Diatomite Particles Research Articles

The Influence of Diatomite on the Sound Absorption Ability of Composites.

Diatomites are well-known mineral materials formed thousands of years ago from the skeletons of diatoms. They are found in many places around the world and have a wide range of applications. This article presents innovative research related to the possibility of using diatomite as a filler in composites to improve their sound absorption properties. The results of the study of the effect of diatomite processing (calcination) and its degree of fineness on the sound absorption coefficient of thermoplastic composites are presented. Three fractions of diatomite (0 ÷ 0.063 mm; 0.5 ÷ 3 mm; 2 ÷ 5 mm) and its variable mass proportion (0, 25, and 50 wt.%) were used. The composites were made with flax fibers as a reinforcement, polylactide as a matrix, and diatomite as an additional filler. This paper also presents the results of oxide chemical composition, diatomite mineral phase composition, morphology, and thermal conductivity coefficient of all diatomite fractions studied. In addition, the average particle size for diatomite powder was also determined. The most important of the studies was the determination of the acoustic properties of the aforementioned composites. As a result of the tests, it was found that the smallest fraction of diatomite particles and a variant without thermal treatment give the best effect in terms of sound absorption.

Stability performance of an Algerian Ni/purified diatomite catalyst in the dry reforming methane reaction: characterization and properties

AbstractThis work aims to characterize and study the properties of an Algerian diatomaceous earth (Sig-Mascara) as a catalyst carrier. A commercial product of diatomite was characterized by granulometric analysis, X-ray fluorescence, X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis/differential scanning calorimetry and scanning electron microscopy/energy-dispersive X-ray spectroscopy methods. To purify the diatomite and remove the impurities (iron oxides, clay minerals, quartz and organic matters), the <63 μm fraction of the diatomite was separated out. The 15Ni/Ds-700 catalyst has lower SiO2, Al2O3 and CaO contents compared with the original diatomite. The NiO content of the catalyst is 15 wt.%, indicating successful impregnation. According to the nitrogen sorption–desorption results, the specific surface area of the purified diatomite particles (<63 μm) increased from 26.47 to 46.33 m2 g–1 compared to crude diatomite. The 15Ni/Ds-700 catalyst was applied in the dry reforming of methane to obtain synthesis gas (CO and H2). The results showed that the catalyst was relatively stable during catalytic measurements for 6 h, although the conversion rate value was low (12%).

The Influence of Diatomite Addition on the Properties of Geopolymers Based on Fly Ash and Metakaolin.

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%.

Feasibility of compacted attapulgite/diatomite amended clayey soils as gas barrier materials

Compacted clay liners are extensively used as barriers to control the upward diffusion of vapors of volatile or semi-volatile organic contaminants released from unsaturated contaminated soils at industry-contaminated sites. This study aimed to investigate the gas diffusion barrier performance of compacted clayey soils amended with three agents including attapulgite and diatomite individually, and attapulgite/diatomite mixture. The properties including water retention, volumetric shrinkage, gas diffusion, and unconfined compressive strength were evaluated through a series of laboratory tests of amended compacted clayey soils. The results demonstrate that the decrease in volume proportions of inter-aggregate pores leads to an increase in unconfined compressive strength (qu). Both hydrophilic groups and microstructures of attapulgite and diatomite result in an increase in water retention percent (Wt) of compacted clayey soil specimens after amendment regardless of the type of agent or initial water content (w0). Furthermore, the ratio of the gas diffusion coefficient (De) to the gas diffusion coefficient in the air (Da) was significantly reduced owing to a decrease in volume proportions of inter-aggregate pores, hydrophilic group, and microstructures of attapulgite and diatomite. Scanning electron microscope analyses revealed that rod-shaped attapulgite filled the inter-aggregate pores formed by clay particles, whereas the disc-shaped diatomite particles, characterized by micropores, failed to obstruct the inter-aggregate pores due to their larger particle size. Mercury intrusion porosimetry (MIP) analyses showed a reduction in pore volume in the inter-aggregate pores, leading to a reduction in the total pore volume for both the attapulgite and attapulgite/diatomite mixture amended clays, which is in accordance with the scanning electron microscope (SEM) results. The findings are pertinent to the practical application of compacted clay liners as gas barriers against the upward migration of volatile or semi-volatile organic contaminants at contaminated sites.

