Adsorption Of Zirconium Research Articles

Adsorption of Zirconium using Hyper Cross Linkage Phospho-thiol Polymer and Application of its Separation from Rosetta Zircon Mineral Concentrate

Adsorption of Zirconium using Hyper Cross Linkage Phospho-thiol Polymer and Application of its Separation from Rosetta Zircon Mineral Concentrate

Adsorption of Zirconium Ions by X-Type Zeolite

Dependence of zirconium adsorption value on agitation time, solution acidity, equilibrium concentrations of zirconium cations, and zeolite NaX particle size was investigated. The two most common adsorption theories Langmuir and Freundlich, were used to analyzing equilibrium adsorption data. Nonlinear approximation shows that the Freundlich adsorption theory provides higher R2 and lower χ2 for zirconium adsorption by NaX than the Langmuir adsorption theory. Experimental maximum adsorption values of NaX toward zirconium and strontium cations are 75 mg·g-1 and 156 mg·g-1, respectively. The desorption studies of zirconium ions from the surface of NaX by 1% oxalic acid and 10% HNO3 were performed. Degradation of the adsorbent in nitric acid was studied in a batch mode. The recovered suspended particles filter cake was investigated by X-ray fluorescence analysis. Alumina oxide (Al2O3) fraction decreases, and MgO is completely washed out from the adsorbent matrix in concentrated HNO3.

Determination of Phosphate in Human Serum with Zirconium/Reduced Graphene Oxide Modified Electrode.

An electrochemical phosphate sensor based on zirconium and reduced graphene oxide modified pencil graphite electrode (Zr/rGO-PGE) is proposed. The XRD, CV and EIS confirmed that GO was partially reduced on the PGE. Scanning electron microscopy (SEM) exhibited the layered and wrinkled structures for the rGO-PGE and Zr/rGO-PGE, respectively. Cyclic voltammetry showed the immobilized rGO was highly stable and had high activity toward zirconium adsorption. The prepared electrode was used for the electrochemical determination of phosphate. Based on the optimum condition using differential pulse voltammetry, the limit of detection and sensitivity for phosphate was obtained as [0.011(± 0.004) μM] (S/N = 3) and [622.4(± 9.6) μA μM-1 cm-2], respectively. The sensor was successfully evaluated for phosphate determination in human serum samples. In practical terms, the construction of this sensor was exceptionally simple, fast, cost effective and reproducible.

Efficient remediation of Zr(IV) using citrus peel waste biomass: Kinetic, equilibrium and thermodynamic studies

In research of low cost adsorbents for the adsorption of radioactive nuclide, citrus peel waste biomass (CPWB) was studied for the adsorption of zirconium (Zr) ions from aqueous medium. Various process variables were investigated for Zr(IV) adsorption and 3.5, 0.05g, 40min, 30°C and 90mg/L pH, biosobent dose, contact time, temperature and initial Zr(IV) ions concentration, respectively were found out to be best for Zr(IV) adsorption. At optimized conditions, 42.02mg/g Zr(IV) was adsorbed onto CPWB. Pseudo-second-order kinetic model and Langmuir isotherm model described the Zr(IV) adsorption on to CPWB well. Thermodynamic study showed that the biosorption of Zr(IV) ions onto CPWB was feasible, spontaneous at room temperature and exothermic in nature. FTIR analysis revealed the involvement of carbonyl, hydroxyl and amino functional group in the adsorption of Zr(IV) ions onto CPWA. In view of efficient adsorption of Zr(IV) ions, CPWB is a potential candidates for the adsorption of radioactive nuclide from waste.

Zirconium adsorption and incorporation on a reconstructed Al-T4 AlN(0001) surface

We discuss the energetic stability and electronic structure of zirconium adsorption and incorporation on a 2×2 reconstructed AlN(0001) surface. We employ density-functional theory within the generalized-gradient approximation to study such effects. First-principles total energy calculations reveal that the most stable positions of a Zr adatom on the reconstructed 2×2-T4 AlN(0001) surface are at the S1 and Sp substitutional sites. In addition, calculating the relative surface energy of several configurations, we constructed a phase diagram showing the energetically most stable surfaces as a function of the aluminium chemical potential. Based on these results, we find that incorporation at Al-substitutional sites is energetically favorable compared to adsorption on the top layers. In particular, we find that Zr-S1 and Zr-Sp structures are stable over the entire chemical potential range. This effect can lead to the formation of a non-reactive interfacial ZrN(111) layer on the AlN(0001) surface, which can offer a good interfacial combination between AlN substrate and other metal contacts, i.e. zirconium.

