Diatomite Samples Research Articles

Comparison with Some Porous Materials and the Effects of Powder Filling on Breakage Parameters of Diatomite in Dry Ball Milling

In this study, a comparison of breakage parameters with some porous materials (pumice, trass, and amorphous silica) and the effects on breakage kinetics of powder filling of diatomite were investigated on at batch grinding conditions. For this purpose, first, standard Bond grindability tests were performed for four porous samples. Second, eight different mono-size fractions of all samples were carried out between 1.7 mm and 0.106 mm formed by a sieve series. Then, Si and Bi,j equations were determined for the size distributions at different grinding times, and the model parameters (Si, aT, α, γ, φj, and β) were tested for four different porous materials. Finally, model parameters were discussed for four different powder filling (3.5, 7, 10.5, and 14%) of diatomite samples. From the results of test, the validity of the relationships between Bond grindability and breakage parameters has been not confirmed with good correlation coefficients. The reason of this negative result could be attributed to different of the geological origin of porous materials. In addition, the results of the effect of powder filling on the grinding were found different than other investigators.

Adsorption of Zinc(II) on diatomite and manganese-oxide-modified diatomite: A kinetic and equilibrium study

The removal of Zn(II) ions from aqueous solution was studied using natural and MnO 2 modified diatomite samples at different temperatures. The linear Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption equations were applied to describe the equilibrium isotherms. From the D–R model, the mean adsorption energy was calculated as >8 kJ mol −1, indicating that the adsorption of Zn(II) onto diatomite and Mn-diatomite was physically carried out. In addition, the pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to determine the kinetic data. The experimental data were well fitted by the pseudo-second-order kinetic model. Thermodynamic parameters such as the enthalpy (Δ H 0), Gibbs’ free energy (Δ G 0) and entropy (Δ S 0) were calculated for natural and MnO 2 modified diatomite. These values showed that the adsorption of Zn(II) ions onto diatomite samples was controlled by a physical mechanism and occurred spontaneously.

Adsorption of BTEX, MTBE and TAME on natural and modified diatomite

The removal of BTEX (benzene, toluene, ethyl-benzene and m-,p-,o-xylenes), MTBE (methyl tertiary butyl ether) and TAME (tertiary amyl methyl ether) from aqueous solutions by raw, thermally, chemically and both chemically and thermally treated diatomite was studied, through batch adsorption experiments. In total, 14 different diatomite samples were created and tested. Selected physical characteristics of the adsorbents, such as specific surface area and pore volume distribution, were determined. Matrix and competitive adsorption effects were also explored. It was proved that the diatomite samples were effective in removing BTEX, MTBE and TAME from aqueous solutions, with the sample treated with HCl being the most effective, as far as its adsorption capacity and equilibrium time are concerned. Among the contaminants, BTEX appeared to have the strongest affinity, based on mass uptake by the diatomite samples. Matrix effects were proved to be strong, significantly decreasing the adsorption of the contaminants onto diatomite. The kinetics data proved a closer fit to the pseudo second order model, while the isotherm experimental data were a better fit to the Freundlich model. However, the latter produced values of the isotherm constant 1/n greater than one, indicating unfavorable adsorption.

Improvement in filtration characteristics of diatomite by calcination

This paper examines the calcination and filtration characteristics of diatomite. For this purpose, diatomite ore was calcined at 1000°C in order to improve the material characteristics for use in filtration. The physical, chemical, thermal and micro-structural features of the raw and the calcined diatomites were then determined to compare them with those of the commercial filter aids currently used. In order to determine filtration efficiency of the diatomite samples, several filtration tests were carried out together with the beer samples and the commercial filter aids taken from a leading beer factory in Turkey. It is shown that the calcined diatomite could successfully be used for beer filtration after suitable arrangement of the particle size distribution, such that the highest possible flow rate and filtrate clarity are obtained.

