Clay Materials Research Articles

The preparation and selection process for a new form stable phase change material (FSPCM) intended for use as thermal storage in applications at intermediate temperatures

There is a greater focus on solar energy since the food processing business requires a lot of thermal energy to remove moisture from agricultural products. This study thoroughly explains how to choose Phase Change Materials (PCMs) within a specific temperature range. The best PCM is selected from the Multiple Criteria Decision Making (MCDM) procedures based on a few characteristics. Based on the results of the MCDM method, the eutectic of paraffin and palmitic acid is chosen. PCM is bound, and FSPCM is formed using clay. The method of preparation of Clay-based FSPCM is described in detail. The amount of clay materials and different clay percentage combinations are chosen from the leakage experiment. Kaolin has the least amount of leakage out of all the clay materials tested. Kaolin-based FSPCM Exhibits improvement in thermal conductivity compared to Pure PCM.

MINERALOGICAL AND PHYSICO-CHEMICAL CHARACTERISATION OF CLAY MATERIALS FROM KWILU-NGONGO (Kongo-Central, DR Congo)

Clay materials collected from two sites (Camp-Beton and Kwilu-Bricks) in the Kwilu-Ngongo region located between 5°30’0’’S and 14°40’60’’E, in the Kongo Central province (DRC), Ten samples selected and subjected to mineralogical, physico-chemical and geotechnical studies with a view to their characterization. Mineralogical analysis by X-ray diffraction made it possible to identify the following minerals: quartz, feldpasth, iron oxide and simple clay minerals including kaolinite. In addition to this kaolinite we also find illite, chlorite and vermiculite. The partical size analysis led to the differentiation of three fractions including: the fine clay fraction, the silty fraction and the sandy fraction. As for the Atterberg Limits, the plasticity Limit ranges from 17 to 30% while the average plasticity index is 13 %. Chemical analyzes made it possible to identify the major oxides elements below: SiO2, Al2O3, TiO2, Fe2O3, K2O, Na2O and MgO.

Multi-criteria assessment of groundwater potential of shallow aquifers in the vicinity of Osun state university, Ikire campus and environs, southwestern Nigeria

In order to investigate the groundwater potentials of shallow water-bearing layers within the vicinity of the Osun State University Campus at Ikire, fifteen vertical electrical sounding (VES) resistivity data were acquired at random. The groundwater potential of the shallow water-bearing layers was inferred from the resistivity data based on three (3) existing criteria namely aquifer resistivity, transmissivity and reflective coefficient. At each VES station, the maximum electrode spreading employed for the resistivity data acquisition was between 200 m and 240 m, with the interpretation of the data carried out using partial curve-matching and computer iterative software. Geoelectric parameters obtained were used to compute the longitudinal conductance, transverse resistance, hydraulic conductivity, transmissivity and reflective coefficient using empirical relationships. The computed parameters were compared with existing classification tables to deduce the groundwater propensity in the shallow water-bearing layers of the study area. Four to five geoelectric layers corresponding to the HQ, HA and HKA geoelectric curve types were observed having lateritic materials as topsoil, sandy clay/clayey sand, weathered/fractured basement and fresh basement. In most cases, the water-bearing layer is mostly of clayey material with high porosity and low permeability and resistivity values that varies from 14.6 Ωm in VES 1 to 65.6 Ωm in VES 6. A few consist of sandy clay also with low resistivity values 76.9 Ωm in VES 7 to 107.1 Ωm in VES 4. The transmitivity values vary from 0.239 m2/day in VES 2 to 2.522 m2/day in VES 5. This same behavior was observed with reflective coefficient values which range from 0.690 in VES 6 to 0.994 in VES 1. The conclusions from the classification tables correlate in most of the VES stations. This study shows that the groundwater potential of the shallow water-bearing layers in the study area is generally poor within 0 to 80 m depth due to the low transmissivity of the clay materials at the shallow depths. Effective groundwater development in the study area must therefore integrate geophysical methods and remote sensing techniques to investigate depths beyond 100 m.