Application of modified multiwall carbon nanotubes as a sorbent for zirconium (IV) adsorption from aqueous solution

Modified multiwall carbon nanotubes (MWCNTs) by nitric acid solution were used to investigate the adsorption behavior of zirconium from aqueous solution. Pristine and oxidized MWCNTs were characterized using nitrogen adsorption/desorption isotherm, Boehm’s titration method, thermogravimetry analysis, transmission electron microscopy and Fourier transform infrared spectroscopy. The results showed that the surface properties of MWCNTs such as specific surface area, total pore volume, functional groups and the total number of acidic and basic sites were improved after oxidation. These improvements are responsible for their hydrophobic properties and consequently an easy dispersion in water and suitable active sites for more adsorption of zirconium. The adsorption of Zr(IV) as a function of initial concentration of zirconium, contact time, MWCNTs dosage, HCl and HNO3 concentration and also ionic strength was investigated using a batch technique under ambient conditions. The experimental results indicated that sorption of Zr(IV) was strongly influenced by zirconium concentrations, oxidized MWCNTs content and acid pH values. The calculated correlation coefficient of the linear regressions values showed that Langmuir model fits the adsorption equilibrium data better than the Freundlich model. Kinetic data of sorption indicated that equilibrium was achieved within 60 min and the adsorption process can be described by the pseudo second-order reaction rate model. Based on the experimental results, surface complexation is the major mechanism for adsorption of Zr(IV) onto MWCNTs. Also, Study on the desorption process of zirconium showed that the complete recovery can be obtained using nitric or hydrochloric acids of 4 M.

Complexation of zirconium(IV), thorium(IV) and uranium(VI) malonates with Arsenazo III and Arsenazo M on fiber ion exchangers

The adsorption of zirconium, thorium, and uranium malonate complexes on fiber materials filled with AV-17, EDE-10p, and AN-31 anion exchangers and ANKB-50 polyampholite is studied by diffuse reflection spectroscopy, and their complexation with Arsenazo III and Arsenazo M in the solid phase is studied. The influence of the basicity of the bulk agent, concentration of malonic acid, and adsorption and complexation conditions in the analytical signal is demonstrated. Conditions for the determination of 0.02–0.025 μg/mL zirconium in the presence of 5- to 6-fold excesses of thorium and uranium, and 0.008–0.12 μg/mL of uranium(VI) in the presence of thorium and zirconium in equal concentrations are formulated.

Solid phase extraction of zirconium as arsenazo(III) complex on agar and spectrophotometric determination

A new solid phase extraction method for the separation and determination of zirconium using agar as an adsorbent is described. The method is based on the adsorption of zirconium as arsenazo(III) complex on agar in a mini-column, elution with sulfuric acid-acetone mixture and determination by spectrophotometry. The effect of different parameters such as pH, concentration of the reagent, eluting reagent, and volume of the sample, amount of the adsorbent and interfering ions was investigated. The calibration graph was linear in the range of 5–300 ng ml−1 of zirconium under optimum conditions. The limit of detection based on 3Sb was 1.3 ng ml−1 and the relative standard deviation (R.S.D) for ten replicate measurements of 15 and 200 ng ml−1 of zirconium was 3.7 and 1.8%, respectively. The method was applied to the determination of zirconium in water and soil samples.

Removal of zirconium from aqueous solution by modified clinoptilolite

Adsorptive behavior of natural clinoptilolite was assessed for the removal of zirconium from aqueous solutions. Natural zeolite was characterized by X-ray diffraction, X-ray fluorescence, thermal methods of analysis and FTIR. The zeolite sample composed mainly of clinoptilolite and presented a cation exchange capacity of 1.46 meq g(-1). K, Na and Ca-exchanged forms of zeolite were prepared and their sorption capacities for removal of zirconium from aqueous solutions were determined. The effects of relevant parameters, including initial concentration, contact time, temperature and initial pH on the removal efficiency were investigated in batch studies. The pH strongly influenced zirconium adsorption capacity and maximal capacity was obtained at pH 1.0. The maximum removal efficiency obtained at 40 degrees C and equilibration time of 24h on the Ca-exchanged form. Kinetics and isotherm of adsorption were also studied. The pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion models were used to describe the kinetic data. The pseudo-second-order kinetic model provided excellent kinetic data fitting (R(2)>0.998) with rate constant of 1.60x10(-1), 1.96x10(-1), 2.45x10(-1) and 2.02x10(-1)g mmol(-1)min(-1) respectively for Na, K, Ca-exchanged forms and natural clinoptilolite. The Langmuir and Freundlich models were applied to describe the equilibrium isotherms for zirconium uptake and the Langmuir model agrees very well with experimental data. Thermodynamic parameters were determined and are discussed.

