Natural Zeolitic Tuff Research Articles

Competing Effects of Chloride, Nitrate, and Sulfate Ions on the Removal of Fluoride by a Modified Zeolitic Tuff

Natural zeolitic tuff was modified with FeCl3 solution for the removal of fluoride, and the effect of chloride, nitrate, and sulfate ions was examined on fluoride sorption from solutions and drinking water. The unmodified zeolitic tuff (Z) and the iron-modified zeolitic tuff (Fe(III)-Z) were characterized by scanning electron microscopy and X-ray diffraction analysis. The elemental composition, the specific surface area, and the point of zero charge of the zeolitic material were also determined. The fluoride adsorption was carried out in a batch system considering the effect of contact time, the initial concentration of fluoride ions, and the effect of other anions naturally present in the drinking water. The kinetic and isotherm results were adjusted to the pseudo-second-order and Freundlich models, respectively, which indicated that the sorption mechanism was chemisorption on a heterogeneous material. The fluoride sorption capacity was higher in solutions (2.7 mg/g) than in drinking water (0.41 mg/g), and this could be attributed to the presence of other anions. Overall, the presence of chloride ions significantly diminished the fluoride adsorption capacity, while the presence of nitrate and sulfate ions did not show any significant effect; the anion removal efficiency by Fe(III)-Z followed the order F− > > Cl− > NO3 − > SO4 2−.

The iron(III)-modified natural zeolitic tuff as an adsorbent and carrier for selenium oxyanions

Se(IV) and Se(VI) anions are the dominant species of Se existing in aqueous systems. In this study, the iron(III)-modified natural zeolitic tuff (Fe-CLI) from the Serbian deposit Zlatokop has been investigated as an adsorbent for the Se oxyanions. Fe-CLI shows adsorption activity for both Se(IV) and Se(VI) which decreases with increasing pH. The adsorption capacity of Fe-CLI is found to be higher for Se(IV) than for Se(VI). Kinetics data follow the pseudo-second-order model and the obtained parameters k indicate that the rates of adsorption and desorption are higher for Se(VI). Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) analyses reveal that Se is bound at the zeolite surface forming not only the Se–O–Fe but also Se–O–Si bonds. The adsorption mechanism depends of the type of oxo ions. Samples of zeolitic tuff which contain Se were tested as soil supplements for the cultivation of Pleurotus ostreatus mushrooms. The fungus adsorbed the inorganic Se from zeolitic tuff transforming it to a more valuable organically bound form.

Fixed-bed study of ammonia removal from aqueous solutions using natural zeolite

Purpose – The purpose of this paper is to investigate the performance of natural Jordanian zeolite tuff to remove ammonia from aqueous solutions using a laboratory batch method and fixed-bed column apparatus. Equilibrium data were fitted to Langmuir and Freundlich models. Design/methodology/approach – Column experiments were conducted in packed bed column. The used apparatus consisted of a bench-mounted glass column of 2.5 cm inside diameter and 100 cm height (column volume = 490 cm3). The column was packed with a certain amount of zeolite to give the desired bed height. The feeding solution was supplied from a 30 liter plastic container at the beginning of each experiment and fed to the column down-flow through a glass flow meter having a working range of 10-280ml/min. Findings – Ammonium ion exchange by natural Jordanian zeolite data were fitted by Langmuir and Freundlich isotherms. Continuous sorption of ammonium ions by natural Jordanian zeolite tuff has proven to be effective in decreasing concentrations ranging from 15-50 mg NH4-N/L down to levels below 1 mg/l. Breakthrough time increased by increasing the bed depth as well as decreasing zeolite particle size, solution flow-rate, initial NH4+ concentration and pH. Sorption of ammonium by the zeolite under the tested conditions gave the sorption capacity of 28 mg NH4-N/L at 20°C, and 32 mg NH4-N/L at 30°C. Originality/value – This research investigates the performance of natural Jordanian zeolite tuff to remove ammonia from aqueous solutions using a laboratory batch method and fixed-bed column apparatus. The equilibrium data of the sorption of Ammonia were plotted by using the Langmuir and Freundlich isotherms, then the experimental data were compared to the predictions of the above equilibrium isotherm models. It is clear that the NH4+ ion exchange data fitted better with Langmuir isotherm than with Freundlich model and gave an adequate correlation coefficient value.

