Clinoptilolite Content Research Articles

The mineralogical composition of the zeolitic rocks of Santorini Island and their potential use as feed additives and nutrition supplements

AbstractThe zeolitic rocks of Akrotiri, on Santorini Island (Aegean Sea, Greece), can be grouped according to the zeolite minerals present. The first group includes zeolitic rocks that contain only clinoptilolite, the second group contains clinoptilolite and mordenite and the third group contains only mordenite. Clinoptilolite accounts for up to 56 wt.% and mordenite for up to 69 wt.% of the rocks. All samples contain feldspars (8–36 wt.%), clay minerals (6–8 wt.%), quartz (3–6 wt.%), opal-CT (2 wt.%), amphibole (2–4 wt.%) and amorphous materials (4–7 wt.%). The studied samples were classified chemically as andesites or dacites. The ammonium-exchange capacity of the studied samples was 104–158 meq 100 g–1. According to Commission Implementing Regulation (EU) No. 651/2013, zeolitic rocks that contain ≥80 wt.% clinoptilolite, ≤20 wt.% clay minerals and are free of fibrous minerals and quartz can be used as feed additives in animal husbandry. Zeolites with fibrous habit (mordenite, erionite, secondarily roggianite and mazzite) and SiO2 minerals such as quartz, cristobalite and tridymite can be dangerous to both humans and animals. The mineralogical study showed that, due to their low clinoptilolite content and the presence of both quartz and fibrous mordenite, the studied zeolitic rocks do not conform with European Regulation No. 651/2013. As a result, their use as feed additives and nutrition supplements is prohibited.

Ultrasonic Activation of Mineral Sorbents

Introduction. Medical clays are polymineral sorbents with a predominance of the underlying clay mineral, the concentration of which determines the quality of mineral raw materials and its adsorption activity. One of the methods of improving the quality of mineral raw materials is its activation by means of ultrasonic treatment.Aim. To study the effect of ultrasound on the activation and adsorption activity of mineral sorbents.Materials and methods. Clinoptilolite mineral raw materials of the Kholinsky deposit, montmorillonite mineral raw materials of the Belgorod deposit and kaolinite mineral raw materials of the Eleninsky deposit were used as objects of research. A high-frequency UZDN-1 unit was used for ultrasonic treatment. Determination of adsorption activity was carried out by methylene blue.Results and discussion. The effect of ultrasound on the activation of mineral sorbents at an ultrasonic wave frequency of 40 kHz for five minutes has been studied. It was found that the average content of Clinoptilolite, taking into account all fractions in the clay of the Kholinsky deposit, increases by 20 %, the average content of Montmorillonite, taking into account all fractions in the clay of the Belgorod deposit, increases by 14 %, the average content of Kaolinite, taking into account all fractions in the clay of the Eleninsky deposit, increases by 18 %. The effect of ultrasound on the adsorption activity of mineral sorbents has been investigated. The use of ultrasonic treatment increases the adsorption activity of mineral sorbents by 12–19 %.Conclusion. The developed method of activation of mineral sorbents by ultrasonic treatment can be used to activate mineral sorbents by increasing the concentration of the underlying mineral (Clinoptilolite, Montmorillonite, Kaolinite), as well as increasing their adsorption activity.

Analysis the Effect of Activated Natural Zeolites for Fe Metal Adsorption

Zeolite, as an adsorbent, can be improved by a chemical activation process. In this study, zeolite was activated using the acid activation method by soaking natural zeolite with HCl and HF, and the activated zeolite was then used to adsorb Fe metal. Zeolite was characterized using SEM and XRD, and the adsorption capacity of the zeolite was analyzed using AAS. The results of SEM analysis show that zeolite after activation has a more significant number of pores than zeolite before activation. The results of XRD analysis show that zeolite that has been activated has a higher content of quartz (SiO2) and clinoptilolite than zeolite that has not been activated. The results of the zeolite adsorption capacity and efficiency test on Fe metal showed that the most excellent adsorption capacity was when the contact time was 60 minutes, with adsorption capacity and adsorption efficiency values of 3.2403 mg/g and 97.21%.

