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Monolithic silica-based aerogels, produced with tetraethoxysilane (TEOS), reinforced with aramid fibers and incorporating aluminosilicates were prepared for the first time. The nanocomposites were obtained by varying the amount and type of aramid fibers and replacing a part of the synthetic Si (up to 35 wt% of Si) of TEOS by natural aluminosilicates, kaolin and palygorskite. The effects of the type and amount of both fiber and mineral in the materials key properties were investigated. Most samples displayed very low volumetric shrinkages during ambient drying (<5%), high porosity (∼90%), and low bulk densities, down to 120 kg m−3. Composites with both minerals exhibited superinsulating thermal performance, with thermal conductivity reaching values as low as 22 mW m−1 K−1, while also showing excellent thermal stability. The mechanical properties of the designed clay mineral-silica aerogels can be tailored, since the addition of short length fibers (Kevlar pulp) produces stiffer composites, while the longer fibers (Teijinconex) lead to more flexible ones. [ABSTRACT FROM AUTHOR]

The paper presents the results of a study of the properties of Poletaevsky kaolin with the aim of using it in the ceramic industry. Based on the results of determining the chemical, mineral and granulometric composition. The mineral composition of Poletaevsky kaolin is kaolinite 80–85 wt %, muscovite and illite 10–15 wt %, quartz up to 10–15 wt %. It has been established that the Hinckley index for Poletaevsky kaolin is 0.68, compared to 1.38 for Glukhovetsky one. The ratio of highly ordered kaolinite to low ordered kaolinite for Poletaevsky kaolin is 22 : 78, for Glukhovetsky kaolin the ratio of highly ordered kaolinite to low-ordered kaolinite is 57 : 43. It was established that Poletaevsky kaolin can be used in the production of ceramic materials by plastic or semi-dry molding. The determined low content of high-ordered kaolinite and the insignificant content of particles less than 2 μm according to the results of laser diffraction analysis can lead to the production of an unstable slip. When firing samples of Poletaevsky kaolin, a minimum water absorption of 5.5 % was achieved at a firing temperature of 1450 °C. In this case, the resulting maximum apparent density was 2.17 g/cm3, the maximum mullite content was 38 %, and the maximum compressive strength was 32 MPa. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigated the strength behaviors of dredged clays treated with metakaolin (MK) and fly ash (FA). A series of laboratory tests including direct shear and unconfined compressive strength tests were performed on MK and FA-treated dredged clay at various MK contents and different curing times. The direct shear test results showed that the shear stress and displacement curves for all specimens tested are strain-softening types and influenced by MK content and curing time. The variation curve at a higher MK content or higher curing time is always higher than that at a lower one. The shear strength from the direct shear test at a given vertical stress consistently increases linearly with the increase of MK content while increasing parabolically with curing time. This indicates both curing time and MK content contribute to the development of the shear strength. Both strength parameters c and φ grow with increasing MK content and curing time. Unconfined compressive strength test results show the strain-softening behavior for all tested specimens. Compared with adding FA alone or MK alone, adding both fly ash and MK exhibited a better treatment effect in the unconfined compressive strength, which increases with increasing MK content and curing time. [ABSTRACT FROM AUTHOR]

Co-transport of Cr(VI) with bentonite colloids (Bc) at different flow rate, pH, ion strength (IS), and colloid concentration in heterogeneous sand media was investigated. The results showed that obvious penetration of dissolved Cr(VI) in co-transport occurred at about 0.5PV, which was mainly due to the heterogeneity of the sand column. The maximum dimensionless transport fraction ((Ct/C0)max) of dissolved Cr(VI) was 0.73 in the co-transport (200 mg·L-1 Bc and 2.5 ml min-1), much lower than that in the single transport of Cr(VI) (0.98). The increase of pH promoted the transport of Cr(VI) in co-transport with Bc. Elevated flow rate, ion strength, and Bc concentration reduced Cr(VI) transport. Cr(VI) in the effluent in co-transport with Bc was dominated by dissolved Cr(VI), and a small amount of colloidal Cr(VI) (～4.97%) was observed. The recovery rates of total transported Cr(VI) (dissolved +colloidal) in co-transport with Bc were obviously lower than those in single transport. (Ct/C0)max values of dissolved Cr(VI) in the co-transport with Bc were also lower than those with other colloids, e.g. kaolin colloid, montmorillonite colloid, and inorganic soil colloid. Application of bentonite may alleviate the transport risk of Cr(VI) to groundwater. [ABSTRACT FROM AUTHOR]

This study concerns the project of high and intermediate level radioactive waste disposal (Cigéo project for Centre Industriel de stockage GEOlogique). Millions of tons of argillite will be excavated during the construction of the site. Therefore, the aim of this work is to reuse this argillite in the formulation of an injectable geopolymer grout and study its evolution in different storage conditions (T = 20 and 80 °C). To achieve this challenge, a metakaolin and calcined Callovo-Oxfordian (COx) argillite were used with potassium silicate solutions. The grouts were successfully obtained from both metakaolin and COx argillite in both temperatures 20 and 80 °C. The range of viscosity of several mixtures respected the required specifications (viscosity ≤5 Pa s and setting time superior to 6 h). The metakaolin-based geopolymers didn't display any major changes no matter the storage temperature, except for the pore size, a coalescence phenomenon was observed with the increase of temperature. In contrast, for argillite or argillite-metakaolin based samples, a decrease of pore size as well as in pH values were observed with the increase of temperature. This behaviour was attributed to the dissolution of argillite's impurities such as illite, providing more oligomers to allow the formation of different geopolymer networks. [ABSTRACT FROM AUTHOR]

Phosphoric acid-activated geopolymer has become a promising ceramic material due to its superior thermal and mechanical properties. However, the gradual shortage of phosphate resources and the high price of phosphoric acid will be the key factors limiting the wide application of phosphoric acid-activated geopolymers. This paper developed a low-cost and low-carbon geopolymer non-sintered ceramics using industrial waste acid. The compressive strength of the prepared specimens can reach 32.2 MPa. The thermal gravimetric analysis indicated that the mass loss of the geopolymer remained almost unchanged in the temperature range between 400 and 1500 °C, indicating the geopolymer exhibited excellent thermal stability. Additionally, the infiltration test showed that the majority of the heavy metals could be solidified successfully with over 90% solidification efficiency, meaning the leaching of the heavy metals into the environment can be well controlled. Finally, the environmental and economic analysis showed that the carbon intensity (kg/m3/MPa) was reduced by 92.7% and 57.7% compared to cement paste and reported geopolymer. The cost intensity ($/m3/MPa) was negative due to the income of waste acid treatment, meaning that additional value benefit was added to the product. This paves a promising way for producing low-cost and low-carbon ceramic materials with excellent thermal and mechanical properties. [ABSTRACT FROM AUTHOR]