Modification of natural clinoptilolite for the nitrate removal from water media

The natural zeolitic tuff from the Zlatokop mine (Vranjska Banja deposit) has been investigated as a starting material for obtaining a low cost adsorbent for the removal of nitrate from water media. The tuff riched with zeolite - clinoptilolite was modified by simple procedures by several oxides: iron(III), manganese(IV) and magnesium in order to make clinoptilolite surface accessible for binding the nitrate ions. The obtained oxide-modified zeolite samples were characterized by scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS), powder X-ray diffraction (PXRD), infrared spectroscopy (FTIR) and by measurement of specific surface area. The effects of the adsorbent dosage (0.5, 1.0, 1.5 and 2.0 g), temperature (25, 35 and 45 ?C) and initial nitrate concentration (C0= 100, 200 and 300 mg dm-3) on the binding efficiency were also studied. For all adsorbents the efficiency increases with temperature. The type of oxides effects the adsorption mechanism and Fe(III) oxide modified zeolite exhibits the best binding ability. For this adsorbent the adsorption kinetics was studied and found that it is best represented by the pseudo-second-order model.

Removal of magnesium in spring water using the natural zeolite in a continuous flow system

The aim of this work is an investigation of the possible application of Serbian natural zeolitic tuff ("Igros Vidojevic" deposit, Brus) for improvement of the spring water quality. Concentration of magnesium in spring waters in Raska area (in southeast Serbia) is grater then 100 mg/dm3 and is unsuitable for everyday consumption. The experiments includied investigation of fluid-mechanics tests of the zeolite particles with diameters of 1.5 mm, 4 mm and 6 mm in a column with diameter of 65 mm and magnesium adsorption/desorption experiments in the column with a diameter of 110 mm. The results showed that using sodium enriched zeolite bed and using optimal fluid-mechanics parameters, the concentration of magnesium in the spring water can be decreased below the maximum allowed concentration of 50 mg/dm3.

Studying competitive sorption behavior of methylene blue and malachite green using multivariate calibration

Sorption of methylene blue MB and malachite green MG (with 96.4% spectral overlap) from bi-solute solution by natural kaolinitic-clay and philipsite-rich-zeolite tuff was addressed where solutes simply quantified using multivariate calibration MVC. For simultaneous quantification of dyes in solution, partial least squares PLS1 (a powerful MVC tool) was found satisfactory with high recovery (98.7–103.2%) and precision (RSD 9.2–11.7%). In MVC, the spectral range 409–700nm is used and 43 spectral points where taken for each sample. Natural clay (80% kaolinite) and zeolite tuff (95% philipsite) showed a high uptake for dyes with maximum capacities of 0.77mmol MB/gclay and 0.64mmol MG/gclay, 0.66mmol MB/gzeolite and 1.22mmol MG/gzeolite reported at 1.0g/L, particle diameter <45μm, 20.0°C and pH 7.0. Due to competition between dyes for active sites, the sorption capacities were reduced and the highest reduction was 30% which observed for MG sorption by clay. The competition between dyes was higher in clay as indicated from competition factors CFs. Sorption isotherms of bi-solute systems have irregular L2 isotherm shape and the data were fairly correlated to Langmuir and competitive Langmuir models. The contribution of ion-exchange mechanism in dyes removal was found significant, 61% and 79% of MB were removed via ion-exchange by clay and zeolite, respectively. Using MVC, studying competitive sorption of MB and MG without the need for chromatographic separation is accomplished. Studying competitive sorption of more than two solutes using PLS1 is also possible indicating the high resolution power of this technique.

