Silver nanoparticles capped with 8-hydroxyquinoline-5-sulfonate for the determination of trace aluminum in water samples and for intracellular fluorescence imaging

We report on a simple method for the determination of traces of aluminum(III) in water at pH 7.4 by using silver nanoparticles (Ag-NPs) functionalized with 8-hydroxyquinoline-5-sulfonate. The modified Ag-NPs undergo (a) a distinct color change from yellow to deep orange, and (b) a strong fluorescence enhancement upon addition of Al(III). Both the ratio of absorbances at 530 and 392 nm, and the intensity of fluorescence at 492 nm can serve as the analytical information. The absorption-based calibration plot increases linearly in the 0.1 to 4.0 μM Al(III) concentration range. The detection limit is 2.0 nM which is much lower than the permissible level (7.4 μM) for drinking water as defined by the World Health Organization. The method was successfully applied to the determination of Al(III) in samples of lake water, tap water and boiler water, and the recoveries were from 98 to 105 %. The assay also was applied to the determination of Al(III) in living mouse myeloma cells via fluorescence imaging. A linear relationship was obtained between relative fluorescence intensity (F/F₀) and the concentration of Al(III) in the 0.05 μM to 4 μM concentration range. The detection limit is 15 nM.

Adsorption characteristics and radiation stability of a silica-based DtBuCH18C6 adsorbent for Sr(II) separation in HNO3 medium

A silica-based adsorbent, (DtBuCH18C6 + dodecanol)/SiO₂-P, which is used for selective separation of Sr(II) from high level liquid wastes, against temperature and gama-irradiation was investigated. The adsorption characteristics of Sr(II), Ba(II), La(III), Nd(III), Gd(III) and Dy(III) under varying nitric acid concentration at different temperatures were measured by batch method. The adsorbent showed higher distribution coefficients (K _d) for Sr(II) compared to other tested metal ions, and the K _d values of Sr(II) decreased with increasing temperature. Thermodynamic parameters of the adsorption process were calculated. The related parameters in adsorption isotherm models were obtained using a non-linear fitting. Uptake capacity from 0.38 to 0.43 mmol g^?1 was obtained for Sr(II) in the temperature range of 298–323 K by the Langmuir equation fitting. The leakage of total organic carbon was below 120 ppm at 298 K and 180 ppm at 323 K, respectively. The degradation of the adsorbent irradiated in 2 M HNO₃ was investigated. It is found that the adsorbed dose of γ-ray more than 50 KGy has a strong influence on K _d of Sr(II). The K _d values of Sr(II) decrease about 3 times ranged from 50 to 500 KGy.     

Influence of pyridazine derivative on corrosion inhibition of mild steel in acidic media

The inhibition behavior of 6-methyl-4,5-dihydropyridazin-3(2H)-one (MDP) on corrosion of mild steel in 1 M HCl and 0.5 M H₂SO₄ was investigated using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements. The results indicated that the corrosion inhibition efficiency depends on concentration, immersion time, solution temperature, and the nature of the acidic solutions. It is also noted that MDP is at its the most efficient in 1 M HCl and least in 0.5 M H₂SO₄. The effect is more pronounced with MDP concentration. It is found that the inhibition efficiency attains 98 % at 5 × 10^?3 M in 1 M HCl and 75 % at 5 × 10^?2 in 0.5 M H₂SO₄. Polarization measurements showed that the MDP acts as a mixed inhibitor. EIS diagrams showed that the adsorption of MDP increases the transfer resistance and decreases the capacitance of the interface metal/solution. From the temperature studies, the activation energies in the presence of MDP were found to be superior to those in uninhibited medium. Finally, a mechanism for the adsorption of MDP was proposed and discussed.     

Chemical separation of enriched cadmium target from copper backing in cyclotron production of radioisotope 111In

A radiochemical purification procedure was developed for the separation of enriched cadmium (¹¹¹Cd and ¹¹²Cd) from natural copper that used as backing; and was based upon the chromatographic adsorption. The separation of copper from cadmium was studied in this work. The ions were selectively separated from aqueous solution. Ion-exchange chromatography was employed as a column (1.5 cm i.d. and 15 cm length) with AG1-X8 resin (chloride form, 100–200 mesh) and a flow rate of 1–2 ml/min throughout the separation. 6 M HCl media was used for the adsorption of Cd and Cu on the resin. Then, Cu was eluted by 2 M HCl and Cd by 100 ml 0.5 M HNO₃. The amount of Cu and Cd ions in the final solution (0.5 M HNO₃) were measured by pulse polarographic method and the concentration of Cu was found to be <0.1 ppm. The Cd was quantitatively recovered and the recovery yield from ion-exchange chromatography was greater than 96 %.     