Preparation of super-amphiphilic waterborne polyurethane diversion mesh coatings with diversion properties and their excellent preservation properties on L. japonicus fillets

To isolate the exudates from food and reduce the secondary pollution of the exudates during transport and storage, a conductive coating with super-amphiphobic properties was constructed. A series of waterborne polyurethane (WPU) mesh coatings with different hydrophobic and oleophobic properties were prepared by impregnation method using diatomite (DE) particles and kaolin (K) particles to construct rough structure, using 1H, 1H, 2H, 2H-perfluorooctane trichlorosilane (PFOTS) to reduce the surface energy. They were characterized and their properties were measured. The modified K/WPU mesh coating (mK/WPU mesh coating) surface shows super-amphiphobic with micro-nano structure. Moreover, the super-amphiphobic mK/WPU mesh coating shows the best conductivity in the same water absorption medium. When the coatings were used as the diversion layer of the preservation pad, they can delay the decrease of sensory score and WHC, and the increases of TVC, pH, TBA and TVB-N of L. japonicus fillets. Meanwhile, it can delay the color changes and texture deterioration of the fish fillets. Among them, the mK/WPU mesh coating preservation pad has the best preservation properties that could extend the shelf life of refrigerated L. japonicus fillets 5 d–10 d, and has application potential.

Flexibility and abrasion tolerance of superamphiphobic coatings with rigid core–shell particles

Superamphiphobic coatings maintain surfaces clean even facing severe oil contamination, which is crucial for ensuring the lifespan of materials in highly polluted environments. Achieving excellent wear resistance and flexibility individually on superamphiphobic surfaces is relatively simple, but simultaneously obtaining both properties is challenging and often requires compromises. In this study, we develop an innovative approach inspired by “overcoming firmness by gentleness” to create superamphiphobic composite coatings with flexibility and abrasion tolerance. This innovative strategy combines a soft polyurethane resin with rigid diatomite/aluminum hydroxide (core–shell) particles, resulting in a coating structure resembling karst topography. Depositing aluminum hydroxide enhances the reactivity and content of hydroxyl groups on diatomite particles, simultaneously improving the hardness and 1H,1H,2H,2H-Perfluorodecyltrichlorosilane (FDTS) grafting degree of the core–shell particles. Residual hydroxyl groups on the semi-fluorination core–shell particles chemically bond with the isocyanate groups in the waterborne polyurethane resin, leading to enhanced crosslinking density and improved wear resistance of the coating. The top coating of F-SiO2 particles leads to a reduction in the surface energy of the core–shell coating. The obtained core–shell coating demonstrates excellent oil resistance even after 800 cycles of Taber abrasion under a load of 250 g and 1000 cycles of 360° bending, demonstrating remarkable wear resistance and flexibility simultaneously. This approach provides valuable insights for developing superamphiphobic composite coatings with flexibility and abrasion tolerance and opens new possibilities for their applications in flexible electronics and droplet manipulation.

Simultaneously realizing enhancement of sensitivity for freshness monitoring and multinomial properties of carrageenan/konjac glucomannan/blueberry anthocyanin-based intelligent film by diatomite

Here, highly sensitive blueberry anthocyanin (BBA)-induced intelligent indicating films were fabricated by incorporating a novel composite ingredient, diatomite (DA), into a matrix of konjac glucomannan (KGM), carrageenan (CAR) and BBA. We systematically investigated the effects of introducing DA and BBA on the structure, physical properties, colorimetric response, and practical application of the KGM/CAR film. Our findings revealed that the DA particles and BBA were well-distributed in the KGM/CAR matrix through hydrogen bonding interactions. This distribution significantly improved tensile strength, surface hydrophobicity, thermal stability, and barrier properties of the KGM/CAR film. Notably, the KGM/CAR-based intelligent film loaded with 6 % DA exhibited the most optimal properties. Furthermore, DA exhibited a hierarchical porous structure, enabling the KGM/CAR film to detect volatile amines with heightened sensitivity. When applied to monitor shrimp spoilage in transparent plastic packaging, the color of the composite film underwent remarkable changes from bright pink to bluish violet. These color changes correlated well with the total volatile basic nitrogen (TVB-N) and pH changes in the shrimp, as determined by standard laboratory procedures. Our work presents a promising approach to the development of high-performance and intelligent food packaging materials. These materials hold great potential for practical applications in the field of food packaging.