Exploring the feasibility of utilizing high plastic clays as an alternative material to bentonite clay in the production of ceramic tile: Advancing towards efficient life cycle cost

The environmental challenges and high cost of raw materials (i.e., bentonite clays) for the production of ceramic tiles raise concerns for the ceramic industry to look for alternative materials. Therefore, the current research aimed at exploring the possibility of using high plastic clays as a replacement for Bentonite clay in the manufacturing of ceramic tiles. Two different types of high plastic clay in different proportions (i.e. 0–5 %) were used in the preparation of ceramic tiles. A comprehensive material characterization, shrinkage, visual index, flexural strength, water absorption, and microstructural investigation was carried out. The results revealed that the incorporation of plastic clays RC1 from 1 % to 5 % showed a decrease in the flexural strength of ceramic tiles as compared to that of ceramic tiles with bentonite clay. The water absorption of ceramic tiles using RC1 increased with the incorporation of high plastic clays for high plastic clays. However, specimens with all replacements of bentonite clay with high plastic clays showed flexural strength greater than the minimum specified limit of ISO 10545-4. Moreover, it was observed that the replacement of bentonite clay with high plastic clays exhibited higher shrinkage. Further, the visual index of all the specimens did not show any sign of the presence of black core in the ceramic tiles incorporating high plastic clays. The life cycle assessment (LCA) was carried out for the possible utilization of high plastic clays in place of bentonite clay to produce ceramic tiles. The results showed that less than 5 % high plastic clay can effectively be used for manufacturing ceramic tiles leading to economical and sustainable construction products. Hence, it can be concluded that the high plastic clays can be utilized as an alternative to bentonite clay material for manufacturing sustainable ceramic tile leading to sustainable finishes in construction.

Thermogravimetric Analysis of Moisture in Natural and Thermally Treated Clay Materials.

Clays are a class of porous materials; their surfaces are naturally covered by moisture. Weak thermal treatment may be considered practical to remove the water molecules, changing the surface properties and making the micro- and/or mesoporosities accessible to interact with other molecules. Herein, a modulated thermogravimetric analysis (MTGA) study of the moisture behavior on the structures of five, both fibrous and laminar, clay minerals is reported. The effect of the thermal treatment at 150 °C, which provokes the release of weakly adsorbed water molecules, was also investigated. The activation energies for the removal of the adsorbed water (Ea) were calculated, and they were found to be higher, namely, from 160 to 190 kJ mol-1, for fibrous clay minerals compared to lamellar structures, ranging in this latter case from 80 to 100 kJ mol-1. The thermal treatment enhances the rehydration in Na-montmorillonite, stevensite, and sepiolite structures with a decrease in the energy required to remove it, while Ea increases significantly in palygorskite (from 164 to 273 kJ mol-1). As a proof of concept, the MTGA results are statistically correlated, together with a full characterization of the physico-chemical properties of the five clay minerals, with the adsorption of two molecules, i.e., aflatoxin B1 (AFB1) and β-carotene. Herein, the amount of adsorbed molecules ranges from 12 to 97% for the former and from 22 to 35% for the latter, depending on the particular clay. The Ea was correlated with AFB1 adsorption with a Spearman score of -0.9. When the adsorbed water is forcibly removed, e.g., under vacuum conditions and high temperatures, the structure becomes the most important, decreasing the Spearman score between β-carotene and Ea to -0.6.

Experimental Studies of Fluidized Bed Calcination of Granulated Clay Material.

The work presents a detailed analysis of the possibilities of the thermal processing of clay raw material granulates in a fluidized bed reactor powered by coal fuel. Potential customers of calcined granulates include the following: plants producing refractory materials for the steel industry, producers of refractory concrete, sanitaryware plants, tile plants, large-size tile plants, industry abrasives, chemicals, paints, paper, food and medical industries and others. The advantage of the presented fluid bed calcination technology is the possibility of the continuous operation of the reactor and the short time of the material in the bed, compared to the previously used methods of calcination in a shaft and rotary kiln, which lasts less than twenty minutes in the temperature range of 650-850 °C. During the experimental studies of calcination in the fluidized bed layer, the influence of the type of coal, its particle size and the mass share of coal in the feed mixture on the calcination process and the final product obtained was analysed. As a result of the conducted research, it was proven that solid fuels such as anthracite and steam coal type 31.2 (flaming) can be successfully used in the fluidized bed calcination process of clay materials. The key parameter determining the fluidized bed calcination process is the fuel particle distribution.

