Preparation of hybrid ion exchanger based on acrylamide for sorption of some toxic metal ions from aqueous waste solutions

Crystalline phases of polyacrylamide titanium tungstophosphate composite material has been synthesized via sol–gel method. The properties of its were determined using different technique. The ion-exchange capacities of the hybrid material for Cs⁺, Co²⁺ and Eu³⁺ ions it was found that 6.22, 2.76 and 1.38 mequiv. g^–1 respectively. The material was found that highly selective for Eu³⁺ and the selectivity sequence for sorption of Cs⁺, Co²⁺ and Eu³⁺ ions on polyacrylamide titanium tungstophosphate was found that; Eu³⁺ > Cs⁺ > Co²⁺. Thermodynamic parameters have been calculated for the studied ions showing that the overall adsorption process is spontaneous and endothermic. The experimental isotherm data were analyzed using the Langmuir and Freundlich models.     

Mechanism of sorption of phenols from aqueous solutions onto surfactant-modified montmorillonite

Equilibrium and kinetic studies on the sorption of phenol, m-nitrophenol (m-NP), and o-cresol from water onto montmorillonite modified with cetyltrimethylammounium bromide (CTAB) were conducted. Experiments were carried out as a function of solution pH, sorbate concentration, and temperature (25-55 degrees C). It was shown that the sorption capacity decreased in the order phenol>o-cresol>m-NP. The Langmuir, dual-mode sorption, and Redlich-Peterson models were tested to fit the sorption isotherms of single-solute systems, whereas the Langmuir competitive model was used to describe bisolute sorption equilibria. Thermodynamic parameters (DeltaH degrees and DeltaS degrees ) and the mean free energy (E) for the sorption of phenols were determined from the temperature dependence of the distribution constant and the Dubinin-Radushkevick equation, respectively. A simplified kinetic model was proposed to confirm the sorption mechanism.     

Sorption investigation on the removal of metal ions from aqueous solutions using chelating terpolymer resin

A novel chelating terpolymer resin has been synthesized from anthranilic acid, phenylhydrazine, and formaldehyde by condensation in glacial acetic acid. The structure of the chelating resin was clearly elucidated by use of a variety of spectral techniques, for example FTIR, and ¹H and ¹³C NMR spectroscopy. The average molecular weight of the terpolymer resin was determined by gel-permeation chromatography. The empirical formula and empirical weight of the resin were determined by elemental analysis. The physicochemical properties of the terpolymer resin were determined. Scanning electron microscopy was used to establish the surface features of the chelating resin. The ion-exchange behaviour of the resin for specific metal ions, viz. Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Pb²⁺, was evaluated by a batch equilibrium method. The study was extended to three variations: evaluation of metal ion uptake in the presence of different electrolytes at different concentrations; evaluation of metal ion uptake at different pH; and evaluation of metal ion uptake at different times. Further, the reusability of the resin was also determined to assess the efficiency of the resin after a few cycles of sorption. From the results it was observed that the resin acts as an effective chelating ion-exchanger.     

Adsorption of uranium ions by crosslinked polyester resin functionalized with acrylic acid from aqueous solutions

In this paper, the crosslinked polyester resin containing acrylic acid functional groups was used for the adsorption of uranium ions from aqueous solutions. For this purpose, the crosslinked polyester resin of unsaturated polyester in styrene monomer (Polipol 353, Poliya) and acrylic acid as weight percentage at 80 and 20%, respectively was synthesized by using methyl ethyl ketone peroxide (MEK_p, Butanox M60, Azo Nobel)-cobalt octoate initiator system. The adsorption of uranium ions on the sample (0.05 g copolymer and 5 mL of U(VI) solution were mixed) of the crosslinked polyester resin functionalized with acrylic acid was carried out in a batch reactor. The effects of adsorption parameters of the contact time, temperature, pH of solution and initial uranium(VI) concentration for U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid were investigated. The adsorption data obtained from experimental results depending on the initial U(VI) concentration were analyzed by the Freundlich, Langmuir and Dubinin–Radushkevich (D–R) adsorption isotherms. The adsorption capacity and free energy change were determined by using D–R isotherm. The obtained experimental adsorption data depending on temperature were evaluated to calculate the thermodynamic parameters of enthalpy (ΔH°), entropy (ΔS°) and free energy change (ΔG°) for the U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid from aqueous solutions. The obtained adsorption data depending on contact time were analyzed by using adsorption models such as the modified Freundlich, Elovich, pseudo-first order and pseudo-second-order kinetic models.     

