141 research outputs found
Highly Efficient Adsorption of Rh(III) from Chloride Containing Solutions by Triazine Polyamine Polymer
No full textAdsorption of Rh(III) ions from the aqueous phase containing chloride ions was investigated batchwise using 1,3,5-triazine pentaethylenehexamine (TAPEHA) resin, which is highly resistant to strong acidic conditions. The effects of pH, temperature, initial concentration, and contact time on adsorption were examined. Rh(III) adsorption is favorable from the aqueous phase containing 3.0 and 0.1 M HCl. In both acidic cases, Langmuir is best fitting isotherm equation to system. The kinetics of Rh(III) adsorption on TAPEHA polymer was found to obey the pseudo-second-order kinetic equation, at both cases. Langmuir monolayer adsorption capacities were calculated as 327.03 and 113.76 mg/g in 3.0 and 0.1 M HCl, respectively. Experimental maximum adsorption capacities were measured as 198 and 100 mg/g in 3.0 and 0.1 M HCl, respectively. Due to different Rh(III) complexes with chlorine depending on acid concentrations, adsorption of Rh(III) from solutions containing 3.0 and 0.1 M HCl occurred via two different mechanisms; namely, ion exchange and surface complexation. The reuse of TAPEHA was also studied by column procedure, and the adsorption capacity of TAPEHA was not changed by using it five times. Adsorbed Rh(III) ions onto TAPEHA were completely eluted with thiourea 3% (w/v) in 1.0 M HCl. These findings showed that TAPEHA has a high resistance to acidic solutions and a higher Rh(III) uptake capacity than commercial adsorbents. Hence it can be used for rhodium recycling
Online Solid-Phase Extraction of Cd(II), Cu(II), and Co(II) Using Covalently Attached Bis(salicylaldimine) to Silica Gel for Determination in Food and Water by Flame Atomic Absorption Spectrometry
No full textIn this study, a novel sorbent material bearing a bis(aldimine) group was designed and successfully synthesized by covalently bonding a 2-[N,N-bis(salicylaldimine)]aminoethyl amine ligand to the silica gel surface that was characterized by carbon, hydrogen, and nitrogen elemental analysis, thermogravimetric analysis, and the Fourier transform infrared spectroscopy technique. The sorbent was used for the online solid-phase extraction (SPE) of Cd(II), Cu(II), and Co(II) ions for their determination at trace concentration levels by flame atomic absorption spectrometry. The effective factors for the online SPE such as the pH and the flow rate of the sample solution, and type, volume, and flow rate of eluent were investigated. The concentration levels of Cd(II), Cu(II), and Co(II) were measured in certified reference materials including Virginia tobacco leaves (CTA-VTL-2) and water-trace elements (NWTM-15.2) to validate this method. The metal levels in environmental water were determined by this method, and the values were checked by spiking and recovery experiments and independent analysis by inductively coupled plasma-mass spectrometry. The adsorption capacities of the sorbent were found to be 41.2, 31.6, and 25.6mg/g for Cd(II), Cu(II), and Co(II), respectively. This method was also successfully used for the determination of Cd(II), Cu(II), and Co(II) concentrations in rice and molasses
On-line Preconcentration of Pd(II) Using Polyamine Silica Gel Filled Mini Column for Flame Atomic Absorption Spectrometric Determination
No full textIn this study, a novel method for determination of Pd(II) ions at trace level was developed using on-line preconcentration onto polyamine group bonded silica (PA-SG) with flame atomic absorption spectrometric determination. Pd(II) uptake dynamics of PA-SG was studied batchwise by investigating acidity and chloride concentration of aqueous phase, contact time and initial concentration of Pd(II) ions. The Pd(II) adsorption capacity of PA-SG was found to be 158.7 mg g(-1) from aqueous phase containing 0.1 M HCl. The on-line preconcentration procedure of Pd(II) was optimized with main analytical parameters including sample and eluent flow rate, eluent type and volume and matrix ions. The optimum eluent type and flow rate of sample and eluent were found to be 1.0% thiourea in 1.0 mol L-1 HCl and 7.5 mL min(-1), respectively. The preconcentration factor and sampling frequency were calculated to be 23.9 and 20 h(-1), respectively. The calibration graph was linear over the range 10-200 mu g L-1. The limits of detection (3 sigma) and quantification (10 sigma) values were computed to be 3 mu g L-1 and 10 mu g L-1, respectively. The RSD, % was found to be 4.6% for five measurement of 25 mu g L-1 of Pd(II) ions. The accuracy of the developed method was successfully checked by determination of Pd(II) level of certified reference material platinum ore (SARM 7B). The proposed method was successfully applied for Pd(II) determination in various environmental water samples such as river, lake, sea and tap water, and spent auto catalyst
Catalytic application of 1,3,5-triazine-pentaethylenehexamine polymer-supported palladium nanoparticles in the convenient reduction of nitroarenes with sodium borohydride or hydrazine
No full textThe catalytic activity of 1,3,5-triazine-pentaethylenehexamine (TAPEHA) polymer-supported Pd nanoparticles was investigated in the reduction of nitro arenes to the corresponding amines by NaBH4 or N-2 H-4.H2O. Optimized reaction conditions for both systems were successfully tested on 20 nitroarenes with different characteristics. Considerably high yields (80%-98% in NaBH4 and 85%-98% in N2H4) were obtained in a short time and at ambient temperature. In addition to these methods being selective against other reducible functionalities such as -CN, -Br, -Cl, and -I, the catalyst can be recovered easily and reused more than ten times
