[en] A column solid-phase extraction method for the preconcentration and determination of cadmium(II), copper(II), cobalt(II), iron(III), lead(II), nickel(II) and zinc(II) dithizone chelates by atomic absorption spectrometry has been described. Diaion HP-2MG was used as adsorbent for column studies. The influences of the various analytical parameters including pH of the aqueous solutions, amounts of ligand and resin were investigated for the retentions of the analyte ions. The recovery values are ranged from 95 to 102%. The influences of alkaline and earth alkaline ions were also discussed. The preconcentration factor was 375, when the sample volume and final volume are 750 and 2 ml, respectively. The detection limits of the analyte ions (k=3, N=21) were varying 0.08 μg/l for cadmium to 0.25 μg/l for lead. The relative standard deviations of the determinations at the concentration range of 1.8x10^-4 to 4.5x10^-5 mmol for the investigated elements were found to be lower than 9%. The proposed solid-phase extraction procedure were applied to the flame atomic absorption spectrometric determinations of analyte ions in natural waters (sea, tap, river), microwave digested samples (milk, red wine and rice) and two different reference standard materials (SRM1515 apple leaves and NRCC-SLRS-4 riverine water)

[en] A switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO_2 (Dry ice) via proton transfer reaction has been used for the microextraction of cadmium(II) as pyrrolidinedithiocarbamate (APDC) chelate. Cd(II)-APDC chelate was extracted into the switchable polarity solvent drops by adding 2 mL 10 M sodium hydroxide solution. Analytical parameters affecting the complex formation and microextraction efficiency such as pH, amount of ligand, volume of switchable polarity solvent and NaOH, sample volume were optimized. The effects of foreign ions were found tolerably. Under optimum conditions, the detection limit was 0.16 μg L"−"1 (3Sb/m, n = 7) and the relative standard deviation was 5.4% (n = 7). The method was validated by the analysis of certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SPS-WW2 waste water, 1573a Tomato Leaves and Oriental Basma Tobacco Leaves (INCT-OBTL-5)) and addition/recovery tests. The method was successfully applied to determination of cadmium contents of water, vegetable, fruit and cigarette samples. - Highlights: • Switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO_2. • The switchable polarity solvent has been used for the microextraction of cadmium(II). • The important factors were optimized. • The method was applied to determination of cadmium in real samples

[en] We developed a selective solvothermal synthesis of palladium nanoparticles on nanodiamond (ND)–graphene oxide (GO) hybrid material in solution. After the GO and ND materials have been added in PdCl₂ solution, the spontaneous redox reaction between the ND–GO and PdCl₂ led to the creation of nanohybrid Pd@ND@GO material. The resulting Pd@ND@GO material was characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectrometry, scanning electronic microscopy (SEM), and atomic absorption spectrometry methods. The Pd@ND@GO material has been used for the first time as a catalyst for the reduction for 2-nitrophenol and the degradation of methylene blue in the presence of NaBH₄. GO plays the role of 2D support material for Pd nanoparticles, while NDs act as a nanospacer for partly preventing the re-stacking of the GO. The Pd@ND@GO material can lead to high catalytic activity for the reduction reaction of 2-nitrophenol and degradation of methylene blue with 100% conversion within ~15 s for these two reactions even when the content of Pd in it is as low as 4.6 wt%.

[en] The authors describe the preparation of a nanocomposite (mag-MoS₂-Fe₃O₄) that was prepared from molybdenum disulfide (MoS₂) and magnetic Fe₃O₄ nanoparticles by a hydrothermal method in an inert atmosphere. The composite is shown to be a viable magnetic adsorbent for dispersive solid phase microextraction of lead(II) and copper(II) ions from water and plant samples. The nanocomposite was characterized by FT-IR, Raman spectroscopy, XRD, SEM, and BET methods. The factors affecting the extraction recovery of the analytes, including the pH value, type of dispersive solvent, sample volume, type and volume of eluent solution, and interfering ions, were optimized. Flame atomic absorption spectrometry was then used for quantitation. Figures of merit of this method include a preconcentration factor of 50 for lead(II) and 35 for Cu(II), LODs of 3.3 μg·L⁻¹ for lead(II) and of 1.8 μg·L⁻¹ for Cu(II), and RSDs of 4.9 and 1.5%, respectively. The method was used to preconcentrate the analytes from plant and water samples prior to their determination by FAAS. It was then validated by analyzing certified reference materials (water and plant), and this resulted in good accuracy. .

[en] Nanosized single crystal orthorhombic Bi₂WO₆ was synthesized by a hydrothermal method and used as a sorbent for vortex assisted solid phase extraction of lead(II). The crystal and molecular structure of the sorbent was examined using XRD, Raman, SEM and SEM-EDX analysis. Various parameters affecting extraction efficiency were optimized by using multivariate design. The effect of diverse ions on the extraction also was studied. Lead was quantified by flame atomic absorption spectrometry (FAAS). The recoveries of lead(II) from spiked samples (at a typical spiking level of 200–400 ng·mL⁻¹) are >95%. Other figures of merit includes (a) a detection limit of 6 ng·mL⁻¹, (b) a preconcentration factor of 50, (c) a relative standard deviation of 1.6%, and (d) and adsorption capacity of 6.6 mg·g⁻¹. The procedure was successfully applied to accurate determination of lead in (spiked) pomegranate and water samples. .

