Ion-exchange Studies Research Articles

Hydrochemistry modelling: evaluation of groundwater quality deterioration due to anthropogenic activities in Lahore, Pakistan

Anthropogenic activities adversely affect the drinking water quality. This study examined the effect of anthropogenic activities on groundwater quality of Lahore city, Pakistan. Hydrochemistry modelling approach was applied to thirteen tube wells of the study area. Lithology profiles (borehole logs and fence diagram) indicated variable lithology in the study area. It was categorized into two types, i.e. clay dominant and sand dominant. The physico-chemical characterization of groundwater samples revealed that all parameters were found within the WHO guidelines for drinking water, except alkalinity, Cd, Cr, Ni and Pb. Piper, Stiff, Durov and Schoeller diagrams indicated the presence of bicarbonates anionic and sodium and potassium cationic systems. The abundance of cations and anions was in the order of Na > K > Ca > Mg and HCO3 > Cl > SO4, respectively. In the ion exchange studies, negative chloro-alkaline indices values indicated the replacement of divalent cations with sodium. Saturation indices by PHREEQC modelling have values < 0 and Gibbs diagram indicated that groundwater tends to dissolve more minerals, leading to precipitation reactions in water. The plot of heavy metal concentrations using GIS maps specified the abundance of heavy metals in tube wells near River Ravi, likely caused by recharge of groundwater by the river which receives heavy quantities of untreated industrial effluents.

Comparative study of nanofiltration and ion exchange for nitrate reduction in the presence of chloride and iron in groundwater

Public concern on the groundwater contamination by nitrate has grown significantly in recent years.The objective of this study was to determine the appropriate treatment to reduce the nitrate content in the presence of other ions from groundwater, for which nanofiltration and ion exchange were evaluated. In nanofiltration, the effects of pressure, feed flow, initial composition, and performance were studied, in ion exchange the flow rate, initial composition, and resin regeneration process.Nanofiltration tests were carried out on four different commercial membranes: NF97, NF99, NF99H, and NF90. Among these, all membranes removed chloride but only NF97 and NF90 were able to remove nitrate in compliance with Chilean drinking water standard, showing rejections of 97% and 87%, respectively, in an optimum pressure range of 12–20 bar in which the NF90 produced 3.5 times more permeated water than NF97.For ion exchange tests, Purolite A520E resin was used, which decreased nitrate content to <1 mg/L. Results leading to the optimal flow within the exchange column indicated that residence time must be at least 2.1 min. The higher nitrate concentration in water did not lead to changes in the maximum resin capacity, 47.1 mg NO3−/g resin, but it did decrease the resin breakthrough capacity when initial concentration increased. Optimal regeneration was assigned to a 3% w/V NaCl solution and up-flow mode.Due to the ability to remove both nitrate and chloride, and being able to remove iron if necessary, nanofiltration was chosen as the appropriate treatment.

Preparation and ion exchange studies of cesium and strontium on sodium iron titanate

Sodium iron titanate (NaFeTiO) inorganic ion exchanger was synthesized and the ion exchange behaviour of cesium, strontium and europium ion on NaFeTiO was studied. The sodium iron titanate was prepared by the hydrolysis of tetraethyl ortho titanate with sodium hydroxide in the presence of ferric chloride at the Ti/Fe mole ratio of 25.7. The ion exchange material was characterized by elemental analysis, sodium exchange capacity, X-Ray diffraction, thermogravimetry, and Raman spectroscopy. The distribution coefficient (Kd, mL/g) of cesium, strontium and europium on NaFeTiO was measured as a function of pH of the aqueous phase, duration of equilibration, concentration of sodium, cesium, strontium and europium ion in aqueous phase. The Kd of cesium gradually increased with increase of pH, and that of strontium also increased up to pH 6 followed by saturation in Kd values. However, the distribution coefficient of europium increased up to pH 4 followed by the precipitation of europium at higher pH values. The rate of ion exchange of cesium and strontium on NaFeTiO was rapid in the initial stages of equilibration followed by the establishment of equilibrium occurring after 200 min. The kinetics of extraction was fitted in to pseudo-first order and -pseudo-second order rate equations. The NaFeTiO was found to follow the ion exchange mechanism, in which the sodium ion from NaFeTiO was exchanged with cesium or strontium ion from aqueous phase. The strontium exchange capacity on NaFeTiO was determined to be 233 mg g−1. The loaded metal ions was recovered using 0.5 M nitric acid.

