Search Results (265)

This study explores the use of diatomite from West Kazakhstan as a silica-containing raw material for borosilicate glass production. Three glass batches, based on quartz sand, chalk, and diatomite, were synthesized with varying ratios of network-forming and modifying oxides. Partial replacement of quartz sand with diatomite enabled glass melting at 1150 °C, producing a homogeneous melt. Glasses with higher diatomite content showed improved chemical and water resistance; specifically, the sample containing 52% diatomite achieved hydrolytic class III and water resistance class IV (XA = 1.0 cm³·g⁻¹), whereas quartz-based control samples corresponded to classes IV–V. Heat resistance ranged from 120 to 160 °C depending on composition. These findings demonstrate that amorphous SiO₂ and active oxides in diatomite promote a stronger three-dimensional glass network, highlighting the potential of locally sourced diatomite as an alternative SiO₂ source for sustainable, energy-efficient borosilicate glass production. Full article

Jujube wine production faces the technical challenge of excessive methanol formation due to the high pectin content of the raw material. This study systematically compared five pre-fermentation treatments (pectinase, chitosan, bentonite, gelatin, and diatomite) for their effects on the methanol content and overall quality of jujube wine, aiming to identify an adsorbent pretreatment strategy that effectively reduces methanol levels while preserving wine quality. Using pectinase treatment as a reference control (representing conventional industrial pectin degradation), the results showed that all adsorbent treatments reduced the pectin content in jujube juice, thereby influencing methanol generation in the fermented wine. Notably, chitosan pretreatment exhibited the most pronounced methanol reduction (113.35 mg/L), which was 59.20% lower than that of the pectinase reference group (277.65 mg/L), and remained far below the methanol limits stipulated by Chinese, EU, and OIV standards (≤400 mg/L). This effectiveness is attributed to the positively charged nature of chitosan, which efficiently removes negatively charged pectin through electrostatic adsorption, thereby blocking methanol formation at the source. Chitosan treatment also resulted in the highest alcohol content (5.82%) and significantly reduced organic acid levels but concurrently led to a slight decrease in some key aroma esters. However, sensory evaluation revealed that jujube wine produced from the chitosan-pretreated juice maintained a harmonious overall taste profile, with an overall score comparable to that of the pectinase reference group. In comparison, bentonite and gelatin showed moderate effectiveness, while diatomite performed poorly. Notably, although pectinase treatment yielded the lowest pectin content, it paradoxically resulted in the highest methanol levels, highlighting the critical mechanism of pectin degradation (rather than removal) promoting methanol formation. In conclusion, chitosan was recommended as an effective pre-fermentation treatment strategy for producing jujube wine with a significantly reduced methanol risk. This study provided a theoretical basis and technical reference for the safe, high-quality industrial production of jujube wine. Full article

Decarbonizing the construction sector requires high-volume replacement of Portland clinker with non-calcined supplementary cementitious materials (SCMs). This study investigates white cement pastes incorporating raw Algerian diatomite—a silica-rich biogenic mineral—at substitution levels from 40% to 95% (5% increments) and a fixed water-to-binder ratio of 0.5. The target application is ultra-lightweight, multifunctional composites for non-structural uses such as decorative panels and partition elements. Increasing diatomite content progressively reduced bulk density from 1.483 g/cm³ (D40) to 0.557 g/cm³ (D95) and increased porosity. 28-day compressive strength decreased monotonically from 16 MPa (D40) to 2.4 MPa (D95) as clinker dilution intensified. Ultrasonic pulse velocity dropped from 6205 m/s to 1495 m/s, reflecting progressive pore development and confirming the material’s lightweight potential. Statistically significant strength gains beyond 28 days were recorded ($+25.87\%$ for compression, p-value $< 0.05$), evidencing delayed pozzolanic activity. These results confirm that raw, non-calcined diatomite is a viable SCM for eco-efficient, low-density construction systems. To overcome the extrapolation instability of purely data-driven approaches, a Meta-Avrami Hybrid Framework was developed. It anchors Gradient Boosting residual learning to a sigmoidal Avrami hydration kernel. The model achieved high predictive accuracy ($R^2\approx 0.999$, $\mathrm{RMSE}\approx 0.010$) under 10-fold cross-validation. Generalization was well-controlled, with a low overfitting gap ($\Delta R^2=0.0226$) and stable fold-to-fold performance ($\mathrm{Std}=0.0204$). These metrics confirm suitability for unseen mix designs. This is particularly relevant for service-life assessment of partition panels and lightweight façade elements, where long-term performance guarantees are required. The physics-informed architecture ensures asymptotic strength stabilization up to a 10-year horizon (amplification ratios 1.03–1.05). This prevents the non-physical divergence observed in polynomial and power-law hybrids (ratios 1.36–1.70). The framework provides a reliable and interpretable tool for service-life design of sustainable low-carbon cementitious systems. Full article