Natural zeolites for heavy metals removal from aqueous solutions: Modeling of the fixed bed Ba2+/Na+ ion-exchange process using a mixed phillipsite/chabazite-rich tuff

The efficiency of Ba2+ removal from aqueous solutions by means of an ion exchange process was investigated. More specifically, a natural zeolitic tuff, namely a Campanian ignimbrite containing both chabazite and phillipsite as exchanger phases was used, and the effect of Ba2+ concentration was studied. The selected material, previously converted into its Na+ form, was used in a laboratory scale fixed bed column, and the kinetics of Ba2+ removal were studied at different concentrations, ranging from 50 to 500g/m3. In all the experiments a very high selectivity of the tuff material towards Ba2+ was observed. The experimental data were interpreted using a diffusional model, based on the Linear Driving Force (LDF) approximation. The model accounted for the presence of two zeolitic phases in the tuff and for mass transfer limitations in both the liquid phase and tuff particles. The model interpreted the data satisfactorily, enabling it to be established that both the internal and external mass transfer resistances played a key role in the kinetics of the ion exchange process.

Novel kinetic model of the removal of divalent heavy metal ions from aqueous solutions by natural clinoptilolite

Removal of heavy metal ions from aqueous solutions using zeolites is widely described by pseudo-second order kinetics although this model may not be valid under all conditions. In this work, we have extended approaches used for derivation of this model in order to develop a novel kinetic model that is related to the ion exchange mechanism underlying sorption of metal ions in zeolites. The novel model assumed two reversible steps, i.e. release of sodium ions from the zeolite lattice followed by bonding of the metal ion. The model was applied to experimental results of Cu(II) sorption by natural clinoptilolite-rich zeolitic tuff at different initial concentrations and temperatures and then validated by predictions of ion exchange kinetics of other divalent heavy metal ions (i.e. Mn(II), Zn(II) and Pb(II)). Model predictions were in excellent agreements with experimental data for all investigated systems. In regard to the proposed mechanism, modeling results implied that the sodium ion release rate was constant for all investigated metals while the overall rate was mainly determined by the rate of heavy metal ion bonding to the lattice. In addition, prediction capabilities of the novel model were demonstrated requiring one experimentally determined parameter, only.

Removal of Pb(II) from water by natural zeolitic tuff: Kinetics and thermodynamics

The present study was aimed at examining the ability of a natural zeolitic volcanic tuff to remove Pb(II) ions from aqueous solutions under various conditions. The effects of various parameters such as optimum adsorbent mass, contact time, pH of the medium, Pb(II) concentration, and temperature were investigated. In addition, different adsorption isotherms were obtained using concentrations of Pb(II) ions ranging from 1 mg/L to 200 mg/L. The adsorption process follows second-order reaction kinetics and follows the Langmuir adsorption isotherm. The thermodynamic parameters are discussed in this article, including changes in Gibbs free energy, entropy, and enthalpy, for the adsorption of Pb(II) on tuff, and it is revealed that the adsorption process was spontaneous and exothermic under natural conditions. The maximum removal efficiency of 92% was obtained at a pH of 5 with a 25-min contact time for a 10 g/L solid-to-liquid ratio and an initial heavy metal concentration of 100 mg/L.

Characterization and Dehydration Behavior of a Natural, Ammonium Hydroxide, and Thermally Treated Zeolitic Tuff

Aqueous NH4OH-treated and subsequently calcined forms of local natural zeolitic tuff were characterized by different techniques including scanning electron microscopy (SEM), X-ray powder diffraction, inductively coupled plasma–atomic emission spectroscopy (ICP-AES), volumetric N2 adsorption at −196°C, thermogravimetry (TG), differential scanning calorimetry (DSC), and transmittance infrared spectroscopy. The dehydration behavior of the samples was investigated using an in situ temperature-programmed diffuse reflectance Fourier transform infrared spectroscopy (TP-DRIFTS) method under vacuum. The DRIFTS spectra recorded yielded information about the effect of the NH4OH treatment and subsequent calcination on the dehydration behavior of the natural zeolite. Changes in the infrared bands corresponding to vibrations of the O–H and N–H bonds upon in situ heating under vacuum were analyzed.

