Solid phase extraction of ultra traces silver(I) using octadecyl silica membrane disks modified by 1,3-bis(2-cyanobenzene) triazene (CBT) ligand prior to determination by flame atomic absorption

Pd Nanocatalyst Adorned on Magnetic Chitosan@N-Heterocyclic Carbene: Eco-Compatible Suzuki Cross-Coupling Reaction

A novel magnetic-functionalized-multi-walled carbon nanotubes@chitosan N-heterocyclic carbene-palladium (M-f-MWCNTs@chitosan-NHC-Pd) nanocatalyst is developed in two steps. The first step entails the fabrication of a three-component cross-linking of chitosan utilizing the Debus-Radziszewski imidazole approach. The second step comprised the covalent grafting of prepared cross-linked chitosan to the outer walls of magnetically functionalized MWCNTs (M-f-MWCNTs) followed by introducing PdCl₂ to generate the m-f-MWCNTs@cross-linked chitosan with a novel NHC ligand. The repeated units of the amino group in the chitosan polymer chain provide the synthesis of several imidazole units which also increase the number of Pd linkers thus leading to higher catalyst efficiency. The evaluation of catalytic activity was examined in the expeditious synthesis of biaryl compounds using the Suzuki cross-coupling reaction of various aryl halides and aryl boronic acids; ensuing results show the general applicability of nanocatalyst with superior conversion reaction yields, high turnover frequencies (TOFs) and turnover numbers (TON). Meanwhile, nanocatalyst showed admirable potential in reusability tests, being recycled for five runs without losing significant activities under optimum reaction conditions. The successfully synthesis of catalyst and its characterization was confirmed using the Fourier transform infrared spectrometer (FT-IR), spectrometer transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photo-electron spectroscopy (XPS) and thermogravimetric analysis (TGA).

Novel magnetic ion-imprinted polymer: an efficient polymeric nanocomposite for selective separation and determination of Pb ions in aqueous media

A novel ion-imprinted polymer (IIP) toward Pb(II) recognition was synthesized on the surface of magnetic multi-walled carbon nanotubes (magnetic MWCNTs). In order to prepare magnetic functionalized-MWCNT/IIP (magnetic f-MWCNT/IIP), copolymerization of methylenebisacrylamide (MBAm) and acrylamide (AM) in the presence of dithizone-Pb(II) complex was carried out on the surface of the magnetic f-MWCNTs. Selectivity of the new synthesized sorbent toward Pb(II) and the influence of a variety of foreign ions on the recognition, preconcentration, and removal of Pb(II) were evaluated using adsorption experiments in aqueous solution. The synthesized sorbent exhibited a good affinity with high adsorption capacity (Q = 80.81 mg/g) and an excellent selectivity toward Pb(II) in comparison with other common cations including alkaline, alkaline earth, and transition metals such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Cd²⁺, and Ni²⁺. The parameters such as adsorption and desorption time, adsorption capacity, effect of the sorbent mass, eluent type, concentration and volume, and also pH of the solutions were investigated. The result demonstrated that the proposed sorbent provided a fast removal and higher maximum binding capacity compared to other reported synthesized sorbents. The characteristics of the magnetic f-MWCNT/IIP were analyzed using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), vibrating sample magnetometer (VSM), and elemental analysis (EA). Graphical abstract ᅟ.

Fast sono assisted ferrofluid mediated silver super - Adsorption over magnesium ferrite-copper sulfide chalcogenide with the aid of multivariate optimization

This research focuses on the development of a fast ultrasonic assisted ferrofluid mediated methodology to obtain the optimum conditions for silver adsorption from aqueous solutions. For this purpose magnesium ferrite-copper sulfide chalcogenide was synthesized and employed as an efficient nanosorbent. The sorbent was characterized with energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD) and vibrational sample magnetometry (VSM) techniques. For obtaining the optimal operating conditions of silver adsorption, response surface methodology (RSM) was used. Tests were performed by Box-Behnken design (BBD). The value of optimum conditions for silver adsorption include pH=2.5, adsorbent dosage=10.0mg, sonicating time=1min and ionic strength=2.2%. According optimum conditions, percentage of removal should be 99.34%. With replication of similar experiment (n=6) average percentage of 100±0.95% was obtained for Ag⁺ adsorption which shows good agreement between predicted and experimental results. Silver ion adsorption follow Langmuir model with maximum sorption capacity of 2113mgg^-1. Ultrasonic power helped to prepare ferrofluid and demonstrated that had an important role in better dispersing of it in solution and efficient adsorption of analyte.

