Surface Of Diatomite Research Articles

Experimental study on inhibiting methane-coal dust explosion by APP-diatomite composite explosion suppressant in the pipe network

To prevent and control the methane/coal dust compound explosion disaster, the APP-diatomite composite powder inhibition of methane/coal dust compound explosion experiments were carried out in the self-constructed pipe network. The composite powder was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The change rules of methane/coal dust composite explosion pressure and flame propagation velocity were analyzed using different compounding ratios of powders in several monitoring points. The results show that the composite powder exhibited irregular morphology and the APP powder is uniformly distributed on the diatomite porous mesh structure. When the APP loading on the surface of diatomite is 40 wt%, composite powder has the best effect on explosion suppression, with the peak maximum explosion overpressure and the peak maximum flame propagation velocity reduced by 71.5% and 92.2%, respectively. The explosion suppression mechanism is revealed through pyrolysis properties, explosion products, and chain reaction.

Regulating pore structure of diatomite with alkali dissolution and its influence on humidity control performance

Alkali dissolution is an effective method to regulate the pore structure of porous mineral material. The main chemical composition of diatomite is amorphous SiO2, which can be dissolved in alkali dissolution. The diatomite samples with alkali dissolution treatment were systematacially characterized by the particle size analysis, low temperature nitrogen adsorption, MIP, fractal theory, SEM, TEM, XRD, FTIR and surface hydroxyl density to analyze the pore structure and surface properties. And the humidity control performance of diatomite was tested under different temperatures and relative humidities. The relationship among pore structure, surface properties and humidity control performance were analyzed. The results show that alkali dissolution can regulate the mesoporous and macroporous of diatomite, and some new microporous can generate at high alkali dosage. The specific surface area, mesoporous pore volume, proportion of macroporous volume, surface roughness, heterogeneity of pore structure and number of hydroxyl groups on the surface of diatomite are important factors which determining the humidity control performance. The humidity control performance of diatomite is positively correlated with the specific surface area, mesoporous volume, surface roughness, heterogeneity of pore structure and number of hydroxyl groups on the surface, while is negatively correlated with the proportion of macroporous volume.

Diatomite supported highly-dispersed ZnO/Zn-co-embedded ZIF-8 derived porous carbon composites for adsorption desulfurization

The metal organic framework (MOFs)-derived porous carbon materials with highly dispersed metal active sites were of the exclusive application foreground in many field, such as catalyst, electrochemistry, adsorption desulfurization and so on. However, the loss issue of metal active sites in MOFs frame was indispensable during the high temperature carbonization because of the lower boiling point of many metals, thus fundamentally affecting the atom-scale uniform distribution merit of MOFs-derived porous carbon materials. This work was to provide a novel strategy to address the loss issue of the active metal volatilization in the fabrication of MOFs-derived porous carbon materials. The ZnO nanosheets were pre-grown on the surface of diatomite by using in-situ microwave-assisted preparation, and thereafter the Zn-containing ZIF-8 particles covered the surface of ZnO nanosheets by virtue of the ZnO-induced growth. The results affirmed that the high content Zn-doped porous carbon materials were achieved and the Zn volatilization in MOFs was restrained on account of the occurrence of ZnO on diatomite (DE) surface during the carbonization. The adsorption desulfurization performance of the ZnO/Zn-embedded porous carbon materials/DE (ZnO/Zn/C@DE) was examined by the sulfur-containing compounds in simulated oil. The adsorption desulfurization performance investigation indicated that the ZnO/Zn/C@DE had the optimum adsorption capacities of 45.3 mg/g for benzothiophene and 37.4 mg/g for thiophene. Nonetheless, the competitive adsorption desulfurization finding of toluene in simulated oil showed that the adsorption capacities of ZnO/Zn/C@DE for TH and BT were dramatically descended, suggesting the presence of S-M interaction, wherein S stood for the S atom in a thiophene molecule and their analogs, and M for Zn atoms in porous carbon materials.

Obtaining New Biocompatible Composite Materials with Antibacterial Properties Based on Diatomite and Biologically Active Compounds.