Study of ion exchange at test solutions purification from nickel (II) ions with gabbro-diabase from abzakovo deposit

The paper presents the results of the study of ion exchange processes during the purification of model solutions from nickel ions with gabbro-diabase from the Abzakovo field. The features of the minerals structure that make up gabbro-diabase predetermine their sorption and cation-exchange properties. During the studies, the course of sorption processes was established, as well as the presence of a suspension effect in the system. By determining the concentration of exchangeable cations (Ca2+, Mg2+, Al3+) in the crystal lattices of gabbro diabase and Ni2 + cations contained in the model solution, the phenomenon of cation exchange purification has been proved. The treatment of gabbro diabase powder with electromagnetic radiation increases the mobility of exchange cations and water treatment efficiency.

Competitive biosorption of Cu2+ and Ag+ ions on brown macro-algae waste: kinetic and ion-exchange studies.

The application of biosorption operation has gained attention in the removal and retrieval of toxic metal ions from water bodies. Wastewater from industrial activity generally presents great complexity due to the coadsorption of cations to the inactive biomass binding sites. In this work, the competitive biosorption of Cu(II) and Ag(I) ions was studied in batch systems. A kinetic study applying a non-acidified and acidified waste of Sargassum filipendula in equimolar and non-equimolar metal samples was carried out and the acidified biosorbent was selected due to higher removal rates and selectivity of silver ions. The assays were performed with 2 g L-1 of biosorbent concentration at 25 °C for 12 h and pH was controlled at around 5.0. Copper presented higher affinity for the biosorbent and a fast biosorption kinetic profile, while silver equilibrium times exhibited dependence on the copper concentration. External diffusion is the rate-limiting step in Cu(II) ion removal and it might also limit the kinetic rates of Ag(I) ions with intraparticle diffusion, depending on the initial concentration of metal cations. The ion-exchange mechanism is evidenced and complexation and electrostatic attraction mechanisms might be suggested, explained by simultaneous chemisorption and physisorption processes during the operation. Calcium and sodium were released in considerable amounts by the ion-exchange mechanism. Characterization analyses confirmed the role of several functional groups in the competitive biosorption accompanied by a homogenous covering of both metal ions on the surface of the particles. Particle porosity analyses revealed that the material is macroporous and an appreciable amount of macropores are filled with metal cations after biosorption.

Removal of the Acid Orange 10 by ion exchange and microbiological methods

The persistent pollutant azo dye, Acid Orange 10, was removed from the environment by an Amberlite IRA 400 anion-exchange resin and then biodegraded by two bacterial strains. Moreover, the pollutant ecotoxicity was studied by a bacterial model. The objective of this study was to offer a new synergetic/compatible physico-chemical and biological method to remove and biodegrade the azo dye, Acid Orange 10, from the environment. Bach method was applied. The Acid Orange 10 sorption on the resin (Acid Orange 10 concentration, its contact time and stability) was characterized based on the various parameters such as pH and temperature. The biodegradation and the ecotoxicity effect of Acid Orange 10 have been monitorized on two bacterial strains such as Salmonella enterica (gram-negative bacteria) and Enterococcus faecalis (gram-positive bacteria). Experimental data detected from ion-exchange studies showed that the strongly basic anion-exchange resin Amberlite IRA 400, can removed efficiently up to 96.8% at 10−2 M of Acid Orange 10 concentration. Moreover, 10−2 M Acid Orange 10 induced in 1 h a significant 50% growth inhibition on S. enterica, but not on the E. faecalis. This result was linked to E. faecalis ability to degrade more than 60% of Acid Orange 10 compared to S. enterica (30% Acid Orange 10 degradation). The methods tested in this study can be used for removed/biodegradation of Acid Orange 10 from different polluted waters.