Effect of clinoptilolite on properties and fractal characteristic of pore structure of polypropylene fiber-reinforced cement-based composite

To further analyze the effect mechanism of clinoptilolite on the macro-mechanics and microstructure of polypropylene fiber-reinforced cement-based composite, the samples with 0, 5%, 10%, 15%, 20% and 25% clinoptilolite contents were investigated by compression test, flexural test, X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP), and the pore structure characteristics were quantitatively analyzed by fractal theory. Results showed that: With the increase of clinoptilolite content, the compressive strength, flexural strength and porosity of samples first increased and then decreased. The addition of clinoptilolite reduced the 7-day strength but increased the 28-day compressive strength, 60-day compressive strength, 28-day flexural strength and 60-day flexural strength of the samples by about 6%, 14.3%, 13.9% and 19.1%. It was recommended that the clinoptilolite content should not exceed 15%. Due to the filling effect and pozzolanic effect of clinoptilolite, adding clinoptilolite into the matrix could promote a hydration reaction to produce more C-S-H gels and reduce the proportion of more harmful pores and harmful pores, effectively improving the internal pore structure of the matrix. Meantime, it was found that the evolution law of pore structure based on fractal dimension calculated by the thermodynamic fractal model was consistent with the variation law of the pore size distribution curves and pore volume measured by MIP. Furthermore, a polynomial relationship model between clinoptilolite content, the quantitative fractal characteristic of pore structure and the macroscopic mechanical behaviors was established, which indicated that the pore fractal dimension could quantitatively describe the effect of clinoptilolite content on the pore microstructure.

Preparation, Characterization, and Performance of Natural Zeolites as Alternative Materials for Beer Filtration.

The clarity of the beer is essential to its marketability and good consumer approval. Moreover, the beer filtration aims to remove the unwanted constituents that cause beer haze formation. Natural zeolite, an inexpensive and widespread material, was tested as a substitute filter media for diatomaceous earth in removing the haze constituents in beer. The zeolitic tuff samples were collected from two quarries in Northern Romania: Chilioara, in which the zeolitic tuff has a clinoptilolite content of about 65%, and the Valea Pomilor quarry, containing zeolitic tuff with a clinoptilolite content of about 40%. Two-grain sizes, <40 and <100 µm, from each quarry were prepared and thermally treated at 450 °C in order to improve their adsorption properties and remove organic compounds and for physico-chemical characterization. The prepared zeolites were used for beer filtration in different mixtures with commercial filter aids (DIF BO and CBL3) in laboratory-scale experiments, and the filtered beer was characterized in terms of pH, turbidity, color, taste, flavor, and concentrations of the major and trace elements. The results showed that the taste, flavor, and pH of the filtered beer were generally not affected by filtration, while turbidity and color decreased with an increase in the zeolite content used in the filtration. The concentrations of Na and Mg in the beer were not significantly altered by filtration; Ca and K slowly increased, while Cd and Co were below the limits of quantification. Our results show that natural zeolites are promising aids for beer filtration and can be readily substituted for diatomaceous earth without significant changes in brewery industry process equipment and protocols for preparation.

Oil spill remediation: Selectivity, sorption, and squeezing capacity of silicone composite foams filled with clinoptilolite

AbstractDue to the enormous use of oil worldwide, accidental spills occur relatively often, threatening sea ecosystem. A remediation strategy, usually, includes materials of macroporous structure, flexibility, and low cost. Furthermore, they need to have oleophilic and hydrophobic characteristics. All these demands fulfill siloxane matrix foams. The addition of a natural zeolite, clinoptilolite, as filler, can improve their sorption characteristics and reusability. Silicone composite foams at different clinoptilolite content (35, 40, and 45 wt%) have been structurally characterized and evaluated by determining the sorption capacity in several liquids (naphtha, kerosene, pump oil, and water). The squeezing efficiency tests were performed to estimate the foams reusability. Compared with the unfilled one, the clinoptilolite filled foams shown lower sorption capacities with very high oil/water selectivity. The squeezing capacity of the foam with 40 wt% of clinoptilolite is equal to the unfilled foam for pump oil. In contrast, the squeezing capacity of 35 wt% clinoptilolite filled foam for naphtha oil is even higher. Compared to the foams, filled with other types of filler, the high effective oil selectivity of the foam with 35 wt% of clinoptilolite was proven, implying its superior suitability for light and heavy oils sorption.

