Lewatit TP Research Articles

Removal of some hazardous heavy metals from aqueous solution using magnetic chelating resin with iminodiacetate functionality

A magnetic chelating resin with iminodiacetate functionality was prepared and investigated. This resin showed a powerful uptake behavior towards Pb(II), Cd(II), Zn(II), Ca(II) and Mg(II). Kinetic and thermodynamic characteristics of uptake process were evaluated. The uptake values obtained are comparable to that of commercial resin with the same functionality (Lewatit TP-207) but with faster kinetics. A correlation was found between the affinity of the resin towards the investigated metal ions and the values of stability constants of their complex formation. The regeneration of the resin was carried out using 0.2 M EDTA with efficiency over 96%. Recovery of Pb(II) (as an example) from aqueous solutions using column technique was carried out. The total adsorption capacity ( N o) value obtained from bed depth service time (BDST) model was found to be comparable with the experimental value of q s. The values of critical bed height ( Z o) and rate constant of adsorption ( K a) were found to be 0.583 cm and 41.9 L/(mol min).

Ion-exchange of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ ions from aqueous solution by Lewatit CNP 80

Removal of trace amounts of heavy metals can be achieved by means of selective ion-exchange processes. The newly developed resins offered a high resin capacity and faster sorption kinetics for the metal ions such as Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ ions. In the present study, the removal of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ ions from aqueous solutions was investigated. Experimental investigations were undertaken using the ion-exchange resin Lewatit CNP 80 (weakly acidic) and were compared with Lewatit TP 207 (weakly acidic and chelating). The optimum pH range for the ion-exchange of the above mentioned metal ions on Lewatit CNP 80 and Lewatit TP 207 were 7.0–9.0 and 4.5–5.5, respectively. The influence of pH, contact time, metal concentration and amount of ion-exchanger on the removal process was investigated. For investigations of the exchange equilibrium, different amounts of resin were contacted with a fixed volume of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ ion containing solution. The obtained sorption affinity sequence in the presented work was Ni 2+ > Cu 2+ > Cd 2+ > Zn 2+ > Pb 2+. The metal ion concentrations were measured by AAS methods. The distribution coefficient values for metal ions of 10 −3 M initial concentration at 0.1 mol/L ionic strength show that the Lewatit CNP 80 was more selective for Ni 2+, Cu 2+ than it was for Cd 2+, Zn 2+ and Pb 2+. Langmuir isotherm was applicable to the ion-exchange process and its contents were calculated. The uptake of metal ions by the ion-exchange resins was reversible and thus has good potential for the removal of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ from aqueous solutions. The amount of sorbed metal ion per gram dry were calculated as 4.1, 4.6, 4.7, 4.8, and 4.7 mequiv./g dry resin for Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+, respectively. Selectivity increased in the series: Cd 2+ > Pb 2+ > Cu 2+ > Ni 2+ > Zn 2+. The results obtained showed that Lewatit CNP 80 weakly acidic resin had shown better performance than Lewatit TP 207 resin for the removal of metals. The change of the ionic strength of the solution exerts a slight influence on the removal of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+. The presence of low ionic strength or low concentration of NaNO 3 does not have a significant effect on the ion-exchange of these metals by the resins. We conclude that Lewatit CNP 80 can be used for the efficient removal of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ from aqueous solutions.

Recovery of nickel from Orimulsion fly ash by iminodiacetic acid chelating resin

Macroporous resins containing imminodiacetic acid (IDA) groups (Lewatit TP-207, Purolite S-930 and Amberlite IRC-748) were studied under dynamic conditions for uptake of nickel ions from the sulphate solution at pH 4 deriving from preliminary acid leaching of Orimulsion fly ash and subsequent vanadium recovery and impurities removal stages. The effects of temperature and ionic medium on the Ni adsorption were investigated. The Lewatit TP-207 showed higher Ni uptake capacity in all operating conditions examined with an adsorption capacity of 1.32 mmol of Ni/g at 40 °C using the real process solution at pH 4. The extraction of Ni adsorbed on the resin was obtained using 10 wt.% H 2SO 4; the resultant concentrated solution of nickel sulphate, containing about 13 g/L of nickel, can be suitable for elettrowinning, precipitation etc.

Model for the determination of diffusion coefficients of heterovalent ions in macroporous ion exchange resins by the zero-length column method

A generalized theoretical model for the measurement of effective diffusion coefficients of heterovalent ions in macroporous ion-exchange resins by the zero-length column method was developed. The model includes the resistance to mass transfer both in the particle and in the film and described ion fluxes with Nernst–Planck equations. Equilibrium was described using the Langmuir type empirical equation. The values of intraparticle diffusivity of Cu 2 + , Cd 2 + , Zn 2 + , and H + on commercial Lewatit TP-207 were obtained by non-linear regression, these values agree fairly well with data reported previously in literature. The following trend was observed: D Cu > D Zn > D Cd .

