Determination of cobalt and copper in water, plant, and soil samples by magnetite nanoparticle-based solid-phase microextraction (SPME) coupled with microsample injection system-flame atomic absorption spectrometry (MIS-FAAS)

A magnetic solid-phase microextraction (SPME) procedure was optimized using Fe3O4 nanoparticles (NPs) to preconcentrate and determine cobalt and copper in real samples using microsample injection system-flame atomic absorption spectrometry (MIS-FAAS). Recoveries over 95% for Co(II) and 80% for Cu(II) from 90 mL of sample buffered to pH 4.0 were obtained using 50 mg Fe3O4 NPs as the adsorbent and 0.5 mL of 0.5 mol L-1 HNO3 as the eluent. The extraction time was 10 min. The preconcentration factors for Co(II) and Cu(II) were 180. The detection limits for Co(II) and Cu(II) were 1.2 and 0.9 mu g L-1, respectively. The relative uncertainties and relative standard deviations were lower than 5.3% and 2.4%, respectively. The developed method was verified by analyzing TMDW-500 drinking water, NIST 1573a Tomato leaves, and NCS DC 78302 Tibet soil as standard reference materials. The spiking experiments provided recoveries exceeding 95%. The method was applied to determine cobalt and copper in water, soil, tea infusion, and vegetable samples

Facile synthesis and characterization of beta-Cd(OH)(2) nanostructures for adsorptive removal of Cr(VI) ions from wastewater: a statistical approach for multivariate sorption optimization

In the present study, nanostructured beta-Cd(OH)(2) adsorbent was synthesized, characterized by Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy analysis, and applied for Cr(VI) ions capturing (adsorption) from environmental aqueous samples. The central composite design of 18 adsorption experiments was employed for multivariate sorption optimization. Maximum adsorption (%) of Cr(VI) ions was calculated and found to be 98.5% with relative standard deviation (RSD) = 3.5 at optimum concentration 15 mg L-1, pH 4.0, adsorbent dosage 50 mg, shaking time 20 min and shaking speed 120 rpm at 25 degrees C. Langmuir, Freundlich and Dubinin-Radushkevich isotherms fitted well to adsorption data with correlation coefficient (R-2) of 0.993, 0.982 and 0.994, respectively. Mono-layered (Q(m)) and multi-layered (K-f) capacities of beta-Cd(OH)(2) adsorbent for Cr( VI) ions retention were calculated and found to be 202.02 +/- 2.0 and 4.95 +/- 2.5 mg g(-1), respectively. Sorption energy was calculated and found to be 8.45 +/- 2.0 kJ mol(-1), indicated chemisorption or ion exchange mechanism for Cr(VI) ions adsorption onto beta-Cd(OH)(2) adsorbent

Facile synthesis of nanostructured ZnCuBi-NO3/SO4 layered double hydroxides for photocatalytic degradation of methylene blue

In this study, nanostructured ZnCuBi-NO3/SO4 layered double hydroxides (LDH) was developed followed by a co-precipitation approach using precursors such as ZnSO4 center dot 7H(2)O, CuSO4 center dot 5H(2)O and Bi(NO3)(3)center dot 5H(2)O, and well characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy-scanning electron microscopy, and thermogravimetric analysis techniques. Using absorbance data, Tauc plot was plotted and band gap energy of ZnCuBi LDH was calculated and found to be 1.73 eV. The material was applied as an efficient photocatalyst for degradation of methylene blue (MB) under visible light of a 100 W Tungsten lamp at optimum factors such as concentration of MB 10 mg L-1, pH 8.0, catalyst dosage 10 mg, and shaking time of 30 min at room temperature. The degradation efficiency of the material was calculated and found to be >= 95.5% with RSD <= 4%. The method worked well on the synthetic solutions of MB, prepared in tap water, wastewater, and seawater of different concentrations.Higher Education Commission, Islamabad, Pakistan [NRPU-8100]The authors gratefully acknowledge financial support from the Higher Education Commission, Islamabad, Pakistan. Project granted under NRPU Program (No. NRPU-8100)