Petrographic and geochemical analyses of pottery from Wadi Tanuf, Oman: Approaching pottery production in south‐eastern Arabia during the second and first millennia BCE

AbstractThis study describes the petrographic and geochemical characteristics of pottery collected from Mugharat al‐Kahf and WTN02 in Wadi Tanuf, north‐central Oman, to clarify interregional similarities and differences in pottery production techniques and examine the existence of interregional trade in pottery with respect to changes in mobile communities. Potsherds from these sites were characterised using thin‐section petrography and instrumental neutron activation analysis. Results revealed that several clay fabrics and tempers were used during the Wadi Suq period (2000–1600 BCE). A region‐wide similarity exists in pottery‐making techniques in terms of the tempering of specific minerals (Oman ophiolite) used in the Early Iron Age (1300–300 BCE). Geochemical results indicate differences in clay sources between the Wadi Suq period and the Early Iron Age in Wadi Tanuf and the unlikelihood of the interregional trade of domestic pottery.

Application of VLF-EM response and geoelectrical sounding in groundwater investigation around an active dumpsite

An integrated geophysical method combining very low frequency electromagnetic (VLF-EM) and vertical electrical sounding (VES) methods were carried out around Adaland, Southwestern Nigeria, located within latitude 7° 54’ 0” and longitude 4° 43’ 0”, with a view to investigate the possible impact of dumpsite on groundwater. This is the major study in the environment to offer extensive evidence regarding the suitability of obtaining quality groundwater. In this research, eight VLF-EM and twelve VES data sets were generated, which were then used to estimate the linear structure, bedrock formation, subsurface geological characteristics, and identification of leachate pathways. The VLF-EM data were analyzed by employing Karous_Hjelt and Microsoft Excel, while the VES data were investigated using the WinRESIST software. TheVLF-EM results confirmed the presence of conductive zones, which might be due to fracture, fault and contact zones or weathered basements. The lithological units acquired from the electrical resistivity results revealed four geoelectrical layers such as topsoil, weathered-based, fractured basement and fresh basement. However, the identified weathered layers and fractured basements from the geoelectrical sections and the corresponding Karous and Hjelt (K-H) pseudo sectionresults around the dumpsite, constitute the main passages for the possible impact of the open dumpsite on groundwater quality, since leachates from the dumpsite could slowly percolate downwards from the topsoil to the water table. Therefore, the impact of the dumpsite on the groundwater is caused by the inadequate clay materials, near-surface features such as fractures/faults, and lateral in-homogeneity. Thus, integrating both methods has been recommended in site characterization for accessing quality groundwater around a dumpsite environment.

Assessing the feasibility of laser induced breakdown spectroscopy for detecting nitrogen in martian surface sediments