Behaviour of Cadmium(II) Ions on Cation-Exchange Resins

Cadmium is one of the most toxic heavy metals known and is considered inessential for living organisms. This element is found at low concentrations in natural environments, but human activities have led to increased levels in all continents. In the present study, the removal of cadmium(II) ions from aqueous solutions was investigated. Experimental investigations were undertaken using the ion-exchange resins Amberlite IR 120 (strongly acidic), Amberlite IRC 718 (weakly acidic and chelating), Lewatit TP 207 (weakly acidic and chelating) and Lewatit CNP 80 (weakly acidic). For investigations of the exchange equilibria, different amounts of resin material were contacted with a fixed volume of a cadmium ion-containing solution. Because the uptake of cadmium ions was mainly dominated by the pH of the liquid phase, the pH value was varied between 0 and 3 with sample sizes of 0.5-5.0 g in each series studied. The initial and final cadmium ion concentrations were measured by ICP-AES methods. Exchange equilibria we...

Modelling of the acid–base properties of natural and synthetic adsorbent materials used for heavy metal removal from aqueous solutions

In this paper a comparison about kinetic behaviour, acid–base properties and copper removal capacities was carried out between two different adsorbent materials used for heavy metal removal from aqueous solutions: an aminodiacetic chelating resin as commercial product (Lewatit TP207) and a lyophilised bacterial biomass of Sphaerotilus natans. The acid–base properties of a S. natans cell suspension were well described by simplified mechanistic models without electrostatic corrections considering two kinds of weakly acidic active sites. In particular the introduction of two-peak distribution function for the proton affinity constants allows a better representation of the experimental data reproducing the site heterogeneity. A priori knowledge about resin functional groups (aminodiacetic groups) is the base for preliminary simulations of titration curve assuming a Donnan gel structure for the resin phase considered as a concentrated aqueous solution of aminodiacetic acid (ADA). Departures from experimental and simulated data can be interpreted by considering the heterogeneity of the functional groups and the effect of ionic concentration in the resin phase. Two-site continuos model describes adequately the experimental data. Moreover the values of apparent protonation constants (as adjustable parameters found by non-linear regression) are very near to the apparent constants evaluated by a Donnan model assuming the intrinsic constants in resin phase equal to the equilibrium constants in aqueous solution of ADA and considering the amphoteric nature of active sites for the evaluation of counter-ion concentration in the resin phase. Copper removal outlined the strong affinity of the active groups of the resin for this ion in solution compared to the S. natans biomass according to the complexation constants between aminodiacetic and mono-carboxylic groups and copper ions.

Performance evaluation of two chelating ion-exchange sorbents for the fractionation of labile and inert metal species from aquatic media.

The performance of two iminodiacetate chelating resins, applied in an element fractionation scheme, was investigated for the characterization of marine and stream water samples collected in potentially contaminated harbor and industrial zones. The comparison involved an evaluation of the sorption/desorption behavior of Cd, Cu, Pb and Zn on Chelex-100, a sorbent extensively employed for metal speciation studies, and on Lewatit TP-207, a material with similar chelating characteristics for which no applications for fractionation studies are reported. A characterization of the latter resin in terms of the influence of sample pH on the uptake of metals from aqueous solutions and their subsequent acid elution was carried out. Fractionation studies were performed on natural water samples and model solutions resembling their composition, spiked with micromolar concentrations of the metals. The operationally defined fractionation scheme is based on dynamic adsorption of the resin-labile fractions of metals on microcolumns made of the sorbents. This stage is followed by a batch procedure in which the eluent from the column is contacted with fresh resin to discriminate between the relatively stable species unable to react with the resin during the column interaction time, and the strongly complexed metals that do not interact with the sorbent even for periods of several hours. Results were obtained from coarsely filtered sub-samples and from specimens passed through membrane filters of pore size 0.45 and 0.22 microm. The method was also assessed with model solutions of the metals containing variable concentrations (in the 10(-3)-10(-7) molar range) of complex forming agents such as nitrilotriacetic acid and trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid. An additional batch method, in which a fixed amount of resin was contacted with sample solution for increasing periods of time and the amount of metal remaining in solution measured as a function of the elapsed time, was used to obtain information on the kinetics of dissociation of species formed in the presence of added complexants. The behavior of both resins was similar, demonstrating that the discrimination of species derived from experiments with Chelex-100 may be properly validated by independent fractionation tests carried out with Lewatit TP-207. The behavior of the sorbents is also discussed in terms of the possible influence of particulate or colloidal materials and of kinetic effects related to the presence of complexing agents.