This study addresses the pressing issue of high-ammonia nitrogen wastewater, such as landfill leachate, by developing immobilized microbial beads that combine high mechanical strength with efficient denitrification performance. The beads were prepared using a composite of sodium alginate (SA), carboxymethyl cellulose (CMC), and diatomite (DE), with a dual-ion (Ca²⁺-Al³⁺) stepwise cross-linking technique to encapsulate Alcaligenes faecalis. The material ratios were systematically optimized through single-factor and response surface methodology (RSM), identifying the optimal conditions as: SA 2.0%, CMC 1.5%, DE 1.0%, CaCl₂ 2.25%, and Al₂(SO₄)₃ 2.0%. Under these conditions, the beads achieved a mechanical strength of 3.20 N and exhibited an ammonia nitrogen removal rate of 93.10% after 96 h of treating actual landfill leachate (NH₃-N ≈ 1000 mg/L). In conclusion, the SA-CMC-DE dual-ion cross-linked beads demonstrate structural stability and efficient mass transfer, offering an economically viable and novel solution for the treatment of high-ammonia nitrogen wastewater. Full article

A highly effective and economical method to immobilize cadmium in alkaline agricultural soil is urgently needed. Using adsorption kinetic and isotherm experiments, soil incubation tests, and cadmium leaching assays, this study aimed to evaluate the applicability of hydroxyapatite–organic fertilizer composite amendment (HO), individual hydroxylapatite (HA), individual organic fertilizer (OF), sepiolite (SP), and diatomite (DE) to passivate soil cadmium and their passivating effect. In the aqueous phase, HO successfully adsorbed Cd²⁺ onto the surface and has superior potential Cd²⁺ adsorption capacity than OF, DE, and SP, with its adsorption capacity closely approaching that of HA, enabling its use as a passivator in field Cd-contaminated soils. In Cd-contaminated soil, HO effectively lowered the pH from 9.22 to 8.59 at a 5% application rate and changed the aggregate-size distribution of the soil. The increase in the amount of passivator also significantly increased the soil aggregate size. Moreover, the addition of HO significantly improved the extractable contents of Cd in the soil. Compared with the control, the combined amendment decreased TCLP (toxicity leaching procedure test)-extractable Cd by 30.95%, 42.86%, 59.52%, and 69.05% at application rates of 0.5%, 1%, 3%, and 5% (w/w), respectively. These results demonstrate that HO is a highly efficient and low-cost organic–inorganic composite passivator for cadmium-contaminated soils. Full article

Rigid polyurethane (PUR) foams are widely used across multiple industries due to their excellent thermal insulation and mechanical properties. However, their environmental impact, flammability, and limited thermal stability pose challenges for sustainable development. In this study, selected natural minerals—including talc, montmorillonite, halloysite, and diatomite—were incorporated into water-blown polyurethane foams to improve their performance while enhancing sustainability. The prepared foams were characterized in terms of apparent density, water uptake, compressive strength, dimensional stability, and thermal and fire resistance. The results indicate that the inclusion of mineral additives significantly improves the physical and mechanical properties of polyurethane foams, increasing durability, resistance to high temperatures, and fire safety. By using naturally occurring minerals, the study promotes the development of polyurethane foams with reduced environmental footprint, longer service life, and safer application potential in construction, automotive, and heating systems. These findings highlight the contribution of mineral-reinforced polyurethane foams to sustainable materials engineering and resource-efficient industrial applications. Full article

