Журнал экологической аналитической химии

A portable X-ray fluorescence method is described for the measurement of lead and arsenic in soils based on calibration with standard reference materials. Both elements exhibited good linear calibration curves. The method was used to analyze dried and ground soil samples obtained from the metropolitan New York City area. Results were compared to measurements obtained by graphite furnace atomic absorption spectrometry with microwave assisted acid leaching. No significant difference was found for lead measurements between the two methods however, arsenic values were significantly different with XRF exhibiting higher values. It is hypothesized that incomplete leaching and spectral interference are the predominant causes of this discrepancy. The XRF method provides a simple, quick, and nondestructive method for the determination of total lead and arsenic content in soils.

The concentrations of trace elements (K, Ca, Mn, Fe, Ni, Cu and Zn) from different soil samples collected around propose Uranium mining KP Mawthabah (Domiasiat) located in high rainfall area were investigated with Energy Dispersive X-ray Fluorescence technique. Among the physical parameters pH, moisture contents, organic matter and Cation Exchange Capacity (CEC) in soil indicated mild acidic to slightly alkaline nature of the soil and low water retention capacity. Depleted concentration of mono and divalent trace elements was observed when compared to the world average soil value.

Two new ligands, ammonium 2,6-dimethylmorpholine dithiocarbamate and ammonium 3-methylpiperidine dithiocarbamate were synthesized for the determination of nickel (II) in various environmental samples. The method was based on chelation of nickel (II) with ADMM-DTC/AMP-DTC in presence of NH4OH at pH 6.4 to produce catalytic hydrogen currents at -1.30V and -1.41 V vs SCE respectively and prior detected by DC polarography at Dropping Mercury Electrode (DME). Optimized polarographic conditions were established by studying effect of pH, supporting electrolyte, ligand and metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the present method. The present technique was successfully applied for the analysis of nickel (II) in different matrices with recoveries ranging from 97.00 - 99.00% and the results obtained were comparable with the differential pulse polarography.

This paper describes the interaction of nickel (II) with ammonium piperidine-1-carbodithioate (APC) using Direct Current (DC) polarography (DCP) & differential pulse polarography (DPP) at the Dropping Mercury Electrode (DME) in NH4Cl-NH4OH buffer medium at pH 6.0. The polarograms shows a predominant peak for nickel (II)-APC at -1.30 V vs SCE, indicating the production of catalytic hydrogen wave (CHW) due to electrostatic interactions between APC and nickel (II). The interactions were characterized with UV-visible spectrophotometer, FT-IR and cyclic voltammetric techniques. The developed method was applied successfully to determine the nickel (II) levels in leafy vegetables and biological samples with acceptable recoveries.

Two novel ligands, (E)-N1-(2-hydroxy-5-nitrobenzlidene) isonicotinoylhydrazone (HNBISNH)/2-(4-fluoro benzlideneamino)benzenethiol (FBBT) were synthesized and used for the quantification of copper (II) in various water and c HNBISNH/FBBT interacts with copper (II) to form 1:1 [L:M] orange /brick red color complexes in presence of phosphate buffer of pH 3.7/4.5 which increases the sensitivity of the complexes. Thus formed colored complex followed the Beer’s law up to 1.6 and 1.9 mg L‑1 with an optimum concentration range over 0.11-1.3 mg L-1 and 0.10-1.7 mg L-1, the slope of Ringbom’s plot are found to be 0.3500 and 0.3300 for copper(II)-HNBISNH and copper(II)-FBBT complexes, respectively. The molar absorptivity and Sandell’s sensitivity of copper (II)-HNBISNH and copper(II)-FBBT complexes were calculated and found to be 4.91×104 L mol−1 cm−1, 6.1×104 L mol−1 and 0.0010 μg cm−2 and 0.0014 μg cm−2 respectively. The detection limits was calculated and found to be 0.043 μg L−1 and 0.036 μg L−1 with HNBISNH and FBBT respectively. Various optimum conditions such as effect of pH, reagent concentration, accuracy, precision and reproducibility were investigated to improve the sensitive for the present method. The detailed study of various excipients confirmed the high selectivity of the method. The proposed method was applied to the determination of copper (II) in different water & soil samples obtained results were in good agreement with atomic absorption spectrometric method (AAS).

The aim of present research is to removal of Pb (II) and Hg (II) heavy metal ions from aqueous solution using a nano-TiO2-phenol-formaldehyde composite resin (TPFR). The resulting adsorbent TPFR was characterized by SEM with EDS, BET, FT-IR, XRD and TGA analyses and tested for metal adsorption. The particle size of adsorbent was 65- 70 μ. The adsorption behavior of Pb (II) and Hg (II) ions from aqueous solution by TPFR was investigated as a function of some parameters such as initial metal ion concentration, contact time, dose and temperature. Adsorption equilibrium data for the removal of Pb (II) and Hg (II) ions were examined by various isotherm models. Kinetic studies indicated that Pb (II) and Hg (II) ions adsorption followed the pseudo-second-order model. The thermodynamics parameters of adsorption systems indicated spontaneous and endothermic process

In this work, Multiwall carbon nanotubes (MWCNTs) were used in the adsorptive removal of Bismarck Brown R (BBR) dye from an aqueous solution. The effects of contact time, MWCNT dosage, dye concentration, pH and temperature on adsorption of BBR dye by MWCNTs were investigated. The adsorption study was analyzed kinetically, and the results revealed that the adsorption followed pseudo-second order kinetics with good correlation coefficients. The equilibrium adsorption data was analyzed using three common adsorption models: Langmuir, Freundlich and Temkin. Gibbs free energy change values showed that the adsorptions of BBR dye on MWCNTs is spontaneous. The results also indicate that the adsorption is physisorption.

Two types of commercial medical tablets of activated charcoal formulations (AC1 and AC2) were used as adsorbents for tartrazine. The adsorption studies were performed at controlled conditions of pH, and temperature (gastrointestinal-like conditions). It was found that pH plays a major role in the adsorption process. At pH 1.5 and 37°C the effect of different parameters affecting dye removal (salinity, adsorbent dose, initial dye concentration and stirring rate) were examined. The effects of some dietary additives like mono- and disaccharides, artificial sweeteners and glycine on the adsorption efficiency were assayed. The maximum adsorption of tartrazine on activated carbon tablets was observed at highly acidic media. The removal efficiency appears to decrease with increasing temperature and salinity indicating an exothermic process. Equilibrium adsorption isotherms for the removal of tartrazine from aqueous solution using activated charcoal tablets have been investigated. Langmuir and Freundlich’s models were applied to the data related to adsorption isotherms. According to Langmuir’s model data, the observed maximum adsorption capacities (qm) were 272.85 and 456.83 mgg-1 at 37°C for AC1 and AC2, respectively. Medical activated charcoal tablets appear as a very prospective adsorbent for the removal of tartrazine from aqueous solution

Various methods for improving the lower detection limit of polymeric membrane ion-selective electrodes have been approached recently. The ion-selective electrode with solid-state membrane is described. Tetraphenyl borate as a lipophilic anion, is incorporated into the membrane of the electrode to improve its detection limit and selectivity. The detection limit was significantly lowered where nanomolar quantities were traced. Other favorable characteristics of the electrode are noticeably short response time of 5 seconds and good selectivity over the common interfering chemical species as well as its proven usefulness for determination of the surfactant in miscellaneous samples.