Ion-exchange Experiments Research Articles

The relationship between the humic degree of oil shale kerogens and their structural characteristics

Elemental analysis, CP/MAS 13C NMR, FTIR, XRD, XPS and ion-exchange experiment were used to study the structural characteristics of Longkou, Huadian and Yilan kerogens in an increasing order of humic degree. The relationship between their humic degree and structural characteristics was studied from three aspects: aliphatic structure, aromatic structure and heteroatom species (O, N and S). The results show that the kerogens are mainly composed of aliphatic structure, dominantly as CH2 chain. Moreover, the ratio of aliphatic carbon (fal, aliphaticity) and average methylene chain length (Cn) decrease with the increase of humic degree. In these kerogens, most of their aromatic clusters are separated by various bridge bonds or many CH2 long chains. Furthermore, the ratio of aromatic carbon (fa, aromaticity) and average aromatic cluster size increase while the substitutive degree of aromatic ring decreases with increasing humic degree. With an increase in humic degree, the content of OCO (carboxyl and ester) decreases and the contents of CO (alcohol, phenol, and ether) increase. Moreover, the content of phenolic hydroxyl groups increases and the content of carboxyl groups decreases with increasing humic degree. The organic nitrogen in the kerogens is distributed as pyridinic nitrogen, amine nitrogen, pyrrolic nitrogen and chemisorbed nitrogen oxides. The contents of pyridinic nitrogen and chemisorbed nitrogen oxides increase while the contents of amino nitrogen and pyrrolic nitrogen decrease with increasing humic degree. In addition, organic sulfur in these kerogens exists as aromatic and aliphatic sulfur, sulfone and sulfoxide. The contents of aromatic sulfur and sulfoxide increase while the contents of aliphatic sulfur and sulfone decrease with increasing humic degree.

Solvent Extraction of Tungsten(VI) from Moderate Hydrochloric Acid Solutions with LIX 63

The solvent extraction of tungsten(VI) from hydrochloric acid solutions using 5,8-diethyl- 7-hydroxydodecan-6-one oxime (LIX 63) was analyzed in solutions having an initial pH range from 2 to 5, by varying the concentration of metal and extractant. In our experimental range, the cationic exchange reaction as well as the solvation reaction occurred simultaneously. The cation exchange reaction was identified by applying a slope analysis method to the extraction data. The existence of cationic tungsten(VI) species was confirmed by ion exchange experiments with Diphonix resin at pH 3. Further study is needed to identify the nature of this tungsten cationic species. (Received November 23, 2016; Accepted January 10, 2017)

Characterization and Utilization of Natural Zeolites in Technical Applications

Zeolites and zeolite rocks are commonly used in different industrial applications. Natural zeolites present an attractive material for environmental applications because of their high abundance, availability and low costs. Depending on geological settings and conditions during mineral formation, natural zeolite deposits usually represent a heterogeneous mixture of zeolite minerals together with varying amounts of gangue minerals (e. g. quartz, feldspars and phyllosilicates). Hence, profound mineralogical knowledge and a detailed characterization of natural zeolites are essential for tapping their full potential in any practical application. However, this is rarely done as detailed mineralogical characterizations are elaborate and often neglected in favour of bulk chemical analyses (e. g. XRF).In this paper we describe typical technical applications for natural zeolites as well as the requirements demanded for their use. An analytical protocol has been developed for the detailed characterization of natural zeolites for ammonium exchange consisting of a combination of mineralogical and chemical methods and is exemplarily demonstrated. The methodology comprises mineralogical investigations with X‑ray diffraction (XRD) and electron microprobe analyses (EPMA) to provide qualitative data on mineral compositions and in-situ analysis of mineral chemistry (Si/Al-ratio, cation contents). The examinations are accompanied by bulk chemical analysis (XRF) as well as thermoanalytical investigations (TG/DSC) to distinguish between certain zeolite minerals. Finally, ion exchange experiments for ammonium have been carried out to determine the cation exchange capacity (CEC) of zeolite samples for a defined range of concentrations.The aim of the study is to develop an analytical routine in order to enable the detailed characterization of natural zeolite samples with standardized means of mineralogical/chemical analysis prior to their application in technical processes. This is important for quality assurance and for identifying the best suited zeolites for specific technical processes, especially when the proposed applications are not standardized.

