ABSTRACT.A sensitive spectrophotometric method has been developed for the trace determination of copper using leucocrystal violet as chromogenic reagent. The proposed method is based on the reaction of copper(II) with potassium iodide in acid medium to liberate iodine, which oxidizes leucocrystal violet to crystal violet dye having absorption maximum at 590 nm. The reaction between copper and potassium iodide is accelerated by irradiating the mixture with microwave energy for 15 s at 480 W. Beer's law is obeyed in the concentration range 0.004 ---0.04 µg mL -1 . The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit were found to be 1.47 x 10 6 L mol -1 cm , respectively. The optimum conditions and other analytical parameters were evaluated. The effect of interfering ions on the determination is described. The proposed method has been successfully applied for the determination of copper in environmental samples like tap water, agricultural run off water, plant materials and pharmaceutical samples.
A novel beads adsorbent, consisting of calcium alginate entrapped on magnetic nanoparticles functionalized with methionine (MFMNABs), was developed for effective elimination of arsenic from water. The material was characterized by FT-IR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopic), XRD (X-ray Diffraction) and TEM (Transmission Electron Microscopy). The arsenic removal capacity of the material was studied by altering variables such as pH of the solution, contact time, adsorbent dose and adsorbate concentration. The maximal removal of As(III) was 99.56% under optimal conditions with an equilibrium time of 110 min and pH 7.0–7.5. The adsorption followed a second order kinetics and data best fitted the Langmuir isotherm with a correlation coefficient of R2 = 0.9890 and adsorption capacity (qm) of 6.6533 mg/g. The thermodynamic study showed entropy change (∆S) and enthalpy change (∆H) to be 34.32 J mol−1 K and 5.25 kJ mol−1, respectively. This study proved that it was feasible to treat an As(III) solution with MFMNABs. The synthesized adsorbent was cost-effective, environmentally friendly and versatile, compared to other adsorbents. The adsorption study was carried by low cost spectrophotometric method using N- bromosuccinimide and rhodamine-B developed in our laboratory.
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