The stability of cementitious materials under the harsh environment they will experience when used for radioactive waste disposal is incredibly important. Therefore, understanding the irradiation resistance of geopolymer cement, a potential alternative binder for the treatment of nuclear waste, is of the utmost importance when trying to develop a safety case for these materials. The study presented here addresses the structural and chemical changes of metakaolin‐based geopolymers, designed with different water contents, and exposed to a total cumulative dose of 1 MGy of gamma radiation. The range of formulations that were tested showed a significant loss of free water related to the irradiation process, which has led to an increase in the porosity. Analysis of the chemical structure has shown minimal changes in the main binding type‐gel phase, demonstrating high microstructural stability. Results showed that in samples cured for longer than 20 h, the bound/gel structure water remained in the sample when the water content was kept low enough. As the porosity and water content increase, more gel water is removed due to radiation exposure. However, the degree to which the water is removed from the gel structure is very small, and minimal changes can be seen across the geopolymers tested. Overall, metakaolin‐based geopolymers appear resistant to irradiation up to 1 MGy, which offers a potentially viable alternative for the immobilization of problematic intermediate‐level waste. [ABSTRACT FROM AUTHOR]

This document is a closure to a previous paper on the behavior of extra-large and extra-extra-large monopiles in clay. It discusses the normalization of the lateral response of these monopiles and includes a table summarizing their details. The proposed normalization method is tested in different types of clay and shows satisfactory results in unifying the moment-rotation curves, although it is less effective in soft, normally consolidated clay. The article suggests that further research is needed to develop a more suitable normalization method for these monopiles in clay. [Extracted from the article]

Modeling of the soil–structure interface has been a critical issue in geotechnical engineering. Numerous studies have simulated complex soil–structure interface behaviors. These models usually are assessed by direct comparisons between the simulations and experiments. However, little work has been done to compare the specific interface behaviors simulated by different interface models. This paper evaluated some frequently recognized interface behaviors for six different interface models. These models either were adopted from the existing literature or modified from the existing soil models, including the exponential model, hyperbolic model, hypoplastic model, MCC model, SANISAND model, and SIMSAND model. Global comparisons and effects of the soil density, normal stiffness, and shearing rate were investigated to evaluate the interface models based on Fontainebleau sand–steel interface experiments and kaolin clay–steel interface experiments. The limitations and advantages of different models under different conditions were discussed. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of carbon fiber and graphite on the cyclic electrothermal performance of geopolymers (inorganic polymers). It was observed that carbon fibers, graphite, and the carbon fiber/graphite composite could form a stable conductive network at low voltage (3 V). However, under high voltages (9 and 12 V), the current of the geopolymer exhibited a peak shape in the first cycle, with higher voltages resulting in larger peak values and decreased conductivity in subsequent cycles. While graphite improved electrical and thermal conductivity, it weakened the microstructure, leading to an increase in microcracks and voids, and a reduction in the strength of geopolymers. The cumulative energy during the electrothermal process was calculated. The failure mechanism of the conductive network in the geopolymer during cyclic electrical heating was explained, highlighting the disruptive effect of gel shrinkage due to water loss on conductive networks. [ABSTRACT FROM AUTHOR]

As a new type of backfill material, Self-compacting solidified soil (SCSS) takes the abandoned slurry of cast-in-place piles after dewatering and reduction as the main raw material, which brings a problem of coordinating the working performance with the mechanical property under the condition of high mobility. In this paper, hydroxypropyl methyl cellulose (HPMC) and metakaolin were introduced as additives to solve this problem. First, the workability and mechanical properties of SCSS were regulated and optimized by means of the water seepage rate test, the flowability test, and the unconfined compressive strength test. Second, this study also used X-ray diffraction (XRD) and scanning electron microscopy (SEM) to investigate the effects of HPMC and metakaolin on the physical phase and microstructure of SCSS. In this way, the results showed that there was a significant impact on the flowability of SCSS, that is, when the dosage reached 0.3%, the water seepage rate of SCSS was reduced to less than 1%, and the compressive strength at 7 days reached its peak. At the same time, HPMC weakened the strength growth of SCSS in the age period of 7 days to 14 days. However, the addition of metakaolin promoted its compressive strength. XRD analysis showed that the additives had no significant effects on the physical phases. And, from the SEM results, it can be seen that although the water-retaining effect of HPMC makes hydration of cement more exhaustive, more ettringite (AFt) can be observed in the microstructure. In addition, it can be observed that the addition of metakaolin can generate more hydrated calcium silicate (C-S-H) due to the strong surface energy possessed by metakaolin. As a result of the above factors, SCSS filled the voids between particles and improved the interface structure between particles, thus enhanced the compressive strength. [ABSTRACT FROM AUTHOR]

This study evaluates Algerian kaolin (Djebel Debbagh (DD1) and Tamazart (KT2)) as potential substitutes for commercial kaolin (Lab) in the production of mullite‐based ceramics. Three compositions were prepared by incorporating the appropriate percentage of alumina to each calcined kaolin to achieve stoichiometric mullite precursors. The phase evolution of individual kaolin powders, as well as their mixtures with alumina, depends strongly on the calcination temperature and kaolin impurities. The differential scanning calorimetry combined with thermogravimetric analysis (TGA) showed lower secondary mullite formation temperature for the KT2‐based mixture. However, X‐ray diffraction revealed a complete mullitization in DD1 mixture. The K2O hindered cristobalite formation and reduced secondary mullite formation rate. Microstructure analysis showed lath‐shaped primary mullite and equi‐axed secondary mullite particles. After sintering at 1600°C, The KT2‐based sample (M3) exhibited higher density (3.013 g/cm3) and hardness (9.9 GPa), whereas the DD2‐based sample (M2) showed moderate densification (2.91 g/cm3) and higher flexural strength (159.42 MPa). Impurities (mainly Fe2O3, and K2O) promoted liquid phase sintering, resulting in greater densification in M3, whereas M2 showed more homogeneous microstructure, refined grains, and lower glassy phase content, contributing to enhanced strength. [ABSTRACT FROM AUTHOR]

Using cheap epichlorohydrin and dimethylamine as monomers in order to introduce cationic groups, acrylamide as another monomer, and ammonium persulfate as initiator through free radical copolymerization in aqueous solution, cationic sacrifice agent (SA1) was synthesized. Similarly, an amphoteric sacrifice agent (SA2) containing both quaternary amine and carboxylate functional group was synthesized. The terpolymers were used as a sacrifice material for polycarboxylate superplasticizer (PCE), and its reactive mechanism in cement–PCE–water with clay system was studied, which is desirable to solve the problem of PCE sensitivity to clay. The flow behavior of cement paste containing PCE in the presence and absence of clay was assessed. It was pointed out that the presence of montmorillonite (MMT) or kaolin significantly reduced the dispersion effect of PCE, eventually decreased the slurry fluidity. Fortunately, the addition of the sacrifice agents hindered this disadvantage. The fluidity of slurry increased with the increase in the amount compared with the lack of sacrificial agent. The sacrifice agent has a positive effect on retaining the fluidity of cement pastes, and to some extent makes up for the poor dispersion of PCE in the presence of clay impurities. The adsorption of SA1 or SA2 by MMT particles was studied by total organic carbon (TOC) analyzer. The results show that SA1 or SA2 can be preferentially adsorbed on particles by MMT compared with conventional PCE which result in more releasing PCE macromolecules and less useless loss. The sacrifice agent provides a possibility for improving the adaptability of PCE in low-quality cementing materials and has a potential application. [ABSTRACT FROM AUTHOR]

