Sorption Of Divalent Metal Ions Research Articles

Sorption of divalent metal ions by modified carbopol-based adsorbent nanocomposite hydrogel

A new adsorbent, modified Carbopol 934-polyacrylamide network polymer (mCarbo-PAm hydrogel), embedded with silver nanoparticles, has been introduced to remove divalent metal ions. It was prepared by supporting nanosized "Ag" onto a porous modified carbopol 934-polyacrylamide polymer network using free radical polymerization. The nanogels were characterized by different methods, including Fourier Transform Infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and swelling kinetics. The outcome exhibited that the loading of Ag nanoparticles onto mCarbo-PAm hydrogel was successful in improving the swelling ability of the gel. The nanocomposite hydrogel sorption results indicated that the affinity order was Pb2+(96.52 %) > Cu2+(86.66 %) > Zn2+(69.64 %) at pH 6.7. Which is better than the mCarbo-PAm hydrogel sample: Pb2+(71.78 %) > Cu2+(69.54 %) > Zn2+(33.92 %). The kinetic results showed that sorption follows pseudo-second-order kinetics at pH 6.7. The thermodynamic studies verified that the adsorption processes were nonspontaneous in the case of Pb2+ and spontaneous in the cases of Cu2+ and Zn2+. The observed adsorption process is endothermic in nature. The work also highlights the reusability of the synthesised adsorbent for the metal ion sorption for upto 8 cycles, wherein, no compromise in adsorption capacity was observed till 5th cycle.

Sorption of divalent metal ions from aqueous solutions on activated carbon with its further separation through electroflotation

Currently, there are multiple methods for wastewater treatment from metal ions. One of the leading methods is the sorption process. The advantage of sorption purification is its ability to extract substances from multi-component mixtures and its high efficiency with low concentrations of wastewater contamination. The purpose of this work was to study the sorption capacity of the “OU-B” activated carbon in relation to metal ions (Cu2+, Zn2+, Mn2+). The following tasks were set: establishing optimal parameters for sorption in a static mode, approximating the obtained data by linear forms of kinetic and adsorption equations, as well as obtaining the ability to separate coal particles from aqueous solutions by electroflotation. To study the patterns, we used the following research methods: low-temperature nitrogen adsorption, atomic absorption spectrometry, and nephelometry. The optimal parameters for sorption in a static mode (sample size of coal, process time, initial concentration of metal ions) were established experimentally. The maximum degree of extraction of metal ions in the course of sorption was achieved with a 1:133 ratio of coal to aqueous solution during 60 minutes and was 82% for Cu2+, 73% for Zn2+, and 63% for Mn2+. The obtained sorption results were analysed using the kinetic models of Zeldovich-Chen-Clayton of pseudo-first and pseudo-second order and adsorption models of Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Flory-Higgins. The analysis showed that the sorption of Cu2+, Zn2+, and Mn2+ on OU-B carbon occurred according to the mechanism of physical adsorption, which was described by the sorption models of Langmuir and Freundlich and the Zeldovich-Chen-Clayton kinetic model. The separation of used sorbents and the aqueous phase was a difficult task from a technological point of view due to the small size of carbon particles. The article showed the prospects of using electroflotation for extracting OU-B carbon from aqueous solutions: the degree of extraction of coal particles reached 97-99% when cationic or non-ionic SAS were added to the solution.

Sorption Of Divalent Metal Ions From Aqueous Solution By Oxidized carbon Nanotubes And Nanocages: A Review

This is a scientific review defining the technical feasibility of surface oxidized carbon nanotubes (CNTs) for sorption of divalent metal ions (Cd 2+ , Cu 2+ , Ni 2+ , Pb 2+ , Zn 2+ ) from aqueous solution. By conducting the detailed literature review it was found that the adsorption capacities of CNTs remarkably increased after conducting their surface oxidization with NaOCl, HNO3 and KMnO4 solutions. Unlike many microporous adsorbents, CNTs possess ï‌