Detection of Ag(+) using graphite carbon nitride nanosheets based on fluorescence quenching

The graphite carbon nitride (g-C3N4) nanosheets were synthesized and applied for the detection of Ag(+) ion in aqueous solutions. Transmission electron microscopy, Fourier infrared spectroscopy, x-ray diffraction, ultraviolet/visible and photoluminescence spectroscopy were used for characterization of g-C3N4 nanosheets. The fluorescence intensity of g-C3N4 nanosheets decreases with the increase in the concentration of Ag(+). The fluorescence probe can be applied for detection of Ag(+). The results show that it has high selectivity to Ag(+) and exhibits a good linearity over the concentration range 0.020-2.0μM with a detection limit of 27nM. Most cations do not have any interference on the detection of Ag(+). The quenching process is assessed and discussed. Finally, the g-C3N4 nanosheets have been successfully used for the detection of Ag(+) in real water samples. The recoveries of spiked water samples are >97%.

Development of new portable miniaturize solid phase microextraction of silver-APDC complex using micropipette tip in-syringe system couple with electrothermal atomic absorption spectrometry

An innovative and simple miniaturized solid phase microextraction (M-SPME) method, was developed for preconcentration and determination of silver(I) in the fresh and waste water samples. For M-SPME, a micropipette tip packed with activated carbon cloth (ACC) as sorbent, in a syringe system. The size, morphology and elemental composition of ACC before and after adsorption of analyte have been characterized by scanning electron microscopy and energy dispersive spectroscopy. The sample solution treated with a complexing reagent, ammonium pyrrolidine dithiocarbamate (APDC), was drawn into the syringe filled with ACC and dispensed manually for 2 to 10 aspirating/dispensing cycle. Then the Ag- complex sorbed on the ACC in micropipette was quantitatively eluted by drawing and dispensing of different concentrations of acids for 2 to 5 aspirating/dispensing cycles. The extracted Ag ions with modifier were injected directly into the electrothermal atomic absorption spectrometry for analysis. The influence of different variables on the extraction efficiency, including the concentration of ligand, pH, sample volume, eluent type, concentration and volume was investigated. Validity and accuracy of the developed method was checked by the standard addition method. Reliability of the proposed methodology was checked by the relative standard deviation (%RSD), which was found to be <5%. Under the optimized experimental variables, the limits of detection (LOD) and enhancement factors (EF), were obtained to be 0.86 ng L(-1) and 120, respectively. The proposed method was successfully applied for the determination of trace levels of silver ions in fresh and waste water samples.

Silver ion imprinted polymer nanobeads based on a aza-thioether crown containing a 1,10-phenanthroline subunit for solid phase extraction and for voltammetric and potentiometric silver sensors

A new nano-sized silver(I) ion-imprinted polymer (IIP) was prepared via precipitation copolymerization using ethyleneglycol dimethacrylate, as a cross-linking agent in the presence of Ag(+) and an aza-thioether crown containing a 1,10-phenanthroline subunit as a highly selective complexing agent. The imprint silver(I) ion was removed from the polymeric matrix using a 1.0M HNO3 solution. The resulting powder material was characterized using IR spectroscopy and scanning electron microscopy. The SEM micrographs showed colloidal nanoparticles of about 52 nm and 75 nm in diameter and slightly irregular in shape for leached and unleached IIPs, respectively. The optimal pH for quantitative enrichment was 6.0 and maximum sorbent capacity of the prepared IIP for Ag(+) was 18.08 μmol g(-1). The relative standard deviation and limit of detection (LOD=3Sb/m) for flame atomic absorption spectrometric determination of silver(I) ion, after its selective extraction by the prepared IIP nanobeads, were evaluated as 2.42% and 2.2×10(-8) M, respectively. The new Ag(+)-IIP was also applied as a suitable sensing element to the preparation of highly selective and sensitive voltammetric and potentiometric sensors for ultra trace detection of silver(I) ion in water samples, with limits of detection of 9.0×10(-10) and 1.2×10(-9) M, respectively.