Mineralogy and technical properties of clayey diatomites from north and central Greece

Abstract Two bulk samples of clayey diatomite of Upper Miocene age originated from Western Macedonia, northern Greece and Thessaly central Greece were examined for their efficiency to be used as industrial absorbents. The samples were characterized using X-Ray Diffraction, Thermo-Gravimetric and Fourier Transform Spectroscopy, Scanning Electron Microscopy and ICP-MS analytical methods. The absorption capability of the clayey samples in oil and water were also examined. The mineralogy of both samples is predominated by the presence of clay minerals and amorphous silica. The clay minerals prevailed in the Klidi (KL) bulk sample, with muscovite being the dominant phase, and kaolinite and chlorite occurring in minor amounts. In the Drimos (DR) bulk sample, vermiculite was the predominant clay phase. Smectite was not found in either sample, whereas detrital quartz and feldspars were present in significant amounts. The amorphous silica phase (opal-A) occurs mainly with the form of disck-shaped diatom frustules. The chemistry of the samples is characterized by the predominance of silica, alumina, and iron, whereas all the other major and the trace elements are in low concentrations. Both clayey diatomite rocks exhibited sufficiently good oil and water absorption capacity, ranging between 70 to 79% in the clay-rich sample KL and 64 to 70% in the opal-A-rich sample DR. Comparing the properties of the rocks studied with other commercial absorbents, it is concluded that they may find applications as absorbents in industrial uses.

Influence of diatomite microstructure on its adsorption capacity for Pb(II)

The effect of microstructural changes caused by mechanical modification on adsorption properties of diatomite samples were investigated. The microstructure has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) while the degree of metal adsorption was evaluated by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP AES). The results show that metal sorption capacity of diatomite is considerably improved after mechanical modification and it can be attributed to amorphysation of the material. Immobilization efficiency increased from 22% for untreated to 81% for the treated sample after 5h at BPR 4.This qualifies natural diatomite as a material for wastewater remediation.

Shelf life stability of diatomites

Diatomites or diatomaceous earths are biogenic sediments mainly consisting of porous siliceous algae skeletons. Some diatomites are industrially processed and used for different applications. For some applications and sometimes for the authorization of products for new applications it is important to prove the ‘shelf life stability’ which means that the properties of the product should not change upon storage. Freshly prepared silica gel is known to alter upon aging e.g. with respect to the specific surface area and porosity, respectively. This can be relevant for diatoms as well since recent skeleton consist of XRD amorphous silica which – upon aging – crystallizes, finally forming microcrystalline silica. The age of most of the diatomites being mined is higher than 1 million years. Accordingly, one could expect that storage for some years does not alter the diatomite properties. However, it is at least conceivable that prolonged open storage (exposure to air) can lead to the adsorption of molecules from air which in turn would block reactive adsorption sites. The aim of this study is to assess the shelf-life-stability of diatomite and perlite based on long term tests. Therefore, two different diatomite samples and a perlite sample (XRD amorphous volcanic alumosilicate glass) were stored at different conditions for 1 year. All materials were investigated with respect to structural aspects as well as adsorption capacity. Using the common mineralogical methods X-ray diffraction (XRD) and infrared spectroscopy no structural changes could be observed. In contrast, the determination of the amount of soda soluble silica turned out to be a valuable tool for the identification of structural changes. Using this method a slightly higher reactivity of the perlite surface after storage at 60 °C in water was found which possibly can be explained by the beginning devitrification process. At the same conditions, the diatomite sample which mostly consists of XRD amorphous silica showed a slight decrease of the amount of soda soluble silica which was interpreted as the beginning (re)crystallization process. The diatomite sample containing swellable clay minerals lost some water adsorption capacity upon extensive drying. Systematic changes of material properties after 1 year storage could only be observed under exaggerated conditions (120 °C or storage in water at 60 °C). It is concluded that the investigated materials are stable under common storage conditions.

An integrated terrestrial paleoenvironmental record from the Mid-Pleistocene transition, eastern North Island, New Zealand