[en] A preconcentration procedure, using a short column filled with Amberlite XAD-8, is proposed for the spectrophotometric determination of traces of molybdenum. Molybdenum as a Mo(V)- thyiocyanate complex is sorbed strongly on the resin and is easily eluted with acetone. The molybdenum complex in the effluent can be determined spectrophotometrically at 462.0 nm. The influence of several ions, as interferents, was discussed. The procedure was applied to the determination of molybdenum in steel with satisfactory results (recovery ≥95%; relative error ≤3%; relative standard deviation ≤5% in the concentration range of 0.006-0.024%; IUPAC detection limit, 60 μg l^-1 in solution)

[en] In this study, Pd nanoparticle-modified magnetic Sm₂O₃–ZrO₂ material (Pd–Fe₃O₄–Sm₂O₃–ZrO₂) as multifunctional catalyst was fabricated and used for catalytic reduction of 2-nitrophenol compound, degradation of methylene blue and rhodamine B dyes, which are toxic pollutants. The magnetic material was used for the first time as a catalyst for the reduction and degradation studies. Pd nanoparticle-modified magnetic Sm₂O₃–ZrO₂ catalyst was prepared using the deposition–precipitation methods and were characterized by X-ray diffraction, scanning electron microscopy, atomic absorption spectrometry, Raman spectroscopy and BET surface analyzer. The Pd nanoparticle-modified magnetic Sm₂O₃–ZrO₂ material can lead to high catalytic activity for the reduction of 2-nitrophenol and degradation of rhodamine B and methylene blue with > 95% conversion within ~ 2 and 80 s even when the content of Pd in it is as low as 5.8 wt%.

[en] The potential use of the lichen biomass (Xanthoparmelia conspersa) to remove mercury(II) ions from aqueous solution by biosorption was evaluated using the batch method. Effects of pH, contact time, biomass concentration and temperature on the removal of Hg(II) ions were studied. The Langmuir isotherm models defined the equilibrium data precisely compared to Freundlich model and the maximum biosorption capacity obtained was 82.8 mg g^-1. From the D-R isotherm model, the mean free energy was calculated as 9.5 kJ mol^-1. It shows that the biosorption of Hg(II) ions onto X. conspersa biomass was taken place by chemical ion-exchange. Experimental data were also performed to the pseudo-first-order and pseudo-second-order kinetic models. The results indicated that the biosorption of Hg(II) on the lichen biomass followed well the second-order kinetics. Thermodynamic parameters, ΔG^o, ΔH^o and ΔS^o indicated the Hg(II) sorption to be exothermic and spontaneous with decreased randomness at the solid-solution interface. Furthermore, the lichen biomass could be regenerated using 1 M HCl, with up to 85% recovery, which allowed the reuse of the biomass in ten biosorption-desorption cycles without any considerable loss of biosorptive removal capacity.

[en] The biosorption potential of Racomitrium lanuginosum as aquatic moss biosorbent for the removal of Pd(II) from aqueous solution was investigated. The effects of pH, biomass dosage, contact time, and temperature on the biosorption processes were systematically studied. Experimental data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. Langmuir isotherm model (R² = 0.994) fitted the equilibrium data better than the Freundlich isotherm model (R² = 0.935). The monolayer biosorption capacity of R. lanuginosum biomass for Pd(II) was found to be 37.2 mg/g at pH 5. The mean free energy was calculated as 9.2 kJ/mol using the D-R isotherm model (R² = 0.996). This result indicated that the biosorption of Pd(II) was taken place by chemical ion-exchange. The calculated thermodynamic parameters, ΔG^o, ΔH^o and ΔS^o showed that the biosorption of Pd(II) on R. lanuginosum biomass was feasible, spontaneous and exothermic under examined conditions. Experimental data were also tested using the biosorption kinetic models. The results showed that the biosorption processes of Pd(II) on R. lanuginosum followed well pseudo-second-order kinetics at 20-50 deg. C (R² = 0.999)

[en] A biosorption procedure for preconcentration-separation of nickel(II) and silver(I) at trace levels on Bacillus sphaericus-loaded Chromosorb 106 (BSLC106) has been presented in this work. The conditions like pH, amounts of microorganism, eluent type, etc. for the quantitative adsorption of the analyte ions on BSCL106 column were investigated. The analyte ions were quantitatively recovered and desorbed at pH range of 6.0-7.0 and 10 mL of 1 M HCl, respectively. The effects of various cationic and anionic interferences on the recoveries of nickel(II) and silver(I) were studied. The detection limits for nickel(II) and silver(I) are 1.42 and 1.05 μg L^-1, respectively. The accuracy of the developed procedure was tested by analyzing NIST SRM 2711 Montana soil and GBW 07310 Stream sediment certified reference materials. The proposed enrichment-separation procedure was successfully applied to the determination of analytes in natural water, black tea, tobacco, soil and sediment samples with satisfactory results.