Adsorption of some bivalent heavy metal ions from aqueous solutions by manganese nodule leached residues

The leached residue, generated after selective extraction of Cu, Ni, and Co in sulfur dioxide-ammonia leaching of manganese nodules, was characterized and batch isothermal adsorption experiments were conducted at ambient temperature to evaluate the effectiveness of the water-washed leached residue for removal of different bivalent metal ions from aqueous synthetic solutions. The effects of pH, initial metal ion concentrations, amount of adsorbent, interfering ions, and heat treatment were also investigated. The uptake of metal ions increased with increasing pH. Under identical conditions the adsorption capacity increased in the order Cd(2+)相似文献   

Removal of heavy metal ions from aqueous solutions by alkaline-earth metal phosphates

The possibility of utilization of calcium or magnesium phosphates of various composition for heavy and non-ferrous metal extraction from aqueous solutions has been studied. The efficiency of the phosphates in removal of Pb(II), Cr(III) and Fe(III) ions has been shown to decrease in the following sequence: Mg₃(PO₄)₂>MgNH₄PO₄>Ca₃(PO₄)₂>CaHPO₄>Ca₁₀(PO₄)₆(OH)₂ which is inverse to their hydrolytic stability series. It has been established that phosphates of non-apatite structure are capable of binding up to 12 mmol g⁻¹ of the named heavy metals by a chemical interaction. Hydroxyapatite interacts with the polyvalent metal ions via either the above mentioned or ion-exchange mechanism, depending on preparation method used for the apatite and the nature of metal.     

Granulated sulfur-containing sorbents for recovery of heavy metal ions from aqueous solutions

Granulated sorbents that can recover zinc salts from aqueous solutions were produced by poly-condensation of organochlorine wastes from manufacture of epichlorohydrin with sodium polysulfide on the surface of ash-and-slag particles formed at thermal power plants in the system constituted by aqueous hydrazine and an alkali.     

Sorption of cadmium ions from aqueous solutions onto nanoporous modified carbon sorbents

Physicochemical properties of nanoporous modified carbon sorbents and sorption of cadmium ions (0.1–20 mg L^?1) onto them from nitrate solutions at pH 5–7 were studied. The acid-base nature of functional oxygen-containing groups on the carbon surface of the sorbents was determined. The ability to sorb cadmium ions depends on the kind of chemical modification of the sorbent surface.     

Multi-element preconcentration of heavy metal ions from aqueous solution by APDC impregnated activated carbon

Ammonium pyrrolidinedithiocarbamate impregnated activated carbon (APDC-AC) has been used for the preconcentration of Cd(II), Cu(II), Ni(II), and Zn(II) from aqueous solution by column solid phase extraction (SPE) technique. Trace metal ions in aqueous solution were quantitatively sorbed onto APDC-AC packed in a SPE column at pH 5.0 with a flow rate of 1.0 mL min⁻¹. The sorbed metals were eluted with 1 M nitric acid in acetone solution at a flow rate of 0.6 mL min⁻¹ and analyzed by flame atomic absorption spectrometry. The effects of sample volume, amount of APDC-AC, volume of eluent and ionic strength of working solution on metal ion recovery have been investigated. The present methodology gave recoveries from 90 to 106% and R.S.D. from 0.6 to 5.5%.     

Adsorption of acid dyes from aqueous solutions onto acid-activated bentonite

The adsorption of two dyes, namely, Acid Red 57 (AR57) and Acid Blue 294 (AB294), onto acid-activated bentonite in aqueous solution was studied in a batch system with respect to contact time, pH, and temperature. Acidic pH was favorable for the adsorption of these dyes. The surface characterization of acid-activated bentonite was performed using the FTIR technique. The pseudo-first-order and pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated. The dynamic data fitted the pseudo-second-order kinetic model well and also followed the intraparticle diffusion model up to 90 min, but diffusion is not the only rate controlling step. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The Freundlich model agrees very well with experimental data. The activation energies of adsorption were also evaluated for the adsorption of AR57 and AB294 onto activated bentonite.     

Kinetics and thermodynamics of the sorption of uranium and thorium ions from nitric acid solutions onto a TBP-impregnated sorbent

Summary Kinetics and equilibrium studies on the sorption of uranium and thorium ions were carried out from nitric acid solutions by tri-n-butyl phosphate (TBP) loaded supported sorbent, commercially known as Egy-Sorb, using batch technique. Analysis of the rate data in accordance with three kinetic models revealed that the particle diffusion process was the rate determining mechanism and the sorption process of the metal ions onto impregnated sorbent follows first order reversible kinetics. The values of the first order rate constants, the rate constants of intraparticle transport, and the particle diffusion coefficients for the uranium and thorium ions were determined from the graphical representation of the proposed models. Experimental isotherms of both ions were successfully fit to Langmuir and Freundlich isotherm models over the entire concentration range studied. The effect of temperature on the equilibrium distribution values has been utilized to evaluate the changes in standard thermodynamic quantities.     