Study on the Characteristics and Influencing Factors of Hydrophobicity Transfer of Superhydrophobic Coating

Insulators covered with superhydrophobic coatings have better anti-pollution flashover performance. In high-pollution areas, the superhydrophobic coating gets covered with a contamination layer. The droplets are in contact with the contamination layer instead of the superhydrophobic coating. However, there is still a lack of relevant research on the hydrophobicity of the contamination layer. It is not conducive to evaluating the functional performance of superhydrophobic insulators in high-pollution areas. Choose diatomite to simulate contamination. The effects of fouling time, environment temperature, diatomite density, and impurity (NaCl) on the hydrophobicity of the contamination layer are analyzed experimentally. The experiment results show that the diatomite layer becomes hydrophobic over time. The higher the temperature is, the faster the hydrophobicity of the contamination layer will increase, and the higher the peak value of the static contact angle will be. However, the diatomite density and the exitance of NaCl have little influence on the hydrophobicity of the diatomite layer. Furtherly, the composition of the superhydrophobic coating is found in the diatomite layer, which proves the existence of hydrophobicity transfer. According to theoretical analysis, the appearance of transfer will enhance the hydrophobicity of diatomite particles. When the angular coordinate of the liquid-protrusions-gas triple line is greater than 90°, the mechanical conditions for the diatomite particles carried away by the droplet can be satisfied. As a result, hydrophobic diatomite is attached to the droplets’ surface.

Possibility of using unshaped thermal insulation of aluminum alloy castings

The possibility of using diatomite from the Ilyinsky deposit as an unshaped thermal insulation for open risers of castings from aluminum alloys of different alloying systems: technical aluminum A5, AK7, AMg10, VAL10 has been studied. It was found that when the continuity of the oxide film on the surface of a diatomite particle is broken, an exchange reaction occurs with the formation of a silicon transition layer. Since silicon is wetted by aluminum, the diatomite particle sinks in the melt, forming a blockage. As a criterion for the continuity of the oxide film, it is proposed to use the Pilling‒Badworth factor of the alloy components. It has been shown that a high level of the Pilling‒Badworth factor, even at a low content of the component (~ 1 %), leads to the formation of blockages. Ill. 6. Ref. 12. Tab. 1.

Superhydrophilic/air-superoleophobic diatomite porous ceramics for highly-efficient separation of oil-in-water emulsion

Facile, eco-friendly and effective separation of oil-in-water emulsion under various conditions is urgently desired. In this work, novel 3D superhydrophilic/air-superoleophobic diatomite porous ceramics (3DSSPC) with superior separation performance for surfactant-stabilized oil-in-water emulsions were successfully fabricated via a foam gelcasting-freeze drying and subsequent surface modification approach. SiO2 whiskers in-situ generated on the surface of disc-like diatomite particles increased the roughness of the porous ceramics, which, along with the organic film formed on their surface, conferred excellent superhydrophilic and air-superoleophobic properties. The continuous separation efficiency of the 3DSSPC for the surfactant-stabilized edible oil-in-water emulsion (oil concentration of 5 wt%) was higher than 99%, with a flux of 5.06 kg·m−2·s−1 ( 18,200 L·m−2·h−1), more importantly, the separation flux for an industrial oil-in-water emulsion containing suspended particles was as high as 5.69 kg·m−2·s−1 ( 20,500 L·m−2·h−1). In addition, the microstructure, superoleophobicity and separation efficiency of the 3DSSPC changed little even after 20 separation cycles. The good mechanical strength and outstanding chemical stability in strong acidic, alkaline, concentrated salty solutions and at high/low-temperature make the 3DSSPC a promising candidate for future treatments of industrial wastewater containing emulsified oil-in-water liquids.

