Rate Of Metal Ion Uptake Research Articles

The efficient recovery of Au(III) ions from acidic solutions by a novel scavenger based on functionalized poly(styrene-co-maleimide) nanoparticles

Tertiary amine functionalized poly(styrene-co-maleimide) nanoparticles were readily synthesized by an organic solvent-free thermal imidization reaction. The obtained spherical nanoparticles, with average diameters of about 50 nm, were shown to be highly effective as a unique scavenger for the recovery of Au(III) ions from strong acidic solution. High equilibrium Au loading capacities (>570 mg/g) were obtained at 25 °C and the rate of metal ion uptake was remarkably fast. The Au(III) ions in the feed solutions were almost quantitatively recovered within 3–10 min, depending on the shaking speed during batch sorption. Elution of the adsorbed Au species was however incomplete with a maximum elution efficiency of 75% using acidified thiourea as eluant. XPS analysis showed that the adsorbed Au species were present as a mixture of Au(0), Au(I), and Au(III), which explained the inadequate elution. An alternative and innovative method to recover the adsorbed Au was developed consisting of digestion of the Au-loaded scavenger followed by reductive precipitation with water as reducing agent. The Au formerly loaded on the scavenger was successfully and completely recuperated as pure metallic Au. This is a step-change in the way Au is recovered from solution and eliminates the need for difficult, partial, and environmentally unfavorable elution processes of Au species strongly adsorbed on the scavenger particles.

Removal of Pb(II), Zn(II), Sn(II) and Cu(II) Ions from Aqueous Solutions by Linear Alternating Poly(4,4'-biphenol oxalate) Oligomer

Poly(4,4′-biphenol oxalate) oligomer was synthesized and characterized by FT-IR, elemental analysis XRD and thermal analysis. The capability of the oligomer to take away Pb(II), Zn(II), Sn(II) and Cu(II) metal ions from aqueous solutions was considered by the known batch and column techniques in terms of concentration, pH value, contact time and temperature. The results indicated that a high initial rate of metal-ion uptake by the oligomer was observed throughout the first 30 minutes, which enlarged slightly amid rising the pH value and then reached its greatest value at pH=5.00 for Pb(II) and Zn(II), pH=4.00 for Cu(II) and pH=6.00 for Sn(II). The oligomer exhibited a high metal-ion uptake capacity to Pb(II) and Zn(II), but a little metal-ion uptake capacity to Cu(II) and Sn(II). Linearized forms of the Langmuir, Freundlich and Dubinin–Radushkevich adsorption isotherms were used to investigate the experimental equilibrium concentration data of Pb(II), Zn(II), Cu(II) and Sn(II). ΔG values demonstrated that the adsorption process of these metal ions on the oligomer is favored while the ΔH values indicated that this process is endothermic. On the other hand, the entropy of the process is positive. In addition to batch experiments, column experiments were performed, where the metal ions were efficiently recovered by treatment of the metal-loaded oligomer with 1.0 M HNO3, 1.0 M HCl and 0.5 M EDTA. The best results were obtained with 1.0 M HNO3 solution.

Biosorption of Cd(II) Ions from Aqueous Solution Using Chitosan-iso-Vanillin as a Low-Cost Sorbent: Equilibrium, Kinetics, and Thermodynamic Studies

In the current study, the removal of Cd(II) ions from aqueous solution using chitosan-iso-vanillin biosorbent has been investigated. The impacts of pH, exposure time, adsorbent dosage and initial amount of studied ion on the removal process have been carried out using batch experiments. The quantity of residual ions has been estimated via atomic absorption spectrometry. The synthesized biosorbent is characterized using infrared spectroscopy, DTA, and SEM techniques. The maximum sorption of Cd(II) ions is achieved at pH 5. Langmuir isotherm works as the best explanation model for the experimental data with the highest adsorption capacity equal to $$38.31\,\hbox {mg g}^{-1}$$ . Kinetic studies reveal that chemisorption is the rate-determining step, and the results point out fast rates of metal ion uptake with 77% highest percentage achieved after 60 min. Thermodynamics suggest spontaneous and endothermic process with raise in randomness at the solid/solution interface throughout the bio-adsorption of Cd(II) ions onto modified chitosan.