Despite the detection of fixed nitrogen in meteorites and directly on Mars' surface, the abundance and distribution of nitrogen sequestered in the martian crust remains unknown. Given that nitrogen is a bioessential element that is required for the synthesis of amino acids, nucleic acids, and other organic molecules vital for life, this gap in knowledge is one of the most important challenges in constraining martian habitability. Laser-induced breakdown spectroscopy (LIBS) has the capability to detect N in natural rock samples and is available as a stand-off survey instrument on multiple currently active Mars rovers, creating an immediate opportunity to map the stratigraphic distribution of N within diverse depositional settings. However, little has been published regarding the detection of N with LIBS.To lay a foundation for N detection on Mars using LIBS, we synthesized a comprehensive suite of samples with variable amounts of nitrogen (as nitrate or ammonium) in either a Mars regolith simulant or a clay matrix. We present baseline spectra of N emission in Mars-relevant matrices and identify spectral interferences. Our results indicate that 17 diagnostic N emission lines are reliably detectable from mineral-bound N against a basaltic background, but only four lines exhibit sufficient sensitivity to be detected across a range of N concentrations and within all tested matrices. To elucidate optimized strategies for quantification, we present an iterative series of PLS models. We find that prediction accuracy is improved by restricting the compositional range of the training set, normalizing the data, subtracting baseline continuum emission, and simultaneously modeling the emission behaviour of multiple diagnostic N lines at once. We observe that the prediction uncertainty increases (worsens) from 8.4% to 29.9% if models are used to predict N in samples with a dissimilar matrix than those used during training, suggesting poor generalizability outside the training range. Consequently, future work should focus on developing a larger, more diverse training set that encompasses the range of N concentrations and phases expected to be encountered on Mars, which may be used to train generalizable models. Overall, this work demonstrates that LIBS is a promising tool for determining the abundance of N sequestered in martian surface materials and lays a foundation for future development.

Influence of Hydrothermal Modification on Adsorptive Performance of Clay Minerals for Malachite Green.

Artificially modified adsorbing materials mainly aim to remedy the disadvantages of natural materials as much as possible. Using clay materials such as rectorite, sodium bentonite and metakaolinite (solid waste material) as base materials, hydrothermally modified and unmodified materials were compared. CM-HT and CM (adsorbing materials) were prepared and used to adsorb and purify wastewater containing malachite green (MG) dye, and the two materials were characterized through methods such as BET, FT-IR, SEM and XRD. Results: (1) The optimal conditions for hydrothermal modification of CM-HT were a temperature of 150 °C, a time of 2 h, and a liquid/solid ratio 1:20. (2) Hydrothermal modification greatly increased the adsorptive effect. The measured maximum adsorption capacity of CM-HT for MG reached 290.45 mg/g (56.92% higher than that of CM). The theoretical maximum capacity was 625.15 mg/g (186.15% higher than that of CM). (3) Because Al-OH and Si-O-Al groups were reserved in unmodified clay mineral adsorbing materials with good adsorbing activity, after hydrothermal modification, the crystal structure of the clay became loosened along the direction of the c axis, and the interlayer space increased to partially exchange interlayer metal cations connected to the bottom oxygen, giving CM-HT higher electronegativity and creating more crystal defects and chemically active adsorbing sites for high-performance adsorption. (4) Chemical adsorption was the primary way by which CM-HT adsorbed cationic dye, while physical adsorption caused by developed pore canal was secondary. The adsorption reaction occurred spontaneously.

Coupled Processes at Micro- and Macroscopic Levels for Long-Term Performance Assessment Studies of Nuclear Waste Repositories

Performance assessment of nuclear waste repositories requires state-of-the-art knowledge of radionuclide transport properties. Additionally, the short-term development under thermal pulses and the long-term development of the near field—due to influences such as gas generation—must be evaluated. Key thermal-hydro-mechanical-chemical processes are strongly coupled on different spatial and temporal scales. To understand these coupling mechanisms, numerous material models and numerical codes have been developed. However, the existing constitutive approaches—which have been adapted to describe small-scale laboratory experiments and validated against real-scale field observations—are often unable to capture long-term material behavior with sufficient precision. To build the confidence, a more comprehensive understanding of the system at micro- and macroscopic scales is required. Most observed macroscopic processes result from microscopic changes in the crystal structure and/or crystalline aggregates, as well as changes in material properties under the influence of various factors. To characterize these physical fields in crystals, microscopic investigations, such as visualization, or geophysical methods are introduced to verify the understanding at the microscale. Two cases are demonstrated for the presented concept using microscale information: one deals with the mechanically and thermally driven migration of fluid inclusions in rock salt, the other with dilatancy-controlled gas transport in water-saturated clay material.