Phase transfer of TiO2 nanoparticles from water to ionic liquid triggered by phosphonic acid grafting.

Controlling the interface between TiO2 nanocrystals and ionic liquids is of high fundamental and applied interest for energy storage and conversion devices. Phase transfer of nanoparticles from a synthesis medium to a processing or an application medium plays a significant role in nanotechnology. Here we demonstrate that surface modification with phosphonic acids bearing cationic end-groups can trigger the phase transfer of TiO2 nanoparticles from an aqueous sol to a typical water-immiscible ionic liquid, [Emim][NTf2]. The transfer involves both the grafting of the phosphonic acid moiety and the exchange of the counter ion of the cationic end-group by NTf2 anions, as demonstrated by solid-state NMR, elemental analysis and independent grafting and ion exchange experiments. Furthermore, the colloidal stability of the TiO2 sols in [Emim][NTf2] strongly depends on the hydrophobic character of the cationic end-groups.

Cu2+ sorption from aqueous media by a recyclable Ca2+ framework

A recyclable Ca-MOF that exchanges Ca2+ by Cu2+ almost quantitatively and quickly was investigated via batch ion-exchange experiments and utilized as a stationary phase in an ion-exchange column for Cu2+ removal from aqueous media.

Environmental Friendly conversion of locally available low-cost materials to zeolite

Mordenite, NaY and NaX zeolites were hydrothermally synthesized from locally available low-cost materials such as, chert rock, barley husk, and shale clay without using organic templates, structure-directing agent, and additives. The as-synthesized zeolites were characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray Fluorescence (XRF) and Field Emission scanning electron microscopy (FESEM). The results verified that mordenite, NaY and NaX zeolites obtained from hydrothermal condition, present a good zeolitic properties and then can be suitable for using in adsorption, ion exchange and catalysis experiments. The properties of zeolite materials formed are strongly depended upon the composition and the type of raw materials used.

ChemInform Abstract: Open‐Framework Oxysulfide Based on the Supertetrahedral [In4Sn16O10S34]12— Cluster and Efficient Sequestration of Heavy Metals.

Abstract[H3O]3[Heta]4.2 [H2dpp]0.3 [In4Sn16O10S32] ·33H2O is prepared by heating a 10:3:3:3 molar mixture of S, SnCl2·2H2O, In(NO3)3, and 1,3‐di(4‐pyridyl)propane (dpp) in ethanolamine (eta) (autoclave, 160 °C, 7 d; 25% yield).

Modelling of Boron Removal from Solutions Using Purolite S 108 in a Batch Reactor

In this study, ion exchange was applied to artificial boron solutions for boron removal by boron selective Purolite S 108 in a batch reactor. The ion exchange experiments were carried out as a function of initial solution pH, resin‐to‐solution ratio, stirring speed, temperature, concentration, regeneration, and time. Optimum removal conditions for 400 mg/L initial boron concentration were determined as pH 8.5, temperature 15°C, stirring speed 300 rpm, and resin‐to‐solution ratio 36 g/500 mL. Maximum boron removal at a concentration of 400 mg/L was obtained as 100%. The highest boron adsorption capacity of the resin was obtained as 9.31 mg/g. The regeneration of the resin was realized by consecutive acid stripping–neutralization–washing treatments. The resin ion exchange capacity values for the first four cycles were found as 8.5, 9.69, 9.37, and 8.45 mg/g, respectively. The obtained kinetic data followed the pseudo second‐order model rather than the pseudo first‐order kinetic model. Particle diffusion was found as the dominant rate controlling mechanism for boron removal. The activation energy of the complexation reaction between boron and the resin was calculated as 33.5 (kJ/mol). An activation energy of <50 kJ/mol generally indicates a film and particle diffusion controlled process, whereas higher values represent chemical reaction processes. Furthermore, based on the adsorption capacity approach an empirical model was developed.