Formation processes of tafoni on pyroclastic rock surfaces with hydrothermal alteration on the Isotake coast, Shimane, Japan

Cliffs along the Isotake coast, Shimane, Japan, have two types of distinctive surfaces with different colours, with tafoni and without tafoni, even though they consist of the same pyroclastic rock. Rockfalls, which result in severe accidents, occur only on the surface without tafoni. Geochemical analyses of the cliff materials and the Schmidt hammer rebound test were conducted to elucidate the process of salt weathering in the formation of tafoni. The strontium stable isotope ratio (87Sr/86Sr) of the calcite (i.e., 0.706298) found on the backwall of tafoni indicated that the calcium in this calcite is derived from cliff materials, although the cliff receives seawater through splashing. Carbon, hydrogen, nitrogen and sulfur elemental analyses and X-ray diffraction pattern measurements revealed that clinoptilolite formed by hydrothermal alteration was more abundant in the cliff surfaces with tafoni than in those without tafoni, indicating a high abundance of calcium available for incorporation into calcite. The hardness of the cliff materials increases as the clinoptilolite content increases in any surface type. Consequently, tafoni preferentially form on surfaces with abundant clinoptilolite produced by hydrothermal alteration, although the surfaces have also been strengthened by hydrothermal alteration. Our results imply that the presence of tafoni indicates an overall lower risk of rockfalls.

Removal Performance of Faecal Indicators by Natural and Silver-Modified Zeolites of Various Particle Sizes under Dynamic Batch Experiments: Preliminary Results

One of the oldest and most promising applications of natural zeolites (NZs) is in water and wastewater treatment processes. Modified zeolites (MZs), with improved ion exchange and adsorption capacities, have been extensively applied to the removal of pollutants from aqueous solutions. However, the application of MZs in pathogens or indicator organisms has not been extensively explored. This study examines the effect of both natural Greek zeolite (NZ), with a clinoptilolite content of up to 85% (OLYMPUS SA-INDUSTRIAL MINERALS), and modified Greek zeolite through incorporation with silver ions (Ag-MNZ), on the survival of two selected faecal indicator bacteria (Escherichia coli and Enterococcus faecalis). A series of dynamic batch experiments with a slow agitation of 12 rpm were conducted at a constant ambient temperature (22°C) in order to examine the inactivation of the above bacteria by NZ and Ag-MNZ. It was found that the Ag-MNZ resulted in a much higher reduction in the bacterial numbers when compared to the NZ and the control (absence of zeolites). Moreover, the reduction in bacterial numbers was affected by NZ particle size, with higher removal rates observed for coarse (1–3 mm) than for fine (0–1 mm) NZ. Finally, the E. faecalis was found to be more resistant than E. coli to Ag-MNZ.

Composites based on nylon 6/clinoptilolite by ultrasound-assisted extrusion for enhanced flame retardant and mechanical properties

Safe, lightweight, high-strength and sustainable materials are required for automotive parts and electrical components. In this paper, a polymeric composite based on nylon 6 and clinoptilolite (green fire retardant) was obtained by ultrasound-assisted extrusion. The materials were analyzed by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and cone calorimetry. From the FT-IR results, the presence of elements corresponding to the composition of the clinoptilolite that was used as an additive and nylon 6 was observed. TGA analysis showed that thermal stability improved, and in DSC analysis, we observed a slight increase in the crystallinity of the clinoptilolite polymer compounds, which was reflected in the flame retardation tests and by the mechanical properties. Significant improvement in the stiffness mechanical properties of nylon 6 with increasing clinoptilolite content was observed. For clinoptilolite contents of 1, 5 and 10% weight, the Young’s modulus increased by 3352.79, 3675.53 and 4327.06 MPa, respectively, compared to that of nylon 6, with a value of 2997.45 MPa. Meanwhile, the flexion resistance of nylon 6 increased from 84.75 to 95.05, 99.9 and 105.4 N/mm2 for the compounds obtained. The homogeneous distribution of clinoptilolite in the polymeric matrix due to processing by ultrasonic-assisted melt extrusion prevents the formation of stress concentration points. Flame retardant properties were studied with cone calorimetry, and a reduction in the peak heat release rate (HRR) was observed.