This study aimed to create new composite materials based on diatomite-a non-organic porous compound-through its surface modification with bioactive organic compounds, both synthetic and natural. Chloramphenicol, tetrahydroxymethylglycoluril and betulin were used as modifying substances. Composite materials were obtained by covering the diatomite surface with bioactive substance compounds as a solution and material dispersion in it. The materials were characterized by IR spectroscopy, SEM and X-ray photoelectron spectroscopy. For the biocomposites, the hemolytic effect, plasma proteins' adsorption on the surface and the antibacterial activity of the obtained materials were studied. Results show that the obtained materials are promising for medicine and agriculture.

Insight on the degradation of P-chlorophenol based on the Co-g-C3N4/diatomite composite photo-Fenton process

The non-metallic photocatalyst g-C3N4 is characterized by non-toxicity and straightforward preparation. Still, the drawbacks of low specific surface area and fast carrier complexation rate limit its practical application in photocatalysis. In this work, Co-doped g-C3N4 was prepared on the surface of diatomite (DE) through a simple one-step calcination method and used to degrade 4-chlorophenol (4-CP). Photocatalytic experiments showed that Co-g-C3N4/DE removed up to 98.7% of 4-CP. The doping of Co could capture the photogenerated electrons, thereby reducing the recombination of photocarriers and accelerating the oxidation–reduction reaction of Co3+/Co2+ and H2O2, promoting the generation of OH. Introducing DE improved the aggregation of g-C3N4 and expanded its surface area. Moreover, the Co-g-C3N4/DE composite material exhibited a low metal leaching rate and good reusability throughout the experiments. In addition, based on DFT calculations, the ROS attack mechanism of 4-CP degradation was speculated and calculated. The final product of 4-CP was found to pose a more minor environmental threat, according to the T.E.S.T. In short, the prepared Co-g-C3N4/DE composite realized the capture of photogenerated electrons and the acceleration of photocatalytic reactions, which are expected to solve the challenges in wastewater treatment.

Physico-chemical properties of Russian natural aluminosilicates for purification of aqueous environment

The paper analyses and compares the physico-chemical properties of aluminosilicate green clay and bentonite and diatomite from the Russian deposits. The research determines specific surface area and the morphological features of aluminosilicates, their pore sizes, and pore distribution by volume. The surface of the green clay includes silicon and aluminum oxides, montmorillonite, kaolinite, impurities of pyrite, saponite, micas, and hydrosludes. It also contains a lot of rounded particles with a diameter of 1-2 μm. According to the research, adsorption isotherms for mesoporous green clay samples belong to type IV; the samples of bentonite and diatomite (Middle Volga regions of Russia) belong to type II. They characterize the monolayer-multilayer concentration of solution components on macroporous bodies. Also the research revealed a sufficiently high amount of adsorbate (31 ml • g-1) to cover the surface of diatomite (Ulyanovsk region, Russia) with a monomolecular layer. The source minerals of diatomite are montmorillonite and muscovite. The study of adsorption and desorption branches for a bentonite sample (Samara region, Russia) indicates the processes asymmetry. Hence, we compared the ability to adsorb iron (II) and lead ions from aqueous systems using green clay extracted in different years (2017 and 2023).

Highly Efficient Photodegradation of RHB-MO-MB Mixture Dye Wastewater by WO3/Fe3O4/Diatomite under Different Condition

In this study, the composite photocatalyst WO3/Fe3O4/Diatomite was developed by solvent thermal method to remove composite dyes from wastewater. The structure and properties of the photocatalyst were characterized and analyzed. Under the effect of Fe3O4, WO3 was found to be enhanced in the direction of (101) and (200) and loaded on the surface of diatomite (DT). The results of UV–vis analysis imply that the Fe3O4 and diatomite can significantly improve the photocatalytic efficiency. The magnetic hysteresis loop shows that the WO3/Fe3O4/DT composites can be recycled by a magnet, indicating the good recyclability of the composite photocatalyst. The WO3/Fe3O4/DT composite showed a good photocatalytic effect in both acidic and alkaline conditions for RHB-MO-MB mixture dye, which exhibits broad application prospects. The results of the free radical analysis indicate that ·O2 − and ·OH were the main active species. The mechanism of photocatalytic removal of dyes was investigated based on radical trapping experiments and energy band structure analysis. It was proved by three photocatalytic cycle experiments that the morphology of the WO3/Fe3O4/DT composites remains unchanged, and the photocatalytic activity is maintained during recycled operations. This work provides a new idea for dye removal from wastewater using photocatalysts.