This study investigated the potential application of geopolymeric material for the separation of oil-in-water emulsions in wastewater treatment. For the first time, an asymmetric membrane made of geopolymers was developed for this specific separation process. The performances of the geopolymeric membrane in oil separation were compared with those obtained by a commercial ceramic membrane. The study also aimed at exploring the effects of emulsion formulation and emulsion properties (surfactant type and concentration, pH, and zeta potential) and membrane parameters (surface charge and material) on permeate volumetric flux and chemical oxygen demand (COD) rejection. Emulsions were prepared using 3% (w/v) dodecane oil in distilled water, with surfactant concentrations of 1x and 10x critical micelle concentration (CMC) and three surfactants of different nature (Oleth-10, Brij 76, and CTAB) at pH values of 2, 5, and 8. Results showed that for the best operating conditions of the geopolymeric membrane, initial and final permeate flux values of 42 and 26 L h−1 m−2, respectively, were achieved. COD rejection values ranged from 95.0 to 99.4% using the geopolymeric membrane thus indicating a very similar behavior between geopolymeric and ceramic membranes. These findings suggest that geopolymers are promising to produce membranes for oil-in-water emulsion microfiltration, promoting an interesting alternative for the treatment of industrial wastewater more sustainable in terms of environmental effects and costs compared to ceramic membranes. • Novel geopolymeric asymmetric membrane was synthetized. • Geopolymer selective layer was successfully deposited on pressed geopolymer support. • The geopolymeric membrane showed excellent fluxes and removal efficiencies. • Flux and rejection properties vary with surfactant concentration and emulsion pH. • Geopolymer membrane performs similarly to a commercial microfiltration ceramic one. [ABSTRACT FROM AUTHOR]

AbstractFine-grained soils containing diatom microfossils exhibit unique geotechnical behavior due to their biological origins, but their strength properties controlled jointly by diatom content (DC) and stress history remain to be revealed. In this study, reconstituted diatomaceous soil was prepared by mixing pure diatom and kaolin powders in different proportions. These mixtures were subjected to undrained consolidated triaxial shear tests performed using the Stress History and Normalized Soil Engineering Properties (SHANSEP) procedures, revealing how the DC and stress history affect the soil strength. Adding diatoms improved the mixture strength, and a critical DC of approximately 20% was determined, beyond which the normalized undrained strength of the soil was considerably higher than that of common clay without diatoms. Also, a DC higher than 20% associates with the dilatancy of the studied soil with high OCR. Improving the strength of diatomaceous soil by adding diatoms differs essentially from the case of common clay because the plasticity index of the former remains almost unchanged. New formulas incorporating DC and OCR are proposed for predicting the strength of diatomaceous soil, and data for several well-studied soils confirm their validity. This study improves the understanding of fine-grained soils with biological origins and provides important data regarding the mechanical behavior of diatomaceous soil. [ABSTRACT FROM AUTHOR]

This study evaluates the potential use of discarded plasterboard paper as fibers from buildings to reinforce concrete. Various concentrations of wastepaper fibers (0.5%, 1%, 1.5%, 2%, and 2.5% by weight of the binder) were investigated in this research. To mitigate the water absorption effect of the paper fibers, metakaolin was employed as a partial cement replacement. The results demonstrate that the inclusion of the wastepaper fiber enhances the mechanical and durability performance of the concrete. The optimal fiber proportion was identified as 1%, leading to a 29% increase in the compressive strength, a 38% increase in the splitting tensile strength, a 12% decrease in the water absorption, and a 23% decrease in the drying shrinkage with respect to the concrete containing 20% metakaolin. However, exceeding this optimal fiber content results in decreased mechanical and durability properties due to the fiber agglomeration and non-uniform fiber distribution within the concrete matrix. Based on the microstructural analysis, the improved performance of the concrete is ascribed to decreased porosity, more refined pore structure, and reduced propagation of microcracks within the concrete matrix in the presence of wastepaper fiber. According to the results, concrete containing 20% metakaolin and 1% wastepaper fiber exhibits durability and mechanical properties comparable to those of the traditional concrete. This finding highlights the significant promise of reducing dependency on conventional cement and incorporating suitable recycled materials, such as discarded plasterboard, and secondary by-products like metakaolin. Such a strategy encourages the preservation of resources, reduction in carbon dioxide emissions, and a decrease in the ecological footprint resulting from concrete production. [ABSTRACT FROM AUTHOR]

The reduction in the rheological parameters and dissolution rate of precursors in geopolymer coatings during early hydration significantly contributes to sagging. This study aims to improve the sag resistance of these coatings by incorporating diatomite filler. Rheological testing was conducted to assess the impact of diatomite and its concentration on the yield stress, plastic viscosity, and thixotropy of the geopolymer coatings. The results indicated that diatomite's large specific surface area and high reactivity have a significant influence on the rheological parameters and early dissolution rate of precursors. With a diatomite concentration of 1.1%, the coating exhibited a yield stress of 2.749 Pa and a plastic viscosity of 0.921 Pa·s, maintaining stability, homogeneity, and no sagging at a thickness of 600 μm. Furthermore, the highly active SiO2 in diatomite participates in the secondary hydration reaction of the geopolymer materials led to the formation of substantial C-(A)-S-H gel. This gel enhances internal interconnectivity within the coating, thereby improving its rheological and mechanical properties. [ABSTRACT FROM AUTHOR]

To assess the physical properties and topographical aspect of dental enamel's surface microhardness (KHN), surface roughness (Ra), and color parameters CIELAB (∆Eab*), CIEDE 2000 (∆E00), and whiteness index for dentistry (∆WID) after toothbrushing with experimental toothpaste formulations with the following mineral clay types: kaolin, Sparclay SGY, and Tersil CGY used as abrasive component. Scanning electron microscopy (SEM) was performed for topographical analyses purposes. A total of 96 bovine incisors were used in the experiment. They were divided into eight experimental groups (n = 12), namely: NC—negative control (no treatment), CT12—Colgate Total 12®, CMP—Colgate® Máxima Proteção Anticáries, K—kaolin experimental toothpaste, SGY—Sparclay SGY experimental toothpaste; CGY—Tersil CGY experimental toothpaste, SD—SiO2 experimental toothpaste, and CC—CaCO3 experimental toothpaste. All samples were subjected to mechanical brushing protocol with 5000 cycles and kept in artificial saliva with daily exchanges. KHN was analyzed through the mixed linear model for repeated measures over time. Ra was analyzed through nonparametric Kruskal Wallis and Dunn tests to compare the groups. Paired Wilcoxon test was run to compare experimental times. ∆WID, ∆Eab*, and ∆E00 were analyzed through Kruskal Wallis and Dunn tests. All analyses were performed in R* software, at 5% significance level. EXP_SGY recorded higher KHN than EXP_SiO2 and EXP_CaCO3, whereas EXP_K showed increased Ra in comparison to CMP (p = 0.0229). ∆Eab and ∆E00 were significantly higher in the CT12, EXP_SiO2, and EXP_CaCO3 groups than in the NC and EXP_K (p < 0.0001). There were no significant changes in ∆WID (p = 0.0852). According to SEM results, toothbrushing with experimental toothpastes added with mineral clay types did not have significant impact on enamel's polishing and smoothness. Clinical Relevance: Mineral clays have a broad application in the cosmetic industry, and recently, they have been used in the formulation of vegan toothpaste. [ABSTRACT FROM AUTHOR]