Mirsid volcanic tuff, alkaline activation, dissolved species, optimum activation time, optimum activating concentration

The purpose of this article is to study the activation of the Mir�id volcanic tuff with NaOH solutions at various concentrations. To be more specific, the work investigated the evolution of the concentrations of species that passed from the tuff into the activating solutions and the quantities of dissolved species from 100 g tuff. The species found in the activating solution were: potassium, magnesium, aluminium and silicon. The shape of the curves - a sudden increase followed by a plateau or a second stage of slower increase - allowed for setting up the optimal activation time at a half-hour. Another finding was the optimal concentration of 1 N for the activating solution. X-ray diffractograms showed the increase of clinoptilolite content in the tuff, thus improving the adsorbent as well as ion exchange properties by activation with NaOH solutions.

Composite clinoptilolite/PCL-PEG-PCL scaffolds for bone regeneration: In vitro and in vivo evaluation.

In this study, clinoptilolite (CLN) was employed as a reinforcement in a polymer-based composite scaffold in bone tissue engineering and evaluated in vivo for the first time. Highly porous, mechanically stable, and osteogenic CLN/PCL-PEG-PCL (CLN/PCEC) scaffolds were fabricated with modified particulate leaching/compression molding technique with varying CLN contents. We hypothesized that CLN reinforcement in a composite scaffold will improve bone regeneration and promote repair. Therefore, the scaffolds were analyzed for compressive strength, biodegradation, biocompatibility, and induction of osteogenic differentiation in vitro. CLN inclusion in PC-10 (10% w/w) and PC-20 (20% w/w) scaffolds revealed 54.7% and 53.4% porosity, higher dry (0.62 and 0.76 MPa), and wet (0.37 and 0.45 MPa) compressive strength, greater cellular adhesion, alkaline phosphatase activity (2.20 and 2.82 mg/gDNA /min), and intracellular calcium concentration (122.44 and 243.24 g Ca/mgDNA ). The scaffolds were evaluated in a unicortical bone defect at anterior aspect of proximal tibia of adult rabbits 4 and 8 weeks postimplantation. Similar to in vitro results, CLN-containing scaffolds led to efficient regeneration of bone in a dose-dependent manner. PC-20 demonstrated highest quality of bone union, cortex development, and bone-scaffold interaction at the defect site. Therefore, higher CLN content in PC-20 permitted robust remodeling whereas pure PCEC (PC-0) scaffolds displayed fibrous tissue formation. Consequently, CLN was proven to be a potent reinforcement in terms of promoting mechanical, physical, and biological properties of polymer-based scaffolds in a more economical, easy-to-handle, and reproducible approach.

Characterization of raw and chemically activated natural zeolite as a potential sorbent for heavy metal ions from waste water

In this study, raw and chemically activated natural zeolite from Zlatokop deposit (Serbia) were investigated by FTIR, XRD, SEM-EDX, TGA and BET in order to define their properties as further potential sorption materials. Obtained results indicate porous (meso-pore range) and defined crystal alumino-silicate structure of these materials, with Na+, K+, such as Ca2+ and Mg2+ as dominating exchangeable cations. Content of clinoptilolite (ca. 90%) indicates the high quality of the zeolite samples. Preliminary sorption analyses of these materials toward copper(II) ion from aqueous solution showed good removal efficiency for base activated zeolite (zVBB) compared to raw natural (zVBN) and acid activated (zVBA) zeolite. Since these were preliminary sorption tests, the investigated zeolites will be further examined under different experimental conditions.

Polymer/zeolite nano-composite hydrogels as promising water reservoir materials: effect of clinoptilolite content on physicochemical properties

In this work, with the aim of improving the water uptake behavior and mechanical properties, a novel nano-composite hydrogel system was synthesized using clinoptilolite as a semi-layered zeolite. Accordingly, the gelatin/SCMC-g-poly (AA-co-AAm)/clinoptilolite semi-IPN nano-composite hydrogel samples were synthesized and studied. The FTIR, XRD, SEM and EDX analysis were accomplished to confirm the successful synthesis of the nano-composite hydrogel samples. Additionally, to investigate the effect of clinoptilolite content on water uptake properties and gel characteristics of the synthesized nano-composite hydrogel samples, water absorption kinetics studies and rheological evaluations were carried out. It is obtained that, there is an optimum amount for additive content which can improve the hydrogel properties. Results showed that nano-composite hydrogel sample with 5% W/W of clinoptilolite with respect to the gelatin amount has the best efficiency from the point of view of the water absorption properties and gel characteristics. This phenomenon is related to the creation of physical cross linking in the hydrogels’ structure which leads to the creation of porous hydrogels.