Optimal Synthesis of Novel Phosphonic Acid Modified Diatomite Adsorbents for Effective Removal of Uranium(VI) Ions from Aqueous Solutions.

The authors synthesized a series of functionalized diatomite-based materials and assessed their U(VI) removal performance. Phosphor-derivative-modified diatomite adsorbents were synthesized by the three-route procedures: polymerisation (DIT-Vin-PAin), covalent (DIT-Vin-PAcov), and non-covalent (DIT-PA) immobilization of the functional groups. The effects of the diatomite modification have been studied using powder XRD, solid state NMR, FTIR spectroscopy, electronic microscopy, EDX, acid-base titrations, etc. The maximum adsorption capacities of DIT-Vin-PAcov, DIT-PA, and DIT-Vin-PAin samples were 294.3 mg/g, 253.8 mg/g, and 315.9 mg/g, respectively, at pH0 = 9.0. The adsorption amount of U(VI) ions using the prepared DIT-Vin-PAin was 95.63%, which is higher compared with that of the natural diatomite at the same concentration. The adsorption studies demonstrated that the phosphonic and hydroxyl groups on the surface of the diatomite played pivotal roles in the U(VI) adsorption. The U(VI) ions as a "hard" Lewis acid could easily form bonds with the "hard" donor P-containing ligands, so that the as-prepared DIT-Vin-PAin sample had excellent adsorption properties. The monolayer adsorption of the analyte on the surface of the raw diatomite and DIT-PA was observed. It was found from the thermodynamic parameters that the uptake of the U(VI) ions by the obtained adsorbents was a spontaneous process with an endothermic effect. Findings of the present work highlight the potential for using modified diatomite as effective and reusable adsorbents for the extraction of U(VI) in the waste, river, and tap waters with satisfactory results.

MIL-100(Fe)/Diatomite Composites for Photo-Fenton Degradation of Phenol

Porous materials based on metal-organic framework MIL-100(Fe) and diatomite were synthesized. Composites possess specific surface area of 322 and 441 m2/g and hierarchical porous structure with broad pores of diatomite and narrow pores of MIL-100(Fe) particles. Influence of synthesis strategy on structure of materials and their catalytic properties in photocatalytic degradation of phenol was investigated. Composite obtained with preliminary wet impregnation of iron nitrate solution show predominant formation of MIL-100(Fe) particles inside the pores of diatomite. Materials demonstrate catalytic activity in phenol degradation by photo-Fenton process. Composite synthesized without preliminary wet impregnation displays highest catalytic activity with predominant formation of MIL-100(Fe) particles on external surface of diatomite.

An investigation on the adsorption of methylene blue from water by MnFe2O4-modified diatomite

The MnFe2O4/diatomite was obtained by wet chemical methods. The specific structure of the material has been determined by modern physicochemical methods. The results showed that the surface of diatomite was coated by the manganese/iron oxide nanoparticles. The prepared MnFe2O4/diatomite material is a good adsorbent for the removal methylene blue (MB) in water. The adsorption kinetics of MB on modulation materials are consistent with the pseudo-second-order kinetics model. The adsorption isotherms well followed the Langmuir isotherm model and maximal adsorption capacity of MB can read 151.52 mg/g at 323K. The adsorption behavior of MnFe2O4/modified is an endothermic and spontaneous process. The results show that MnFe2O4/diatomite is a promising adsorbent for the efficient removal of cationic dyes from wastewater.

Adsorption of rare earth elements onto diatomite M45: Experimental investigations and modeling with statistical physics theory

The separation of rare earth elements using diatomite M45 from aqueous solutions was studied. The experimental isotherms for the adsorption of trivalent lanthanum, cerium, and neodymium cations on this adsorbent were quantified under strongly acidic conditions (pH 2) at 298–328 K. The adsorption equilibria of these earth elements were analyzed using two statistical physics models (homogeneous and heterogeneous monolayer models). The results show that the adsorption of these ions implies a multi-ionic mechanism, which is exothermic. Si-containing functional groups are responsible for the adsorption of these rare-earth elements on the diatomite surface. A heterogeneous statistical physics model confirms that two Si-based functional groups participate in the separation of these cations. The calculated adsorption capacities at saturation follow the order: neodymium > cerium > lanthanum. Calculated interaction energies range from 28600 to 40100 J/mol, indicating physical adsorption on diatomite M45. This study demonstrates that diatomite M45 is a promising separation medium that can be used for the recovery of REEs dissolved in aqueous solutions via adsorption.