Kinetic Studies on the Removal of Some Lanthanide Ions from Aqueous Solutions Using Amidoxime-Hydroxamic Acid Polymer.

Lanthanide metal ions make distinctive and essential contributions to recent global proficiency. Extraction and reuse of these ions is of immense significance especially when the supply is restricted. In light of sorption technology, poly(amidoxime-hydroxamic) acid sorbents are synthesized and utilized for the removal of various lanthanide ions (La3+, Nd3+, Sm3+, Gd3+, and Tb3+) from aqueous solutions. The sorption speed of trivalent lanthanides (Ln3+) depending on the contact period is studied by a batch equilibrium method. The results reveal fast rates of metal ion uptake with highest percentage being achieved after 15–30 min. The interaction of poly(amidoxime-hydroxamic) acid sorbent with Ln3+ ions follows the pseudo-second-order kinetic model with a correlation coefficient R2 extremely high and close to unity. Intraparticle diffusion data provide three linear plots indicating that the sorption process is affected by two or more steps, and the intraparticle diffusion rate constants are raised among reduction of ionic radius of the studied lanthanides.

Toxic metal ion removal by terpolymer ion-exchanger from aqueous environments: synthesis, thermal degradation, batch separation, kinetic and isotherm studies

ABSTRACTA novel chelating resin was synthesized and characterized by elemental, physico-chemical, GPC, NMR, and SEM analyses. Batch separation was adopted to study the recovery of selected metal ions with respect to the pH, time, concentrations, and electrolytes. From the results, it was observed that the order of the rate of metal ion uptake by the resin was Fe3+ > Cu2+ > Zn2+ > Ni2+ > Co2+ > Pb2+ ions. The adsorption kinetics follows first order, and isotherm models were also found to fit each other. The resin showed three-step thermal degradation, and its kinetic and thermodynamic parameters were also evaluated.

Competitive adsorption of metal ions onto goethite–humic acid-modified kaolinite clay

A binary mixture of humic acid and geothite was prepared and used to modify kaolinite to produce geothite–humic acid (GHA)-modified kaolinite adsorbent useful for the adsorption of Pb2+, Cd2+, Zn2+, Ni2+ and Cu2+ from Single and Quinary (5) metal ion systems. The cation exchange capacity (CEC) and specific surface area of GHA-modified kaolinite clay adsorbent were found to be 40 meq/100 g and 13 m2/g, respectively, with the CEC being five times that of raw kaolinite clay (7.81 meq/100 g). The Langmuir–Freundlich equilibrium isotherm model gave better fit to experimental data as compared with other isotherm models. In Quinary metal ion system, the presence of Zn2+ and Cu2+ appears to have an antagonistic effect on the adsorption of Pb2+, Cd2+ and Ni2+, while the presence of Pb2+, Cd2+ and Ni2+ shows a synergistic effect on the adsorption of Zn2+ and Cu2+. The GHA-modified kaolinite showed strong preference for the adsorption of Pb2+ in both metal ion systems. Brouers–Weron–Sotolongo (BWS) kinetic model gave better fit to kinetic data compared with other kinetic models used. Data from BWS kinetic model indicate that adsorption of metal ions onto GHA-modified adsorbent in both metal ion systems followed strictly, diffusion-controlled mechanism with adsorption reaction proceeding to 50 % equilibrium in <2 min in the Single metal ion system and <1 min in the Quinary metal ion system. Adsorption of metal ions onto GHA-modified kaolinite is fairly spontaneous and endothermic in nature in both metal ion systems although the rate of metal ion uptake and spontaneity of reaction are reduced in the Quinary metal ion system.