Sorption of protons and metal ions from aqueous solutions by a strong-base anion-exchange resin loaded with sulphonated azo-dyes

Two sulphonated azo-dyes, which bear a nitrogen donor atom in the diazo group and are known to complex many heavy metal ions in aqueous solution, have been found to be sorbed by a strong-base anion-exchange resin (Dowex 1-X8) simply by ion-exchange. The resin containing the dyes behaves like a chelating resin, able to sorb copper(II) and nickel(II) from aqueous solution, if the proper conditions are chosen. The acidity, ionic composition and volume of the aqueous solution, and the amount and nature of the sorbed ligand are the factors which determine the fraction of metal ion sorbed when the batch technique is used. The experimental results are interpreted by using a model of the resin based on the Donnan equilibrium concept, which allows prediction of the sorption conditions on the basis of some independently determined quantities, such as the protonation and complex formation constants in aqueous solution, and the activity of the counter-ion in the resin phase. The exchange of protons between the resin and the aqueous solution can also be explained with this model.     

Recovery of heavy metal ions from aqueous solutions using modified organosilicas

Sorption of Cu(II), Pb(II), Cd(II), and Zn(II) from aqueous solutions on two-component organosilicas was studied as influenced by sorbent composition, contact time, ratio of solid and liquid phases, solution pH, nature and concentration of heavy metal ions, and content of modifying agent. The degrees of sorption of these metal ions from aqueous solutions using organosilicas modified with aluminum(III) added into the siloxane matrix or with copper(II) grafted to the sorbent surface layer were compared.     

Kinetic modeling analysis for the removal of cesium ions from aqueous solutions using polyaniline titanotungstate

Polyaniline titanotungstate has been synthesized by incorporation of organic polymer polyaniline into the inorganic precipitate of titanotungstate. This material was characterized using X-ray, IR and TGA studies. The influences of initial concentration of metal ions, particle size and temperature have been reported. The comparison of composite and inorganic materials was studied and indicating that the composite material is better than the inorganic in selectivity of Cs⁺ ions. Thermodynamic parameters, such as changes in Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) have been calculated. The numerical values of ΔG decrease with an increase in temperature, indicating that the sorption reaction of adsorbent was spontaneous and more favorable at higher temperature. The positive values of ΔH correspond to the endothermic nature of sorption processes and suggested that chemisorptions were the predominant mechanism. A comparison of kinetic models applied to the sorption rate data of Cs⁺ ions was evaluated for the pseudo first-order, the pseudo second-order, intraparticle diffusion and homogeneous particle diffusion kinetic models. The results showed that both the pseudo second-order and the homogeneous particle diffusion models were found to best correlate the experimental rate data. Self diffusion coefficient (D_i), Activation energy (Ea) and entropy (ΔS^*) of activation were also computed from the linearized form of Arrhenius equation.     

The characteristics of sorption of heavy metal ions with a protein sorbent from aqueous media

Equilibrium-kinetic properties of a protein sorbent with respect to Cu²⁺, Fe²⁺, Ni²⁺, Cd²⁺, and Zn²⁺ ions were studied. The dependences of the degree of recovery of metasl on their structure and pH of the medium were determined.     

Specific features of sorption of heavy metal ions by a cellulose-containing sorbent from aqueous media

Sorption of Cd²⁺, Cu²⁺, Fe²⁺, Nu²⁺, and Zb²⁺ ions by a polysaccharide biosorbent was studied. The effect of the pH of the medium on the process of distribution of metal cations in a heterophase system constituted by an aqueous solution of a metal sulfate and a cellulose-containing sorbent was determined.     

Characteristics of sorption of uncomplexed and complexed Pb(II) from aqueous solutions onto peat

Batch experiments aimed at the sorption of Pb(II) onto peat were performed from an aqueous solution in both the absence and presence of common complexing agents (acetate or citrate). The influence of the initial pH of the solution, metal ion concentration and contact time on the sorption efficiency of Pb(II) was examined at ambient temperature (18 ± 0.5) °C for each experiment. The results showed that the presence of acetate improved the efficiency of the sorption process, while the presence of citrate in the aqueous solution decreased the efficiency of the Pb(II) sorption onto peat. The equilibrium data fitted well with the Langmuir isotherm model and confirmed the monolayer sorption of uncomplexed and complexed Pb(II) species onto peat. The values of maximum sorption capacities (q _max) were 135.13 mg g⁻¹ for Pb(II) complexed with acetate, q > 79.36 mg g⁻¹ for uncomplexed Pb, q > 38.46 mg g⁻¹ for Pb(II) complexed with citrate. The kinetics of Pb(II) sorption onto peat, in both the absence and presence of complexing agents, indicated a pseudosecond order mechanism. Analysis of IR spectra showed that carboxylic and hydroxyl groups had an important role in the binding process of Pb(II) species onto peat.     

Sorption of metal ions from multicomponent aqueous solutions by activated carbons produced from waste

Activated carbons produced by thermal treatment of a mixture of sunflower husks, low-grade coal, and refinery waste were studied as adsorbents of transition ion metals from aqueous solutions of various compositions. The optimal conditions and the mechanism of sorption, as well as the structure of the sorbents, were studied.