1D-3D biological template loaded NiCo nanowires at high temperatures as a broadband, lightweight electromagnetic wave absorbing material

To meet the requirements of electromagnetic radiation control, especially broadband and high temperature resistance, electromagnetic wave absorbing materials (EWAMs) have been intensively studied. In this work, NiCo NWs were synthesized by a one-step hydrothermal method. The composite has a one-dimensional(1D) NiCo NWs core-shell structure on a three-dimensional(3D) diatomite(De) surface and subsequently calcined at different temperatures. The samples calcined at 400 °C showed excellent EWA performance with a minimum reflection loss(RLmin) of −82 dB at a matched thickness of 7.1 mm and a maximum effective absorption bandwidth(EAB) of 9.53 GHz at a thickness of 8 mm. By adjusting the thickness, full coverage of X-band and Ku-band can be achieved. The conduction loss of the 1D material and the impedance matching of the bionic substrate De are considered to jointly contribute to the microwave attenuation capability. This combination of using bionic materials and 1D transition metal oxides provide a viable strategy for addressing electromagnetic pollution.

Ferrous sulfide supported on modified diatomite for the removal of Cr(VI): Performance and mechanism

How to remove hexavalent chromium (Cr(VI)) from aqueous solution has always been a challenging problem in the environmental field. In this study, a novel composite of oxalic acid modified diatomite (DT) supported ferrous sulfide (FeS) was prepared by hydrothermal synthesis. The experiment results showed that the oxalic acid modified diatomite retained its original porous structure and possessed rougher surface, which could be used as a good loading/dispersing material to provide more adsorption sites. The composite material FeS/DT (the mass ratio of ferrous sulfide to modified diatomite is 1:1) can reduce more than 99 % of Cr(VI) to Cr(III) within 20 min, and Cr(III) can be adsorbed to the surface of diatomite. FeS/DT had a good adsorption and reduction effect at initial pH 3.0–9.0. The experimental results were in agreement with pseudo-second-order kinetic model and Langmuir isotherm adsorption model. Maximum adsorption capacity of FeS/DT for Cr(VI) can reach 141.6 mg/g. The reasons for the excellent reduction and adsorption ability of the FeS/DT were the reducibility of ferrous sulfide and porous structure of modified DT. This study revealed the reaction mechanisms of FeS/DT with Cr(VI), and demonstrated the feasibility of FeS/DT in the removal of Cr(VI) from water environment.

Strengthening the surface and adsorption properties of diatomite for removal of Cr(VI) and methylene blue dye

The main purpose of this work was to boost the surface and adsorption characteristics of diatomite (D) through chemical modifications with chitosan (DC), chitosan/titanium isopropoxide (DCTi), or chitosan/ graphene oxide (DCGr), respectively. Physicochemical characteristics of the prepared samples were investigated using SEM, TEM, XRD, FTIR, TGA, and porosity measurements. The impact of such modifiers into the D surface on the removal efficiency of chromium (VI) ions and methylene blue dye was studied in an equilibrium mode. Langmuir and Freundlich isotherms were used to analyze the adsorption data. Modifiers considerably enhanced the surface and textural properties of D through insertion of the main surface functional groups of chitosan and graphene oxide together compared to chitosan and titanium isopropoxide together or chitosan alone. In addition, the total surface area and total pore volume parameters of the unmodified D sample were improved greatly from 16.5 m2/g, 0.036 cm3/g to 39.8 m2/g and 0.174 cm3/g for DCGr, while they were 17.7 m2/g and 0.132 cm3/g for DC. The best adsorption results were well-defined with the Langmuir isotherm equilibrium model. Accordingly, the DCGr sample exhibited the highest uptake of Cr(VI) (about 167 mg/g) and methylene blue (66.7 mg/g). Hence, the chemical modification strategy of diatomite performed by using chitosan and graphene oxide significantly boosted the surface active sites and porosity properties and thus gave rise to the high adsorption capacity of Cr(VI) and methylene blue dye from wastewater. Hence, these findings affirmed the validity of the current strategy for surface modification of diatomite with chitosan and graphene oxide.