New facile benign agrogenic-nanoscale titania material—Remediation potential for toxic inorganic cations

A new facile benign (eco-friendly) Nauclea diderrichii agrowaste-nanoscale titania hybrid adsorbent (TND) used in the sequestration of Cr(III) and Pb(II) ions is reported in this paper. Surface characterization techniques such as thermogravimetric analysis (TG), X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) surface area and porosimetric analyses indicated that N. diderrichii agrowaste (NDS) was successfully modified with nano-titania. TG analysis proved that modification of N. diderrichii agrowaste with nano-titania improved its thermal stability and rate of metal ion uptake. Pseudo-second order kinetic equation gave better fit to experimental data than pseudo-first order kinetic equation. The adsorption capacity of NDS and TND adsorbents for Cr(III) were 5.57mg/g and 6.21mg/g, respectively. Also, the amounts of Pb(II) sequestered by NDS and TND adsorbents were 6.82mg/g and 7.49mg/g, respectively. Also, the initial sorption rates of Cr(III) and Pb(II) by TND adsorbent was higher than for NDS adsorbent, making TND material a better adsorbent for toxic metal ions removal from aqueous effluents than NDS adsorbent.

Batch separation studies for the removal of heavy metal ions using a chelating terpolymer: Synthesis, characterization and isotherm models

Chelating terpolymer resin was synthesized from anthranilic acid and 2-amino pyridine with formaldehyde to remove the heavy metal ions present in the solutions. The synthesized terpolymer resin was characterized by spectral techniques such as FTIR, NMR (1H and 13C) and elemental analysis to elucidate the structure of the resin. The physico-chemical parameters have also been evaluated for the terpolymer resin. The surface morphology of the terpolymer resin without the metal ion uptake and with the incorporation of the metal ion was examined by scanning electron microscopy. The chelation ion-exchange property of the terpolymer resin was evaluated by batch equilibrium method for specific metal ions viz. Fe3+, Co2+, Ni2+, Cu2+, Zn2+, and Pb2+. The study was extended to three variations such as evaluation of metal ion uptake in presence of various electrolytes in different concentrations, evaluation of the distribution of metal ion uptake at different pH ranges and evaluation of the rate of metal ion uptake at different time intervals. The adsorption isotherm was evaluated by means of Langmuir and Freundlich isotherm models. The order of the kinetics was also determined and the resin follows first order kinetics which shows that physisorption may be involved in the ion-exchange process. From the results, it was observed that the terpolymer resin acts as an excellent cation-exchanger. Compared to the commercially available phenolic and polystyrene resins, the synthesized terpolymer resin showed an excellent ion-exchange capacity with the selected metal ions.

Ion Exchange Properties of Resins Derived from p‐Hydroxybenzaldehyde, Resorcinol and Formaldehyde

The terpolymeric resins were prepared by base catalyzed polycondensation of p‐hydroxybenzaldehyde, resorcinol and formaldehyde. Resin obtained by molar monomer composition, p‐hydroxybenzaldehyde: resorcinol: formaldehyde as 1:1:3 was abbreviated as PHBRF‐I and that prepared by 1:2:4 composition was abbreviated as PHBRF‐II. These resins were characterized by physicochemical methods such as elemental analysis, UV‐Vis, IR and NMR. ion‐exchange study was carried out with Cu2+, Zn2+, Ni2+, Co2+, Pb2+ &amp; Cd2+ by batch equilibrium method. The rate of metal ion uptake by PHBRF‐II terpolymeric resin was higher than that of PHBRF‐I. Effect of pH and electrolytes under specified condition were also studied. The terpolymeric resins show high selectivity for Cu2+, Zn2+ and Co2+ as compared to Ni2+, Pb2+, and Cd2+.

