Homogenizer assisted dispersive liquid-phase microextraction for the extraction-enrichment of phenols from aqueous samples and determination by gas chromatography.

In this research, dispersive liquid-phase microextraction has been used for the extraction of some phenols including phenol, 3-methylphenol, 4-nitrophenol, 2-chlorophenol, tert-buthylphenol from aqueous samples, and then the analysis was done by the gas chromatography-flame ionization detector technique. For the first time, a laboratory homogenizer has been applied for dispersing of extracting organic solvent. To improve the chromatographic behavior, acetic anhydride was used as a derivatization reagent of the analytes. The effective parameters on the extraction and derivation process such as extraction solvent type and volume, amount and time of derivatization, sample pH and ionic strength, homogenization time and speed were investigated and optimized. The analytical performances of the method, such as linear dynamic range, repeatability, and detection limit were evaluated under the optimum condition. Under the optimal experimental conditions, the calibration plots were linear the range of 1-500 µg L-1 with the detection limits between 0.1-0.9 µg L-1, and the repeatability in the range of 2.6 to 10.0%. These values vary depend on the compounds. The proposed method was evaluated for the determination of the studied phenolic compounds in different real samples such as river water, tap water and industrial wastewater. The relative recoveries were between 90 and 111%.

Removal of uranium(VI) ions from aqueous solutions using Schiff base functionalized SBA-15 mesoporous silica materials.

Functionalized SBA-15 mesoporous silica particles, bearing N-propylsalicylaldimine and ethylenediaminepropylesalicylaldimine Schiff base ligands, abbreviated as SBA/SA and SBA/EnSA respectively, were prepared and characterized by FT-IR, elemental analysis, TGA, XRD, TEM and SEM techniques. The potentials of these adsorbents were examined by using them in solid phase extraction of U(VI) ions from water samples. It is shown that 20 mg of SBA/SA or SBA/EnSA can remove rapidly (∼15 min) and quantitatively uranium(VI) ions from 10 to 200 mL of water solutions (pH 4) containing 0.2 mg of the ions, at 25 °C. The adsorbed ions were stripped by 1 mL of dilute nitric acid solution (0.1 mol L(-1)). It means that the studied adsorbents are able to be used for removal and concentration of uranyl ions. This allowed achieving to a concentration factor of 200 for uranyl ions. The variation in the ionic strength in the range 0-1 mol L(-1) did not affect the extraction efficiencies of the adsorbents. The adsorbents showed selective separation of uranyl ions from Cd(2+), Co(2+), Ni(2+), Mn(2+), Cr(3+), Ba(2+), Fe(3+) and Eu(3+) ions. Thermodynamic investigations revealed that the adsorption of uranyl ions by the adsorbents was spontaneous and endothermic. The Langmuir model described suitably the adsorption isotherms. This model determined the maximum adsorption capacity of the adsorbents SBA/SA and SBA/EnSA as 54 and 105.3 mg uranyl/g adsorbent, respectively. The kinetics of the processes was interpreted by using Pseudo-second-order model.