Conformational 2-Fold Interpenetrated Uranyl Supramolecular Isomers Based on (6,3) Sheet Topology: Structure, Luminescence, and Ion Exchange

Six new 2-fold interpenetrated uranyl coordination polymers with two distinct types of (6,3)-net layers, (H3O)[(UO2)(L)]·H2O (1), (Hbipy)[(UO2)(L)]·H2O (2), (Hbib)[(UO2)(L)]·H2O (3), (H2dib)[(UO2)2(L)2]·H2O (4), [Zn(H2O)6][(UO2)2(L)2]·5H2O (5), and (NH4)[(UO2)(L)]·H2O (6), (bipy = 2,2'-bipyridine, bib = 4,4'-di(1 H-imidazol-1-yl)-1,1'-biphenyl, and dib = 1,4-di(1 H-imidazol-1-yl)benzene), were hydrothermally prepared from a tripodal polycarboxylate ligand, tri(4-carboxyphenyl)phenylsilane (H3L), with different N-bearing organic templates as the stacking templates and charge compensators. Structural analyses indicate that these compounds comprise two sets of conformational supramolecular isomers because of the same framework compositions but different conformations of the carboxylate ligands. The solid-state emission spectra of compounds 1-6 were recorded. Ion-exchange studies revealed that the ammonia hydrate in 6 can be selectively substituted by alkali metal cations with appropriate ionic radii, and that the resulting structures remain stable, as demonstrated by crystallographic characterization.

Synthetic Na/K-birnessite for efficient management of Sr(II) from nuclear waste

The efficient separation for alternate use and management of 90Sr in nuclear waste is an important research activity in nuclear power industries. Herein we have demonstrated an efficient separation of Sr2+ by birnessite type sodium and potassium phyllomanganates (AxMn2O4-yH2O; A = Na+ and K+). Both the materials were prepared by oxidation of Mn(OH)2 by flowing oxygen atmosphere in presence of large excess of alkali hydroxide. Mn(OH)2 was prepared by precipitation method using solutions of MnCl2 and NaOH or KOH. The XRD studies revealed that both materials have layered monoclinic (C2/m) structures made of sheets of edge shared MnO6 octahedra. The Na+ or K+ ions were located in between these layers and provide charge neutrality to the structure. From thermogravimetric and XRD studies, the compositions of the prepared phyllomanganates are found to be Na0.5Mn2O4-0.96H2O (NMO) and K0.5Mn2O4-0.6H2O (KMO). The ion exchange studies carried out using radioactive 85Sr2+ solutions revealed large distribution constant (Kd) in a wider range of pH (2 to 14). Maximum Kd (27,000 mL/g) for NMO is observed in neutral medium which decreased to ∼19,000 mL/g at pH 14, while the Kd (∼22,000 mL/g) of KMO is relatively insensitive to pH. Higher preference of Sr2+ ions over Na+ and K+ have been concluded from the kinetics of exchange process. Ion exchange capacities of NMO and KMO are: 9.64 mmol/g and 1.09 mmol/g, respectively. Interference studies with several commonly present ions in nuclear waste like Al3+, Ca2+, H+ and Na+ ions, indicated appreciable interference only from Al3+.

Assessment of amenability of sandstone-hosted uranium deposit for in-situ recovery

Laboratory studies to characterise mineralogy and hydrometallurgical behaviour can be used as an essential and critical sub-component of field leach trials to reduce the risk associated with the implementation of an in-situ recovery process. Sample characterisation, bottle-roll leach tests, column leach tests and ion-exchange studies were conducted on samples from the sandstone-hosted Bennet Well deposit (Yanrey Station) in Western Australia, to obtain an understanding of the ore properties, leach behaviour and lixiviant/oxidant options, uranium recoveries and impurity treatment with a view to determining the suitability of this deposit for in-situ recovery processing. Drill core samples from the deposit contained coffinite, were suspected to contain autunite, and contained uranium associated with coal particles and titanium oxides. The main gangue mineral was quartz, and moderate quantities of K-feldspar, kaolinite and muscovite were present. Bottle-roll and column leach tests indicated that sulfuric acid or a carbonate/bicarbonate lixiviant would be suitable for leaching, with the former yielding a higher maximum uranium extraction. Acid column tests on five drill core samples from different deposit locations yielded between 57% and 84% uranium extraction, and 32% to 69% uranium extraction was achieved for the carbonate column leach tests, without oxidant addition. Oxidant addition increased the uranium extraction to 93%–98% for the acid column leach tests and 38%–70% for the carbonate column leach tests, however, oxidant addition complicates downstream processing. Column leach tests yielded lower recoveries compared with the bottle-roll leach tests and recoveries are expected to be lower for a field-scale implementation. A number of ion-exchange resins were found to be suitable for uranium recovery, with up to 100% loading and elution achieved in the acid and carbonate systems. This approach provides an experimental guideline for similar application to deposits that may be amenable to ISR processing.