This study investigated the mechanical properties of a boltless hexagonal segment lining structure in TBM tunnels through a 1:10 scale similarity model test. The analysis considered the effects of burial depth and lateral pressure coefficient. A gypsum-diatomite composite simulated C50 concrete segments, and a custom loading system applied equivalent soil-water loads. The tests examined variations in bending moment, axial force and displacement. The results demonstrate that: (1) The tongue-and-groove joints behave like hinges, effectively reducing joint bending moments. (2) The unique staggered interlocking structure induces significantly higher axial forces at the joints than traditional rectangular segments, increasing susceptibility to stress concentration. (3) Increased burial depth has the most significant impact on the tunnel crown, where the bending moment, axial force, and displacement change most notably. (4) The lateral pressure coefficient (λ) alters the joint load transfer mechanism by modifying the structure’s triaxial stress state. An optimal λ of 0.6 maximizes axial force transfer efficiency, while excessively high values impair horizontal load-bearing capacity. (5) Structural failure was ductile, with a final ovality slightly exceeding 10‰. The findings of this study can provide a reference for the design and application of similar boltless hexagonal segment tunnels. Full article

In this study, the milling process of eco-friendly polymer composites enriched with an organic filler was analyzed. Polyhydroxyalkanoate was filled with 0.5%, 1%, and 2% of diatomite and produced via injection molding. Then, the milling process was performed on the obtained samples to determine the effect of diatomite content on the machinability of the produced composites. The results showed that the analyzed diatomite content in the machined samples had no significant influence on the cutting process. If the cutting parameters are not properly selected, excessive heat generated during machining can lead to a heterogeneous geometric surface microstructure. The milling process resulted in a series of high-quality surfaces (Ra < 2 μm), chip temperatures below 90 °C, and a feed component of the total cutting force below 11 N. Full article

Capillary barrier covers (CBCs) have gained widespread application as engineered surface layers in landfill systems, agricultural water retention infrastructures, and slope protection designs due to their superior water storage capacity and lateral drainage characteristics. During the long-term service of CBCs, fine particles may enter into the coarse-grained layer, which affects the water storage capacity and even causes CBCs to fail. Therefore, this study investigated the influence of admixing different types of soils (into the coarse-grained layer) and their proportions on water storage capacity through laboratory soil column experiments. The results indicate the following: (1) A method is proposed to determine the failure of the capillary barrier by utilizing the variation pattern of volumetric water content (VWC) at the fine–coarse-grained layer interface. (2) An effective capillary barrier can only be formed if the saturated permeability coefficient of the coarse-grained layer is at least one order of magnitude greater than that of the fine-grained layer. (3) When the saturated hydraulic conductivity of the fine particles incorporated into the coarse-grained layer is less than 10⁻⁵ cm/s, the matric potential of the fine-grained layer consistently exhibits a CBC line type. When the saturated hydraulic conductivity of the fine particles is greater than 10⁻⁵ cm/s, the matric potential of the fine-grained layer shows a homogeneous line type at an incorporation ratio of 1:0.6. (4) When the particle size of the fine particles mixed into the coarse-grained layer (quartz sand, silt, and diatomite with admixture ratios of 1:0.1, 1:0.3, 1:0.6, and 1:1) is smaller than that of the particles in the fine-grained layer, the water storage capacity of CBCs is only affected by the proportion of fine particles added to the coarse-grained layer and is independent of the type of fine particle used. Full article