To rapidly eliminate toluene from aqueous environments during leakage accidents, this paper synthesized porous silico-aluminate nanoparticles (SANs) via a hydrothermal method, using cost-effective and non-toxic natural kaolin as the basic raw material. The morphology and structure of the porous SANs were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and BET-specific surface area tests. The effects of different conditions, such as the dosage of porous SANs, initial concentration of toluene, temperature, capture time, and pH, on the adsorption performance of porous SANs were analyzed. The as-prepared SANs exhibited a high removal efficiency and rapid adsorption performance toward toluene in aqueous solution. Finally, the kinetics of the adsorption of toluene in aqueous solution by porous SANs were investigated. The mechanism of the adsorption of toluene by porous SANs was further discussed. These findings provide a cost-effective and highly efficient absorbent for the emergency disposal of toluene leakage accidents. [ABSTRACT FROM AUTHOR]

This study explored the feasibility of utilizing varying proportions of metakaolin – MK (4, 6, or 8 wt%) and two types of alkaline liquid reagents – LR (incorporating nanosilica and NaOH or KOH) to induce in situ geopolymer formation in high-alumina refractory castables. The impact of geopolymeric binders on processing behavior, as well as on the physico-mechanical and structural properties of the designed refractories, was investigated within a temperature range of 40–1250 °C. Optimal physico-mechanical performance and thermal shock resistance were achieved with compositions 8 MK-Na (prepared with 8 wt% MK and NaOH-based LR) and 6 MK-K (containing 6 wt% MK and KOH-based LR). The liquid generation during viscous sintering enhanced castable densification at 1100–1250 °C and promoted the formation of nepheline, kalsilite or leucite phases. This resulted in microstructures featuring a suitable interfacial bond strength between the glassy phase and alumina grains, leading to an interlocking structure and improved castable properties. These achievements underscore the potential of geopolymer-bonded high-alumina castables for applications involving intermediate temperatures (800–1200 °C), such as those found in the petrochemical and non-ferrous metal industries. [ABSTRACT FROM AUTHOR]

Experimental studies on the thermo-mechanical properties of binary mixtures have not been well addressed. In this study, we conducted a series of temperature-controlled triaxial drained compression tests to investigate thermal effects on shear responses of binary mixtures of quartz sand and kaolin clay. The results demonstrated that the peak state deviatoric stress, the peak state friction angle, the axial strain of the specimen at the peak state, the relative softening coefficient, maximum dilatancy angle, and the secant modulus of the sand-clay mixtures are considerably influenced by the confining pressure, fine content or temperature. A modified stress-dilatancy equation was proposed by incorporating the influences of fine content and temperature, and the calculated results show that the stress-dilatancy behavior of sand-clay mixtures can be described within a limited range. [ABSTRACT FROM AUTHOR]

• Sulphate decomposition by galvanic sludge calcination forms a spinel solution. • The amount of kaolin and red clay influences the formation of a spinel solid solution. • Reuse of 300 tons/year of galvanic sludge helps Amazonian rainforest preservation. • Amazonian clays guarantee the sustainability of a highly toxic environment. This study presented the influence of two types of clay: kaolin (Kao) and red clay (RC) on the chemical and physical properties of ceramic specimens when galvanic sludge (GS) is incorporated to encapsulate heavy metals. Samples were obtained of GS from the industrial district of Manaus – Amazonas State, Brazil, and kaolin (Kao), and red clay (RC) from the Central Amazon. A fourth sample was prepared by mixing GS, Kao, and RC in the ratio 1:1:8 (GS + Kao + RC). This mixture was ground, and ceramic specimens were prepared, and heat treated at 950 °C and 1200 °C for three hours for phase detection, compressive strength, leaching of Fe, Ni and Cr metals and life cycle assessment. Galvanic sludge, Kao, and RC were also, and heat treated to at 950 °C and 1200 °C for three hours, obtaining GS950, GS1200, Kao950, Kao1200, RC950, and RC1200. The samples were submitted to XRF, XRD, Rietveld refinement, Mössbauer spectroscopy, TG/DTG/DSC, and SEM. The results show that the formation of nickel oxide and a spinel solid solution of the type F e 3 + { F e 1 - y 3 + , F e 1 - x 2 + , N i x 2 + , C r y 3 + } O 4 (in which [] = tetrahedral site, {} octahedral site) occurs in GS1200, which is caused by sulfate decomposition to SO 2. At 1200 °C, heavy metals are encapsulated, forming other phases such as nickel silicate and hematite. Life cycle assessment was used to verify the sustainability and value of GS in clay for making bricks, and it indicated that the production of ceramics is feasible, reduces the use of clays, and is sustainable. [ABSTRACT FROM AUTHOR]

AbstractAddressing the need for sustainable construction materials that minimize environmental impact and reduce CO2 emissions, particularly in OPC compositions. Assessing alccofine and metakaolin in OPC compositions to determine their impact on concrete strength, durability, and microstructure in alkaline environments for sustainable material development. Experimental investigation involved incorporating alccofine and metakaolin into OPC concrete mixes, creating binary and ternary blended systems. Modified concrete specimens were subjected to various alkaline attacks using diluted solutions of magnesium sulfate (MgSO4), sodium sulfate (Na2SO4), and sodium chloride (NaCl) both individually (5%) and in combination (2.5%), resulting in significant improvements in concrete strength and durability. The modified concrete exhibits enhanced resistance to alkaline attacks, reduced weight and compression strength loss, and superior performance in Base Durability Factor (BDF) and Base Attack Factor (BAF) compared to conventional specimens. Scanning electron microscopy (SEM) study of the altered concrete’s microstructure shows that it has a densely packed microstructure, which increases its load-bearing capability. Mineral admixtures aid pore clogging, leading to denser, more alkali-resistant concrete due to finer particles. Notably, Alccofine and metakaolin offer effective solutions for sustainable construction materials, aiding in the decrease of CO2 releases during cement production and addressing critical gaps in sustainable material development. [ABSTRACT FROM AUTHOR]