Open-Framework Oxysulfide Based on the Supertetrahedral [In4Sn16O10S34](12-) Cluster and Efficient Sequestration of Heavy Metals.

The new ion-exchange oxy-sulfide material has a three-dimensional open framework comprising the pseudo-T4 supertetrahedral [In4Sn16O10S34](12-) cluster. This material has large pores and is a fast ion exchanger. It exhibits high selectivity in sequestering heavy metal ions from aqueous solutions including solutions containing heavy concentrations of sodium, calcium, ammonium, magnesium, zinc, carbonate, phosphate, and acetate ions. Moreover, the ion-exchange efficiency in competitive ion-exchange experiments involving mixtures of metal ions is significantly higher than for solutions of single metal ions.

Preparation and optimization of a drug delivery system based on berberine chloride-immobilized MgAl hydrotalcite

Hydrotalcite (HT), also known as a layered double hydroxide (LDH) compound, has been widely used in past years in the formulation of drugs due to its specific properties including good biocompatibility, null toxicity, high chemical stability and pH-dependent solubility which aid in drug controlled release. In this work, berberine chloride (BBC) class antibacterial agent was immobilized into magnesium-aluminum LDH in order to improve the drug efficiency as well as to achieve the controlled release property. BBC molecules were immobilized into MgAl LDH through a conventional ion exchange reaction and co-precipitation method. The ion-exchange experiments of BBC on MgAl LDH were investigated with particular attention paid to the influence of the layer charge, the nature of the intercalated anion and the morphology. The immobilization efficiency was dependent upon the LDH properties and the immobilization process. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and contact angle measurements revealed that the interaction of BBC with MgAl LDH occurs by adsorption rather than intercalation of BBC within LDH layers. In vitro anti-bacterial tests were carried out using disc diffusion assay to prove the effectiveness of these novel biohybrid beads as a controlled drug delivery method. Consequently, the BBC-LDH co-precipitated formulation revealed an enhanced anti-bacterial activity compared to the ion-exchanged formulation not only due to an improvement of chemical stability and retained amount of BBC molecules but also due to the release property.

Generation of Second-stage Structure in the Alkylammonium Cation and Potassium Sericite Mica System

Sericite (SE) and dehydrated sericite (dhSE) were examined using ion-exchange experiments with dodecylammonium (DDA) solutions of various initial concentrations (DDA+/K+ mole ratio = 1.0, 3.0, and ...

Production of colorless liquid sugar by ultrafiltration coupled with ion exchange

Liquid sugar is an alternative product to crystal sugar, which is currently being considered by many sugar companies. However, production of colorless liquid sugar is still a big challenge. This work aimed to study the performance of ultrafiltration membrane and ion exchange (IE) both as single and integrated processes for decoloring cane sugar solution. The experiments were performed by using 10, 20, 50, and 100kDa commercial UF membranes. Two commercial resins were used in ion exchange experiments. The results of decoloring sugar solution using UF membranes showed that the 20kDa UF membrane made of polysulfone displays the best performance in term of flux and color removal. Integrating ion exchange process into UF membrane improves the color reduction resulting colorless liquid sugar. The UF–IE configuration shows a better performance than both the IE–UF and UF/IE alone configurations. These results provide important information about technologies that should be used for liquid sugar production.

Thermodynamic analysis for the sorptive removal of cesium and strontium ions onto synthesized magnetic nano zeolite

The present study aims at examining the feasibility of using synthesized magnetic nano zeolite for the sorptive removal of cesium and strontium ions existing in the liquid radwaste stream. Cs+/Na+ and Sr2+/Na+ binary ion exchange experiments were performed in the batch mode at different three temperatures (298,303 and 313 K), optimized proton concentration (pH), equilibrium time and constant total normality. The thermodynamic analysis of both binary systems was performed using four types of model equations: Langmuir; Freundlich; Radlish-Peterson and thermodynamic equilibrium models. The extended Debye–Huckel relation and the Wilson equation were used to estimate the solution and the solid phase activity coefficients, respectively. The results obtained during this study demonstrated the correlation of the four examined models with the experimental equilibrium data, which proved to be satisfactory. On the other hand, the thermodynamic non-idealities was found to give the best results. Thermodynamic parameters such as enthalpy change, Gibbs free energy change and entropy change were also calculated. The obtained affirmative results demonstrated that the synthesized magnetic nano zeolite can be used as an efficient sorbent for the removal of Cs+ and Sr2+ ions from the contaminated solutions.