Comparative study on lanthanum(III) sorption onto Lewatit TP 207 and Lewatit TP 260

Batch experiments are carried out for the sorption of La(III) onto commercial macroporous resins containing iminodiacetic (Lewatit TP 207) and aminomethylphosphonic acid groups (Lewatit TP 260). The operating variables studied are initial La(III) concentration, pH, temperature and contact time. Since the extraction kinetics were fast, with a mixture of 0.1 g of resin and 5 mL of lanthanum ions 0.5 × 10^?3 mol L^?1 solution, extraction equilibrium was reached within 30 min of mixing. The optimum pH values level for quantitative sorption were between 1.5 and 4.6 with Lewatit 207 and about 5.2 with Lewatit TP 260. The sorption capacities of Lewatit TP 207 and Lewatit TP 260 resins are 114.7 and 106.7 mg g^?1, respectively. Adsorption equilibrium data were calculated for Langmuir and Freundlich isotherms. It was found that the sorption of La(III) on Lewatit TP 207 was better suited to the Langmuir adsorption model while Freundlich adsorption model fitted better sorption on Lewatit TP 260. Thermodynamics data leads to endothermic and spontaneous process. ΔG° decreases with increasing temperature indicating that sorption process of La(III) on both Lewatit TP 207 and Lewatit TP 260 was more favored at high temperature.     

Synthesis of nano-pore size Al(III)-imprinted polymer for the extraction and preconcentration of aluminum ions

In this study, an ion imprinted polymer (IIP) was prepared for the selective separation and preconcentration of trace levels of aluminum. Al(III) IIP was synthesized in the presence of Al(III)-8-hydroxyquinoline (oxine) complex using styrene and ethylene glycol dimethacrylate as a monomer and crosslinker, respectively. The imprinted Al(III) ions were completely removed by leaching the IIP with HCl (50 % v/v) and were characterized by FTIR and scanning electron microscopy. The maximum sorption capacity for Al(III) ions was found to be 3.1 mg g^?1 at pH 6.0. Variables affecting the IIP solid phase extraction were optimized by the univariable method. Under the optimized conditions, a sample volume of 400 mL resulted in an enhancement factor of 194. The detection limit (defined as 3 S _b/m) was found to be 1.6 μg L^?1. The method was successfully applied to the determination of aluminum in natural water, fruit juice and cow milk samples.     

Adsorption mechanism of Chromium(III) from water solution on bone char: effect of operating conditions

The adsorption capacity of bone char (BC) towards Cr(III) from an aqueous solution was studied in this work. The characterization of the BC showed that the BC is mainly composed of hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂, and its point of zero charge was 7.7. The infrared spectroscopic analysis of the BC loaded with Cr(III) revealed that the Cr(III) adsorbed on BC interacted with the phosphate of the hydroxyapatite. The adsorption capacity increased 2.6 times by raising the solution pH from 3 to 5. This tendency was due to the interactions between the surface charge and the cationic species of Cr(III) in aqueous solution. The adsorption capacity was enhanced 2.5 and reduced 1.3 times when the temperature was increased from 15 to 25 °C and from 25 to 35 °C, respectively. The effect of temperature on the adsorption capacity of BC showed an anomalous behavior since the adsorption capacity exhibited a maximum at T = 25 °C. It was demonstrated that the main adsorption mechanism of the Cr(III) species was coordination to the phosphate ions and the Ca(II) in the BC was substituted or replaced by the Cr(III) species from the solution. This latter result was further corroborated by XPS analysis.     

Dynamic desorption of CO2 and CH4 from amino-MIL-53(Al) adsorbent

Dynamic adsorption–desorption measurements of CO₂ and CH₄ in amino-MIL-53(Al) were carried out in an adsorption breakthrough setup at different temperatures (303, 318, and 333 K) and pressures (1, 5, and 30 bar) to study the desorption dynamics of CO₂ in amino-MIL(Al) as it plays an important role in the design of pressure swing adsorption (PSA) process for the upgrading of biogas. 13X zeolite was used as a reference material. The dynamic adsorption selectivity as well as the desorption efficiency of CO₂ in both amino-MIL-53(Al) and 13X zeolite were calculated to evaluate the potential of amino-MIL-53(Al) for the upgrading of biogas by PSA process.     