Zirconium decontamination from aqueous media using lateritic minerals

Abstract The sorption behavior of zirconium on minerals from a lateritic weathering has been carried out to evaluate its potential for the decontamination of zirconium ions from aqueous solutions. Various physico-chemical parameters such as selection of appropriate electrolyte, equilibration time, amount of adsorbent, concentration of adsorbate, effect of diverse ions and temperature were studied in order to simulate the best conditions under which this material can be used as an adsorbent, employing batch method and radiotracer technique. Maximum adsorption was observed at 0.005 mol L−1 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 0.3 g of adsorbent for 1.499×10−4 mol L−1 zirconium concentration in five minutes equilibration time. Studies show that the adsorption of zirconium decreases with the increase in the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the range of 7.5×10−5 to 3.0×10−3 mol L−1 zirconium concentration. The characteristic Freundlich constants i.e. 1/n = 0.55±0.03 and K=1.36×10−3±7.0×10−5 mol g−1 have been computed for the sorption system. The sorption mean free energy from the Dubinin–Radushkevich isotherm is 11.2±0.4 kJ mol−1 indicating ion-exchange mechanism of chemisorption. The uptake of zirconium increases with the rise in temperature (283-323 K). Thermodynamic quantities i.e. ΔG, ΔS and ΔH have also been calculated for the system. The sorption process was found endothermic.

Investigation of interaction of metal melts and zirconia

The wetting of zirconia by a number of pure metals was studied. The wetting of zirconia by Cu-Ga-Ti, Cu-Ga-Zr, Cu-Ge-Ti and Cu-Ge-Zr alloys was studied. For Cu-Ga-Ti the minimal contact angle was near 60°, for Cu-Ga-Zr it was near 30°. Cu-Ge based alloys wet the zirconia worse because of the low solubility of titanium and zirconium in germanium. The wetting of different zirconia ceramic by a few molten alloys was compared. Contact angles for equal alloys are close. The substrate structure influences the wetting: polycrystal zirconia is wetted by active alloys worse than monocrystal form. The kinetic of ZrO 2 variation of stoichiometry in contact with active alloys was investigated. The dark zone dimension was found to very according a to parabolic law; and the diffusion coefficients of F-centers in ZrO 2 -ceramic were calculated. For Cu-Ga-Ti on zirconia adsorption of titanium on the substrate surface and the formation of a TiO layer close to zirconia was revealed. Similarly, for Cu-Ga-Zr adsorption of zirconium on substrate was also found. Interface reactions were described, showing negative Gibbs energy. The average F-centers concentration was calculated. Metals wet better nonstoichiometric than stoichiometric zirconia. At contact to noble metals melts in a vacuum nonstoichiometric (black) zirconia becomes white. Obviously Zr-O bond are weak in black zirconia and a larger quantity of zirconium/metal bonds forms, so the black zirconia is wetted better. When in contact to noble metals some part of zirconium diffuse into metal and so the oxygen deficit disappears. Finally, The brazing of zirconia to metal was briefly discussed.

Properties and Mechanism of Molybdenum and Zirconium Adsorption by a Macroporous Silica‐Based Extraction Resin in the MAREC Process