A comparative study of two chelating ion-exchange resins for the removal of chromium(III) from aqueous solution

Macroporous resins containing iminodiacetic acid (IDA) groups (Lewatit TP 207 and Chelex-100) were investigated as a function of concentration, temperature and pH for their sorption properties towards chromium(III). The chromium(III) ions sorbed onto the resin and in the equilibrium concentration were determined by inductively coupled plasma spectrophotometer. The maximum sorption for chromium ions was observed at pH 4.5. Solution pH had a strong effect on the equilibrium constant of Cr(III). The equilibrium constants were 320 and 7 at pH value 4.5 for Lewatit TP 207 and Chelex-100 resin, respectively. The Langmuir isotherm was used to describe observed sorption phenomena. Both the sorbents had high bonding constants with Lewatit TP 207 showing stronger binding. The equilibrium related to adsorption capacity and energy of adsorption was obtained by using plots of Langmuir adsorption isotherm. It was observed that the maximum adsorption capacity of 0.288 mmol of Cr(III)/g for Chelex-100 and 0.341 mmol of Cr(III)/g for Lewatit TP 207 was achieved at pH of 4.5. The rise in temperature caused a slight increase in the value of the equilibrium constant ( K c) for the sorption of chromium(III) ion.

A Kinetic study of Cadmium(Ii) Adsorption on Lewatit Tp260 Resin

Cadmium(II) adsorption from aqueous sulphate medium on Lewatit TP260 cationic (di-Na+) ion exchange resin was investigated. The influence of operating variables such as aqueous pH, metal concentration, time and temperature on the equilibrium parameters was studied. Cadmium(II) adsorption on the resin can described by the Langmuir equation, whereas cadmium(II) uptake is particle diffusion controlled. The moving boundary particle diffusion model only fits the initial metal adsorption on the resin.

The removal of toxic metals from liquid effluents by ion exchange resins. Part II: cadmium(II)/ sulphate/Lewatit TP260

The adsorption of cadmium (II), from aqueous sulphate solutions, on Lewatit TP260 resin has been investigated in batch equilibrium experiments. The influence of pH and temperature on metal adsorption capacity have also been examined. The kinetic performance of the resin has been assesed and the results have been correlated by the pore diffusion model. The resin has been used in mini-columns to study its performance under dynamics conditions. The desorption of metal ion is achieved using sulphuric acid (0.25M and 0.5M).

Equilibrium and simulation of the operation for the adsorption of albumin proteins in an iminodiacetic-Cu bounded ion exchange resin (IMAC)

IMAC (Immobilized Metal Affinity Chromatography) is one of most selective chromatographic techniques for protein retention. In this technique, a complexing resin containing, for example, iminodiacetic groups, is saturated with a metallic ion, and when the solution of proteins is contacted with the saturated resin; the affinity of the proteins for the metallic ions produces the retention of the protein by the support. In the present study, an iminodiacetic resin (Lewatit TP-207) was saturated with copper and the retention of bovine serum albumin and α-lactalbumin was tested. Equilibrium analysis was carried out in column, a constant separation factor isotherm being used to obtain the equilibrium constants. The kinetics was studied in batch experiments; a superficial mass transfer and a pore diffusion model were considered to obtain the mass transfer coefficient in the film and the pore diffusivity. The equilibrium is unfavorable and the kinetics very fast. Finally, breakthrough curves were obtained and modeled with a proposed column model taking into account equilibrium, kinetics and hydrodynamic parameters. The column model adequately fits the experimental breakthrough curves. This resin may be used to retain proteins from wastes from the food industry.

Ion exchange on resins with temperature-responsive selectivity: III. Influence of complex formation stoichiometry on temperature dependence of resin selectivity