Geopolymer materials, considered to be an alternative to Portland cement-based concretes, can be produced from various types of waste aluminosilicate raw materials. This article presents the results of research related to the use of diatomite as an additive in geopolymers. The results of testing geopolymer composites with 1%, 3%, and 5% additions of diatomite with a grain size of 0–0.063 mm after and without thermal treatment were presented. This article presents the physical properties of the diatomite additive, the morphology of diatomite particles SEMs, thermal analysis, and compressive strength test results. In this research, diatomite was treated as a substitute for both fly ash and metakaolin (replaced in amounts of 1 and 3%) and as a substitute for sand introduced as a filler (in this case, 5% of diatomite was added). As a result of this research, it was found that the addition of diatomite instead of the main geopolymerization precursors in amounts of 1 and 3% had a negative impact on the strength properties of geopolymers, as the compressive strength was reduced by up to 28%. The introduction of crushed diatomite instead of sand in an amount of 5% contributed to an increase in strength of up to 24%. [ABSTRACT FROM AUTHOR]

In response to the environmental implications of the massive quantities of excavation soil generated by global urbanization and infrastructure development, recent research efforts have explored the repurposing of calcined excavation soils as sustainable supplementary cementitious materials (SCMs). As it is still at an early stage, current research lacks systematic analysis across diverse soil deposits regarding their reactivity and mechanical properties within cementitious binders, despite recognized geographical variability in kaolinite content. Through comprehensive experimentation with soils sourced from four major southern Chinese cities, this study presents a pioneering assessment of the compressive strength, pozzolanic reactivity (X-ray diffraction, Fourier-transform infrared spectroscopy, solid-state nuclear magnetic resonance), and microstructural development (mercury intrusion porosimetry, scanning electron microscopy) of mortars modified by various calcined excavation soils (up to 28 days curing). The experimental data suggest that soils with a kaolinite content above 53.39% produce mortars of equal or superior quality to plain cement mixes, primarily due to their refined pore structures, microstructural densification, and enhanced hydration reactions. The findings highlight kaolinite—specifically, aluminum content—as the principal indicator of excavation soil viability for SCM application, suggesting a promising avenue for sustainable construction practices. [ABSTRACT FROM AUTHOR]

Rapid urbanization in many cities has produced massive amounts of problematic excavation soil. The direct disposal of untreated excavation soil often leads to significant land use and severe environmental concerns. A sustainable solution is to transform the soil waste into high-quality nano-calcined excavation soil (NCES) for application as a substitute for cement in construction. However, research in this area is very limited. This study presents a systematic investigation of the nano-sized calcined soil materials from preparation to application in cementitious material. The influence of milling parameters, including the rotational speed, milling duration, ball diameter, and milling strategy, was investigated to produce NCES with various specific surface areas. The effect of NCES substitution (15 wt% of Portland cement) in cementitious materials was then examined for mechanical performance, hydration dynamics, hydration products, and microstructure. A cement mix with very fine NCES (specific surface area of 108.76 m2/g) showed a 29.7% enhancement in mechanical strength and refined pore structure while a cement mix with un-grounded calcined soil showed a mechanical loss in comparison to the Control specimen. Delayed and reduced heat release at an early age was observed in a cement paste mixed with NCES. The underlying mechanism was investigated. The results of this work will contribute to the high-quality application of excavation soil waste. [ABSTRACT FROM AUTHOR]

Thermal storage materials are typically made of materials with high thermal storage density, high thermal conductivity and high temperature stability. In this study, corundum-mullite composite thermal storage ceramics were prepared by solid-phase sintering using widely available and low-cost α-Al 2 O 3 , kaolin, and quartz as raw materials. The effects of silicon source and Al 2 O 3 /SiO 2 ratio on the physical properties and structural properties of corundum-mullite composite ceramics were investigated. The results showed that the A3 sample (α-Al 2 O 3 : 85.77 wt%, kaolin: 14.23 wt%) after sintering at 1650 °C had the excellent performance, with thermal conductivity of 15.01 W (m K)−1 (25 °C), thermal storage density of 965.15 kJ kg−1, and bending strength of 145.9 MPa. The multiple ions introduced by kaolin can effectively promote the liquid-phase mass transfer at high temperatures, accelerate the diffusion rate of Si4+, increase the growth rate of mullite, and accelerate the densification process of the samples, which in turn improves the physical properties of the samples. When used in a solar thermal storage system, the A3 sample per unit volume can provide 911.53 kW h of electricity to the grid, saving 112.12 kg of coal and reducing 358.78 kg of CO 2 emissions. [ABSTRACT FROM AUTHOR]

High-molecular-weight anionic polyacrylamide was used to analyze the effect of kaolin on the structure of particle aggregates formed in freshwater and seawater. Batch flocculation experiments were performed to determine the size of the flocculated aggregates over time by using focused beam reflectance measurements. Sedimentation tests were performed to analyze the settling rate of the solid–liquid interface and the turbidity of the supernatant. Subsequently, a model that relates the hindered settling rate to the aggregate size was used to determine the mass fractal dimension ( D f ). Flocculation kinetics revealed that greater amounts of kaolin generated larger aggregates because of its lamellar morphology. The maximum size was between 10 and 20 s of flocculation under all conditions. However, the presence of kaolin reduced the settling rate. The fractal dimension decreased with the increase in the kaolin content, resulting in the formation of irregular and porous aggregates. By contrast, factors such as the flocculation time, water quality, and quartz size had limited influences on the fractal dimension. Seawater produced a clearer supernatant because of its higher ionic strength and precoagulation of particles. Notably, the harmful effect of clays in seawater was reduced. [ABSTRACT FROM AUTHOR]

This study utilized several coupled approaches to create powerful algorithms for forecasting the compressive strength (Cs) of concretes that include metakaolin (MK) and fly ash (FA). For this purpose, three various methods were considered, named random forests (RF), Categorical boosting model (CB), and extreme gradient boosting (XGB) by considering the seven most influential input variables. It was tried to divide the concrete components to binder value (B) to achieve the non-dimensional input variables. Herein, the cutting-edge Tasmanian devil Optimization (TDO) algorithm was linked with RF, XGB, and CB for the purpose of determining the optimal values of hyperparameters (named TD - CB, TD - RF, and TD - XG). It is worth mentioning that developing the mentioned algorithms optimized with TD to estimate the mechanical properties of the concrete containing several important admixtures can be recognized as this study’s contribution to practical applications. The findings indicate that the algorithms possess a notable capacity to precisely forecast the Cs of concrete, which includes MK and FA, with R2 bigger than roughly 0.97. The lower value of OBJ comprehensive index belonged to the TD - CB at 1.5762, followed by TD - XG at 1.9943 and then 2.3317 related to TD - RF with almost 70% reduction. The sensitivity analysis demonstrated that the prediction of Cs is highly influenced by all input parameters, which are higher than 0.8659, but a higher influence from MK/B at 0.9548. [ABSTRACT FROM AUTHOR]