Solid-phase extraction of heavy metal ions on bucky tubes disc in natural water and herbal plant samples

A preconcentration-separation procedure has been established based on solid-phase extraction of Fe(III) and Pb(II) on bucky tubes (BTs) disc. Fe(III) and Pb(II) ions were quantitatively recovered at pH 6. The influences of the analytical parameters like sample volume, flow rates on the recoveries of analytes on BT disc were investigated. The effects of co-existing ions on the recoveries were also studied. The detection limits for iron and lead were found 1.6 and 4.9 μg L⁻¹, respectively. The validation of the presented method was checked by the analysis of TMDA-51.3 fortified water certified reference material. The presented procedure was successfully applied to the separation-preconcentration and determination of iron and lead content of some natural water and herbal plant samples from Kayseri, Turkey.

Solid phase extraction of ultra traces mercury (II) using octadecyl silica membrane disks modified by 1,3-bis(2-ethoxyphenyl)triazene (EPT) ligand and determination by cold vapor atomic absorption spectrometry

A facile and highly efficient method was developed for the preconcentration of the ultra trace amounts of mercury (II) ions. Octadecyl silica membrane disk was modified by the recently synthesized triazene ligand, 1,3-bis(2-ethoxyphenyl)triazene (EPT), and cold vapor atomic absorption spectrometry was used to determine the resultant preconcentrated Hg(II) ions. Solution studies with EPT and a series of metal ions were done in advance, and the results showed a strong affinity of EPT to the mercury ions. To perform solid phase extraction, various parameters such as pH of the sample, flow rates and the amount of the ligand were optimized. A linear calibration curve was obtained in the range of 0.02-1.90 μg L(-1) with r(2) = 0.9990 (n = 8), and the limit of detection (LOD) based on three times the standard deviation of the blank was 10.6 ng L(-1). The relative standard deviation (RSD) for the determination of 0.1 μg L(-1) Hg(II) found to be 2.9% while a RSD value of 1.1% was obtained for the determination of 1.0 μg L(-1) Hg(II) (n = 8). The preconcentration and improvement factors were 380 and 74, respectively. The newly developed method was successfully applied to the determination of mercury ions in real water samples.

Preconcentration-separation of Co2+, Ni2+, Cu2+ and Cd2+ in real samples by solid phase extraction of a calix[4] resorcinarene modified Amberlite XAD-16 resin

A new method is described for the simultaneous preconcentration of trace metal ions. The method is based on the adsorption of Co(2+), Ni(2+), Cu(2+) and Cd(2+) ions on 2,4,6,8-tetra(2-hydroxyphenyl)-1,3,5,7(1,3)tetrabenzenzcyclooctaphane-14,16,34,36,54, 56,74,76-octol (salicylaldehyde calix[4] resorcinarenes) (new resorcinarenes derivative) modified on Amberlite XAD-16. The adsorbed analyte ions were eluted with 6 mL 3M HCl in acetone solution, which then were determined by atomic absorption spectroscopy. The influences of the analytical parameters including pH, ligand amount and solid phase ingredient, eluting solution conditions and sample volume were investigated. Common coexisting ions did not interfere with the separation and determination. The preconcentration factor is 208. The sorbent exhibited excellent stability and its sorption capacity under optimum conditions has been found to be more than 60 microg of ions per gram of sorbent. The relative standard deviation under optimum conditions is lower than 4.10%. The accuracy of the method was estimated by using different real samples.

Utilization of membrane filtration for preconcentration and determination of Cu(II) and Pb(II) in food, water and geological samples by atomic absorption spectrometry

A method for separation-preconcentration of Cu(II) and Pb(III) ions by membrane filtration has been presented. The analyte ions were collected on acetate membrane filter as their 1-2-pyridylazo 2-naphthol (PAN) complexes. The analytes were determined by flame atomic absorption spectrometry. The analytical parameters including pH, eluent type, sample volume, amount of PAN, etc. were examined in order to gain quantitative recoveries of analyte ions. The effects of foreign ions on the recoveries of analyte ions were also investigated. The detection limits by three sigma were found to be 1.2 and 3.5 microg L(-1) for Cu(II) and Pb(II), respectively. The preconcentration factor was 60 for Cu(II) and 20 for Pb(II). The validation of the presented procedure was checked by the analysis of certified reference materials. The optimized method was successfully applied to food, water and geological samples with good results.