Paraffin-based phase change materials (PCMs) have emerged as promising candidates for thermal energy storage (TES) applications due to their high latent heat, chemical stability, and low cost. However, their inherently low thermal conductivity and the risk of leakage during melting–solidification cycles significantly limit their practical performance. To address these limitations, numerous studies have investigated composite PCMs in which paraffin is incorporated into porous supporting matrices. Among these, diatomite has garnered particular attention due to its high porosity, large specific surface area, and chemical compatibility with organic materials. Serving as both a carrier and stabilizing shell, diatomite effectively suppresses leakage and enhances thermal conductivity, thereby improving the overall efficiency and reliability of the PCM. This review synthesizes recent research on paraffin–diatomite composites, with a focus on impregnation methods, surface modification techniques, and the influence of synthesis parameters on thermal performance and cyclic stability. The mechanisms of heat and mass transport within the composite structure are examined, alongside comparative analyses of paraffin–diatomite systems and other inorganic or polymeric supports. Particular emphasis is placed on applications in energy-efficient buildings, passive heating and cooling, and hybrid thermal storage systems. The review concludes that paraffin–diatomite composites present a promising avenue for stable, efficient, and sustainable phase change materials (PCMs). However, challenges such as the optimization of pore structure, long-term durability, and large-scale manufacturing must be addressed to facilitate their broader implementation in next-generation energy storage technologies. Full article

Heavy metal pollution remains one of the major environmental challenges due to the persistence and toxicity of metals such as Pb(II). This study investigates the potential of natural diatomite from Mugaldzhar, Kazakhstan, as a low-cost and sustainable sorbent for lead removal from aqueous solutions. The effects of key parameters, including sorbent dosage, particle size, contact time, temperature, and initial Pb(II) concentration, were systematically examined. Adsorption experiments revealed a maximum adsorption capacity of 74.9 mg/g at 45 °C and an initial Pb(II) concentration of 800 mg/L. The adsorption behavior followed the pseudo-second-order kinetic model, indicating a chemisorption mechanism, while isotherm analysis showed a transition from Langmuir to Freundlich type with increasing temperature. Thermodynamic data confirmed the spontaneous and endothermic nature of the process. These results demonstrate that unmodified natural diatomite exhibits high efficiency for Pb(II) removal, emphasizing its suitability as an eco-friendly and cost-effective material for water purification and environmental remediation. Full article

Activated carbon used as one of the layers of a rain garden may be a promising solution for removing nutrients (nitrogen and phosphorus compounds) from stormwater runoff. Progressive urbanization degrades the quality of stormwater that reaches water collectors. Rain gardens are a potential solution—nature-based systems that retain, infiltrate, and purify stormwater. The aim of this study was to evaluate the effectiveness of a model rain garden in the form of retention columns, depending on the composition of the filling material and the conditions of the simulation. The base column was filled with sand, gravel, and dolomite. The next two columns were enriched with diatomite, in a weight ratio to sand of 1:4 and 1:2, respectively. The experiment was based on four scenarios: (1) 30 min of heavy rain, (2) 2 h of rain after a drought, (3) during standard operation, and (4) with modification of the filtration material. This modification consisted of a uniform addition of granular activated carbon (GAC), which was intended to influence the column performance. The characteristics of the activated carbon were determined using XRD, SEM-EDS, and BET analysis. Pollutant concentrations were determined using a spectrophotometer and ion-selective electrodes. The analyses confirm the significant impact of the column filling materials on the efficiency of nutrient removal from stormwater, achieving even complete removal of phosphate ions, while nitrate ions were removed at a level of almost 40% and ammonium ions at >90%. Full article

Microbial herbicides, recognized for their target specificity, environmental compatibility, and simple production processes, hold promising potential for sustainable agriculture. This study isolated a strain of Alternaria gaisen (designated GD-011) from infected Medicago sativa L. in Qinghai Province, China, and evaluated its herbicidal potential through systematic development and efficacy assessment. Using single-factor and orthogonal experimental designs, the optimal sporulation substrate was identified as wheat bran, and the fermentation medium was optimized to consist of 14.5 g wheat bran, 19.4 g wheat middlings, 1.5 g rapeseed cake, and 14.6 g corn flour. Based on colony diameter and OD₆₀₀ measurements, diatomite was selected as the most suitable carrier, while bentonite, humic acid, and polyvinyl alcohol were chosen as the stabilizer, protectant, and dispersant, respectively. Pot trials under controlled conditions demonstrated strong herbicidal activity of GD-011 against three common weed species: Chenopodium album L., Elsholtzia densa Benth., and Galium aparine L. The highest efficacy was observed against C. album, with disease incidence and fresh weight inhibition reaching 80.83% and 79.87%, respectively. Inhibition rates for both E. densa and G. asparine exceeded 60%. A wettable powder formulation developed from GD-011 showed particularly effective control of C. album and E. densa, providing a practical foundation for the application of GD-011 as a novel bioherbicide. Full article