Adding fibers into cement to form fiber-reinforced soil cement material can effectively enhance its physical and mechanical properties. In order to investigate the effect of fiber type and dosage on the strength of fiber-reinforced soil cement, polypropylene fibers (PPFs), polyvinyl alcohol fibers (PVAFs), and glass fibers (GFs) were blended according to the mass fraction of the mixture of cement and dry soil (0.5%, 1%, 1.5%, and 2%). Unconfined compressive strength tests, split tensile strength tests, scanning electron microscopy (SEM) tests, and mercury intrusion porosimetry (MIP) pore structure analysis tests were conducted. The results indicated that the unconfined compressive strength of the three types of fiber-reinforced soil cement peaked at a fiber dosage of 0.5%, registering 26.72 MPa, 27.49 MPa, and 27.67 MPa, respectively. The split tensile strength of all three fiber-reinforced soil cement variants reached their maximum at a 1.5% fiber dosage, recording 2.29 MPa, 2.34 MPa, and 2.27 MPa, respectively. The predominant pore sizes in all three fiber-reinforced soil cement specimens ranged from 10 nm to 100 nm. Furthermore, analysis from the perspective of energy evolution revealed that a moderate fiber dosage can minimize energy loss. This paper demonstrates that the unconfined compressive strength test, split tensile strength test, scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) pore structure analysis offer theoretical underpinnings for the utilization of fiber-reinforced soil cement in helical pile core stiffening and broader engineering applications. [ABSTRACT FROM AUTHOR]

Geopolymer concrete (GPC) represents an innovative green and low-carbon construction material, offering a viable alternative to ordinary Portland cement concrete (OPC) in building applications. However, existing studies tend to overlook the recyclability aspect of GPC for future use. Various structural applications necessitate the use of concrete with distinct strength characteristics. The recyclability of the parent concrete is influenced by these varying strengths. This study examined the recycling potential of GPC across a spectrum of strength grades (40, 60, 80, and 100 MPa, marked as C40, C60, C80, and C100) when subjected to freeze–thaw conditions. Recycling 5–16 mm recycled geopolymer coarse aggregate (RGAs) from GPC prepared from 5 to 16 mm natural coarse aggregates (NAs). The cementitious material comprised 60% metakaolin and 40% slag, with natural gravel serving as the NAs, and the alkali activator consisting of sodium hydroxide solution and sodium silicate solution. The strength of the GPC was modulated by altering the Na/Al ratio. After 350 freeze–thaw cycles, the GPC specimens underwent crushing, washing, and sieving to produce RGAs. Subsequently, their physical properties (apparent density, water absorption, crushing index, and attached mortar content and microstructure (microhardness, SEM, and XRD) were thoroughly examined. The findings indicated that GPC with strength grades of C100, C80, and C60 were capable of enduring 350 freeze–thaw cycles, in contrast to C40, which did not withstand these conditions. RGAs derived from GPC of strength grades C100 and C80 complied with the criteria for Class II recycled aggregates, whereas RGAs produced from GPC of strength grade C60 aligned with the Class III level. A higher-strength grade in the parent concrete correlated with enhanced performance characteristics in the resulting recycled aggregates. [ABSTRACT FROM AUTHOR]

The article investigates the high-temperature interaction and sintering processes of samples of low-temperature firing high-alumina for technical ceramics based on the kaolin – alumina-containing component – dolomite ternary system and establishes the areas of formation of high-alumina body for technical ceramics on the ternary diagram. It is shown that as a result of high-temperature interaction, the formation of new crystalline phases of minerals occurs, including mullite, corundum, β-cristobalite, as well as in a small amount of anorthite and an amorphous glassy phase, which impart the necessary physical and mechanical properties to the fired sample. The area of optimal compositions for obtaining low-temperature sintering high-alumina ceramic bodies based on the kaolin – alumina-containing waste – dolomite ternary system was determined. [ABSTRACT FROM AUTHOR]

Mining activities in the kaolin mining area have led to the disruption of the ecological health of the mining area and nearby soils, but the effects on the fungal communities in the rhizosphere soils of the plants are not clear. Three common plants (Conyza bonariensis, Artemisia annua, and Dodonaea viscosa) in kaolin mining areas were selected and analyzed their rhizosphere soil fungal communities using ITS sequencing. The alpha diversity indices (Chao1, Shannon, Simpson, observed-species, pielou-e) of the fungal communities decreased to different extents in different plants compared to the non-kauri mining area. The β-diversity (PCoA, NMDS) analysis showed that the rhizosphere soil fungal communities of the three plants in the kaolin mine area were significantly differentiated from those of the control plants grown in the non-kaolin mine area, and the extent of this differentiation varied among the plants. The analysis of fungal community composition showed that the dominant fungi in the rhizosphere fungi of C. bonariensis and A. annua changed, with an increase in the proportion of Mycosphaerella (genus) by about 20% in C. bonariensis and A. annua. An increase in the proportion of Didymella (genus) by 40% in D. viscosa was observed. At the same time, three plant rhizosphere soils were affected by kaolin mining activities with the appearance of new fungal genera Ochrocladosporium and Plenodomus. Predictive functional potential analysis of the samples revealed that a significant decrease in the potential of functions such as biosynthesis and glycolysis occurred in the rhizosphere fungal communities of kaolin-mined plants compared to non-kaolin-mined areas. The results show that heavy metals and plant species are the key factors influencing these changes, which suggests that selecting plants that can bring more abundant fungi can adapt to heavy metal contamination to restore soil ecology in the kaolin mining area. [ABSTRACT FROM AUTHOR]

Diatomites, or natural soils containing diatoms are found in the marine environment all over the world. Diatomites tend to have skeleton microstructures, resulting in unique rheological behaviors. In marine areas, the rheological behavior of diatomite significantly contributes to geohazards, especially submarine landslides. Predicting and preventing submarine landslides require a profound understanding of the rheological characteristics of diatomites. Therefore, to assess the rheological characteristics of diatomite with different diatom and water contents, we prepared different diatom-kaolin mixtures (diatom contents ranging from 0 to 100% and water contents from 66.8% to 640 %) and subjected them to rheological shearing tests. The Herschel-Bulkley model and the Cheng's model were used to analyze the critical rheological parameters (i.e., dynamic and static yield stresses) and the flow behaviors of the samples. The results show that kaolin mixed with 20% diatoms exhibits the highest value in yield stress. Also, the addition of diatoms alters the microstructure of kaolin which may lead to static yield at low water content and shear thickening at high water content. This study offers valuable references regarding critical rheological parameters and flow regimes for simulating submarine landslides in regions covered by natural sediments containing diatoms. [ABSTRACT FROM AUTHOR]

Open-cell cordierite-based foams with high porosity were synthesized by a facile replica route, using geopolymers as precursors and polyurethane foams as polymer templates. The geopolymer precursors, incorporating MgO as an additional magnesium source, were prepared using metakaolin and fly ash under activation of NaOH solution and sodium silicate solution. Polyurethane foams with geopolymer were obtained by an impregnation method. The hybrid foams comprising polyurethane foam and geopolymer were cured/solidified at 75 °C for 24 h. Subsequently, the hybrid foams were subjected to ammonium ion-exchange followed by sintering at 1200 °C for 2 h to produce porous cordierite-based ceramics. The resulting foamed ceramics were characterized in terms of bulk density, porosity, structural evolution, and mechanical properties. Porous cordierite-based ceramic foams exhibiting a total porosity of approximately 88.64 vol% and a compressive strength of around 0.47 MPa were successfully fabricated by the replica route. [Display omitted] [ABSTRACT FROM AUTHOR]

