Mustafa Imamoglu

Tea-industry waste activated carbon, as a novel adsorbent, for separation, preconcentration and speciation of chromium

Activated carbon was produced from tea-industry wastes (TIWAC) and employed as a low cost and effective solid phase material for the separation, preconcentration and speciation of chromium species without using a complexing agent, prior to determination by flame atomic absorption spectrometry (FAAS). The characterization of TIWAC was performed by utilizing several techniques such as Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis. The adsorption experiments were conducted in a batch adsorption technique. Under the experimental conditions, Cr(VI) adsorption amount was nearly equal to zero, however the adsorption percentage of Cr(III) was in the range of 95-100%. Therefore total chromium was determined after the reduction of Cr(VI) to Cr(III) and Cr(VI) was calculated by subtracting Cr(III) concentration from total chromium concentration. The suitable conditions for adsorption and speciation processes were evaluated in terms of pH, eluent type and volume, TIWAC concentration, adsorption and desorption contact time, etc. Adsorption capacity of TIWAC was found to be 61.0 mg g(-1). The detection limit for Cr(III) was found to be 0.27 μg L(-1) and the preconcentration factor was 50 for 200mL of sample volume. The procedure was applied to the determination and speciation of chromium in stream, tap and sea water. Also, the proposed method was applied to total chromium preconcentration in microwave digested tobacco and dried eggplant samples with satisfactory results. The method was validated by analyzing certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and the results were in good agreement with the certified values.

Separation, Preconcentration, and Recovery of Pd(II) Ions using Newly Modified Silica Gel with Bis(3-Aminopropyl)Amine

Bis(3-aminopropyl)amine bonded silica gel (BAPA-SG) was synthesized and characterized by elemental analysis and FT-IR spectroscopy, and tested for adsorption, preconcentration, and recovery of Pd(II) ions. The effective parameters on the preconcentration of Pd(II) ions such as pH, volume, and flow rate of the Pd(II) solution, and the type and volume of eluent solution, and also matrix ions such as alkaline and heavy metals were investigated. Flame atomic absorption spectrometry was used for the determination of Pd(II) concentration. The modified silica gel could adsorb Pd(II) ions quantitatively from the solutions up to 400 mL at pH 1.0 by the flow rate of 5 mL/min. The retained Pd(II) ions could be easily eluted by using 5 mL of 1% (m/v) thiourea in 1.0 M HCl solution. The recovery of Pd(II) ions was 95 ± 2% at 95% confidence level. The analytical detection limit of Pd was found to be 0.36 µg L−1 at the preconcentration factor of 80. Selective adsorption of Pd(II) ions over some base metal ions was also investigated. The developed method was applied to spent auto catalyst for palladium recovery, and a certified ore sample for the determination of palladium content.

Determination of gold, palladium and copper by flame atomic absorption spectrometry after preconcentration on silica gel modified with 3-(2-aminoethylamino)propyl group

A preconcentration method of gold, palladium and copper based on the sorption of Au (III), Pd (II) and Cu (II) ions on a column packed with 3-(2-aminoethylamino)propyl bonded silica gel is described. The modified silica gel was synthesized and characterized by FT-IR and C, H, N elemental analysis. At column preconcentration, the effects of parameters such as pH, volume, flow rate, matrix constituents of solutions and type of eluent on preconcentration of gold, palladium and copper were studied. The recoveries of Au (III), Pd (II) and Cu (II) were 98.93±0.51, 98.81±0.36 and 99.21±0.42 % at 95 % confidence level, respectively. The detection limits (δ) of the elements were 0.032, 0.016 and 0.012 μg ml−1, respectively. The preconcentration method was applied for determination of gold and palladium in certified reference material SARM 7B and copper in river and synthetic seawater by FAAS. Gold, palladium and copper were determined with relative error lower than 10 %.

Removal of methylene blue from aqueous solutions using phosphoric acid activated carbon produced from hazelnut husks

In this study, activated carbon (HHPAAC) was prepared from hazelnut husks using phosphoric acid activation and characterized by some physicochemical analyses. Surface area and zero point charge of pH (pHPZC) were found to be 770 m2 g−1 and 4.5, respectively. Removal of methylene blue (MB) from aqueous solution was performed using a batch technique for determination of the effects of initial pH, contact time, dosage, and temperature. Adsorption of MB was elevated with increasing pH and temperature. The equilibrium data were analyzed by Langmuir and Freundlich equations, and it was found that the data were reasonably well represented by the former with an adsorption capacity of 204 g kg−1. Change in Gibbs free energy (ΔG), entropy (ΔS), and enthalpy (ΔH), were also calculated. Adsorption kinetics were pseudo-second order.

Adsorption of cobalt by activated carbon from the rice hulls

Abstract The removal of cobalt (II) ion from aqueous solutions, by adsorption on activated carbon prepared from the rice hulls (ACRH), has been investigated depending on pH, activated carbon dosage, contact time, initial metal concentration and solution temperature. The optimum values of pH, ACRH dosage and contact time have been determined as 6–7, 1.5 g ACRH/50 mL solution and 40 minutes respectively. Freundlich and Langmuir isotherm constants have been calculated at two different temperatures of 293 K and 313 K. Furthermore the other thermodynamic data for ΔG° and ΔS°, have been also calculated at two temperatures of 293 K and 313 K. The adsorption of Co (II) ion from aqueous solutions has been found to be exothermic (ΔH°= ‐1.543 KJ/mol).