Tb/Eu-AV-9: A lanthanide silicate for the sensing and removal of cesium ions from aqueous solutions

The ion exchange of Cs+ from aqueous solutions was studied using a novel microporous lanthanide silicate with photoluminescence properties, Tb/Eu-AV-9. This mixed lanthanide silicate was prepared by hydrothermal synthesis, characterized by scanning electron microscopy, powder X-ray diffraction, and photoluminescence spectroscopy.Batch ion exchange experiments were performed at room temperature (295K) to measure isotherm and kinetics (removal curves). The Langmuir–Freundlich equation provided a good fit to the equilibrium data. A kinetic model based on the Maxwell–Stefan equations was implemented and adjusted to the cesium removal curves, and achieved average deviation of 8.37%. The model parameters were the diffusion coefficients, while the convective mass transfer coefficient was purely estimated. The Maxwell–Stefan diffusivities for the interaction of the counter ions Cs+ and K+ with the solid exchanger were ÐAs=8.373×10−15m2s−1 and ÐBs=2.795×10−14m2s−1, respectively, being consistent with other values in the literature.With respect to photoluminescence studies, the differences found between the emission spectra of native and Cs+-exchanged Tb/Eu-AV-9 disclosed the potential of this sorbent for qualitative/quantitative Cs+ sensing purposes.

Biosorption of Sr(II) from aqueous solutions using aerobic granules: equilibrium and mechanisms

Aqueous strontium biosorption using aerobic granules was investigated. Parameters affecting the biosorption were optimized, including initial pH, biomass dosage, temperature, and rotation speed. The equilibrium data were fitted using Langmuir and Freundlich models, and both could well describe the process (R2 = 0.987 and 0.989, respectively). Ion exchange and water-desorption experiments were conducted, and ion exchange together with physical adsorption were found to be the main mechanisms. The aerobic granules were characterized with methods including scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The results showed that surface complexation could also be involved in the Sr(II) biosorption.

Cs+ ion exchange over lanthanide silicate Eu-AV-20: Experimental measurement and modelling

The ion exchange of Cs+ from aqueous solutions was studied using for the first time a microporous lanthanide silicate with photoluminescence properties, Eu-AV-20. It was prepared by hydrothermal synthesis, characterized by SEM, PLS, PXRD and ICP-MS, and several batch ion exchange experiments were performed to measure isotherm and removal curves. Additional curves were measured to evaluate the competition with Na+. The results evidenced the great selectivity of Eu-AV-20 towards Cs+ since cesium removal was slightly modified even for Na+/Cs+ concentrations ratio of 190. The emission photoluminescent spectra of native and Cs+-exchanged Eu-AV-20 were also determined for the first time, and significant modifications were detected, which discloses the potential of Eu-AV-20 for Cs+ sensing purposes.The Langmuir equation provided a good fit to the equilibrium data, with average error of 5.3%, and the Maxwell–Stefan based model adopted to represent the kinetic curves (i.e., concentration versus time) achieved a deviation of 19.0%. An analysis of variance confirmed that the model was statistically significant to represent the uptake curves.The Maxwell–Stefan based model comprises three parameters, namely, the diffusion coefficients associated to the interactions of Cs+ and Eu-AV-20, Na+/K+ and Eu-AV-20, and Cs+ and Na+/K+, whose fitted values were 2.706×10−15, 5.713×10−15 and 9.446×10−17m2s−1. Such low values evidenced that the intraparticle mass transport mechanism is surface diffusion. This fact is ascribed to the small pores of the Eu-AV-20 crystal, 5.8×6.8Å, because the counter ions never escape from the force field of the framework co-ions, mainly due to the strong and long range nature of the electrostatic interactions.