Bioregeneration of Chabazite During Nitrification of Centrate from Anaerobically Digested Livestock Waste: Experimental and Modeling Studies.

Nitrification of high total ammonia nitrogen-strength wastewaters is challenging due to free ammonia (FA) inhibition of nitrification. FA inhibition can potentially be alleviated by temporarily adsorbing ammonium (NH4+) to natural zeolite, such as chabazite, followed by direct zeolite bioregeneration via nitrification. In this research, the effectiveness of chabazite addition for reducing nitrification inhibition during treatment of centrate from anaerobic digestion of swine waste was quantified. A mathematical model was developed that accounts for ion exchange of NH4+ and sodium at the chabazite surface, surface diffusion of adsorbed NH4+ within the chabazite grains, sequential nitrification of aqueous NH4+ to nitrite and nitrate, and inhibition of nitritation and nitratation rates by NH4+. The model was calibrated using results of abiotic ion exchange and nitrification studies. Subsequently, nitrification tests were carried out with synthetic wastewater with a NH4+-N concentration of 1000 mg L-1, with and without chabazite. A chabazite dose of 150 g L-1 decreased the FA concentration to below the inhibitory level and increased the nitrification rate from 0.16 to 0.36 mg-N (g-VSS)-1 h-1. Following calibration, the model could predict the experimental data with no additional fitting parameters or parameter adjustment, in both the presence and absence of chabazite. The results suggest that the mathematical model provides a theoretically sound conceptual understanding of ion exchange assisted nitrification.

Synergistic Methodology Based on Ion Exchange and Biodegradation Mechanisms Applied for Metal Complex Dye Removal from Waste Waters

This study investigates the synergistic effects of ion exchange and biodegradation methods to remove the Acid Blue 193 also called Gryfalan Navy Blue RL (GNB) dye from wastewater. Ion exchange studies were performed using a strongly basic anion exchange resin Amberlite IRA 400. The equilibrium was characterized by a kinetic and thermodynamic points of view, establishing that the sorption of the GNB dye was subject to the Freundlich isotherm model with R2 = 0.8710. Experimental results showed that the activated resin can removed up to 93.4% when the concentration of dye solution is 5.62�10-2 mM. The biodegradation of the GNB was induced by laccase, an enzyme isolated from white-rot fungus. It was also analyzed the role of pH and dye concentration on GNB biodegradation, so 5�10-2 mM dye had a maximum discoloration efficiency of 82.9% at pH of 4. The laccase showed a very fast and robust activity reaching in a few minutes a Km value of 2.2�10-1mM. In addition, increasing the GNB concentration up to 8�10-1 mM did not triggered a substrat inhibition effect on the laccase activity. Overall, in this study we proposed a mixt physicochemical and biological approach to enhance the GNB removal and biodegradability from the wastewaters and subsequently the environment.

Synthesis and Characterization of Nanocomposite Ion Exchanger for the Removal of Heavy Metals

In material science, organic-inorganic hybrid materials have attracted a great deal of attention prepared by sol-gel approach. Organic polymer part of the composite provides chemical stability and mechanical strength whereas the inorganic part supports the ion-exchange behavior and thermal stability. Such modified composite materials can be applied as an electrochemically switchable ion exchanger for water treatment, especially water softening. Polyaniline zirconium (IV)iodate nanocomposite ion exchanger is prepared by sol-gel method. Polyaniline zirconium (IV)iodate nanocomposite ion exchanger is synthesized and characterized by Fourier transform-infrared spectra (FTIR), ultraviolet-visible spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo gravimetric analysis (TGA), ion exchange, conductivity, and antimicrobial studies. The synthesis process of the polyaniline zirconium (IV)iodate nanocomposite ion exchanger was discussed. The route reported here may be used for the preparation of other nanocomposite ion exchangers.