The influence of temperature (293< T<353 K) on Cu 2+–Ni 2+; Zn 2+–Co 2+, and Cu 2+–Co 2+ ion-exchange equilibrium at pH=1.55–3.0 from either aqueous sulfate or aqueous nitrate media on iminodiacetic (IDA) resin Lewatit TP-207 was studied. A novel approach for evaluation of the resin phase composition from α versus T dependencies has been proposed and the validity of such an approach is demonstrated. The temperature dependence of the equilibrium separation factor, α, in the Cu 2+–Ni 2+ exchange varies from nitrate to sulphate medium and it depends on the formation of different IDA complexes with the minor component (Ni 2+) in the resin phase. In the nitrate medium, formation of (IDA) 2–Ni complex is prevailing at 293< T<308 K, while at T>308 K 1:1 IDA:Ni 2+ complex is dominating. The Cu 2+–Ni 2+ exchange equilibrium from sulfate medium is characterized by the formation of nickel complexes of both stoichiometries within the whole temperature range studied. The dependence of α on T in Zn 2+–Co 2+ exchange system has been shown to be weaker than that in the Cu 2+–Ni 2+ system. This result is in a good agreement with the predictions made in the first communication of this series. The results of thermostripping experiments carried out for Cu 2+–Co 2+ exchange have shown that the efficiency of the thermostripping process depends on both the interval of working temperatures (Δ T) and its position on the temperature scale. The efficiency of thermostripping rises with an absolute Δ T value and also increases following the shift of temperature interval to the lower temperature range.

Arsenic(V) Removal from Aqueous Solutions by Iron(III) Loaded Chelating Resin

A study of arsenic adsorption using iron(III) loaded chelating resin as adsorbent is presented. The experiments were carried out in batch mode by using aqueous solutions containing 1000 ppm As, and using an iron(III) loaded iminodiacetate resin (LEWATIT TP 207) with sorption capacity of 168 mg Fe/g resin. The equilibrium time for adsorption was found to be one hour under the experimental conditions used. The influence of pH was studied in the range of 0.8÷8.5. The highest arsenic adsorption was found at pH 1.7. Under these conditions the adsorption capacity for As was approximately 60 mg As/g resin.

Ion exchange on resins with temperature-responsive selectivity: IV. Influence of solution and column parameters on efficiency of reagentless separation of copper and zinc using thermo-induced concentration waves technique

The effect of solution and column parameters such as pH, ratio of metal ions and the height of resin bed on formation of the thermo-induced concentration waves (TICW) in the course of the thermostripping process of Cu 2+ and Zn 2+ ions from iminodiacetic resin Lewatit TP-207 has been studied. The formation of TICW is attributed by both different diffusivities of metal ions and the presence of the third (H +) ion in the system. This effect makes it possible to carry out a reagentless separation of metal ions by using either the metal depletion or metal concentration mode of operation. The efficiency of the TICW-based separation process by using the metal depletion mode appears to be the higher the lower relative concentration of metal ion under removal (slower diffusing ionic species). The mathematical model proposed allows for qualitative and quantitative description of thermostripping processes in a wide range of pH and solution compositions. The physical model of the TICW process proposed makes it possible to account for the influence of different process parameters and generalise the applicability of the TICW separation technique to the binary mixtures of any metal ions with different diffusivities.

EQUILIBRIUM OF METALS WITH IMINODIACETIC RESIN IN BINARY AND TERNARY SYSTEMS

ABSTRACT Experiments of binary and ternary ion exchange equilibrium of heavy metals and sodium were carried out in a complexing iminodiacetic resin Lewatit TP 207. First, binary equilibrium data were obtained at different temperatures and ionic strength and fixed to models considering two different ion exchange stoichiometrics. For ternary equilibrium data, two distinct simple models were applied. One to be applied to systems showing very different selectivity for the metals (for instance, Cu2+/Co2+/Na+) and the other for systems with similar selectivity for the metals (such as Zn2+/Co2+/Na+). The ternary equilibrium data obtained is presented in this work and fitted using the two above mentioned models. These models allow us to obtain the equilibrium parameters for binary and ternary system to be used in the design of equipment using this iminodiacetic resin.

Ion exchange on resins with temperature-responsive selectivity: II. Thermo-induced concentration waves in ion-exchange column

The kinetics of H +–Cu 2+, H +–Zn 2+, Zn 2+–Cu 2+, and Cu 2+–Zn 2+ exchanges on iminodiacetic resin Lewatit TP-207 at 293 K has been studied. The effective diffusion coefficients of Cu 2+ and Zn 2+ have been determined to be 2.6×10 −8 and 1.4×10 −7 cm 2/s, respectively, for the given conditions. The kinetics of Cu 2+ and Zn 2+ thermostripping from the resin preequilibrated with a mixture of zinc and copper sulfates at pH 1.8 have been shown to be influenced by the different metal ion diffusivities and by the presence of a third component (H +) in the system so that an oscillation of ion concentration is observed. This phenomenon is observed more clearly with the increase of resin beds when studying the dynamics of the column thermostripping process. Formation of a concentration wave results in the enrichment of the first halfwave with Zn 2+ while the second halfwave appears to be enriched with Cu 2+. A mathematical model of ion-exchange dynamics of components with dissimilar diffusivities has been developed. The phenomenon of formation of concentration waves is interpreted within the model as a result of the influence of a local electrical field, arising in the resin phase, from the difference on fluxes of exchanging ions. The results of computer simulation of the thermostripping process within the frame of the model proposed are in a good agreement with those obtained in thermostripping experiments.