Recovery of molybdenum from alkali leaching solution of low-grade molybdenum concentrate by ion exchange

AbstractIn order to extract molybdenum (Mo) from alkali leaching solution of low-grade Mo concentrate, static and dynamic ion exchange experiments were performed. The static experiments results indicated that the adsorption capacity of D201 resins reached 93.50% at pH 3.5, while the adsorption capacity of D314 resins was 95.47%. Therefore, D314 resin was adopted for further experiments. The dynamic experiments results indicated that the adsorption capacity of Mo reached 96.77% when the flow rate of leaching solution was 1 ml/min. The loaded resin could be desorbed by 10% ammonia solution. In consequence, the maximum concentration of Mo in eluate was 122 g/l. In the precipitation process, the Mo recovery reached 97.81%, and the obtained Mo oxide products met the requirement of YMo 55 national standard in GB/T24482-2009 and Grade A standard of ASTM A146-04 (2014).

Recovery of Platinum from Chloride Leaching Solutions of Spent Reforming Catalysts by Ion Exchange

Platinum and base metals (Al, Fe, Si) are present in the chloride leaching solutions of spent reforming catalysts. In order to develop a process to recover platinum from such leaching solutions, batch and continuous ion exchange experiments were performed using a strong anionic resin (DiaionSA10AP). The adsorption equilibrium data of Pt are described by the Langmuir adsorption isotherm. Batch experiments indicate that it is possible to separate Pt and Fe from other metal ions in the present leaching solution. Fe was selectively removed from the loaded resin using diluted HCl, while Pt was eluted using thiourea after Fe removal. The results of column experiments verified the feasibility of the separation and recovery of platinum from leaching solutions using the present process. The elution efficiency exceeded 99% for both Pt and Fe. The recovery percentage of Pt from the leaching solution using this method was 99.3%. [doi:10.2320/matertrans.M2015027]

A STUDY ON ADSORPTION AND DESORPTION BEHAVIORS OF 14C FROM A MIXED BED RESIN

Spent resin waste containing a high concentration of 14C radionuclide cannot be disposed of directly. A fundamental study on selective 14 C stripping, especially from the IRN-150 mixed bed resin, was carried out. In single ion-exchange equilibrium isotherm experiments, the ion adsorption capacity of the fresh resin for non-radioactive HCO₃- ion, as the chemical form of 14 C, was evaluated as 11mg-C/g-resin. Adsorption affinity of anions to the resin was derived in order of NO₃- > HCO₃- ≥ H₂PO₄-. Thus the competitive adsorption affinity of NO₃- ion in binary systems appeared far higher than that of HCO₃- or H₂PO₄-, and the selective desorption of HCO₃- from the resin was very effective. On one hand, the affinity of Co 2+ and Cs+ for the resin remained relatively higher than that of other cations in the same stripping solution. Desorption of Cs+ was minimized when the summation of the metal ions in the spent resin and the other cations in solution was near saturation and the pH value was maintained above 4.5. Among the various solutions tested, from the view-point of the simple second waste process, NH₄H₂PO₄ solution was preferable for the stripping of 14 C from the spent resin.

Removal of Potassium from Molasses by Solvent Extraction and Ion Exchange

The high content of potassium in molasses limits its usage as a raw material for stock feed. Moreover, its high viscosity makes it difficult to develop an efficient removal process. In this study, ion exchange and solvent extraction experiments have been performed to investigate the removal of potassium from a mixture of molasses with water. Cationic exchange resins (AG50W-X8 and Diphonix) showed a high loading percentage of potassium but the occurrence of breakthrough in few bed volumes was a drawback to the industrial application. Among the cationic extractants (D2EHPA, PC 88A, Cyanex 272) tested in this study, saponified PC 88A was found to be the best extractant for the removal of potassium. Batch simulation studies on a three stage counter current extraction confirmed that 85% of potassium was removed from 50 wt % molasses solution in water by using saponifed PC 88A.