Synthesis and ion-exchange studies of resins derived from 2,2′-dihydroxybiphenyl-diamine-formaldehyde

Terpolymeric resins (2,2′-DHBPBDF) (DHBP = dihydroxybiphenyl; BD = butylenediamine; F = formaldehyde) were synthesized by the condensation of 2,2′-DHBP, 1,4-BD and formaldehyde in the presence of an acid catalyst with varied molar ratios of reacting monomers. Resin composition was determined on the basis of its elemental analyses. Their number-average molecular weight was determined by conductometric titration in non-aqueous media. The viscosity measurements were carried out in N,N-dimethylformamide at room temperature. Ultraviolet–visible, infrared and proton nuclear magnetic resonance spectral studies were undertaken to elucidate the structure of these resins. The thermal stability and kinetics of the thermal decomposition of these newly synthesized resins have been evaluated on the basis of thermogravimetric analysis and differential thermal analysis. The ion-exchange properties of these resins were studied for different metal ions. A batch equilibrium method was employed to study the selectivity of metal ion uptake. The study was carried out over a wide range of pH and ionic strengths of different electrolytes.

Reversible and Efficient Sequestration of Cesium from Water by the Layered Metal Thiophosphate K0.48 Mn0.76 PS3 ⋅H2 O.

Water body contamination with radioactive species is an important issue due to significant developments in nuclear energy. Cesium (137 Cs) radioisotope is a non-actinide fission product of uranium and plutonium that is long-lived. Hence, selective removal/capture of cesium is essential for managing radioactive waste. Herein, a detailed Cs+ ion-exchange study on a potassium intercalated layered metal thiophosphate, K0.48 Mn0.76 PS3 ⋅H2 O (K-MPS-1), is reported. The sorption of Cs+ by K-MPS-1 follows the Langmuir model with a high capacity of 337.5 mg g-1 and high distribution coefficients in the order of about 104 mL g-1 . K-MPS-1 can sequester Cs+ efficiently, even from very low concentrations (ppb level). K-MPS-1 exhibits high cesium uptake over a broad pH range of 2-12 and the ion-exchange process reaches equilibrium within a short time (≈15 min), following pseudo-second-order kinetics. Moreover, K-MPS-1 demonstrates selectivity towards Cs+ capture in the presence of complex solutions containing excess Na+ , Ca2+ , and Mg2+ ions; this is due to favorable interactions between Cs (soft Lewis acid) and S (soft Lewis base). K-MPS-1 reversibly captures Cs+ and it can be regenerated by treating Cs-MPS-1 with a solution of KCl.

Removal of dissolved silica from industrial waters using inorganic ion exchangers

Dissolved silica is ubiquitous in impaired waters, a fouling agent in desalination membranes, resistant to existing antiscalants, and difficult to remove from power plant feed waters, thereby inhibiting long term reuse of industrial water. Herein we report a systematic materials study of an inorganic anion exchanger, hydrotalcite (HTC, (Mg6Al2(OH)16(CO3)•4H2O)), for the highly selective removal of silica from aqueous solutions. HTCs exist in two different forms: crystalline uncalcined and calcined (550°C) phases. Variables studied in ion-exchange studies include pH, HTC concentration, duration and selectivity with competing anions. Results indicate calcined HTC effectively removes silicate anion from different waters including simulated concentrated cooling tower water (CCTW), and waters with high concentration of competing ions, such as SO42− and Cl−. The non-optimized HTC can be easily regenerated and recycled. Calcined HTC has a silica adsorption capacity of 45mg SiO2/g HTC. The single path flow through (SPFT) studies indicate that using ∼1.1g/L calcined HTC effectively removes >90% of the dissolved silica from the CCTW. A pseudo-second order kinetic model was fit the experimental data of calcined HTC. Data is supported by Fourier transform infrared (FTIR), Thermogravimetric-Mass analyses (TGA-MS), Energy dispersive spectroscopy (EDS) and powder X-ray diffraction (XRD).