Diatomite hemostatic particles with hierarchical porous structure for rapid and effective hemostasis

The development of fast, safe and effective hemostatic materials is crucial for pre-hospital first aid. In this study, diatomite hemostatic granules (Dhp) were developed by rotating granulation method using silica sol as binder. During rotating granulation process, the Pre-Dhp were prepared by rolling snowball effect, in which nano-silica in silica sol uniformly distributed on the surface of diatomite and polymerized through hydrogen bond to produce strong adhesion. After high-temperature calcination, the hydrogen bond transformed to silica oxygen bond and the three-dimensional gel network formed by silica sol was destroyed to exposed the pores of diatomite. Dhp retained the porous structure of diatomite with hierarchical porous structure (from nano to micro scale). Dhp could quickly adsorb the tangible components in the blood, exhibited rapid hemostatic ability (clotting time was shortened by 43 % than that of control group), and good biocompatibility (hemolysis rate < 7 %, no cytotoxicity). Dhp residue was not found in the wound of rat tail amputation model, indicating that the adhesion of silica sol and high-temperature curing treatment enhanced the stability of Dhp and reduced the hidden danger of micro thrombosis caused by residual substances entering blood vessels. Our study proved that Dhp prepared by silica sol bonding and rotary granulation was excellent hemostatic material with non-toxic side effects and rapid coagulation promotion.

Facile Synthesis of Diatomite/β-Cyclodextrin Composite and Application for the Adsorption of Diphenolic Acid from Wastewater.

Diphenolic acid (DPA) is a kind of endocrine-disrupting compound, which brings serious health problems to humans and animals. An eco-friendly and cost-effective adsorbent was prepared through a simple method, in which the β-Cyclodextrin(β-CD) was crosslinked onto the surface of diatomite (DA), the as-prepared DA/β-CD composite showed higher adsorption efficiency for DPA than DA as the host–guest interaction between DPA and β-CD. DA is a kind of biosilica with a hierarchical pore structure that provides enough surface area for the DA/β-CD. The surface area and pore size of DA/β-CD were investigated by nitrogen adsorption and desorption. The DA/β-CD composite illustrated a good adsorption capability, and was used for removing DPA from wastewater. The adsorption ratio of DPA could achieve 38% with an adsorption amount of 9.6 mg g−1 under room temperature at pH = 6. The adsorption isotherm curves followed the Langmuir (R2 = 0.9867) and Freundlich (R2 = 0.9748) models. In addition, the regeneration rate of the DA/β-CD was nearly at 80.32% after three cycles of regeneration. These results indicated that the DA/β-CD has the potential for practical removal of the EDC contaminants from wastewater.

Engineering active sites on nitrogen-doped carbon nanotubes/cobaltosic oxide heterostructure embedded in biotemplate for high-performance supercapacitors

At present, both easy agglomeration of carbon nanotubes themselves and waste caused by chemical vapor deposition (CVD) have great pollution, which limits the use of carbon nanotubes (CNTs). A large number of hollow polyhedrons containing N-doped carbon nanotubes and Co3O4 nanoparticles (Co3O4 NPs) were well fabricated on a biotemplate by hydrothermal method, stirring method and pyrolysis process. The regular polyhedron was uniformly arranged on the external surface of diatomite with a natural porous structure, which aims to avoid the agglomeration of CNTs. The electrochemical testing result shows that the composite has promising electrochemical performance, which is embodied in a high specific capacity 894.6 F/g at 2 A/g, good rate performance and high cycling property. Finally, an assembled Co3O4 NP@CNTs@Diatomite//GR asymmetric supercapacitor has maximal energy density of 36.8 Wh/kg and maximal power density of 16,326.6 W/kg. Indeed, electrode design in this work provides an environmental synthesis idea for the decoration of CNTs on a certain substrate and displays an original electrode material based on diatomite.