Compared arsenic removal from aqueous solutions by synthetic mixed oxides and modified natural zeolites

Layered Double Hydroxides of Mg–Al–Fe and their mixed metallic oxides of high specific surface area were synthesized by the coprecipitation method. A natural zeolite from a regional quarry with high clinoptilolite content was conditioned and modified. Initially, an acid treatment was applied and subsequently Fe(III) was incorporated by the wet impregnation method. Then the prepared solid materials were characterized by XRD, N2 adsorption–desorption at 77 K, SEM, DRS UV–Vis, and MP-AES to determine their physicochemical properties. Finally, the solid materials were evaluated as adsorbents for arsenic removal in water. The tracking of As and its species concentration at trace levels was carried out by cathodic stripping Square-wave voltammetry, which has proved to be a highly selective and sensitive electrochemical method. High levels of effectiveness in terms of removal were achieved, particularly with the natural zeolites and mixed oxides of highest iron content.

Adsorption characteristics of a clinoptilolite-rich zeolite compound for Sr and Cs

The Sr and Cs adsorption capacities of LithoFill™, LithoGran™ and a competing clinoptilolite containing zeolite product were investigated by radioanalytical methods (85Sr and 134Cs gamma spectroscopy). The dependence of adsorption and adsorption rate on physical factors including temperature, available ions and time were assessed. In addition, the reversibility of adsorption under high ionic strength conditions was also examined. In general, cesium is more strongly adsorbed than strontium, adsorption yields are generally independent of temperature (from room temperature to 65 °C) and adsorption is relatively rapid (identical results for 2 or 5 day adsorption times). As expected, increasing the concentration of other ions in solution tends to reduce adsorption of cesium and strontium. In general, Cs adsorption ranges between 54.5 and 45.2 mg/g for LitoFill and LitoGran samples and between 36.9 and 24.4 mg/g for the competing product. For Sr adsorption, ranges are 30–21 mg/g and 7.3–6.7 mg/g respectively, leading to the conclusion that the higher content of clinoptilolite in the LitoFill/LitoGran samples results in better adsorption characteristics.

УСЛОВИЯ ОБРАЗОВАНИЯ ЦЕОЛИТОВЫХ МЕСТОРОЖДЕНИЙ ГАЗАХСКОГО ПРОГИБА МАЛОГО КАВКАЗА

The paper deals with regularities of formation and location of zeolite-containing deposits of the Gazakh trough of the Lesser Caucasus. The Aydag deposit is located in the Tauz district of Azerbaijan, 7 km away from the Tauz city. The Aydag deposit productive stratum of natural zeolitized ash tuffs in combination with the same characteristics of the enclosing rocks can be classified as a complex deposit with a relatively non-uniform composition and structure of the productive stratum. The mineral and chemical compositions of zeolite-bearing rocks of the Aydag deposit have been thoroughly studied. Special feature of this deposit is the high content of clinoptilolite. According to X-ray diffractometry and mineralogical analysis of average samples, its content is around 70-80%. The porosity of this rock is around 15-20%, or even more, and does not depend on the stratigraphic level. It was found that the high-silica zeolitites of the Upper Cretaceous strata of the Lok-Karabagh zone belong to the hydrothermal-epigenetic type, which formed after the uplift of the enclosing strata, and generally the resource material for the formation of zeolites used to be volcanic glass of acidic, medium, rarely basic composition, contained in tuffs.