Solid phase extraction and determination of metal ions in aqueous samples using Quercetin modified Amberlite XAD-16 chelating polymer as metal extractant

A new chelating polymer has been developed using Amberlite XAD-16 anchored with Quercetin. The modified polymer was characterised by Fourier Transform Infra Red (FTIR) spectroscopy, thermogravimetric analysis, surface area analysis and elemental analysis. The Quercetin anchored polymer showed superior binding affinity for Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) with greater than 95% adsorption under optimum conditions. The optimum pH conditions for the quantitative sorption of metal ions were studied. The developed method showed superior extraction qualities with high metal loading capacities of 387, 313, 195, 473, 210 and 320 µmol g−1 for Cu(II), Co(II), Cr(III), Fe(III), Mn(II) and Ni(II), respectively. The rate of metal ion uptake i.e. kinetics studies performed under optimum levels, showed t 1/2 for Co(II), Cu(II), Cr(III), Fe(III), Mn(II) and Ni(II) is 20, 15, 25, 10, 30 and 15 min, respectively. Desorption of metal ions was effective with 10 mL of 2 M HCl prior to analysis using flame atomic absorption spectrophotometer. The chelating polymer was highly ion selective in nature even in the presence of interferent ions, with a high preconcentrating ability for the metal ions of interest. The developed chelating polymer was tested on its utility with synthetic and real samples like river, tap water samples and also with multivitamin tablets. It showed relative standard deviation (R.S.D.) values of/less than 3.0% reflecting on the accuracy and reproducibility of data using the newly developed chelating polymer.

Preparation and Characterization of Poly(bisphenol A oxalate) and Studying its Chelating Behavior Towards Some Metal Ions

Poly(bisphenol A oxalate) was synthesized by condensation polymerization of Bisphenol A and oxalyl chloride in dichloromethane under dry nitrogen atmosphere below 5°C. The resulting linear alternating polymer was characterized by inherent viscosity, FTIR, 1H‐NMR, and 13C‐NMR. The thermal behavior of the polymer was evaluated by differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The chelating behavior of the synthesized polymer towards some divalent metal ions was studied by the batch equilibrium technique as a function of pH and contact time. The isothermal behavior and kinetics of the metal ions uptake onto the polymer were also investigated. The polymer showed high rates of metal ion uptake toward Pb(II), Cu(II), and Mg(II), but low rates toward Ni(II) and Cd(II) in the measurement of metal uptake. Interestingly, the polymer was found to selectively chelate Pb(II) and Mg(II) ions in the concentration variation isotherm experiments.

Synthesis and chelation properties of Mannich polymers derived from piperazine and some hydroxy benzaldoximes

Two new oxime containing polymers, poly(salicylaldoxime-3,5-diyl (piperazine N, N′-bismethylene)), polymer I, and poly(2,4-dihydroxy-benzaldoxime-3,5-diyl (piperazine N, N′-bismethylene)), polymer II, were prepared through Mannich-type condensation of the appropriate hydroxy benzaldoxime with formaldehyde and piperazine. The sorption properties of these polymers towards the trivalent lanthanide ions, Gd 3+, Tb 3+, Sm 3+, Nd 3+, and La 3+ were studied by a batch equilibration technique as a function of contact time, pH, and counter ion. Polymer II exhibited improved chelation characteristics in comparison with polymer I and displayed faster rates of metal ion uptake and relatively higher capacities and selectivities.

Enhanced metal extractive behavior using dual mechanism bifunctional polymer: an effective metal chelatogen

A new class of chelating polymers using Amberlite XAD-16 (AXAD-16) modified with ( N-(3,4-dihydroxy)benzyl)-4-amino,3-hydroxynapthalene-1-sulphonic acid has been developed based on dual mechanism bifunctional polymers, for the extraction of transition and post-transition metal ions. The optimum pH conditions for the quantitative sorption of metal ions were studied. The developed method showed superior extraction qualities with high metal loading capacities of 71, 85, 182, 130 and 46 mg g −1 for Ni(II), Cd(II), Pb(II), Cu(II) and Co(II), respectively. The rate of metal ion uptake i.e. kinetics studies performed under optimum levels showed a time duration of <5 min except for Co(II) which required 20 min, for complete metal ion saturation. Desorption of metal ions were effective with 15 ml of 2 M HCl/HNO 3 prior to detection using flame atomic absorption spectrophotometer. The chelating polymer was highly ion-selective in nature even in the presence of large concentrations of alkali and alkaline earth metal ions, with a high preconcentrating ability for the metal ions of interest. The developed chelating matrix was tested on its utility with synthetic and real samples like river/sea/tap/well water samples and also with multivitamin/mineral tablets, showed R.S.D. values of <2.5% reflecting on the accuracy and reproducibility of data using the newly developed resin matrix.