Hydrometallurgy Wastewater Split-Up by Fluidized-Bed Ion-Exchange Continuous Equipment

ABSTRACT A proposed operation of a semicontinuous fluidized-bed ion-exchange system was studied. The system splits a liquid current into two currents, one being more concentrated and the other more depleted. This operating technique has been used to split up a mixture of alkaline ions (Na+, K+) using a strongly acidic resin. The equipment operates simultaneously in two multistage columns, one for loading and the other for elution of the resin. The experimetal testing system employs a hydrometallurgy wastewater containing cobalt and copper as heavy metallic ions, and the resin used was of the chelating iminodiacetic type, Lewatit TP-207. At cyclic steady state, the equipment can split up the wastewater, producing an effluent concentrated in cobalt in the outlet stream of the loading column, and a concentrated stream of copper in the effluent of the elution column. The hydrodynamics and approach to the stationary state of the system were analyzed, and the selective recovery of metals was subsequently tested experimentally. This behavior presents certain similarities with a parametric pumping operation of the system, with the two columns operating at different pH values or temperatures.

Mercury Removal from Chloro-Alkali Plant Waste Waters by Ion Exchange

Equilibrium and kinetic studies of mercury extraction by ionic exchange with Lewatit MP 64 (anionic resin) and Lewatit TP 214 (cationic resin) were carried out in batch tests, using Erlenmeyer flasks and an orbital shaker. Synthetic solutions were used to simulate the composition of waste waters produced in chloro-alkali plants. The influence of temperature, stirring level, chloride and sulphate concentration on equilibrium and on kinetics were studied. Equilibrium tests were carried out using different amounts of resin for the same volume of solution with different chloride and sulphate concentrations. In kinetic studies, the influence of stirring and temperature was studied. The results show that for a stirring speed lower than 250 rpm, the rate of mercury extraction is affected by the level of stirring, and the kinetic process depends on the diffusion in solution. However, for higher stirring speeds, the process is also controlled by the diffusion inside the resin grains. Using the kinetic data, the effective diffusivities of mercury species in solution and inside the resin grains were estimated. The increase in temperature affects favourably the kinetics of the process, but decreases the final equilibrium concentration. Considering the values of effective diffusivities in the resin grains, the calculated activation energy for diffusion with the MP 64 and the TP 214 resin were, respectively, 8.1 and 9.3 kJ mol−1.

Application of the reagentless dual-temperature ion-exchange technique to a selective separation and concentration of copper versus aluminum from acidic mine waters

Acidic mine waters represent natural effluents from pyritic ore deposits and they are mainly characterized by a low pH and a high concentration of metal ions such as Fe 3+, Zn 2+, Cu 2+, Mn 2+, A1 3+, Ca 2+, Mg 2+ and Na +. The treatment of these waters is of great economic and ecological importance. The present study was targeted at the development of a reagentless and wasteless dual-temperature ion-exchange technique for concentrating copper from the natural acidic mine waters of Rio Tinto area (Huelva, Spain). The carboxylic ion exchanger (Lewatit R 250-K) and iminodiacetic resin (Lewatit TP-207) were used. Values of the resin capacity towards mine water metal ions and the equilibrium separation factors (α) for different metal ion couples have been determined at different temperatures in the range 20–80°C. Acrylic resin has been found to be selective for Al 3+ and iminodiacetic resin demonstrates high selectivity for Cu 2+. Furthermore, the sorbability of Al 3+ increases while that of Cu 2+ decreases with temperature for both resins. This effect gives the possibility for a selective thermostripping of Cu 2+ from the resins pre-equilibrated with cold mine water (at 20°C) using hot mine water at 80°C. The increase in the Cu 2+ concentration in the eluate is 30% for acrylic resin and 20% for iminodiacetic resin. The concentration of Al 3+ in the stripping solution drops to 50% in the first case and to 70% in the second.

Iron removal from tap water by a cation exchanger

Removal of iron from tap water at pH 6.0–7.3 was performed with an ion-exchange resin (Lewatit TP-207) with a chelating iminodiacetic acid group. More than 90% of the iron was removed by passing the water through the resin at a flow rate of 200 bed volumes per hour. The capacity of the resin for divalent iron was 25–30 g/l resin. The regeneration of the resin was carried out with 2 N HCl.