Evaluation study on properties of isohexyl-BTP/SiO2-P resin for direct separation of trivalent minor actinides from HLLW

In order to develop a direct separation process for trivalent minor actinides from fission products in high level liquid waste (HLLW) by extraction chromatography, a novel macroporous silica-based 2,6-bis(5,6-diisohexyl)-1,2,4-triazin-3-yl)pyridine resin (isohexyl-BTP/SiO₂-P resin) was prepared. The content of isohexyl-BTP extractant in the resin was as high as 33.3 wt%. The resin exhibited much higher adsorption affinity for Am(III) in 2–3 M (mol/L) HNO₃ solution over U and FP which are contained in HLLW. The kinetic data were analyzed using pseudo-second-order equation. The results suggested that the Eu(III), Gd(III), and Dy(III) adsorption was well explained by the pseudo-second-order equation. Quantitative desorption for adsorbed elements was achieved by using H₂O or thiourea as eluting agents. However, the kinetics of adsorption and desorption were rather slow and this drawback needs to be resolved. Stability of the resin against HNO₃ was also examined. It was found that the resin was considerably stable against ≤4 M HNO₃ solution for the reasons of an extremely small leakage of the extractant into the solution from the resin and the adsorption performance keeping for rare earths in 3 M HNO₃ solution.     

Non-destructive radioanalytical technique in characterization of anion exchangers Amberlite IRN78 and Indion H-IP

The present study deals with characterization of industrial grade anion exchange resins Amberlite IRN78 and Indion H-IP for which non-destructive radiotracer technique using ¹³¹I and ⁸²Br was used. The radioisotopes were used to trace the kinetics of iodide and bromide ion-isotopic exchange reactions taking place in the two resins. It was observed that under identical experimental conditions of 40.0 °C, 1.000 g of ion exchange resins and 0.003 M labeled iodide ion solution for iodide ion-isotopic exchange reaction, the values of specific reaction rate (min^?1), amount of iodide ion exchanged (mmol), initial rate of iodide ion exchange (mmol min^?1) and log K _d were 0.285, 0.544, 0.155 and 12.6 respectively for Amberlite IRN78 resin, which was higher than 0.093, 0.315, 0.029 and 4.9 respectively as that obtained by using Indion H-IP resins. Also at a constant temperature of 40.0 °C, as the concentration of labeled iodide ion solution increases 0.001–0.004 M, the percentage of iodide ions exchanged increases from 68.10 to 74.00 % for Amberlite IRN78 resin, which was higher than the increase of 40.20–42.80 % as observed for Indion H-IP resins. The identical trend was observed for the two resins during bromide ion-isotopic exchange reaction. The overall results indicate that that under identical experimental conditions Amberlite IRN78 resins shows superior performance over Indion H-IP resins.     

Adsorption behavior of trivalent americium and rare earth ions onto a macroporous silica-based isobutyl-BTP/SiO2-P adsorbent in nitric acid solution

To separate minor actinides from high level liquid waste (HLLW) of PUREX reprocessing, a silica-based macroporous isobutyl-BTP/SiO₂-P adsorbent was synthesized by impregnating isobutyl-BTP (2,6-di(5,6-diisobutyl-1,2,4-triazin-3-yl)pyridine) extractant into the macroporous SiO₂-P support with a mean diameter of 60 μm. A partitioning process using extraction chromatography for the treatment of HLLW was designed consisting five separation columns. As a partly work focused on isobutyl-BTP/SiO₂-P separation column, adsorption behavior of ²⁴¹Am and trivalent rare earth (RE) from simulated HLLW onto silica-based isobutyl-BTP/SiO₂-P adsorbent was investigated by batch method. Meanwhile, the chemical and radiolytic stabilities of isobutyl-BTP/SiO₂-P adsorbent against 0.01 M HNO₃ solution and γ-ray irradiation were studied. It was found that isobutyl-BTP/SiO₂-P adsorbent exhibited good adsorption selectivity for ²⁴¹Am over RE(III) in 0.01 M HNO₃ solution and showed weak or no adsorption affinity to light and middle RE(III) groups. In addition, in stability experiments, isobutyl-BTP adsorbent showed excellent stability against 0.01 M HNO₃ solution and γ-ray irradiation over 4 months contact time.     