Severe trauma with massive active blood loss, including liver and spleen rupture, arterial bleeding and pelvic fracture, will lead disability, malformation and even death. Therefore, it is very important to develop new, fast and efficient hemostatic materials. In this study, a novel Gelatin/Kaolin (GE/KA) composite sponge was developed. Meanwhile, to further investigate the effect of kaolin content on sponge properties, we prepared four types of sponges: GE/5% KA, GE/10% KA, GE/15% KA and GE/20% KA. The results of coagulation test in vitro showed that compared to the other groups, there were more activated adhered platelets and red blood cells on the surface of GE/15% KA. The results of hemostasis test in vivo showed that compared to other experimental groups, the GE/15% KA group had significantly less hemostasis time (liver hemostasis model: 69.50 ± 2.81 s; femoral artery hemostasis model: 75.17 ± 3.06 s) and bleeding volume (liver hemostasis model: 219.02 ± 10.39 mg; femoral artery hemostasis model: 948.00 ± 50.69 mg), and was similar to the commercial hemostasis material group. Additionally, the material properties of the sponge were characterized and its biocompatibility was verified as well through cell experiments and in vivo embedding experiments. All these results indicate that the optimal content of kaolin is 15%, which provides a theoretical basis for subsequent research. All in all, the novel GE/KA composite sponge prepared in this study can be used as a multifunctional hemostatic wound dressing for the treatment of complex wounds under various trauma scenes. [ABSTRACT FROM AUTHOR]

Binary and ternary blended mortars were prepared by replacing ordinary Portland cement with varying percentages of MK (10%, 15%, 20%) and NS (1.5%, 3%, 4.5%) to study their performance under elevated temperatures. Superplasticisers were not used to ensure an unadulterated assessment of thermal performance. Heat resistance was evaluated based on the area under the relative residual compressive strength curve concerning temperature. After heat treatment, surface cracking, spalling frequency, and weight loss were assessed. Morphological changes due to elevated temperature exposure were observed through SEM analysis. The findings indicate that the ternary mortar mix with 10% MK and 1.5% NS exhibited the highest thermal resistance. Increased MK and NS proportions resulted in decreased thermal resistance. The mortars remained crack-free until 350°C, with spalling observed at 650°C. Mortar MK10NS3 displayed higher spalling frequency due to its denser pore structure, showcasing the potential of MK and NS in enhancing thermal resistance. [ABSTRACT FROM AUTHOR]

Background: The use of combustible vegetable waste in the manufacture of refractory insulating firebricks has a double advantage: making use of vegetable waste and decreasing the production cost of bricks. Results: Ground date seeds were added to kaolin and grog at different ratios and their blend was mixed with water. The wet mixtures were shaped in steel molds, dried overnight at 90 °C and fired at 1200 °C for 2 h. The physical and mechanical properties of the fired bricks were determined and found to be incompatible with standard values. Small amounts of polystyrene beads and perlite were then added to decrease the bulk density and increase the crushing strength. A mixture composed of 6% date seed, 72.5% kaolin, 17.5% grog, 2.5% perlite and 1.5% polystyrene produced bricks that abided by Indian Standards 2042 requirements regarding their bulk density, porosity, crushing strength, percent linear change on reheat and thermal conductivity at 600 °C. Conclusions: Date seeds have been successfully used as pore generating material in the preparation of Class B insulating firebricks, in a mixture with kaolin, grog and small amounts of polystyrene and perlite. [ABSTRACT FROM AUTHOR]

Biodiesel stands out as a promising contender in the quest for renewable energy solutions, offering a greener alternative to traditional fossil fuels. Derived primarily from the transesterification of vegetable oils or animal fats, biodiesel offers an eco-friendly energy avenue with a minimized carbon footprint. Catalysts are central to the success of this process, which significantly enhance yield rates. Geopolymers, traditionally associated with construction applications due to their inorganic nature, have been derived from aluminosilicate sources activated using alkaline solutions. However, recent advancements spotlight geopolymers in a new light, emphasizing their prospective role as nanocatalytic agents for biodiesel synthesis. This paradigm shift suggests improved production efficiency and an innovative method of repurposing industrial waste. This study centers on the pioneering application of geopolymers, fortified with magnetite, as potent heterogeneous catalysts for biodiesel generation from soybean and safflower oils. By leveraging a meticulously crafted geopolymer matrix—consisting of metakaolin, sodium hydroxide, and magnetite—this research replaced traditional catalysts with this advanced nanostructured geopolymer variant in the biodiesel methylation process. The research delved deep to ascertain the prime synthesis conditions. Furthermore, utilizing cutting-edge machine learning methodologies provided an analytical lens to navigate the extensive experimental data, thereby fine-tuning the optimization trajectory. One of the salient takeaways from this research is the validation that geopolymer catalysts, rooted in kaolinite, can be ingeniously tailored to ensure elevated biodiesel yields across a spectrum of oil sources, underscoring their unparalleled efficiency and versatility in the biofuel domain. [ABSTRACT FROM AUTHOR]

Sticky rice–lime mortar, a representative ancient binding material widely employed in construction applications across Asian countries, has been a subject of substantial academic research and development efforts for its restoration. However, conventional sticky rice–lime mortar is characterized by suboptimal strength and limited toughness, necessitating further enhancements to expand its practical utility. This study presents the formulation of a high-performance sticky rice–lime mortar by incorporating metakaolin and hemp fibers. A comprehensive investigation of various parameters influencing the compressive and flexural properties of the resulting composite was undertaken, encompassing the volume content of hemp fibers, the mass content of sticky rice paste, and the mass content of metakaolin. The experimental outcomes demonstrate the efficacy of metakaolin and sticky rice paste in significantly elevating the compressive strength of the sticky rice–lime composite. Notably, the presented sticky rice–lime mortar attains a remarkable compressive strength of up to 3.5 MPa, exceeding that of conventional sticky rice–lime mortar by more than threefold. Moreover, the introduction of hemp fibers effectively enhances the flexural strength of the sticky rice–lime composite through fiber bridging mechanisms. The research culminates by proposing a relationship equation, derived from the empirical data, to characterize the compressive and flexural strength of the high-performance sticky rice–lime composite. Overall, these findings emphasize the importance of optimizing sticky rice–lime mortar through the integration of advanced constituents, thus highlighting its potential as a durable and versatile binding material for historical preservation and sustainable construction practices within Asian contexts and beyond. [ABSTRACT FROM AUTHOR]