Biocomposites Based on Polyamide 11/Diatoms with Different Sized Frustules.

Amorphous diatomite was used as a filler for a thermoplastic polymer of polyamide 11 obtained from natural sources. The diatomite particles of different sizes were previously fractionated by sedimentation to obtain powders with varying particle size distribution, including powders with or without frustule particles, crushed, uncrushed or agglomerated. Biocomposites containing 2.5, 5, 10 and 20% filler were tested for their mechanical properties, including tensile strength, flexural strength and impact strength. In addition, a particle size analysis (by Dynamic Light Scattering, DLS) was performed and the dispersion of the filler in the polymer matrix (Scanning Electron Microscopy, SEM), thermal parameters (Differential Scanning Calorimetry, DSC, and Dynamic Mechanical Analysis, DMA) were determined. Testing showed that biocomposites modified with diatomaceous earth have a higher mechanical strength than the reference system, especially with larger amounts of the filler (10 and 20%), e.g., the tensile strength of pure PA11 is about 46 MPa, while 20OB and 20OF 47.5 and 47 MPa, respectively, while an increase in max. flexural strength and flexural modulus is also observed compared to pure PA11 by a maximum of 63 and 54%, respectively Diatomaceous earth can be obtained in various ways—it is commercially available or it is possible to breed diatoms in laboratory conditions, while the use of commercially available diatomite, which contains diatoms of different sizes, eliminates the possibility of controlling mechanical parameters by filling biocomposites with a filler with the desired particle size distribution, and diatom breeding is not possible on an industrial scale. Our proposed biocomposite based on fractionated diatomaceous earth using a sedimentation process addresses the current need to produce biocomposite materials from natural sources, and moreover, the nature of the process, due to its simplicity, can be successfully used on an industrial scale.

Endosulfan Elimination Using Amine-Modified Magnetic Diatomite as an Adsorbent.

Pesticides are among the most dangerous developing toxins since they are very hazardous to the environment and threaten human health. In this study, researchers successfully manufactured surface-modified magnetic diatomite (m-DE-APTES) and used them as a sorbent to extract endosulfan from an aqueous solution. There is no other study like it in the scholarly literature, and the results are astounding. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), electron spin resonance (ESR), and surface area measurements were used to analyze magnetic diatomite particles with surface modification. According to the analysis results, magnetic diatomite has a wide surface area and a porous structure. Furthermore, m-DE-APTES has a higher endosulfan adsorption capacity (97.2 mg g−1) than raw diatomite (DE) (16.6 mg g−1). Adsorption statistics agree with Langmuir adsorption isotherm (R 2 = 0.9905), and the adsorption occurred spontaneously at −2.576 kj mol−1 in terms of ΔGo. Finally, m-DE-APTES are a viable alternative adsorbent for removing pesticides from aqueous solutions.

Diatom biosilica in plasmonics: applications in sensing, diagnostics and therapeutics [Invited

Several living organisms are able to synthesize complex nanostructures provided with peculiar physical and chemical properties by means of finely-tuned, genetically controlled biomineralization processes. Frustules, in particular, are micro- and nano-structured silica shells produced by ubiquitous diatom microalgae, whose optical properties have been recently exploited in photonics, solar energy harvesting, and biosensing. Metallization of diatom biosilica, both in the shape of intact frustules or diatomite particles, can trigger plasmonic effects that in turn can find application in high-sensitive detection platforms, allowing to obtain effective nanosensors at low cost and on a large scale. The aim of the present review article is to provide a wide, complete overview on the main metallization techniques applied to diatom biosilica and on the principal applications of diatom-based plasmonic devices mainly but not exclusively in the fields of biochemical sensing, diagnostics and therapeutics.

Preparation of Adsorbent Based on Polyacrylate Latex Solid Waste and Its Application in the Treatment of Dye Wastewater.