Removal of nickel(II) ions from aqueous solutions using the natural clinoptilolite and preparation of nano-NiO on the exhausted clinoptilolite

The natural zeolite tuff (clinoptilolite) from a Serbian deposit has been studied as adsorbent for Ni(II) ions from aqueous solutions. Its sorption capacity at 298 K varies from 1.9 mg Ni g −1 (for the initial solution concentration of 100 mg Ni dm −3) to 3.8 mg Ni g −1 (for C 0 = 600 mg Ni dm −3) and it increases 3 times at 338 K. The sorption is best described by the Sips isotherm model. The sorption kinetics follows the pseudo-second-order model, the activation energies being 7.44, 5.86, 6.62 and 6.63 kJ mol −1 for C 0 = 100, 200, 300 and 400 mg Ni dm −3, respectively. The sorption involves a film diffusion, an intra-particle diffusion, and a chemical cation-exchange between the Na + ions of clinoptilolite and the Ni 2+ ions. The sorption is endothermic (Δ H° being 37.9, 33.4, 30.0, 27.7 and 24.3 kJ mol −1 for C 0 = 100, 200, 300, 400 and 600 mg Ni dm −3, respectively) and spontaneous in the 298–338 K temperature range. Thermal treatment of the Ni(II)-loaded clinoptilolite results in the formation of spherical nano-NiO particles of approx. 5 nm in diameter which are randomly dispersed in the clinoptilolite lattice.

Cationic surfactants-modified natural zeolites: improvement of the excipients functionality

Context: In this study an investigation of cationic surfactants-modified natural zeolites as drug formulation excipient was performed. Objective: The aim of this work was to carry out a study of the purified natural zeolitic tuff with high amount of clinoptilolite as a potential carrier for molecules of pharmaceutical interest. Materials and methods: Two cationic surfactants (benzalkonium chloride and hexadecyltrimethylammonium bromide) were used for modification of the zeolitic surface in two levels (equal to and twice as external cation-exchange capacity of the zeolitic tuff). Prepared samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric, high-performance liquid chromatography analysis, and powder flow determination. Different surfactant/zeolite composites were used for additional investigation of three model drugs: diclofenac diethylamine, diclofenac sodium, and ibuprofen by means of adsorption isotherm measurements in aqueous solutions. Results: The modified zeolites with two levels of surfactant coverage within the short activation time were prepared. Determination of flow properties showed that modification of zeolitic surface reflected on powder flow characteristics. Investigation of the model drugs adsorption on the obtained composites revealed that a variation between adsorption levels was influenced by the surfactant type and the amount present at the surface of the composites. Discussion and conclusion: In vitro release profiles of the drugs from the zeolite-surfactant-drug composites revealed that sustained drug release could be attained over a period of 8 hours. The presented results for drug uptake by surfactant-zeolite composites and the afterward drug release demonstrated the potential use of investigated modified natural zeolite as excipients for advanced excipients in drug formulations.

Influence of natural zeolitic tuff and organozeolites surface charge on sorption of ionizable fumonisin B 1

Natural zeolitic tuff was modified with 2, 5 and 10 mmol M +/100 g of octadecyldimethylbenzyl ammonium (ODMBA) ions and the products were denoted as OZ-2, OZ-5 and OZ-10. The starting material and organozeolites were characterized by determination of the point of zero charge (pH pzc) and by thermal analysis. In vitro sorption of fumonisin B 1 (FB 1) was studied for all sorbents at pH 3, 7 and 9. The pH pzc for the zeolitic tuff was 6.8 ± 0.1, while the pH pzc for OZ-2, OZ-5 and OZ-10 pH pzc was 7.0 ± 0.1. The curves pH final = f (pH initial) suggest that the surfaces of all sorbents are positively charged at pH 3 and uncharged at pH 7 and 9. High sorption of FB 1 by the zeolitic tuff in acidic solution suggests electrostatic interactions between the anionic FB 1 and the positively charged surface. At pH 7 and 9, adsorption of FB 1 is prevented because anionic FB 1 cannot be adsorbed at the uncharged surface. From the pH pzc for the organozeolites, it is possible that with lower amounts of ODMBA (OZ-2 and OZ-5), at pH 3, beside interactions between head groups of ODMBA and its alkyl chains and anionic FB 1, electrostatic interactions between positive uncovered surface and anionic FB 1 contribute to the sorption, while at pH 7 and 9 there is only the possibility for interactions between FB 1 and ODMBA. When the zeolitic surface was completely covered with ODMBA (OZ-10), FB 1 sorption was independent of the form of FB 1 suggesting only interactions between ODMBA and FB 1.