A tephra-bearing lake sequence from near Ormond, New Zealand, provided the opportunity to conduct a multi-proxy paleoenvironmental analysis within the Mid-Pleistocene time period. A 10.5-m-thick section was measured and analysed for pollen, spores, diatoms, macrofossils, and tephra geochemistry. Palynological assemblages in the lower 4 m of the section indicate an ameliorating temperate climate and increased humidity. The upper 6.5 m is dominated by diatomite that did not yield sufficient palynomorphs for study. The source vegetation was distal lowland mixed broadleaf podocarp forest, swamp forest from ca. 2.5–4.0 m, and proximal scrubland with sporadic forest encroachment. Abundant freshwater algae in the samples suggest that any brackish influence in the lower part of the section was minor. Marine dinoflagellates found in the basal pollen samples could be mostly recycled. Diatomite samples were overwhelmingly dominated by a freshwater but mildly salt-tolerant diatom. We interpret the section as representing a shallow coastal lowland lake that intermittently had access to the sea. The chronology of the section is based on a single glass-ITPFT age of 0.62±0.09 Ma from a tephra interbed (T8) in the lower part of the section. In addition, the lowermost tephra in the sequence (T1) is geochemically correlated to AT-485, preserved in the marine record east of New Zealand, with an astronomically tuned age of 0.7163 Ma. This chronology places the basal portion of the Ormond section within the Brunhes normal Chron with sequence deposition occurring during either the OIS 18/17 or 16/15 transitions. However, paleomagnetic data indicate a clear reverse polarity from an equivalent stratigraphic position and at this stage it is difficult to reconcile this age discrepancy.

An inter-laboratory comparison of Si isotope reference materials

Three Si isotope materials have been used for an inter-laboratory comparison exercise to ensure reproducibility between international laboratories investigating natural Si isotope variations using a variety of chemical preparation methods and mass spectrometric techniques. These proposed standard reference materials are (i) IRMM-018 (a SiO2 standard), (ii) Big-Batch (a fractionated SiO2 material prepared at the University of California Santa Barbara), and (iii) Diatomite (a natural diatomite sample originally deposited as marine biogenic opal). All analyses are compared with the international Si standard NBS28 (RM8546) and are in reasonable agreement (<+/- 0.22 parts per thousand. 1 sigma(SD) delta Si-30) given the different measurement techniques involved. These methods include both acid and alkaline dissolution/fusion, Si separation using cation exchange, selective co-precipitation, and gas-source versus plasma-ionization (high and low resolution) mass-spectrometric techniques. The average delta Si-30 for Diatomite, IRMM-018, and Big-Batch are + 1.26 parts per thousand, -1.65 parts per thousand and -10.48 parts per thousand, respectively, with corresponding delta Si-9 values of + 0.64 parts per thousand, -0.85 parts per thousand and -5.35 parts per thousand for the same standards, respectively. For the most fractionated standard (Big-Batch), results demonstrate a kinetic mass-dependent fractionation effect for atomic Si (i.e., delta Si-29 similar to 0.51 x delta Si-30). There is almost no statistical difference between the mean values obtained by each participating laboratory, with the notable exception of the IRMM-018 standard. This effect could be caused by heterogeneity or contamination of this standard. The results for the other two standards indicate that data sets produced using any of the methods employed in this study will have similar precision and differences are limited to 0.2 parts per thousand in mean delta Si-30 values for a given sample between laboratories, or differences of 0.13 parts per thousand. in mean delta Si-29 values.

Natural diatomite process for removal of radioactivity from liquid waste

Diatomite has a number of unique physical properties and has found diversified industrial utilization. The filtration characteristics are particularly significant in the purification of liquids. The purpose of this study was to test natural diatomaceous earth (diatomite) as an alternative material that could be used for removal of radioactivity from liquid waste. A pilot-scale column-type device was designed. Natural diatomite samples were ground, sieved and prepared to use as sorption media. In this study, real waste liquid was used as radioactive liquid having special conditions. The liquid waste contained three radionuclides (Cs-137, Cs-134 and Co-60). Following the treatment by diatomite, the radioactivity of liquid waste was reduced from the initial 2.60 Bq/ml to less than 0.40 Bq/ml. The results of this study show that most of the radioactivity was removed from the solution by processing with diatomite.

Preparation of filter aids based on diatomites

Two major deposits of diatomaceous earth (diatomite) in the region of the Balkan Peninsula, the Kolubara basin (Serbia and Montenegro) and the Vesje deposit (Former Yugoslav Republic of Macedonia), were selected for detailed investigation of their possible application in preparation of beer filter aids. Chemical, mineralogical and structural properties of diatomite samples were analyzed with the aim of predicting the filtration efficiency. Results of beer filtering compounds preparation are presented in this paper. The parameters of crushing, drying, calcination and classification are also defined. Beer filtration tests proved diatomites to be satisfactory and not causing any degradation of filtration process or beer quality. Technological flow scheme for obtaining the beer filter aids is proposed in the paper.