Investigation and modeling of physicochemical properties of bentonite-chitosan composites versus the concentration of chitosan added by intercalation

This study attempts to understand the relationship between structural and physicochemical changes of clay modified by a chitosan intercalation, and to valorize the clay-chitosan composites for wastewater treatment purpose. More precisely, the main aim was a characterization and modeling of the physicochemical properties of clay-polymer composites (especially bentonite-chitosan composites) versus the concentration of chitosan added by intercalation. We first developed a method for intercalating chitosan into the clay matrix, with different polymer concentrations (6g/L, 12g/L, 18g/L, 24g/L, 27g/L and 30g/L). Second, we carried out a characterization of the structural and physicochemical properties of clay-polymer composites based on X-Rays Diffraction (XRD), Fourier Transform Infrared (FTIR) and Scanning Electric Microscopy (SEM). In particular, the results of these analyses show that the measured pores within the composites with chitosan concentrations 6g/L and 30g/L are of nanometric order, while the composite at 12g/L is rather of microscopic order. Third, XRD measurements allow the determination of the clay interlayer space (basal distance) and particles size versus the polymer concentration. For basal distance, we have demonstrated the existence of five regimes depending on the value of the polymer concentration, namely (i) dilute regime, (ii) first semi-dilute regime, (iii) well-regime, (iv) second semi-dilute regime and (v) saturation regime. Finally, these bentonite-chitosan composites may be used as kinds of filtration membranes for wastewater, retaining, for example, a dye whose adsorption quantity was found to be improved by an amount of 76.92 %.

Enrichment mechanisms of Nb, Zr, and REY in the Late Permian coal-bearing strata in western Guizhou, SW China

Niobium, Zr, REE, and Y are widely enriched in the Upper Permian coal-bearing strata in southwestern China and are regarded as a substantial resource. To better understand the occurrence modes and enrichment mechanisms of these rare metals, comprehensive heavy-mineral separation, Micro-Raman spectroscopy, EPMA, and LA-ICP-MS analyses of primary and secondary metal minerals were conducted in the polymetallic beds in western Guizhou. In addition, the XRD, XRF, and ICP-MS analyses of bulk rocks were carried out. Our results suggest that Nb is primarily hosted in secondary TiO2 polymorphs which converted from primary Nb-rich rutile, and occurs as minor ilmenorutile and columbite-(Fe). The Zr is sequestered in both detrital zircon and secondary microcrystalline zircon. REE and Y (REY) are mainly incorporated into secondary florencite-(Ce), rhabdophane-(Ce), churchite-(Y), and zircon, also partially adsorbed by clay minerals. The assemblage of detrital zircon, Nb-rich rutile, and discrete Nb minerals reveals that rare metals are preconcentrated during the waning-stage Emeishan alkaline magmatisms. Complex zonings in rutile crystals may result from the diffusion of Nb5+ and Fe2+, and these grains are further overprinted by magmatic-hydrothermal and enveloped by ilmenorutile and columbite-(Fe). Furthermore, magmatic rutile is commonly converted into anatase, brookite, and leucoxene under supergene conditions, and then persisted as stable phases. Authigenic REY-rich (Al)-phosphates and zircon are sourced from the leaching, even decomposition of primary REY-phosphates and zircons. Their colloidal aggregates are precipitated from the acidic and oxidizing low-temperature fluids, which are superposed onto clay matrix. The mineralogical and geochemical features suggest that the polymetallic beds are enriched by both alkaline magmatic-hydrothermal processes in source rocks and supergene fluid alterations in sediments. This study gives new insights into the enrichment processes and conditions, and further extraction of critical metals in the coeval coal-bearing strata in southwestern China.