To achieve effective separation of molybdenum and zirconium in the MAREC process, the adsorption properties and mechanism of Mo(VI) and Zr(IV) with a macroporous CMPO/SiO2‐P (CMPO: octyl(phenyl)‐N,N‐diisobutylcarbamoylmethylphosphine oxide) extraction resin have been studied. By investigating the influence of the aqueous concentrations of H+ and NO3 − on the adsorption of Mo(VI), the composition of complex of Mo(VI) and CMPO/SiO2–P is determined as H2MoO4 · 2CMPO/SiO2–P for dilute aqueous HNO3 and H2MoO3 (NO3)2 · 2CMPO/SiO2–P for concentrated aqueous HNO3, respectively. Similarly, the composition of Zr(IV) and CMPO/SiO2–P is determined as ZrO(NO3)2 · 2CMPO/SiO2–P or Zr(NO3)4 · 2CMPO/SiO2–P in 0.3–4.0 M HNO3, while ZrO2 · 2H2O · 2CMPO/SiO2–P is assumed for lower HNO3 concentration. Based on the compositions of Mo(VI) and Zr(IV) with CMPO/SiO2–P and the elution behavior of Mo(VI) and Zr(IV) by using 0.05 M diethylenetriaminepentaacetic acid (DTPA) at 0.01–1.0 M HNO3, a dynamic interconversion equilibrium between the complexes of Mo(VI) or Zr(IV) and CMPO/SiO2–P is demonstrated to take place in the elution process. To verify the adsorption mechanism, the adsorption and elution behavior of Mo(VI) and Zr(IV) with 0.05 M DTPA‐pH 2.0 was performed from a simulated high level radioactive liquid waste (HLLW) containing Pd(II), Gd(III), Y(III), Eu(III), Sm(III), Mo(VI), and Zr(IV). The results indicate that Mo(VI) and Zr(IV) not only can be efficiently eluted with 0.05 M DTPA‐pH 2.0, but also the elution efficiency is much better than that of 0.5 M H2C2O4 previously used in the MAREC process. The reverse equilibrium of complexes between Mo(VI) or Zr(IV) and CMPO/SiO2–P in high and low acidity was demonstrated, respectively.

Adsorption and Reaction of Zirconium(IV) Nitrate on Polycrystalline Zirconia

The adsorption of zirconium nitrate ZN] on thin films of polycrystalline zirconia was investigated with temperature-programmed reaction mass spectrometry (TPR) and X-ray photoelectron spectroscopy (XPS). TPR measurements demonstrate that adsorbed ZN undergoes competitive desorption and reaction near 340 K. The reaction is the first in a series of steps that ultimately leads to formation. Several gas-phase products are formed as a result of ZN decomposition, including NO, and The gas-phase products evolve from two temperature envelopes centered at and with the envelopes at somewhat higher temperature than the NO and envelopes. Partitioning between the desorption and decomposition pathways is a function of the heating rate, β, during TPD, with the ZN desorption fraction varying between 0.05 at and 0.4 at The XPS measurements reveal that the zirconium oxidation state is constant at during the decomposition sequence. However, the identities of the gas-phase products suggest that the ligands undergo oxidation-reduction chemistry during decomposition. On the basis of the TPR and XPS measurements, it is proposed that adsorbed peroxides of formula and are intermediates on the decomposition pathway. Both peroxides contain states of oxygen that are oxidized relative to oxygen in ZN. © 2002 The Electrochemical Society. All rights reserved.

Selective separation behavior of silica gel for zirconium in simulated high level radioactive liquid waste

Zirconium in simulated high level radioactive liquid waste (HLLW) was selectively adsorbed and separated by self-made high adsorption activity silica gel. The selective adsorption mechanism was analyzed according to the structure character of self-made silica gel and performance of zirconium in acid simulated HLLW. The results show that the adsorption selectivity of self-made silica gel for zirconium is strong, because zirconium has higher positive charge and zirconium ion hydrolyzes easily. Distribution coefficient of self-made silica gels for zirconium is 53.5 ml/g. There are 6.5 (OH)/nm2 on the surface on self-made silica gels which provide more adsorption activity places, thus self-made silica gels have higher adsorption capacity for zirconium (31.4 mg/g). The elution rate of the adsorption of zirconium on self-made silica gel by 0.2 mol/l H2C2O4 is more than 99%. The solubility of the self-made silica gel in nitric acid is low, the chemical stability of self-made silica gel is very strong.

Studies on the Adsorption of Traces of Zirconium on Manganese Dioxide from Acid Solutions

Abstract The adsorption of zirconium on manganese dioxide from nitric and perchloric acid solutions has been investigated at different concentrations of electrolyte, adsorbent, and adsorbate. The effect of other cations and anions on adsorption has been studied. Fluoride, citrate, oxalate, molybdate, tartrate, carbonate, phosphate, Fe(III), Sr(II), Zn(II), Cr(III), and Mg(II) drastically reduce adsorption. Adsorption of other metal ions on the oxide has been measured under identical conditions. Based on these data, separation of zirconium from a number of elements, including cobalt, zinc, caesium, neodymium and lutetium, can be achieved. Zirconium adsorption follows Freundlich's equation C Ads = AC 1/n Bulk with the values of 1/n = 0.92 and A = 40 mmol/g. Thus manganese dioxide can be used for the separation and preconcentration of zirconium from dilute solutions.