Calorimetric evolution of the early pozzolanic reaction of natural zeolites

The pozzolanic reaction between natural zeolite tuffs, portlandite and water was investigated over the course of the early reaction period up to 3 days. Isothermal conduction calorimetry experiments supplemented by TG/DTG and XRD analyses assisted in the elucidation of the sequence of reaction processes taking place. The calorimetry experiments clearly showed the dependence of the pozzolanic reaction rate and associated heat release on the fineness of the zeolite tuff. Higher external surface areas of pozzolans yield higher total heat releases. Also the exchangeable cation content of the zeolites influences the reaction rate. Release of exchangeable alkalis into solution promotes the pozzolanic reaction by raising the pH and zeolite solubility. The appearance of an exotherm after approximately 3 h of reaction is more conspicuous when alkali-rich zeolites are reacted. This exotherm is conceived to be related to a transformation or rupture of initially formed reaction products covering the zeolite grains. The formation of substantial amounts of ‘stable’ calcium silicate hydrate (C–S–H) and calcium aluminate hydrate (C–A–H) reaction took place after an induction period of more than 6 h. The openness of the zeolite framework affects the proneness of the zeolite to dissolution and thus its reactivity. Open framework zeolites such as chabazite were observed to react much more rapidly than closed framework zeolites such as analcime.

Removal of aqueous manganese using the natural zeolitic tuff from the Vranjska Banja deposit in Serbia

The natural zeolite tuff from the Vranjska Banja deposit (Serbia) has been studied as sorbent for Mn(II) ions from aqueous solutions. The zeolite sample containing mainly clinoptilolite (more than 70%) removes Mn(II) ions by ion-exchange process, which was confirmed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDXS). XPS showed that there is no surface accumulation of Mn but an almost uniform distribution inside the sorbent; EDXS confirmed that Mn(II) replaced the clinoptilolite Na counter ions. The sorption isotherms were studied at 298 K by batch experiments showing that the Mn(II) removal is best described by the Langmuir–Freundlich or Sips model. The kinetics followed the pseudo-second-order model, the activation energy being 128 kJ mol −1. The intra-particle diffusion is not the rate-controlling step in the sorption of Mn(II) on clinoptilolite. Thermodynamic data suggest spontaneity of the endothermic ion-exchange process in the 298–338 K range.

Kinetics of proton transfer in the zeolitic tuff

Abstract The kinetics of a proton transfer into dilute acid solutions containing natural zeolitic tuff was studied by following the pH evolution of the liquid phase. Four different solutions with tuff contents of 9, 3, 1 and 0.5 (% wt) and three different particle size fractions (≤ 2000 μm) were studied. The proton concentration of the solution was decreased by increasing the zeolite amount and decreasing the particle size fraction. The proton transfer reaction was analyzed with chemical reactions and diffusion model equations. Analysis shows that the adsorption and/or ion exchange are possible mechanisms and are expressed by a second order reaction model.

The influence of using Jordanian natural zeolite on the adsorption, physical, and mechanical properties of geopolymers products

Geopolymers consist of an amorphous, three-dimensional structure resulting from the polymerization of aluminosilicate monomers that result from dissolution of kaolin in an alkaline solution at temperatures around 80 °C. One potential use of geopolymers is as Portland cement replacement. It will be of great importance to provide a geopolymer with suitable mechanical properties for the purpose of water storage and high adsorption capacity towards pollutants. The aim of this work is to investigate the effect of using Jordanian zeolitic tuff as filler on the mechanical performance and on the adsorption capacity of the geopolymers products. Jordanian zeolitic tuff is inexpensive and is known to have high adsorption capacity. The results confirmed that this natural zeolitic tuff can be used as a filler of stable geopolymers with high mechanical properties and high adsorption capacity towards methylene blue and Cu(II) ions. The XRD measurements showed that the phillipsite peaks (major mineral constituent of Jordanian zeolite) were disappeared upon geopolymerization. The zeolite-based geopolymers revealed high compressive strength compared to reference geopolymers that employ sand as filler. Adsorption experiments showed that among different geopolymers prepared, the zeolite-based geopolymers have the highest adsorption capacity towards methylene blue and copper(II) ions.