Effect of humic acid on sorption of trace metal ions by sodium aluminosilicate

Sorption of trace metal ions (Pb 2+, Zn 2+ and Hg 2+) on synthesized sodium aluminosilicate (Na–AS), an important clay mineral, was carried out in the presence and absence of humic acid (Aldrich) at different pH (3 to 10). The material was synthesized by solution route method and it was characterized by using different techniques such as X-ray diffraction, FT-IR, zeta potential measurement, BET surface area analysis and site density measurement. A series of experiments were made to find out the effect of ionic strength, calcium ions, sorbent dose, metal ions concentration and temperature on the sorption of divalent metal ions by Na–AS. The sorption was found to be dependent on pH as well as humic acid. At lower pH (< pH 6) sorption was observed to be enhanced in the presence of humic acid. Ionic strength played an important role in the sorption of metal ions. Sorption was observed to be decreased with increase in metal ion concentration (10 −5 M to 10 −2 M) and data was fitted well in Freundlich isotherm. Thermodynamic study showed endothermic, entropy favorable and spontaneous sorption behavior of metal ions by sodium aluminosilicate.

Binding stoichiometry in sorption of divalent metal ions: A theoretical analysis based on the ion-exchange model

Two stoichiometric assumptions have been compared for describing divalent metal ion binding by protonated sorbent/biosorbent. The first one corresponds to the classical model in which each metal ion (M) binds to two binding sites (X) forming a single MX(2) complex while the second one, proposed by Schiewer and Volesky and used for description of biosorption equilibria, assumes the existence of M(1/2)X complexes. Mathematical expressions corresponding to both these models have been developed by applying the ion-exchange model and methods of statistical thermodynamics. The M(1/2)X model appears to be nonphysical because it does not take into account the basic fact that two sites binding one metal ion must be neighboring. On the other hand, this latter assumption is the part of the MX(2) model which has been shown using Nitta's approach. Nevertheless, equations associated with the M(1/2)X model can be successfully used for description of the experimental data as they can simulate quite well the behavior predicted by the MX(2) model. This is especially true when considering the range of relatively high metal concentrations in the bulk solution and significant degree of surface heterogeneity characteristic of the sorbent surface.

Modelling the solid–liquid adsorption processes using artificial neural networks trained by pseudo second order kinetics

A three-layer feed forward neural network was constructed and tested to analyze the second order kinetics of solid–liquid adsorption process. The pseudo second order kinetics of auramine O onto activated carbon was used to train the artificial neural network (ANN) to model the sorption system for various operating conditions. The operating variables studied are the contact time, initial dye concentration, agitation speed, temperature, initial solution pH and activated carbon mass. The studied operating variables were used as the input to the constructed neural network to predict the dye uptake by pseudo second order kinetics at any time as the output or the target. The dye uptake predicted by ANN trained by pseudo second order kinetics was found to be precise in representing the experimental kinetics of auramine O uptake by activated carbon. The constructed network was also found to be precise in predicting the sorption kinetics of auramine O by activated carbon for the new input data which are kept unaware of the trained neural network showing its applicability to determine the dye uptake rate for any operating conditions under interest. The ANN was also trained using pseudo second order kinetics of sorption of divalent metal ions onto peat particles and also using the second order kinetics of cadmium ions onto tree fern particles. The ANN and pseudo second order kinetics compliment each other to model the studied sorption systems for a wide range of operating conditions.

Sorption of divalent metal ions from aqueous solution by carbon nanotubes: A review

In this article, the technical feasibility of various kinds of raw and surface oxidized carbon nanotubes (CNTs) for sorption of divalent metal ions (Cd 2+, Cu 2+, Ni 2+, Pb 2+, Zn 2+) from aqueous solution is reviewed. The sorption mechanisms appear mainly attributable to chemical interactions between the metal ions and the surface functional groups of the CNTs. The sorption capacities of CNTs remarkably increased after oxidized by NaOCl, HNO 3 and KMnO 4 solutions and such surface oxidized CNTs show great potential as superior sorbents for environmental protection applications. Effects of process parameters, such as CNT characterizations (surface area, pore size distribution, sorbent mass, and surface total acidity), solution properties (ionic strength, pH, initial sorbate concentration and temperature) and competition for sorption sites by multiple metal ions, on the performance of CNTs are addressed in some detail. The recovery of metal ions and the regeneration of CNTs can be achieved using acid elution with little effect on the CNT performance. The utilization of CNTs for the treatment of water and wastewater containing divalent metal ions is gaining more attention as a simple and effective means of pollution control. Future research works on developing a cost-effective way of CNT production and testing the toxicity of CNTs and CNT-related materials are recommended.