Effect of Chemical and Thermal Treatment Priority on Physicochemical Properties and Removal of Crystal Violet Dye from Aqueous Solution

AbstractThe release of pollutants, especially dyes, has been a significant concern as it affects the stability of ecosystems due to poor implementation of waste protocols. In this study, the diatomite samples were characterized by pHpzc, ICP, pore size distribution, XRD, TG‐DTA, BET, SEM and FTIR (before‐after). The adsorption properties of a cationically charged dye, crystal violet (CV), on the diatomite samples were investigated by varying the adsorption parameters with the aim of evaluating the adsorption mechanism. Nonlinear Langmuir, Freundlich, Dubinin‐Radushkevich and Redlich‐Peterson isotherm models, pseudo‐first and pseudo‐second order kinetic models, intraparticle diffusion and Boyd models were evaluated. The adsorption mechanism was explained by the Langmuir isotherm model and the maximum adsorption capacities for CV (at pH 7.0) of DHCl, D800 °C+HCl and DHCl+800 °C were 5.07 mg g−1 and 4.93 mg g−1 and 65.78. mg g−1 at 298 K, respectively. It was also shown that the CV adsorption was reasonable according to the second‐order kinetic model (R2=1). Adsorption occurred via two mechanisms: hydrophobic interactions and the combination of surface hydrogen bonding between the hydroxyl groups on the diatomite surface and the nitrogen atoms of the CV. The results indicated that using DHCl+800 °C would provide a simple, energy‐saving, and cost‐effective approach to removing cationic dyes from an aqueous solution.

Insight into peroxymonosulfate assisted photocatalysis over Fe2O3 modified TiO2/diatomite composite for highly efficient removal of ciprofloxacin

The ternary Fe2O3/TiO2/diatomite (Fe2O3/TDE) composite was synthesized through a chemical precipitation-calcination method to boost the ciprofloxacin (CIP) degradation performance under persulfate catalysis and visible-light photocatalysis (PMS+Vis) synergistic system. It is indicated that Fe2O3 and TiO2 uniformly dispersed on the surface of diatomite, leading to the increase of active sites. Moreover, the lower recombination of electron-hole pairs promoted the photocatalytic performance and PMS activation. Therefore, the obtained Fe2O3/TDE composite (Fe2O3/TDE-5) exhibited superior degradation efficiency of CIP with the removal rate of approximately 88% under PMS+Vis system, and the degradation rate constant was 3.58 and 8.06 times higher than Vis and PMS single system, respectively. Besides, the introduction of diatomite not only enhanced the activation of PMS by superficial hydroxyl groups, but also enhanced the migration of photogenerated carriers. In addition, the radical pathway (h+, O2−, SO4− and OH) and non-radical pathway (1O2) work together for the removal of CIP. This work provides a deep insight for coupling application of photocatalysis and PMS activation for water environmental remediation.

Preparation of biochemical fulvic acid‐modified diatomite and its adsorption characteristics for tetracycline in water

AbstractBACKGROUNDDiatomite and biochemical fulvic acid were used as raw materials to prepare biochemical fulvic acid‐modified diatomite using by the sol–gel method. The structure and properties of samples were investigated by X‐ray diffraction, scanning electron microscopy, etc. The effects of solution pH and reaction temperature on the adsorption performance of adsorption materials were evaluated by taking tetracycline as the target pollutant. The adsorption kinetics, adsorption rate mechanism and adsorption isotherm of tetracycline were revealed.RESULTSThe results showed that the main form of diatomite is amorphous SiO2. The surface and channels of diatomite were loaded with biochemical fulvic acid, and the specific surface area of the modified material increased from 9.182 to 13.774 m2 g−1, while the average pore size decreased from 10.972 to 7.15 nm. The pH of the tetracycline solution was 5 and the initial concentration was 20 mg L−1; the adsorption capacity of the modified sample increased 1.93‐fold to 29.84 mg g−1. When the adsorption temperature was increased from 10 to 60 °C, the adsorption capacity of the modified material increased nearly fourfold, reaching 78.8 mg g−1.CONCLUSIONQuasi‐second‐order reaction kinetics has a correlation coefficient R2 of 0.993, which suggests a good fit to the adsorption process of tetracycline by the modified diatomite. Both Freundlich and Redlich–Peterson adsorption isotherm equations can elucidate the adsorption process of the composites. The adsorption is heterogeneous adsorption on the surface, mainly multi‐layer adsorption and electrostatic attraction adsorption. © 2022 Society of Chemical Industry (SCI).