It is a great challenge to sustainably produce and apply water-based coatings and inks in terms of realizing the green resource utilization of polyacrylate latex solid waste (PLSW) and avoid its secondary pollution. In this paper, a kind of high value-added amphoteric ion-exchange resin (AIER) was prepared by using diethylenetriamine to amidate PLSW under the optimized conditions from a Box-Behnken design. Its adsorption and regeneration properties and the universality of the method were investigated. The results suggested that AIER possessed a high removal efficiency to anionic dyes, and the batch dye adsorption processes were endothermic and spontaneous, which is consistent with a pseudo-second-order kinetic model. The penetration adsorption capacities of AIER were recorded to be 987.08 mg/g for RR239 and 1037.75 mg/g for RB5 at the optimized operating conditions of column height = 6.4 cm, flow rate = 1 mL/min, and dye solution of 500 mg/L. They were more than 200 times larger than that of commercial activated carbon when the mixture composed of AIER particle and diatomite particle (filter aid agent) was used as a fixed-bed adsorbent. Zeta potential analysis results indicated that the good adsorption and regeneration performances of AIER were mainly attributed to the presence of amino and carboxyl groups in the molecular structure of AIER. Most importantly, this method possessed excellent practicability and universality for different types of PLSW from factory wastewater. The results provide a feasible method and theoretical basis for the green resource utilization of PLSW, and the goal of “waste control by waste” was fundamentally achieved.

Oil-in-water high-internal-phase poly(styrene-acrylate) Pickering emulsions and their applications as waterborne damping coatings

Herein, we report the synthesis of a series of oil-in-water high-internal-phase Pickering emulsions (HIPEs) within styrene and acrylate as monomer and oil phases, using composite stabilizers containing hydrophobic modified diatomite particles and small molecular surfactants. Internal-phase HIPE levels of up to 80 wt% were achieved, which was far higher than those of conventional emulsions. Meanwhile, the mechanical performance, thermal stabilities, and damping capacities of polymer films prepared using these HIPEs were superior to those of polymer films prepared using conventional emulsions. Synergistic emulsification of the composite stabilizer was found to be crucial for stabilizing the emulsion during HIPE synthesis and for improving the mechanical and damping performance of the polymer films.

Removal of europium, cobalt and strontium from water solutions using MnO(OH)-modified diatomite

The paper describes researches on new materials based on the MnO(OH)-modified diatomite synthesized for application in sorption of Eu, Co and Sr from aqueous solutions. The material was obtained through precipitation of MnO(OH) from initial solution on the surface of diatomite particles using MnO(OH) concentrations from 0.5 up to 10 wt%. Efficiency and sorption capacity were investigated, especially towards europium, cobalt and strontium solved in water. Since sorption efficiency of the pure diatomite is not high, it was demonstrated that its surface modification with MnO(OH) increased sorption capacity towards several heavy metals up to 95% and 98% in the range of pH between 4 and 8. Higher concentrations of MnO(OH) deposited on the diatomite particles surface increased sorption capacity. It was found that 1 wt% of MnO(OH) provided capacity 15, 10, and 17 mg/g towards Co, Eu, and Sr, respectively. Further, 10 wt% concentration of MnO(OH) ensured respective capacities toward the same elements 28, 16, and 64 mg/g. These results demonstrated capability of surface-modified with MnO(OH) diatomite particles to remove ions of divalent and trivalent metals out of the potable water.

Diatomite‐filled epoxy resin composites: Curing behavior, dielectric, and thermal properties

AbstractIn this study, a kind of novel curing agent composed of acrylic acid and 4,4′‐(hexafluoroisopropylidene)bis(p‐phenyleneoxy)dianiline was mixed, with different contents of diatomite (CP) particles, into the epoxy resin (E51) to obtain bio‐composites that can be rapidly molded and cured at room temperature. Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry were used to study the curing behavior of epoxy resin and bio‐composites. The influence of CP particle dosages on the mechanical, including tensile, flexural and impact properties, and thermal properties of the prepared composites were discussed. Thermogravimetric analysis result showed that the thermal stability increased with increasing of CP fillers content. Dielectric property tests confirmed that the dielectric constant of composites decreased attributed to the incorporating of novel curing agent and CP fillers with porous structure into epoxy resin. Finally, Scanning Electron Microscope revealed the excellent adhesion between the cured resin and the fillers.