Magnesium phosphate cement (MPC) exhibits a faster setting time and higher early strength, making it suitable for crack repair. However, its application in civil engineering is hindered by its fast initial hydration rate and poor water resistance. To address these limitations, metakaolin (MK) and silica fume (SF) were utilized to enhance the properties of MPC. The effects of MK and SF on the setting time, compressive strength, water resistance, hydration process, and microstructure of MPC were investigated. The results demonstrate that both MK and SF significantly prolong the setting time of MPC and improve its water resistance. The main hydration products of MPC, after incorporating MK and SF, are k‐struvite (MgKPO4·6H2O) and unreacted MgO. The presence of MgSiO3 and AlPO4 also contributes to the enhancement of compressive strength and water resistance. The incorporation of MK and SF actively participates in the hydration reaction of the MPC system. Furthermore, MgSiO3 and AlPO4 intertwine with MKP, resulting in a denser internal structure of the cured MPC, thereby improving its water resistance. [ABSTRACT FROM AUTHOR]

Microbially induced carbonate precipitation (MICP) is an effective method for stabilizing sandy soil. However, this method is not effective for coarse sands. A kaolin-nucleating method was proposed in this study to improve the biotreatment of coarse sands. We comprehensively studied the effect of the kaolin concentration, the volume ratio of the bacterial solution to the cementation solution, the grouting interval between two slurry injections, and the bacterial density on the compressive strength of biotreated coarse sands. We found that the kaolin concentration and the bacterial density are positive factors for enhancing the compressive strength and there are also suitable values for the volume ratio of the bacterial solution to the cementation solution and the grouting interval to improve the biotreatment when other factors are specified. Interestingly, the biotreated condition for the specimen with the maximum strength was identical to that with the maximum ratio of the precipitate volume to the specimen void but different from that with the maximum calcium carbonate content. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) film composites filled with two clays, Raw Kaolin (KAO), an inorganic structure, and Leonardite (LEO), an organic structure, as well as KAO/LEO mixtures, were prepared via solvent casting method. The main aim of this research was to investigate both the individual and the synergetic effects of LEO and KAO; they are incorporated together into a PLA matrix. The influence of these fillers content on the morphological and structural characteristics of the composites was investigated by the DSC, TGA, FT-IR, SEM, XRD, color, haze, and opacity analysis. According to the TGA analysis, significant decreases in Tmax2 were observed with the addition of LEO in PLA. It is also seen in films with KAO/LEO that support this result. Utilizing the solvent casting method, two melting points were formed in PLA films. The P0 film has lower Tg, Tcc, and Tm1 values than other films. However, there were small changes in Tg and Tm2 values in all films. Up to 7.5% amount of LEO and KAO, the mechanical properties of the films improved. The 3L film exhibited the best mechanical properties. The filler materials used were mostly homogeneously distributed, according to the SEM analysis, and as the amount increased, agglomerations were observed in the fillings on the surface. The addition of LEO and KAO changed the surface color, visual appearance, and opacity significantly. The haze values of films are near 100. These film composites have been shown to improve many properties of the P0 film. [ABSTRACT FROM AUTHOR]

• A series of novel chitosan-based magnetic flocculants was prepared by molecular structure control. • Fe 3 O 4 @SiO 2 @CTS-P(AM-DMC) can effectively removal turbidity from 200 to 2000 NTU. • Magnetic flocs form eddy currents and experience acceleration, stabilization, and deceleration stages. • Charge neutralization was dominant under acidic and neutral conditions, while adsorption and bridging effects play an important role in alkaline environments. A series of novel chitosan-based magnetic flocculants FS@CTS-P(AM-DMC) was prepared by molecular structure control. The characterization results showed that FS@CTS-P(AM-DMC) had a uniform size of about 21.46 nm, featuring a typical core-shell structure, and the average coating layer thickness of CTS-P(AM-DMC) was about 5.03 nm. FS@CTS-P(AM-DMC) exhibited excellent flocculation performance for kaolin suspension, achieved 92.54% turbidity removal efficiency under dosage of 150 mg/L, pH 7.0, even at high turbidity (2000 NTU) with a removal efficiency of 96.96%. The flocculation mechanism was revealed to be dominated by charge neutralization under acidic and neutral conditions, while adsorption and bridging effects play an important role in alkaline environments. The properties of magnetic aggregates during flocculation, breakage, and regeneration were studied at different pH levels and dosages. In the process of magnetophoretic, magnetic particles collide and adsorb with kaolin particles continuously due to magnetic and electrostatic attraction, transform into magnetic chain clusters, and then further form three-dimensional network magnetic aggregates that can capture free kaolin particles and other chain clusters. Particle image velocimetry confirmed the formation of eddy current of magnetic flocs and experienced three stages: acceleration, stabilization, and deceleration. [Display omitted] [ABSTRACT FROM AUTHOR]

The utilization of natural clay minerals for the adsorption of endocrine‐disrupting chemicals (EDCs) presents a cost‐effective and environmentally friendly approach. However, the hydrophilic nature of clay minerals' surface limits their efficacy in removing these hydrophobic pollutants. To overcome these limitations, this study employed two cationic surfactants, cetylpyridinium chloride (CPC) and cetyltrimethylammonium chloride (CTAC), to modify kaolin minerals to enhance their capacity to adsorb a specific type of EDCs, bisphenol A (BPA), and its analogs. The experimental results validated that the surfactant‐modified kaolin exhibited remarkable efficiency in removing BPA from water. The equilibrium adsorption capacities of CPC‐K and CTAC‐K for BPA were determined to be 11.4 mg/g (pH = 2.0–8.0) and 13.4 mg/g (pH = 2.0–6.5), respectively. Kinetic analysis revealed that the BPA adsorption followed a pseudo‐second‐order kinetic process, while isotherm analysis suggested that the BPA adsorption was better described by the Freundlich model (R2 = 0.993–0.998). The surfactant‐modified kaolin demonstrated a retention of over 70% of its initial adsorption capacity after five cycles of desorption and regeneration, further confirming its potential for recycling. Additionally, these modified adsorbents exhibited excellent compatibility in removing bisphenol analogs. These findings provide valuable insights into the practical application of surfactant‐modified clay minerals for the elimination of hydrophobic organic pollutants from water. [ABSTRACT FROM AUTHOR]

Tolerably mobile subsea foundations are designed to slide on the seabed to accommodate flowline thermal expansion and contraction, and are a potential alternative to conventional (fixed) foundations. During the periodic sliding events that occur during operation, soil berms form at the extremities of the foundation footprint. The size of the berm increases throughout the life-cycle of the foundation, leading to increasing peak sliding resistance. This may hinder mobility of the foundation and overstress the pipeline connections that the foundation is designed to support. Equally, the berms may be relied on to reduce sliding and thus minimize settlement of the foundation, which can also overstress pipeline connections. This paper analyses the mechanism leading to berm accumulation and its mobilisation, also addressing periodic remoulding and reconsolidation of the sediment in the berm. A framework is proposed to predict the accumulation of soil berms and the resulting peak sliding resistance, and is validated by eight centrifuge model tests performed on a kaolin clay and a calcareous silt. [ABSTRACT FROM AUTHOR]