螯合树脂研究——ⅩⅥ.以壳聚糖为母体的含硫、氮螯合树脂的合成及其吸附性能

 壳聚糖与环硫氯丙烷反应合成了一系列含S和N的交联型螫合树脂。这类树脂对贵金属离子如:金、银、钯、铂等具有优良的吸附性能。     

Sorption of americium from low-level liquid wastes by nanocrystalline MnO2

Nanocrystalline MnO₂, synthesized by alcoholic hydrolysis of KMnO₄, has been studied as a sorbent for removal of americium from low level liquid waste solutions. The synthesized MnO₂ was found to have BET surface area of 230 m² g^?1. Am(III) was found to be sorbed by MnO₂ quantitatively within 15 min at pH 5. The sorption was found to be more than 90 % at as low a pH as 1.2 and reached to near 100 % at all pH values above pH 3.0 There was no effect of ionic strength (0.01–1.0 M NaCl, CaCl₂) on the sorption suggesting the sorption following inner sphere complexation mechanism at all the pH values. Adsorption isotherm studies were carried out using Eu(III) as a chemical analogue of Am(III). These studies showed the isotherm data to follow Langmuir adsorption isotherm.     

The structure of μ-oxo dimer of aluminium(III) porphyrin: a theoretical study

The gas-phase molecular structure of μ-oxo dimer of aluminium(III) porphyrin, (AlP)₂O, has been studied for the first time by density functional theory calculations using the B3LYP and M06 functionals and triple-ζ valence basis sets. The molecule has two conformers with equilibrium structures of D _4d and D _4h symmetries with parallel macrocycles and aluminium-oxygen distances of 1.680–1.684 Å (M06/cc-pVTZ). The aluminium atom lies out of the plane of the four central nitrogen atoms and forms a square-based pyramid with them, with the following parameters (M06/cc-pVTZ): r(Al–N) = 2.030–2.031 Å, r(N···N) = 2.803–2.804 Å (the side of the pyramid base), z(Al)–z(N) = 0.434–0.446 Å (the height of the pyramid).     

Inhibition Effect of N-(Pyridin-2-yl-Carbamothioyl) Benzamide on the Corrosion of C-Steel in Sulfuric Acid Solutions

N-(Pyridin-2-yl-carbamothioyl)benzamide (PCMB) was newly synthesized and tested as a corrosion inhibitor for C-steel in 0.5 M H₂SO₄ using chemical and electrochemical techniques. Polarization measurements showed that the synthesized compound acted as a mixed inhibitor. The inhibition efficiencies obtained from the different methods were in good agreement. The inhibitive action of this compound is discussed in terms of blocking the electrode surface by adsorption of the inhibitor according to the Langmuir isotherm. The effect of temperature on the corrosion behavior in the absence and presence of 2.5 × 10^?5 M of PCMB was studied (283–308 K). The associated activation energies (E _a) and the thermodynamic parameters (ΔH*, ΔS*, K _ads, ΔG°_ads) for the adsorption process were determined. The ΔG°_ads value is ?36.55 kJ/mol, which indicated that the adsorption mechanism of PCMB on C-steel in 0.5 M H₂SO₄ solution was combined between physisorption and chemisorption processes.     

Nanoparticles of type Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>-SiO<Subscript>2</Subscript>-graphene oxide and coated with an amino acid-derived ionic liquid for extraction of Al(III), Cr(III), Cu(II), Pb(II) prior to their determination by ICP-OES

An amino acid derived ionic liquid, Fe₃O₄ nanoparticles and graphene oxide (GO) were used to prepare a material for the magnetic solid phase extraction (MSPE) of the ions Al(III), Cr(III), Cu(II) and Pb(II). The material was characterized by Fourier transform infrared spectral (FT-IR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), magnetic analysis and isoelectric point (pI) analysis. It is shown to be a viable sorbent for the separation of these metal ions. Single factor experiments were carried out to optimize adsorption including pH values, ionic strength, temperature and solution volume. Following desorption with 0.1 M HCl, the ions were quantified by inductively coupled plasma optical emission spectrometry. Under the optimum conditions, the method provides a linear range from 10 to 170 μg· L^?1 for Al(III); from 4.0 to 200 μg· L^?1 for Cr(III); from 5.0 to 170 μg· L^?1 for Cu(II); and from 5.0 to 200 μg· L^?1 for Pb(II). The limits of detection (LOD) are 6.2 ng L^?1 for Al(III); 1.6 ng L^?1 for Cr(III); 0.52 ng L^?1 for Cu(II); and 30 ng L^?1 for Pb(II). Method performance was investigated by determination of these ions in (spiked) environmental water and gave recoveries in the range of 89.1%–117.8%.

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Graphical abstract The graph shows that Al(III), Cr(III), Cu(II), Pb(II) are not adsorbed quantitatively by Fe₃O₄-SiO₂. On the other hand, Cr(III) and Pb(II) are adsorbed quantitatively by Fe₃O₄-SiO₂-GO while Al(III) and Cu(II) are not quantitatively retained. However, 3D–Fe₃O₄-SiO₂-GO-AAIL adsorb all these 4 metal ions quantitatively.