Synthesis of several novel coordination complexes: ion exchange, magnetic and photocatalytic studies

Eight different novel polymers by the reactions of H2L and metal ions (Zn2+, Cu2+, Co2+) in the presence or absence of auxiliary ligands were constructed. The Zn2+ in complexes 1–3 could be partially exchanged with Cu2+ ions.

Equilibrium ion exchange studies of Zn2+, Cr3+, and Mn2+ on natural bentonite

Bentonite is a clay mineral often used in ion exchange processes due to its high ion exchange capacity. In the present study, a commercially available in Greece market bentonite was obtained and characterized by XRD, XRF, FTIR, BET, and TG/DTA analysis. Monmorillonite was the main component of bentonite sample (>80%). Ion exchange equilibria of Zn2+, Cr3+, and Mn2+ on bentonite was examined by use of batch equilibrium isotherms, distribution coefficients, and maximum exchange levels (MELs) under the same normality for all metals (0.01 N) at 25 ± 2°C. The equilibrium isotherms for the metals studied exhibit a favorable-type isotherm. Selectivity series deduced from equilibrium isotherms are Cr3+ > Zn2+ > Mn2+, and the same occurs for MELs. The Langmuir and Freundlich models were applied and fitted the equilibrium data for the metal ion uptake. A detailed literature review on heavy metals-bentonite equilibrium is provided.

Diverse Lanthanide Coordination and Selective Ion Exchange in the Microporous Selenites Na4Ln4(SeO3)7O·nH2O (Ln = Gd, Tb, Dy, Ho, Er, Tm, and Yb)

Seven isomorphous alkali metal lanthanide selenites, Na4Ln4(SeO3)7O·nH2O (Ln = Gd, Tb, Dy, Ho, Er, Tm, and Yb), exhibiting a new structure type, have been prepared by hydrothermal methods. The four crystallographically unique Ln3+ cations within the structure exhibit three different coordination environments that are best described as bicapped trigonal prisms, trigonal dodecahedra, and pentagonal bipyramids. These polyhedra edge- and corner-share to yield diamond-shaped channels that extend along the a axis and are approximately 8.4 A × 10.5 A. These channels house alkali metal cations and disordered water molecules. The Ho-analog was chosen for ion-exchange studies that indicate that the Na+ cations in the channels can be selectively exchanged for Rb+, but ion exchange with other monovalent cations does not occur.

Integrated approach to industrial sewage water treatment - a way of water resources rational use and protection

Ion-exchange softening plants wash water treatment studies are provided in order to bring them back to the process. Poorly soluble Ca and Mg compounds formation conditions have been studied during the course of such water caustic treatment using the potentiometric titration method. Information has been provided about the Ca and Mg hydroxide sludge sorption properties with regard to the characteristic contaminants of the sewage water generated by the textile industry enterprise. Suitability of the hydroxide sludge has been established for use in the sewage water treatment technology in order to remove the persisting organic compounds, such as the synthetic dyes.

Heavy Metal Separation from Industrial Effluent and Synthetic Mixtures using Newly Synthesized Composite Material

A stable composite cation exchange adsorbent for the treatment of heavy metal ions has been synthesized by sol-gel method and characterized by FTIR, XRD, SEM, TGA and TEM analysis. Ion-exchange capacity, pH titration, elution behavior and distribution studies have been also carried out to determine the primary ion-exchange characteristics of the composite. The material shows exchange capacity of 1.49 meq g-1 (for Na+). The composite material exhibits improved ion-exchange capacity, chemical and thermal stability. It can be used up to 300°C with 87.5% retention of initial ion-exchange capacity. The pH titration data reveals bifunctional behaviour of composite. On the basis of distribution coefficient (Kd), the material has been selective for Cd(II), Ba(II), Hg(II) and Pb(II) ions. A number of important and analytically difficult quantitative separations of metal ions have been achieved using columns packed with this exchanger. The composite cation exchanger has been applied for the treatment of sewage water and synthetic mixture successfully.