High temperature coadsorption study of zirconium and oxygen on the W(100) crystal face

The coadsorption of zirconium and oxygen on W(100) has been studied by Auger electron spectroscopy, low energy electron diffraction, mass spectroscopy, ion sputtering, and work function measurement techniques. Adsorption of zirconium onto W(100) followed by heating in an oxygen partial pressure produces rapid diffusion of a ZrO complex into the bulk and the formation of a tungsten oxide layer. Heating in vacuum causes desorption of the tungsten oxide and segregation of the ZrO complex to the surface. The activation energy for the ZrO bulk-to-surface diffusion is 30 ± 2 kcal/mole. Upon heating in vacuum at 2000 K the composite surface exhibits predominantly a (1 × 1) LEED structure with a room temperature field emission retarding potential work function of 2.67 ± 0.05 eV. The Richardson work function for this unusually thermally stable surface is 2.56 ± 0.05 eV with a pre-exponential of 6 ± 2. The effects of carbon and nitrogen contamination on this low work function ZrOW composite surface are discussed and a structural model for the surface is presented.

Adsorption of zirconium on tungsten single crystal planes

The adsorption of zirconium on the (110), (112), (100), (111) and (310) planes of tungsten field emitter substrates has been studied. Work function against coverage measurements have been made and the dipole moment and effective adsorbate polarizability determined for (100) adsorption. Comparison is made with contact potential difference measurements. As for uranium adsorption, the modified Topping point dipole depolarization model is found to be inadequate in describing adsorption on the (100) plane.

Angular Confinement of Field Electron and Ion Emission

Three methods of confining the angular dispersion of a field electron beam from 〈100〉 oriented tungsten emitters are investigated; they are (1) thermal-field buildup, (2) selective work function reduction by zirconium adsorption, and (3) high-temperature field evaporation. All three methods confine the emission to a beam half-angle of less than 9° in the dc current range 0.1 to 100 μA. Method (1) results in a ∼50% reduction in beam voltage. Provided that the vacuum level is good (∼10−10 Torr), long and short term current instabilities are negligible for dc current levels below 10 μA at 300°K for each of the emitter end forms investigated. The angular dispersion and beam voltage of a field ion beam can also be reduced by method (1) as described briefly in this paper.

The adsorption and nucleation of zirconium on tungsten field emitters

The adsorption of zirconium on clean tungsten, at residual gas pressures below 1 × 10 −10 Torr, has been studied by field emission microscopy. It was necessary to outgas the Zr above 2400 °K to obtain reproducibility. The gases evolved during degassing of the zirconium were predominantly CO, CH 4 and H 2. Mass spectra of the evaporant flux showed no tungsten or oxide contamination after thorough outgassing. It was found that heating below the α-β phase transition temperature of Zr (1135 °K) resulted in the formation of large cap-shaped nuclei on the high index planes, while above this temperature the deposit became smoothed on the {100} planes. A model is proposed involving a closepacked square array of Zr atoms on the W(100). We conclude that the above two temperature regions are eminently suitable for studying epitaxy following the initial growth processes of nucleation or of monolayer addition. The presence of contamination impeded both surface migration and nucleation and lowered the work function.

The Determination of Zirconium-95 Plus Niobium-95 By Anion-Exchange Separation From Other Fission Products

A rapid and simple anion-exchange method is described for the separation of Zr 95 plus Nb 95 from other fission products. The zirconium and niobium are adsorbed onto a 7 mm diameter column 100 mm in length of Dowex-l-X4, 100–200 mesh resin from a hydrofluoric acid solution of the fission products. The resin is counted directly, using a 3-in. NaI(T1) well-type crystal and a gamma scintillation spectrometer. Yields of greater than 99.5 per cent are obtained. The activity levels of the major fission products (Ru 106 , Cs 137 and Ce 144 ) are reduced by more than 95 per cent. Distribution coefficients were established for the adsorption of zirconium and niobium from HF solutions ranging from 0.1 to 6 M in concentration. Elution characteristics are described for tracer amounts of Ru 106 , Ce 144 and Cs 137 in HF solutions alone and in the presence of macro amounts of U, Fe and Al. The maximum amount of U which can be tolerated and an estimation of the error in counting caused by the displacement of Zr and Nb by U are given.