Optimization of mechanical, thermo-mechanical, melt-flow and thermal performance of TPU green composites by diatomaceous earth content

In the present paper the effect of the diatomite, also known as diatomaceous earth and kiesel guhr (KG), content on mechanical, thermo-mechanical, melt-flow and thermal performance of thermoplastic polyurethane-based composites was investigated. Composites were fabricated by melt blending method with 10, 20, 30 and 40% filling ratios of KG. and injection molded test samples were characterized using tensile, hardness, dynamic mechanical analysis (DMA), melt flow index (MFI), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) analysis. According to test results, KG inclusions effect mechanical, thermal and morphological properties of composites positively up to 30% KG content. Further addition of KG caused remarkable reductions in related properties. Tensile strength of unfilled TPU exhibited increasing trend and elongation showed no obvious difference after KG loadings. TPU/KG composites yield relatively higher MFI values with respect to unfilled TPU. Glass transition temperature of TPU shifted to 6 points higher value by the help of KG incorporation. TGA findings revealed that KG additions caused improvement for thermal stability of TPU. Homogeneous dispersion of KG particles for their lower content, whereas agglomorate formations for higher loading level of KG were confirmed by SEM micrographs. TPU composite containing 10% KG showed the highest results among samples. • Diatomite additions yield positive impact on mechanical and thermal behaviors of polyurethane elastomer. • Thermal stability of TPU was enhanced by inclusion of diatomaceous earth. • Composites exhibited higher MFI parameter compared to TPU which was attributed to porous structure of diatomite. • Homogeneous dispersion of diatomite particles into TPU matrix at lower filling ratios was confirmed by SEM analysis.

Pickering emulsion strategy to control surface wettability of polymer microspheres for oil–water separation

Surface wettability, one of the most important parameters for oil–water separation, depends on the chemical composition and surface roughness of a material. Herein, the Pickering emulsion template method is proposed to control the surface wettability of polymer microspheres. Upon the dispersion of modified diatomite particles in the aqueous phase, a superhydrophobic surface was formed on the polymer microspheres via Pickering emulsion polymerization, with a water contact angle of 152°. When the initial dispersion location of the modified diatomite particles changed from water to oil, a hydrophilic/underwater superoleophilic surface with micro/nanoscale hierarchical structures formed on the polymer microspheres. This special wettability enabled the microsphere layer to serve as an adsorbent with underwater superoleophilicity, achieving efficient oil separation from various oil-in-water emulsions with high separation efficiency of >99.8%. Hence, this study provides a valuable strategy based on the Pickering emulsion template method to design materials with special wettability for realizing promising emulsion separation.

Fluorescent Polyimide Films Produced with Diatomite and Mesoporous Silica as Promising High-Tech Material

Due to their excellent properties, polymides (PIs) result promising as high-performance materials in different technological fields. In this research, both micron-sized tubular mesoporous silica (mSiO2) and double-tube tubular diatomite particles with cadmium sulfide quantum dots are prepared by chemical deposition method. A cluster of type fluorescent particles is prepared by self-assembling carbon quantum dots (CDs) on the inner surface of the above materials. Then, a fluorescent polyimide film is prepared by uniform dispersion of fluorescent particles. The study of different properties of the film becomes then mandatory to evaluate possible application perspectives. Therefore, after synthesizes, all samples were investigated in term of chemical structure, microstructure and fluorescence properties by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and fluorescence spectrophotometry. Fluorescence performance of diatomite-based fluorescent particles (diatomite@CdS@CDs) results not as good as the mSiO2-based fluorescent particles (mSiO2@CdS@CDs) ones; the mechanical properties of the composite film deteriorate as the content of the inorganic component increases. The performance of PI/mSiO2@CdS@CDs is 7.6 times the PI/diatomite@CdS@CDs ones.