Separation and recovery of gold(III) from base metal ions using melamine-formaldehyde-thiourea chelating resin
No full textMelamine-formaldehyde-thiourea (MFT) chelating resin has been prepared. An 31 ions uptake behavior and selectivity of the chelating resin were investigated by both batch and column methods. MFT resin showed higher affinity toward Au3+ compared with base metal ions, CU2+ and Zn2+. The highest Au3+ uptake values were obtained at pH 2 and Au3+ adsorption capacity of the resin was calculated as 48 mg Au3+/g resin (0.246 mmol Au3+/g resin) by batch method. it was concluded that Au3+ ions could be selectively concentrated from the solution including Cu2+ and Zn2+ base metal ions by column method. (C) 2007 Wiley Periodicals, Inc
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No full textKun fire dage inden Istanbuls borgmester Imamoglu skulle udpeges som præsidentkandidat for Det Republikanske Folkeparti (CHP), blev han anholdt. Ekrem Imamoglu nyder stor popularitet blandt alle borgere i Tyrkiet, uanset deres partipolitiske tilhørsforhold
1,3,5-Triazine-pentaethylenehexamine polymer for the adsorption of palladium (II) from chloride-containing solutions
No full textA triazine-hexamine (TAPEHA) polymer demonstrating high acid-resistance, good affinity to noble metals, and a high density of amine and triazine functional groups has been designed and synthesized. The obtained polymer was used as an adsorbent for the recovery of palladium (II) ions from chloride-containing solutions. Effects of pH, pCl, contact time, initial Pd(II) concentration, and temperature on adsorption were investigated and optimized by batch adsorption experiments. The pseudo second-order kinetic equation provides the best correlation for the process. While five isotherms were used, the nonlinear resolution of the Langmuir isotherm equation has been found to prOvide the closest fit to the equilibrium data. The monolayer adsorption capacity which is highest among literature is 517.2 mg/g. All thermodynamic parameters suggest that Pd(II) adsorption onto TAPEHA particles is a spontaneous, physisorptive, and exothermic process. The formation of TAPEHA and Pd-adsorbed TAPEHA has been characterized by FE-SEM, EDAX, XRD, and FTIR instrumentations. Adsorption of the negatively charged chloropalladium (II) species mostly takes place via ligand exchange mechanism. Ease of synthesis and low cost, coupled with highly efficient and rapid removal of Pd(II) ions, make TAPEHA an attractive adsorbent. (C) 2015 Elsevier B.V. All rights reserved
Au (III) uptake by triazine polyamine polymers: Mechanism, kinetic and equilibrium studies
No full textTriazine-polyamine polymers were successfully synthesized and adsorption of the gold (III) ions from chloride containing solutions was carried out by comparing the effect of amine chain lengths in the polymers triazine-ethylenediamine (EDA), triazine-triethylenetetramine (TETA) and triazine-pentaethylene hexamine (PEHA). The second-order kinetic equation provides the best correlation for the adsorption process. Langmuir equation has a good fit for all the adsorption systems. Langmuir monolayer adsorption capacities of the EDA, TETA and PEHA polymers were 548, 1003 and 1086 mg/g, respectively. Adsorption mechanism was determined using FTIR, XPS, SEM, SEM Mapping and EDS. Adsorption mechanism is followed by ionic and surface complex formation mechanisms. Hydroxy chloro gold complexes were more interacted with nitrogen atoms of amine groups in polymers than nitrogen atoms in triazine rings. The adsorption capacity did not decrease after using all polymers five times. Furthermore, elution of the adsorbed Au (III) ions was made easily using 3% (m/v) thiourea solution in 1 M HCl. From the results, it was concluded that EDA, TETA and PEHA polymers have a high gold uptake capacity and are highly efficient for the recycling of gold. (C) 2016 Elsevier B.V. All rights reserved
Solid Phase Extraction of Au and Pd by Silica Gel Functionalized With Triethylenetetramine for Determination by FAAS
No full textFlame atomic absorption spectrometry (FAAS) was used throughout the study for the determination of Au, Pd, and other metal concentrations. The detection limits of FAAS (3 delta) for Pd(II) and Au(III) were 0.26 and 0.24 mu g L-1, respectively, using a preconcentration factor of 100. The developed method was applied to certified reference material SARM 7B for the determination of palladium and gold with good agreement
Solid-phase extraction of trace Ni(II) ions on ethylenediamine-silica material synthesized by sol-gel method
No full textA solid-phase extraction method using ethylenediamine-silica (EDA-SIL) material for the determination of Ni(II) ions at trace level by flame atomic absorption spectrometry (FAAS) was presented in this study. EDA-SIL was synthesized with 3-(2-aminoethylamino) propyltrimethoxysilane (EDA-silane) and tetraethyl orthosilicate by sol-gel technique performing acidic hydrolysis and basic gelation procedure. EDA-SIL was characterized by FT-IR and C, H, and N elemental analysis. Solid-phase extraction of Ni(II) ions was carried out using mini column filled with EDA-SIL. The important variables governing the recovery of Ni(II) including pH, flow rate, eluent type, eluent volume, and matrix ions were studied. At the optimum preconcentration conditions, the recovery of Ni(II) was found to be 100 +/- 3% at 95% confidence level. The detection limit of Ni(II) was calculated based on the three times of standard deviation of blanks and found to be 0.32 ng mL(-1) using a preconcentration factor of 50. The developed method was validated using certified water samples (Ontario Lake water, NWTMDA-54.4) and applied to synthetic sea water samples for the determination of Ni concentration by FAAS
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