Kinetic Studies on the Exchange of Bivalent Metal Ions on Amberlite IRC‐718—An Iminodiacetate Resin

The rate of uptake of alkaline earth metals, copper, and lead have been investigated by a chelating ion exchange resin containing iminodiacetic acid as ligand attached to the copolymer of styrene and divinyl benzene of macroporous matrix structure. It binds alkaline earth metals, Cu, and Pb by the formation of chelate complexes with the carboxylate group of this resin. The experiments discussed in this work have allowed to establish the paramount importance of the presence of this chelating group in obtaining practically useful rates of metal ion uptake. The kinetic parameters like diffusion coefficient (D o), activation energies (ΔE a) and entropy of activation have been evaluated under the conditions favoring a particle diffusion control mechanism and the study followed the three models i.e., Nernst Planck, B t technique and Ash model. K d values in demineralised water (DMW) were found in the order Cu2+ > Pb2+ > Mg2+ > Sr2+ > Ba2+ > Ca2+.

SYNTHESIS AND CHELATION PROPERTIES OF SOME NEW MANNICH CONDENSATION POLYMERS CONTAINING A SALICYLALDOXIME GROUP

ABSTRACT A new oxime containing polymer, Poly(salicylaldoxime-3,5-diyl (N,N′-dimethylethylenediamine N,N′-bismethylene)), polymer 1, was prepared through a Mannich-type condensation of salicylaldoxime with formaldehyde and N,N′-dimethylethylenediamine. Polymer 2, a crosslinked chelating ion exchange resin, was obtained by a similar Mannich condensation in presence of resorcinol as the crosslinker. The sorption properties of these polymers towards the divalent ions, Mg2+, Ca2+, Ni2+, Zn2+, Cd2+, and Cu2+ were studied by a batch equilibration technique as a function of contact time and pH. Crosslinking is found to have profound effects on the surface morphology and the chelation properties of these polymers. The crosslinked Polymer 2 exhibited improved chelation characteristics in comparison with Polymer 1 and displayed faster rates of metal ion uptake and relatively higher capacities and selectivities. These findings are in keeping with the observed increase in hydrophilic character upon crosslinking.

Studies on the Binding of Lead and Zinc Ions by Modified Cellulosic Materials of Tropical Origin

Cellulosic materials of tropical origin, seed husks of flamboyant tree (Delonix regia) and Prosopis (Prosopis africana) were modified with ethylenediamineteraacetic acid and treated with lead (II) and zinc (II) ions and the absorption behaviours were examined. The amount of metal ions removed from solution depended on the metal ion-substrate contact time, the metal ion concentration, the metal ion type and the substrate type. The amount of these ions absorbed varies with the cellulosic material and in the order Pb (II) > Zn (II). It is shown that the cellulosic materials could bind substantial amount of heavy metal ions and the amount of metal ions absorbed per gram of the cellulosic substrate increased with increasing initial metal ion concentration. In all cases, the rate of metal ion uptake by the prosopis husk was higher than that of the flamboyant husk. Discovery and Innovation Vol. 13 no. 3/4 December (2001) pp. 119-122 KEY WORDS: flamboyant husk, prosopis husk, absorption, lead, zinc, contact time

Synthesis and properties of a copper selective chelating resin containing a salicylaldoxime group

A chelating ion-exchange phenol-formaldehyde polymer, poly(salicylaldoxime 3,5-diylmethylene) was synthesized and characterized. The sorption properties of the chelate-forming resin towards various divalent ions (Mg 2+, Ca 2+, Ni 2+, Cu 2+, Zn 2+ and Cd 2+) were studied by a static batch equilibration technique as a function of pH and contact time. The resin exhibited high selectivity towards Cu 2+ ions and showed fast rates of metal ion uptake, particularly for Cu 2+ which experienced >90% uptake in less than 1 h. In a dynamic column operation, it was demonstrated that the resin can be used for effective removal of copper ions from aqueous solutions.