Synergistic effects of Reflux Flotation Cell's downcomer and reverse fluidization bed in rejecting clay entrainment during particle separation

The Reflux Flotation Cell (RFC) technology is heralded as an innovative game-changer, promising significant advancements in particle separation, and offering generational benefits for the resources industry. This paper meticulously assessed the RFC's capabilities in tackling another critical industry challenge in resources processing— severe entrainment of waste clay particles during flotation separation and compared the performance with conventional mechanical flotation. Through flotation tests where kaolinite particles were separated from combustible materials, in-situ particle aggregation measurements and calculating air fractions in both flotation systems, this study identified the superior performance of the RFC in reducing kaolinite entrainment and producing a high product quality. This was attributed to a synergistic function between the RFC's downcomer for kaolinite dispersion and the RFC's fluidization bed for generating a low air fraction in reducing kaolinite entrainment. While kaolinite dispersion avoided the blocking of water drainage channels between air bubbles by aggregates, a low air fraction ensured a large gap between air bubbles to allow the displacement of entrained fine particles with fluidization water. Herein, the research findings will guide the resources industry to process low quality resources by successfully rejecting clay and other fine waste materials.

The role of compaction in the diagenetic evolution of Pre-Salt Aptian deposits of Santos Basin, Brazil

The discovery of huge oil accumulations in the South Atlantic Pre-Salt carbonate lacustrine deposits has attracted much exploration and research interest on these challenging reservoirs, but no work has focused on the compaction processes. A petrological and geochemical study was therefore performed on two cored wells in Santos Basin to identify the main syngenetic and diagenetic constituents, and to identify the compaction features that affected these deposits. They are mainly composed of Mg-clays, calcite spherulites and fascicular shrubs, which have undergone a heterogeneous diagenetic evolution. Mechanical compaction occurred during shallow burial, promoting a closer packing of the constituents, reorientation and fracturing of calcite spherulites and bioclasts, and deformation of the clay matrix. Pressure dissolution occurred under increasing pressure and temperature during burial, developing inter-aggregate sutured contacts, dissolution seams and stylolites, as consequence of overburden. Macrocrystalline quartz and calcite, drusy quartz, and saddle dolomite precipitated during burial diagenesis, related to basinal fluids and probably to pressure dissolution, as source for the late carbonate phases. Understanding the role of compaction is essential to evaluate trends of porosity destruction, thickness modification and mass transfer, which directly impacted the quality and the dynamic evolution of fluids in the deep Pre-Salt reservoirs.

Evaluation of shielding properties of a developed nanocomposite from intercalated attapulgite clay by Cd/Pb oxides nanoparticles

The study investigated new nanocomposites’ γ-ray and neutron shielding properties based on raw attapulgite, a clay matrix intercalated with different weight percentages of mixed nano metal oxides CdO and PbO. The various percentages were as follows: (100–2x)% Attapulgite + x%CdO + x%PbO, abbreviated as (AT100–2x CdxPb x ), where x = 5, 10, 15%. The nanocomposites were characterized using XRD, FTIR, and EDX, confirming their successful preparation. SEM images revealed that the mixed oxide nanoparticles were successfully intercalated into the layers of attapulgite clay, with an average particle size of approximately 31.46 nm. The bulk densities of the prepared nanocomposites were measured to be in the range of 2.034 to 2.555 g/cm3. GEANT4 simulations were employed to evaluate the nanocomposites’ γ-ray and neutron shielding performance in the photon energy range of 0.015 to 15 MeV. Phys-X code was used for verification. The simulation results showed a maximum difference of approximately 9.5% between GEANT4 and Phys-X predictions. To assess the γ-ray shielding performance, various shielding parameters were calculated at selected photon energies. The μ m values ranged from 4.589 to 0.020 cm2.g−1, 6.311 to 0.021 cm2.g−1, 8.350 to 0.022 cm2.g−1 and 10.804 to 0.023 cm2.g−1 for raw attapulgite, AT90Pb5Cd5, AT80Pb10Cd10, AT70Pb15Cd15 across the photon energy range. The AT70Pb15Cd15 nanocomposite exhibited the highest μ m , Z eff , Z eq , and the lowest T 1/2, T 1/10, and MFP values. Notably, it also demonstrated the highest FNRCS (approximately 0.1 cm−1). These findings suggest that clay-based nanocomposites represent a new class of low-cost, locally available advanced materials with potential applications in γ-ray and neutron shielding characteristics.