Synthesis, characterization and drug release properties of 3D chitosan/clinoptilolite biocomposite cryogels

Three-dimensional (3D) biocomposites based on chitosan (CS) and clinoptilolite (CPL) were prepared by cryogelation and their potential application as drug carriers was investigated. Variation of CPL content from 0 to 33wt.% allowed the formation of biocomposites with heterogeneous morphologies consisting of randomly distributed pores. The further increase of CPL content led to ordered porous architectures where parallel pore channels were observed. The CPL content had a strong influence on water uptake, as well as on the cumulative release of diclofenac sodium (DS) and indomethacin (IDM). It was demonstrated that the drug delivery preferentially takes place in phosphate buffer saline (pH 7.4) in comparison to simulated gastric fluid (pH 1.2), where only a reduced drug release was observed. The drug release mechanism dominating these systems is described as a pseudo-Fickian diffusion, but it changes to non-Fickian release when 33wt.% of CPL was entrapped into the CS matrix or when IDM was loaded into biocomposites.

Effect of modification and regulation on physicochemical properties of clinoptilolite, as well as nitrogen and phosphates removal performance

Natural clinoptilolite was modified by NaCl‐firing to produce modified clinoptilolite. Afterwards, the modified clinoptilolite was regulated by LaCl3 to produce composite clinoptilolite. Modified clinoptilolite and composite clinoptilolite were used to adsorb ammonia‐nitrogen and phosphates from wastewater. The modified clinoptilolite and composite clinoptilolite had high sorption efficiency and removal performance. The ammonia‐nitrogen and phosphate removal rate of the modified clinoptilolite reached 96.46 % and the phosphate removal rate of the composite clinoptilolite reached 86.26 %. Furthermore, the structure was characterized by SEM, EDS, XRD, IR, and N2‐porosimetry analyses. Results showed that the surface of modified clinoptilolite became loose and some pores appeared, which increased the specific surface area. In addition, total pore volume, micropore area and average pore width increased after modification by NaCl firing and LaCl3 regulation, where in the micropore area exhibited the highest increase. The modification process did not change the overall skeletal structure and structural holes for both the modified clinoptilolite and the composite clinoptilolite. The main components were Si, Al, and O. The Na ion content of the modified clinoptilolite increased from 0.77 % to 2.45 % and the La ion content of composite clinoptilolite increased from 0 % to 2.52 %. The modification and regulation mechanisms were based on the Na+ replace Ca2+ and Mg2+ of clinoptilolite. Hydrous lanthanum oxide could be loaded only to the surface of clinoptilolites. In addition, the ion‐exchange capacity of both the modified clinoptilolite and the composite clinoptilolite improved compared with natural clinoptilolite.

Influence of Clinoptilolite Replacement on Durability of Cement Mortars

AbstractThis paper presents the experimental results of a study on the durability properties of clinoptilolite blended cement mortars. In the study, clinoptilolite was used at 0, 5, 10, 15, 20, and 30% replacement by weight of cement while sand and water quantities were kept constant. Fire resistance, abrasion resistance, and shrinkage of the mortars were examined. The results showed that the replacement of cement with clinoptilolite in mortar improved the fire resistance of mortar and that water cooling resulted in higher strength losses than air cooling. Also, the abrasion resistance of mortars increased with an increase in the content of clinoptilolite. After the abrasion tests with a full 352 cycles, although the abrasion loss of control mortar was 2.83%, the abrasion losses of the mortars containing clinoptilolite ranged from 2.12 to 2.81% and the lowest abrasion loss was obtained from the mortars including 30% clinoptilolite. However, the incorporation of clinoptilolite in the mixture caused some in...

Evaluation of Ammonium Removal Performances of Some Zeolitic Volcanic Tuffs from Transylvania, Romania

In this study, zeolitic volcanic tuffs (ZVT) originated from Transylvania, Romania were used, to remove ammonium ions from model solution. The zeolitic volcanic tuff samples used as ionic exchangers were characterized by means of chemical analysis, optical microscopy, SEM, XRD, FTIR, and BET analysis. The main zeolite species identified in the volcanic tuffs from mentioned areas is clinoptilolite. All samples were subjected to chemical treatment with HCl and NaCl, followed by the ionic exchange process. The ionic exchange process was realized in batch and fixed bed column conditions. We found that ionic exchange efficiency varies according to their zeolite content, therefore P (Pâglişa) and M (Măcicaş) samples, which have the highest clinoptilolite content, proved to be more efficient.