Investigation of properties of low-strength lightweight concrete for thermal insulation

In this study, block elements with diatomite, which have different aggregate granulometries and cement contents, were produced and the effect of these parameters on physical and mechanical properties of block elements were investigated. Diatomite samples were taken from the region of Afyon. In the mixes, water/cement ratio was kept at 0.15. Analyses include compressive strength, thermal conductivity, ultrasonic velocity tests, bulk density and specific porosity. According to experimental results, while dry unit weight is varied between 900 and 1190 kg/m 3, compressive strength of 7–56 days specimens ranged from 2.5 to 8 MPa. Materials with a ratio of 30% fine, 40% medium and 30% coarse size have the best compressive strength and thermal insulation in all series. Due to low thermal conductivity, lightweight aggregate concrete with diatomite can be used to prove high isolation in the structure.

Palynofacies distribution in a lacustrine basin

The Miocene basin of La Cerdanya (Pyrenees, Catalonia, Spain) consist of lacustrine diatomites and fan-deltaic (palustrine) lutites with lignites. A multidisciplinary analysis of palynofacies, organic geochemistry, taphofacies of plant macroremains and sedimentology was carried out in order to characterise taphonomically this basin. Palustrine facies contain highly diverse assemblages of palynomorphs and other palynological matter. The presence of relatively high amount of planar organic remains, mostly cuticles, in this palynofacies is indicative of deposition in the proximal parts of the basin. The organic content is low (1% TOC) except in the case of lignites, where it reaches up to 50%. Generally the Hydrogen Index (HI) values of the palustrine sediments are also relatively low (HI 70–189). Diatomite samples from the lake centre are characterised by high amount of the chlorococcalean alga Botryococcus and sapropelic organic matter and a HI above 500. In contrast, samples from the lake margins comprise Botryococcus, bisaccates and other anemophilous angiosperm pollen and have HI below 410. The TOC of lacustrine samples may reach levels of up to 45.5%. Palynofacies distribution shows a positive correlation with plant taphofacies only in the palustrine sediments but not in the lacustrine facies of the basin. Taphofacies of plant macroremains in the lacustrine sediments display a downslope polarity whereas palynofacies are distributed radially. A variety of transport mechanisms and different origins of palynological matter in comparison to plant macroremains account for this difference.

The removal of textile dyes by diatomite earth

The adsorption of some textile dyes by diatomite was investigated using Sıf Blau BRF (SB), Everzol Brill Red 3BS (EBR), and Int Yellow 5GF (IY). Adsorption of these textile dyes onto diatomite earth samples was studied by batch adsorption techniques at 30 °C. The adsorption behavior of textile dyes on diatomite samples was investigated using a UV–vis spectrophotometric technique. The effect of particle size of diatomite, diatomite concentration, the effect of initial dye concentrations, and shaking time on adsorption was investigated. Adsorption coverage over the surface of diatomite was studied using two well-known isotherm models: Langmuir's and Freundlich's. These results suggest that the dye uptake process mediated by diatomite has a potential for large-scale treatment of textile mill discharges. According to the equilibrium studies, the selectivity sequence can be given as IY > SB > EBR. Values of the removal efficiency of the dyes ranged from 28.60 to 99.23%. These results show that natural diatomite holds great potential to remove textile dyes from wastewater.

The hydroxyl species and acid sites on diatomite surface: a combined IR and Raman study

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), Raman spectroscopy of adsorbed pyridine molecules (Py-Raman) and in situ Py-IR have been used to investigate the hydroxyl species and acid sites on diatomite surfaces. The Lewis (L) and Brønsted (B) acid sites, and various hydroxyl species, including isolated hydroxyl groups, H-bonded hydroxyl groups and physically adsorbed water, are identified. The L acid sites in diatomite samples are resulted from the clay impurities, and the B acid sites are resulted from some moderate strength H-bonded hydroxyl groups. At room temperature, both of the isolated and H-bonded silanols associate with the physically adsorbed water by hydrogen bond. After calcination treatment, physically adsorbed water will be desorbed from the silanols, and the silanols will condense with the increase of temperature. Generally, the H-bonded silanols condense more easily than the isolated ones. The properties of surface hydroxyl species of diatomaceous silica are more similar to precipitated silica rather than fumed silica.