Temperature and pH Effect on the Sorption of Divalent Metal Ions by Silica Gel

The sorption of Zn2+, Ni2+ and Cd2+ ions by silica gel was studied as a function of ion concentration, pH and temperature. An increase in all three parameters led to an increase in the extent of sorption for all the metal cations studied. The selectivity of the solid was observed to be in the order Zn2+ &gt; Ni2+ &gt; Cd2+. Sorption of the metal cations was accompanied by the release of H+ ions into the bulk phase. On average two moles of H+ ions were released per mole of metal cation sorbed. The sorption data fitted the linear forms of both the Kurbatov and Langmuir adsorption equations. The values of the binding constants were used to estimate the apparent thermodynamic parameters, ΔH and ΔS, for the adsorption process. FT-IR spectroscopic studies also showed that the uptake of metal cations by the silica gel occurred via a cation-exchange process.

Study of the Sorption of Divalent Metal Ions on to Peat

A pseudo-second order rate equation describing the kinetics of sorption of divalent metal ions on to sphagnum moss peat at various initial metal ion concentrations and peat doses has been developed. The sorption kinetics were followed based on the concentrations of metal sorbed at various time intervals. Results show that chemical sorption processes might be rate-limiting for the sorption of divalent metal ions on to peat during agitated batch contact time experiments. The rate constant, the equilibrium sorption capacity and the initial sorption rate were calculated. From these parameters, an empirical model for predicting the concentrations of metal ions sorbed was derived.

The kinetics of sorption of divalent metal ions onto sphagnum moss peat

A pseudo-second order rate equation describing the kinetics of sorption of divalent metal ions onto sphagnum moss peat at different initial metal ion concentrations and peat doses has been developed. The kinetics of sorption were followed based on the amounts of metal sorbed at various time intervals. Results show that sorption (chemical bonding) might be rate-limiting in the sorption of divalent metal ions onto peat during agitated batch contact time experiments. The rate constant, the equilibrium sorption capacity and the initial sorption rate were calculated. From these parameters, an empirical model for predicting the sorption capacity of metal ions sorbed was derived.

Sorption of divalent metal ions on an iminodiacetic resin from artificial seawater

Sorption of divalent metal ions on an iminodiacetic resin from artificial seawater

Sorption of divalent metal ions on an iminodiacetic resin from artificial seawater

The sorption of some bivalent metal ions on the iminodiacetic resin Chelex 100 was examined in artificial seawater as an example of a complex matrix, and in the presence of an organic chelating substance in the aqueous phase. The curves reporting the fraction of sorbed metal ions in function of the solution pH were determined experimentally under different conditions and the exchange coefficients were calculated. The intrinsic complexation constants, which are independent of the conditions, were evaluated on the basis of the Gibbs-Donnan model for the resin and agree with those previously obtained in the case of the sorption of the same metals on Chelex 100 from solutions of simpler composition. In some instances the intrinsic complexation constants were similar to the corresponding complexation constants in aqueous solution, while in other cases they were different, depending on the activity coefficient ratio of the species inside the resin. It has been demonstrated that the method derived from the Gibbs-Donnan model can be used for describing and predicting the sorption equilibria also from complex solutions, if all the equilibria set up in the considered system are known.

Sorption of metal ions on a weak acid cation-exchange resin containing carboxylic groups

The sorption properties of a commercial resin containing a carboxylic active group, Amberlite® CG-50, for magnesium, calcium, copper and zinc were investigated on the basis of the Donnan model. It is assumed that the main driving force for the sorption of divalent metal ions is the complexation by the carboxylic groups inside the resin. Under typical batch conditions (large excess of ligand) only the 1:2 complexes are formed for all metal ioas considered, whereas in aqueous solution only 1:1 complexes are reported for calcium and magnesium and the monomeric analogues of the active group of Amberlite® CG-50. The intrinsic complexation constants obtained from the batch experiments agree well with those in aqueous solution. The same holds for the intrinsic complexation constant evaluated from Chromatographic experiments. This confirms some previous results obtained with a chelatteg resin containing an iminodiacetic group, Chelex 100. The values of the complexation constants for the carboxylic groups found with Chelex 100 are in agreement with those found with Amberlite® CG-50.