed better than those made from maize cob.

Glass frit-ink development and relevant process technology for fabricating functionally graded material-structured ceramic filters via binder-jetting 3D printer

Glass frit-ink development and relevant process technology for fabricating functionally graded material-structured ceramic filters via binder-jetting 3D printer

A high-selectivity ceramic bandpass filter with controllable transmission zeros

Abstract This paper proposes a microstrip filter with controllable transmission zeros based on the λ/4 stepped impedance resonator. This filter utilizes hybrid electric-magnetic coupling to generate transmission zeros, which can improve selectivity and stop-band performance. A fifth-order filter is designed and manufactured on a ceramic substrate with a center frequency of 26 GHz, bandwidth of 2 GHz and the signal suppression level is better than 42.51 dB from 10 to 22.8 GHz and 48.23 dB from 29.1 to 40 GHz. Furthermore, the proposed filter has a compact size of 2.074 × 1.071 mm (0.566λ g × 0.292λ g ).

Effect of nano-carbon black content on wetting phenomenon of molten steel and alumina–carbon ceramic filter substrates

Effect of nano-carbon black content on wetting phenomenon of molten steel and alumina–carbon ceramic filter substrates

Development of ceramic filter tube for passive sampling of PFAS in waters

To enhance the detection of the escalating presence of per- and poly-fluoroalkyl substances (PFAS) in aquatic environments, the development of innovative sampling techniques becomes imperative. This study focuses on testing a novel passive sampler for in situ sampling of PFAS, employing a ceramic filter tube (CFT) coupled with a hydrogel containing adsorbent-imbedded weak anion exchange resin (WAX) in rod format. The WAX gel rod demonstrated swift binding of the targeted PFAS and potential reusability at least five times. The integrated passive sampler, CFT-WAX, exhibited a linear accumulation pattern for five PFAS in the lab, resulting in a lower diffusive coefficient through the CFT wall than other samplers due to the thicker wall. Notably, variations in pH, ionic strength, and dissolved organic matter did not significantly influence the performance of CFT-WAX. Field deployment in a wastewater treatment plant (WWTP) demonstrated its reasonable performance compared to traditional grab sampling. Though further optimisation in the future is warranted, the findings of this study underscore the efficacy of the developed CFT-WAX passive sampler as a promising tool for in-situ sampling PFAS in aquatic environments.

Increasing the Efficiency of Wastewater Treatment from Galvanic Production Using Titanium-containing Coagulants and Membrane Treatment

It has been stated that the use of complex titanium-containing agents can significantly increase the efficiency of wastewater treatment and achieve a reduction in residual concentrations of heavy metal compounds down to standard values. For further separation of coagulated sludge from purified water, it is proposed to use filtration methods with ceramic tubular filters. A significant increase in the filtration rate of titanium-containing coagulation sludge has been confirmed, leading to an increase in the productivity of treatment equipment by 20–30 %. It is recommended for purification of acid-base and chromium-containing wastewater to combine the process of coagulation of impurities by treating the wastewater with a complex titanium-containing coagulant, followed by filtering the resulting sludge using special ceramic tubular filters.