Co-microprecipitation/flotation of trace amounts of cadmium from environmental samples through its complexation with iodide and neutralization with cetyltrimethylammonium bromide in the presence of perchlorate ions

ABSTRACT

A fast, cost-effective and reliable method is presented for separation and preconcentration of trace amounts of cadmium based on co-precipitation and flotation prior to its flame atomic absorption (AAS) spectrometric determination. Cadmium (II) was complexed with iodide and neutralized with cetyltrimethylammonium bromide (CTAB) in the presence of perchlorate ions. This resulted in the formation of a bulky precipitate containing the ternary complex of CdI₄(CTA)₂, floating on the top of the solution. The aqueous layer was then simply drained out, the floated layer was dissolved in 1.0 mL of acetonitrile, and its Cd content was determined by flame atomic absorption spectrometry. The parameters affecting the designed separation method such as KI, CTAB, and ClO₄^? concentration, pH, ionic strength, volumes of sample and dissolving solvent, and extraction time were studied and optimized. For preconcentration of 200 mL of the sample, the calibration graph was linear in the range of 1–30 μg L^?1 of cadmium with a correlation coefficient of 0.9997, enhancement factor of 194 and a limit of detection of 0.18 μg L^?1. The relative standard deviation for seven replicate determinations at 20 μg L^?1 levels of cadmium was found to be 2.1%. The effect of the presence of different common cations and anions on the separation and determination of Cd(II) by the developed method was studied. The method was successfully applied to the determination of trace amounts of Cd(II) ions in different types of real samples including tap water, polluted industrial wastewater, dust, and soil with the recoveries in the range of 95.3 to 103.4.     

Electrophoretic preparation of graphene-iron oxide nanocomposite as an efficient Pt-free counter electrode for dye-sensitized solar cell

Journal of Solid State Electrochemistry - Fe3O4-reduced graphene oxide (Fe3O4-RGO) binder-free counter electrode (CE) is prepared by using an easy and low-cost electrophoretic deposition method and...     

Nanoparticles tungstophosphoric acid supported on polyamic acid: catalytic synthesis of 1,8-dioxo-decahydroacridines and bulky bis(1,8-dioxo-decahydroacridine)s

Tungstophosphoric acid nanoparticles supported on polyamic acid (TPA NPs/PAA) was prepared and employed as a catalyst for the facile selective synthesis of 1,8-dioxo-decahydroacridines and some bulky bis(1,8-dioxo-decahydroacridine)s via one-pot condensation of 5,5-dimethyl-1,3-cyclohexanedione and various aldehydes with aniline or ammonium acetate in ethanol–water solution. This catalyst was characterized by FT-IR, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), energy-dispersive X-ray analysis (EDAX), and inductively coupled plasma optical emission spectrometry (ICP-OES). The catalyst showed high thermal stability and good reusability. The products were isolated in high purity and the catalyst was easily separated in a simple workup and recycled several times without noticeable loss of activity under the described reaction conditions. The reaction is characterized by short reaction time, high efficiency, and mild reaction conditions.     

Chemical characterization and therapeutic properties of Achillea biebersteinii leaf aqueous extract synthesized copper nanoparticles against methamphetamine-induced cell death in PC12: A study in the nanotechnology and neurology fields

Recently, scientist have used metallic nanoparticles for synthesizing many new drugs in the field of neurology. One of the metals used in the metallic nanoparticles is copper. The role of Achillea biebersteinii in increasing the physiological activities of central nervous system in Iranian traditional medicine is well known. In this study fresh leaves of A. biebersteinii were used for the biosynthesis of copper nanoparticles. We also assessed the effect of copper nanoparticles on methamphetamine-induced cell death in the PC12 cell line. The nanoparticles were analyzed by Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, and ultraviolet–visible spectroscopy. A 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging experiment was carried out to assess the antioxidant properties of Cu(NO₃)₂, A. biebersteinii, and CuNPs. The DPPH test revealed similar antioxidant activities for A. biebersteinii, CuNPs, and butylated hydroxytoluene. In the cellular and molecular part of the present study, the Trypan blue test was performed to assess cell viability. The terminal deoxynucleotidyl transferase 2′-Deoxyuridine, 5′-Triphosphate (dUTP) nick end labeling test clarified the DNA fragmentation and apoptosis occurrence. The Griess reaction was used to measure nitric oxide production and caspase-3 activity was evaluated by spectrophotometry. The obtained results were fed into SPSS-22 software and analyzed by one-way ANOVA, followed by Tukey's post hoc test (p ≤ 0.01). The results indicate that both doses of CuNPs had cell death-suppressing effects on nerve cells. In particular, both doses of CuNPs significantly (p ≤ 0.01) increased cell viability and NO production, and decreased cell cytotoxicity, cell death index, and caspase-3 activity near the normal. According to these results, it seems that CuNPs could be administrated as a neuroprotective supplement or drug for the treatment of central nervous system disorders in clinical trials.     

Optimal TiO2–Graphene Oxide Nanocomposite for Photocatalytic Activity under Sunlight Condition: Synthesis,Characterization, and Kinetics

TiO₂–graphene oxide nanocomposites have been fabricated by the sol–gel technique for degradation of a typical cationic dye solution. The prepared photocatalysts were characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric‐differential analyses, Brunauer–Emmett–Teller surface area measurement, and scanning and transmission electron microscopy. In addition, the photocatalytic activities of samples were evaluated by degradation of methylene blue aqueous solution under the sunlight irradiation. The change in color of solution was evaluated by the UV–vis spectroscopy, and the maximum photocatalytic decoloration (94%) was achieved within 60 min, which exceeded that of pure anatase under the same conditions. The results show that the nanocomposite containing 9.0 wt% of graphene oxide has the superior photocatalytic performance to either single‐phase anatase or other composites containing different amounts of graphene oxide. The experimental degradation data obtained from the batch tests were analyzed by a modified kinetic model, which predicted the performance with higher regression coefficients and lower relative errors. The distribution of TiO₂ nanoparticles (<20 nm) on graphene oxide sheets is proposed to be the efficient factor in the homogeneous degradation of dye which can concomitantly improve the photocatalytic activity.     

Minimizing vehicle noise passing the street bumps using Genetic Algorithm

The purpose of this paper is to optimize noise emission level associated with two types of speed reducers for different speeds of a vehicle (20, 40, 60 km/h) by Genetic Algorithm and Artificial Neural Network. The optimization shows that the maximum level of noise is sensitive to speed reducer dimensions. It is reduced by 24 dB(A) by changing the width from 0.6 m to 0.3 m for the height 0.04 m whereas, it is reduced by 32 dB(A) by changing from the height 0.055 m and the width 0.9 m to the height 0.04 m and the width 0.3 m.