Synthesis and Properties of a Chelating Resin Containing a Salicylaldimine Group

A phenol-formaldehyde polymer, poly(salicylaldehyde 3,5-diylmethylene) was synthesized and characterized. A chelating ionexchange resin was obtained by reacting the polymer with nbutylamine. The chelation characteristics of the chelate-forming resin was studied by a batch equilibration technique. The resin showed fast rates of metal ion uptake and was found to selectively chelate Cu2+ and Cd2+ ions with capacities up to 3.56 mmol/g over a pH range of 5–8.

Hydroxyethylation and its effect on the rate of metal ion ingress into macrocyclic ligands

The hydroxyethylation effect, by which the rate of metal ion uptake by tetraaza macrocyclic ligands is enhanced, was previously known to occur when all four nitrogen atoms are hydroxyethylated or when two, on adjacent nitrogens, are so treated. In this work two mono-hydroxyethylated tetraaza macrocycles, 1-(2-hydroxyethyl)-1,4,8,11-tetraazacyclotetradecane and 1-(2-hydroxyethyl)-4,8,11-trimethyl-1,4,8,11-tetraazacyclotetradecane have been synthesised as well as one tri-hydroxyethylated macrocycle, 1,4,8-tris(2-hydroxyethyl)-11-methyl-1,4,8,11-tetraazacyclotetradecane. The stability constants for the monometallic complexes formed from these ligands with Co 2+, Ni 2+, Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ have been determined in aqueous solution at 298.2 K by potentiometric titration. During the course of these titrations it was noted that the tri-hydroxyethylated macrocycle complexes establish equilibrium at each titration point within a maximum of 5 min of the addition of each aliquot of base. The mono-hydroxyethylated ligands, on the other hand, equilibrate very much more slowly. This indicates that the facilitation of metal ion ingress into tetraaza macrocycles, afforded by pendant hydroxyethyl groups, requires a minimum of two hydroxyethyl groups located on adjacent nitrogen atoms.

Metal binding affinity of imidazole ligands immobilized on poly(glycidyl methacrylateco-ethylene dimethacrylate) and on silica

Four new chelating ion-exchangers have been obtained by ring-opening reaction of the epoxy groups on poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (GMA-EDMA) and on two types of epoxy-modified silica with the primary amine group of histamine and the primary amine group of 4-(5-methyl-4-imidazolyl)-1-amino-3-thiabutane (memia). The ligand concentration on the resins varied between 0.25 and 1.9 mmol of the ligand per gram of solid carrier, the highest ligand concentration being obtained for histamine-modified GMA-EDMA. For all materials the batch extraction capacities, in the pH range 0.5–5.7, were higher for Cu 2+ than for Cd 2+, Zn 2+, Ni 2+, Co 2+ and Ca 2+. The highest capacity for Cu 2+ was found for GMA-EDMA functionalized with histamine, i.e. 1.1 mmol Cu 2+ per g resin. No detectable uptake of Ca 2+ took place on any of the new materials in the pH range studied. Competitive experiments, which were performed with solutions containing mixtures of metal chloride salts showed that the ion exchange materials described here selectively sorb Cu 2+. Kinetic experiments suggest that the rate of metal ion uptake, and also of metal ion stripping with H 2SO 4, is mainly determined by the particle size of the carrier material and less by the anchored ligand and the type of backbone material (silica or GMA-EDMA). Apparently, diffusion of the metal ions into the pores of the solid supports is rate determining. Good results, viz. loading and de-loading (stripping) within a few seconds, were obtained with ion-exchange material based on the silica Sorbsil C200, which consists of small porous particles.