Adsorption of Oxygenates from Used Transformer Oil Using Surfactant- and Microemulsion-Impregnated Clays

This paper presents batch adsorption experimental results for oxygenate removal from used transformer oil using surfactant- and microemulsion-impregnated diatomite as adsorbents. The efficiency of the removal is evaluated by total acidity number (TAN) analysis (ASTM method D-974). TAN results decreased from 0.17 mg of KOH/g to as low as 0.07−0.09 mg of KOH/g for some of the impregnated diatomite samples.

FT-IR spectroscopic investigations of benzidine and bipyridyls adsorbed on diatomite from Anatolia

FT-IR spectra of benzidine (bnz), 2,2′-bipyridyl (2,2′-bpy) and 4-4′-bipyridyl (4-4′-bpy) adsorbed on natural diatomite from Kutahya-Alayunt (Anatolia, Turkey) have been investigated. Vibrational results indicate the presence of chemisorbed species. No physical sorbed species has been detected. Bnz and 2,2′-bpy treated diatomite samples were found to be coloured, whereas 4,4′-bpy treated diatomite was not altered in colour. The formation of cationic (bnz+ and bnz2+) or anionic (2,2′-bpy−) surface species has also been detected in the case of bnz or 2,2′-bpy treated diatomite, respectively.

生物起源珪藻土からの高純度シリカの製造について

Diatomaceous earth, which is found throughout the world, is mainly composed of diatom crusts associated with a small amount of clay and detrital rocks. The diatom crust, amorphous silica, is characterized by dissolution in caustic alkaline solution. In this study we examined the distribution of silica and trace elements leached from diatomaceous earth by 10 w / v % NaOH solution in detail. The results are as follows:(1) 31 diatomite samples of seawater origin were collected from 4 ore deposits located in Akita Prefecture and 28 samples of freshwater origin were collected from 2 ore deposits in Okayama and Oita Prefecture. The specimens mainly consisted of a white or grayish white assemblage of diatoms in the range of μ ∼ mm order.(2) By qualitative analysis, abundant silica and small amounts of 16 elements in dissolved solutions were detected, while the presence of 26 elements in bulk specimens were confirmed. Taking into account the sensitivities of the AAS and ICP-AES analyses, Si, Al, K, Fe and B were quantitatively analyzed. An abundance of silica extracted from diatomite reached 86 ∼ 98 % in bulk samples, Al, K and Fe content were relatively high in the range of 25,000 ∼ 200 ppm. B was present at the less than 150 ppm. Based on similarities among the distribution patterns of each element, it was observed that Silica and B were derived from diatoms, and Al, K and Fe from detrital rocks.(3) The need for high quality silica as a raw material has been increasing, and reserves of high purity quartz will be exhausted in the near future; thus, how to produce high quality silica from diatomaceous earth is of great importance. In particular, the B content in silica must be very low below a few ppm. At present, some solutions extracted from diatomite with a freshwater origin have lower concentrations (4.3 ∼ 13 ppm) than those of seawater origin(80 ∼ 150 ppm). From the data we suggest that diatomaceous earth should be considered as a potential source of high purity silica.

Spontaneous imbibition characteristics of diatomite

A systematic investigation of fluid flow characteristics within diatomite (a high porosity, low permeability, siliceous rock) is reported. Using an X-ray computerized tomography (CT) scanner, and a novel, CT-compatible imbibition cell, we study spontaneous cocurrent water imbibition into diatomite samples. Air–water and oil–water systems are used and the initial water saturation is variable. Mercury porosimetry and a scanning electron microscope (SEM) are employed to describe diatomite pore structure and the rock framework. Diatomite exhibits a fine pore structure and significant pore-level roughness relative to sandstone thereby aiding the flow of imbibing water. Despite a marked difference in permeability and porosity as compared to sandstone, we find similar trends in saturation profiles and dimensionless weight gain vs. time functions. Although diatomite is roughly 100 times less permeable than sandstone, capillary forces result in a strong imbibition potential for water such that imbibition rates rival and surpass those for sandstone

Removal of uranium from aqueous solutions by diatomite (Kieselguhr)

In this study, the removal of uranium from aqueous solutions by diatomite earth (Kieselguhr) fine particules has been investigated. Diatomite earth is an important adsorbent material in chromatographic studies. Uranium adsorption capacity of four different types of diatomite was determined. The adsorption of uranium on the chosen diatomite sample was examined as a function of uranium concentration, solution pH, contact time and temperature. The adsorption of uranium on diatomite followed a Langmuir-type isotherm.