This research is to assess the potential use of phosphate sludge from the Gafsa (Tunisia) phosphate laundries as an alternative raw material for the manufacture of ecological refractory bricks. Feasibility was evaluated through comprehensive physico-chemical and mineralogical characterizations of the raw materials using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and thermal analysis (TGA-DTA). Bricks were formulated by substituting phosphate sludge with clay and diatomite, then activated with potassium silicate solution to produce geopolymeric materials. Specific formulations exhibited mechanical performance ranging from 7 MPa to 26 MPa, highlighting the importance of composition and minimal water absorption values of approximately 17.8% and 7.7%. The thermal conductivity of the bricks was found to be dependent on the proportions of diatomite and clay, reflecting their insulating potential. XRD analysis indicated the formation of an amorphous aluminosilicate matrix, while FTIR spectra confirmed the development of new chemical bonds characteristic of geopolymerization. Thermal analysis revealed good stability of the materials, with mass losses mainly related to dehydration and dehydroxylation processes. Environmental assessments showed that most samples are inert or non-hazardous, though attention is required for those with elevated chromium content. Overall, these findings highlight the viability of incorporating phosphate sludge into fired brick production, offering a sustainable solution for waste valorization in accordance with the circular economy. Full article

This paper presents the development and characteristics of geopolymer foams modified with paraffin-based phase change materials (PCMs) encapsulated in diatomite. The aim was to increase both the thermal insulation and heat storage capacity of the foams while maintaining sufficient mechanical strength for construction applications. Eleven variants of composites with different PCM fractions (5–10% by mass) and grain sizes (<1.6 mm to >2.5 mm) were synthesized and tested. The inclusion of PCM encapsulated in diatomite modified the porous structure: the total porosity increased from 6.6% in the reference sample to 19.6% for the 1.6–1.8 mm_10% wt. variant, with pore diameters ranging from ~4 to 280 µm. Thermal conductivity (λ) ranged between 0.090–0.129 W/m·K, with the lowest values observed for composites 2.0–2.5 mm_5–10% wt. (≈0.090–0.091 W/m·K), which also showed high thermal resistance (R ≈ 0.287–0.289 m²·K/W). The specific heat (Cp) increased from 1.28 kJ/kg·K (reference value) to a maximum value of 1.87 kJ/kg·K for the 2.0–2.5 mm_10% mass variant, confirming the effective energy storage capacity of PCM-modified foams. Mechanical tests showed compressive strength values in the range of 0.7–3.1 MPa. The best structural performance was obtained for the 1.6–1.8 mm_10% wt. variant (3.1 MPa), albeit with a higher λ (≈0.129 W/m·K), illustrating the classic trade-off between porosity-based insulation and mechanical strength. SEM microstructural analysis and mercury porosimetry confirmed the presence of mesopores, which determine both thermal and mechanical properties. The results show that medium-sized PCM fractions (1.6–2.0 mm) with moderate content (≈10% by weight) offer the most favorable compromise between insulation and strength, while thicker fractions (2.0–2.5 mm) maximize thermal energy storage capacity. These findings confirm the possibility of incorporating natural PCMs into geopolymer foams to create multifunctional materials for sustainable and energy-efficient building applications. A unique contribution to this work is the use of diatomite as a natural PCM carrier, ensuring stability, compatibility, and environmental friendliness compared to conventional encapsulation methods. Full article