Dehydrated hazelnut husk carbon: a novel sorbent for removal of Ni(II) ions from aqueous solution

Abstract The present study has been performed to examine the adsorption ability of novel sorbent dehydrated hazelnut husk carbon (DHHC) towards Ni(II) ions from aqueous solution using the batch adsorption technique. The effective factors such as initial pH of the aqueous solution, contact time, initial Ni(II) concentration, adsorbent dosage, and temperature were investigated. The studies were also conducted to understand the effect of some co-existing ions which may be present in aqueous solutions. DHHC showed good adsorption potential for Ni(II) ions. The optimum initial pH value was selected as 5.0. The experimental data fitted well to the Langmuir adsorption isotherm model. Among the kinetic models tested for the adsorption of Ni(II), the pseudo-second-order model showed a good fit of the kinetic data. The thermodynamic parameters including the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes indicated that the adsorption of Ni(II) ions onto DHHC was feasible, spontaneous, and exothermic...

Column Solid Phase Extraction of Copper and Nickel on Triethylenetetramine Bonded Silica Gel for their Atomic Absorption Spectrometric Determination

Abstract A procedure for the preconcentration of Cu(II) and Ni(II) is proposed using a minicolumn filled with silica gel modified by triethylenetetramine. The retained analytes on the modified silica gel were eluted with hydrochloric acid solution. The metal ions in the eluate were determined by flame atomic absorption spectrometry. The effect of various factors, such as pH of the sample solution, sample volume, flow rate of the sample solution, type of eluent, and matrix content of the sample solution, on preconcentration were examined to obtain optimum conditions. The recoveries for Cu(II) and Ni(II) ions under optimum preconcentration conditions were 98.3±1.3 and 99.2±1.4% at 95% confidence level, respectively. The analytical detection limits of Ni and Cu were found to be 0.22 and 0.36 µg L−1, respectively. The proposed method was applied to the determination copper and nickel in river and synthetic sea water.

Adsorption of Cd(II) Ions onto Activated Carbon Prepared from Hazelnut Husks

In this study, a batch adsorption of Cd(II) ions onto activated carbon (AC) produced from hazelnut husks were investigated. The factors controlling the adsorption process such as initial pH, agitation time, dosage and initial concentration have been examined. The AC was showed a high affinity to Cd(II) ions at pH values between 5.0 and 7.0. The equilibrium time was found to be 300 minutes. Cd(II) adsorption equilibrium was analyzed with both Langmuir and Freundlich isotherm equations and it was found that Langmuir equations fitted well with the experimental data. Maximum Cd(II) adsorption capacity of AC was calculated to be 20.9 mg g−1. Cd(II) adsorption kinetics described well with the pseudo second order model. The activated carbon prepared from hazelnut husks is efficient sorbent material for the removal of Cd(II) ions from aqueous solutions.

Novel Functionalized Silica Gel for On-line Preconcentration of Cadmium(II), Copper(II), and Cobalt(II) with Determination by Flame Atomic Absorption Spectrometry

ABSTRACT Silica gel functionalized with 2-[N,N’-bis(2,3-dihydroxybenzaldimin)] aminoethylamine was employed as a novel sorbent for preconcentration of copper(II), cobalt(II), and cadmium(II) by flow injection-solid phase extraction. The pH of the analyte solution, sample and eluent flow rate, eluent volume, and the presence of concomitant ions were optimized. The limits of detection were 0.65, 0.52, and 1.42 µg/L and preconcentration factors were 12.3, 21.5, and 7.31 for cadmium(II), copper(II), and cobalt(II), respectively. The adsorption capacities of the functionalized silica gel for cadmium(II), copper(II), and cobalt(II) ions were 41.1, 31.7, and 26.5 mg/g. The preconcentration method was validated by determination of cadmium(II), copper(II), and cobalt(II) levels in Virginia Tobacco Leaves (CTA-VTL-2) and Water-Trace Elements (NWTM-15.2) certified reference materials. The method was also used to analyze water and food samples, and offers simplicity, reproducibility, high recovery, rapid and automated analysis, favorable ease of use, and low detection limits.

1,3,5-triazine-triethylenetetramine polymer: an efficient adsorbent for removal of Cr(VI) ions from aqueous solution

The synthesis of 1,3,5-triazine-triethylenetetramine (TATETA), its characterization by infrared spectroscopy and elemental analysis, and its application for removal of Cr(VI) ions from aqueous solution is reported. The effects of pH, contact time, initial concentration of Cr(VI), sorbent dose, and temperature on adsorption were investigated and optimized by batch adsorption experiments. Adsorption was highest at acidic conditions with an equilibration time of 25 min. The adsorption followed a Langmuir model, with an adsorption capacity of 303 mg g−1, was second order in its kinetics, and exothermic and thus spontaneous.