Comparative Study of Zn2+, Cd2+, and Pb2+ Removal From Water Solution Using Natural Clinoptilolitic Zeolite and Commercial Granulated Activated Carbon. Equilibrium of Adsorption

The aim of this work is to study the effectiveness of regional, low-cost natural clinoptilolitic zeolite tuff in heavy metal ions removal from aqueous solution, through comparative study with commercial granulated activated carbon. The equilibrium of adsorption of Cd2+, Pb2+, and Zn2+ on both adsorbents have been determined at 25, 35, and 45°C in batch mode. The granulated activated carbon has shown around three times higher adsorption capacity for Cd2+ and Zn2+ than natural zeolite, and almost the same adsorption capacity for Pb2+ as the natural zeolite. The metal ion selectivity series Pb2+ > Cd2+ > Zn2+, on a mass basis, has been obtained on both adsorbents. The Langmuir and Freundlich model have been used to describe the adsorption equilibrium. The thermodynamic parameters were calculated from the adsorption isotherm data obtained at different temperatures. The study of the influence of the acidity of the metal ion aqueous solution has shown an increase of metal ion uptake with increase of the pH. The sorption mechanism of Cd2+, Pb2+, and Zn2+ on natural zeolite changes from ion-exchange to ion-exchange and adsorption of metal-hydroxide with increase of the pH from 2 to 6 (and 7 for Zn2+). The preliminary cost calculation, based on adsorbents maximum adsorption capacity and their price, have revealed the potential of natural zeolite as an economic alternative to the granulated activated carbon in the treatment of heavy metal polluted wastewater.

Adsorption of arsenic (V) by iron (III)-modified natural zeolitic tuff

Adsorption of arsenic (V) by natural zeolitic tuff, modified with iron (III), was investigated. Also, the iron (III) adsorption characteristics by natural zeolitic tuff was evaluated. It was determined that iron (III) adsorption by starting zeolitic tuff was best represented by the Freundlich type of isotherm, having correlation coefficient (r2) of 0.990. Arsenic (V) adsorption by iron (III)-modified zeolitic tuff followed a nonlinear type of isotherm. The best fit of the experimental data was obtained using the Langmuir–Freundlich model (r2 = 0.99), with the estimated maximum of arsenic (V) adsorption to iron (III)-modified zeolitic tuff of 1.55 mg/g.

Adsorption of Cu(II), Pb(II) and humic acid on natural zeolite tuff in single and binary systems

A natural zeolite tuff was used for adsorption of heavy metals, Cu 2+ and Pb 2+, and humic acid (HA) in aqueous solution. Its adsorptive behaviour was investigated in both single component and binary component systems. For single component system, the adsorption capacities of Cu 2+, Pb 2+ and humic acid at 30 °C, pH 5 are 23, 68 and 78 mg/g, respectively. Solution pH was found to influence the adsorption. For heavy metals, adsorption is enhanced at higher pH while humic acid adsorption is reduced when solution pH is increased. In Pb 2+/humic-acid system, Pb 2+ exhibits competitive adsorption with humic acid on the natural zeolite, resulting in reduced adsorption of both Pb 2+ and humic acid. However, in Cu 2+/humic-acid system, competitive adsorption and complexation between Cu 2+ and humic acid influence the adsorption, resulting in decreased adsorption of humic acid but increased adsorption of Cu 2+. The complexation structure of Pb–HA/zeolite and Cu–HA/zeolite in three-component system was proposed as S-Pb–HA and S-HA-Cu, respectively.