     

Studies on Water and Ammonia Programmed Thermodesorption of Mixed M(III)-vanadyl Phosphates

Hydrated M(III)-vanadyl phosphates (M (III)=Mn, Fe, Ga, Al) have been prepared and studied for water and ammonia adsorption properties by TG/DTA, NH₃ TPD, FTIR and XRD techniques. The compounds have the same tetragonal layered structure of VOPO₄ ⋅2H₂ O, but shorter interlayer distances. Ammonia adsorption leads to intercalation of large amounts (0.19–0.39 mol/mol) of base between the layers of the materials, without displacement of water. The ammoniated phases obtained from these compounds have interlayer distances shorter than that of the corresponding precursors. In this connection an interaction mechanism NH₃ -host is proposed. Treated at 450°C the materials adsorb ammonia only on the external surface because of the large decrease of the interlayer distance that prevents NH₃ from entering the interlayer space. All M(III)-vanadyl phosphates present a wide distribution of strength of ammonia adsorbing sites. This revised version was published online in July 2006 with corrections to the Cover Date.     

Optimization using response surface methodology for fast removal of hazardous azo dye by γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>@CuO nanohybrid synthesized by sol–gel combustion

An efficient adsorption system was developed for removal of hazardous Direct Blue 71 as a sample azo dye. The γ-Fe₂O₃@CuO adsorption system was synthesized based on a sol–gel combustion route and characterized by energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) analysis, vibrating-sample magnetometry (VSM), and field-emission scanning electron microscopy (FESEM) techniques. The response surface methodology with Box–Behnken design was used to evaluate the effects of pH, shaking time, and adsorbent dose on dye adsorption. The results showed that solution pH was the parameter with greatest effect on dye adsorption. Adsorption equilibrium was reached quickly, within 8 min. Study of isotherms revealed adsorption capacity of 45.7 mg g^?1 according to the Freundlich model. Sorbent regeneration could be performed using methanol–NaOH (0.1 mol L^?1) solution.     

The effect of physicochemical parameters on the separation recovery of plutonium and uranium from aqueous solutions by cation exchange

The effect of physicochemical parameters such as pH, salinity (e.g. [NaCl]) and competitive cation (e.g. Ca²⁺ and Fe³⁺) concentration on the separation recovery of plutonium and uranium from aqueous solutions by cation exchange has been investigated. The investigation was performed to evaluate the applicability of cation exchange as separation and pre-concentration method prior to the radiometric analysis of uranium and plutonium isotopes in natural water samples. Application of the method to test solutions of constant radionuclide concentration and variable composition (0.1, 0.5 and 1 M NaCl; 0.1 and 0.5 M Ca(NO₃)₂; 0.1 and 1 mM FeCl₃; 10) has generally shown that: (1) the optimum pH is 4.5 for uranium and plutonium, (2) increasing salinity results in slightly lower for uranium and significantly higher chemical recovery plutonium and (3) the presence of Ca(II) cations doesn’t significantly affect the chemical recovery of both radionuclides. Contrary, the presence of Fe(III) cations ([Fe(III)] > 0.1 mM) results in significantly lower chemical recovery for both radionuclides (<50%). The later is attributed to the formation of Fe(III) colloids, which present increased chemical affinity for uranium and plutonium and hence compete with the radionuclide binding by the resin. Nevertheless, the results indicate that the method could be successfully applied to a wide range of natural waters.     

CO<Subscript>2</Subscript> capture by Mg–Al and Zn–Al hydrotalcite-like compounds

Hydrotalcite-like compounds (HTC) are distinguished by their properties for CO₂ capture, like high surface area, basic sites, thermal stability and good adsorption/desorption efficiency. Mg–Al e Zn–Al HTCs with Al³⁺ molar ratios x = 0.20, 0.28 and 0.33 were synthesized by coprecipitation, and subsequently calcined at 400 °C. For both HTCs, X-ray diffraction patterns have attested the formation of mixed oxides through calcination. The amount of basic sites, measured by temperature-programmed desorption of CO₂, decreases as x increases. The CO₂ adsorption was performed in a thermogravimetric balance using an adsorption temperature of 50 °C. Mg–Al and Zn–Al samples with x = 0.33 molar composition presented the highest CO₂ adsorption, 0.91 and 0.21 mmol g^?1, respectively. The Langmuir isotherm fitted well to the experimental data. It was also found that increasing the number of adsorption/desorption cycles the CO₂ adsorption decreases, which is associated with the irreversible chemisorption.