Pre-treatment of hydrolysable nuclear organic liquids prior to their waste management: Solid impregnation of vegetable oil on surfactant-grafted clay particles

In the context of advancing nuclear waste management techniques, this study delves into the novel use of surfactant-grafted clay particles for pre-treating hydrolysable nuclear organic liquids. Our research explores the potential of modified clay materials in immobilizing vegetable oil, a surrogate for complex nuclear waste. We investigate the adsorption capabilities of various clays, including metakaolin, diatomaceous earth and sepiolite, when grafted with cetyltrimethylammonium bromide (CTAB) as cationic surfactant, or decyl glucoside (DG) as non-ionic surfactant. This study employs characterization techniques to assess the physicochemical transformations in clays post surfactant-grafting. Grafting was initially highlighted by TGA, where the breakdown of surfactants can be observed. This is also evidenced by measurements of the ζ-potential, which demonstrate a reduction in surface charge upon the addition of the cationic surfactant, excepted for sepiolite for which the surface charge did not change. Additionally, Washburn measurements indicate that the grafting process converts hydrophilic particles into hydrophobic ones. The oil absorption tests indicated that the CTAB-grafted sepiolite demonstrated superior characteristics, notably exhibiting no oil rejection. Consequently, this specifically synthesized powder was utilized in a two-step process consisting in pre-impregnation of oil up to 20 %v of vegetable oil prior to its immobilization within a geopolymer matrix. Furthermore, the outcomes of the leaching tests revealed that the vegetable oil remained effectively confined within the immobilization matrix, ensuring its retention. The research contributes to the goal of enhancing hydrolysable nuclear waste management practices, ensuring long-term sustainability and environmental safety.

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.

Evaluation and application of Moroccan clay materials in ceramic tiles: Composition and technological behavior

This paper aims to assess the suitability of various Moroccan clay materials for application in ceramic tile production. Six clay samples (S1–S6) sourced from cities including Fez-Meknes, Safi, Berrechid, and Benslimane were collected and subjected to comprehensive characterization to elucidate their chemical and mineralogical composition, as well as their morphological and thermal behavior. The impact of sintering temperatures ranging from 900 to 1100 °C on parameters such as bulk density, porosity, water absorption, shrinkage, flexural strength, and chemical resistance was investigated. Results revealed elevated levels of Fe2O3 (>3 %), indicative of dark firing clays across all samples. Additionally, the samples exhibited a composition comprising clay minerals, quartz, feldspars, and carbonates. Based on the findings, it was determined that these clay materials are suitable for the production of cottoforte and majolica falling within the BIIb and BIII ceramic classes (ISO 13006). The study underscores the potential of these materials for utilization in industrial ceramic products, given their demonstrated characteristics.

Variation and correlation between water retention capacity and gas permeability of compacted loess overburden during wetting-drying cycles

Landfill gases can have numerous detrimental effects on the global climate and urban ecological environment. The protective efficacy of the final cover layer against landfill gases, following exposure to periodic natural meteorological changes during long-term service, remains unclear. This study conducted centrifuge tests and gas permeability tests on compacted loess. The experiments examined the impact and relationship of wetting-drying cycles and dry density on the soil water characteristic curve (SWCC) and gas permeability of compacted loess. Research findings reveal that during the dehumidification process of compacted loess, the gas permeability increases non-linearly, varying the gas permeability of soil with different densities to different extents under wetting-drying cycles. Two models were introduced to describe the impact of wetting-drying cycles on gas permeability of loess with various dry densities, where fitting parameters increased with the number of wetting-drying cycles. Sensitivity analysis of the parameters in the Parker-Van Genuchten-Mualem (P-VG-M) model suggests that parameter γ′s accuracy should be ensured in practical applications. Finally, from a microstructural perspective, wetting-drying cycles cause dispersed clay and other binding materials coalesce to fill minuscule pores, leading to an increase in the effective pores responsible for the gas permeability of the soil. These research results offer valuable guidance for designing water retention and gas permeability in compacted loess cover layers under wetting-drying cycles.