<Emphasis Type="SmallCaps">l</Emphasis>-Cysteine-functionalized magnetic nanoparticles (LCMNP): as a magnetic reusable organocatalyst for one-pot synthesis of 9-(1<Emphasis Type="Italic">H</Emphasis>-indol-3-yl) xanthen-4-(9<Emphasis Type="Italic">H</Emphasis>)-ones

l-Cysteine-functionalized magnetic nanoparticles (LCMNP) were introduced as an efficient and magnetically separable organocatalyst for the synthesis of 9-(1H-indol-3-yl) xanthen-4-(9H)-one derivatives. This class of compounds was synthesized via a one-pot three-component coupling reaction of 2-hydroxybenzaldehyde, dimedone, and indole in the presence of catalytic amount of LCMNP under mild and green conditions. High yields, short reaction time, easy workup, using environmental friendly conditions, and magnetic reusable catalyst are the advantages of this synthetic methodology. The LCMNP catalyst was reusable in this reaction at least for 6 times without significant decreasing in its catalytic activity.     

Removal of Arsenic (III) from natural contaminated water using magnetic nanocomposite: kinetics and isotherm studies

The application of newly synthesized Fe₃O₄/TiO₂–SiO₂ that is modified with zinc (FTSZ) as a sorbent, for the removal of arsenic from contaminated water has been investigated in the present study. SEM, FTIR, XRD, BET, Zeta potential sizer (ξ) analyses are used to determine the sorbent characterization. The effect of the operational parameters such as initial pH, initial concentration, and the contact time were studied. In addition, the equilibrium behavior of FTSZ in As(III) removal was investigated in the temperature range of 20–40 °C. The results showed that the equilibrium data were fitted well with Langmuir than Freundlich isotherm model. The maximum monolayer adsorption capacity estimated by Langmuir isotherm was 24.010 mg g^?1. Thermodynamic parameters, ?H°, ?S° and ?G° were also calculated from graphical interpretation of the experimental data. Standard heats of sorption (?H°) were found to be endothermic and ?S° values were calculated to be positive for the sorption of As(III) onto the adsorbent.     

SBA-15/Metformin as a novel sorbent combined with surfactant-assisted dispersive liquid–liquid microextraction (SA-DLLME) for highly sensitive determination of Pb,Cd and Ni in food and environmental samples

This paper established a new, rapid and sensitive method for the ultra-trace determination of lead, cadmium and nickel in food and environmental samples preconcentrated by dispersive solid-phase extraction (DSPE) combined with surfactant-assisted dispersive liquid–liquid microextraction (SA-DLLME) prior to graphite furnace atomic absorption spectrometry. SBA-15/Met was synthesized and used as a new efficient sorbent for the extraction of metal ions in DSPE. It was characterized by TEM and TGA techniques. After DSPE step, stripped metal elements were complexed with dithizone, and then, the complexes were extracted into carbon tetrachloride by using SA-DLLME. A conventional nonionic surfactant, triton X-100 was used as a disperser agent. Under the optimized conditions, the limit of quantifications was found to be 2.5 ng L^?1 for Pb²⁺, Cd²⁺ and 5.0 ng L^?1 for Ni²⁺. The limits of detection were 1.5 ng L^?1 for Ni²⁺ and 0.75 ng L^?1 for Pb²⁺ and Cd²⁺, with enrichment factor of 1650. The optimized method exhibited a good precision level with relative standard deviations (RSDs%) values of 4.9, 5.2 and 5.0% for 1 μg L^?1 Pb²⁺, Cd²⁺ and Ni²⁺, respectively (n = 7). Application of the proposed method to the analysis of fish-certified reference material produced results that were in good agreement with the certified values.     

Preparation of PVA nanofibers reinforced with magnetic graphene by electrospinning method and investigation of their degradation kinetics using master plot analyses on solid state

Journal of Thermal Analysis and Calorimetry - In this study, magnetic graphene nanoparticles have been prepared by Hummers method. The synthesized magnetic graphene nanoparticles were applied in...     

MnO<Subscript>2</Subscript>/3MgO Nanocomposite for Preconcentration and Determination of Trace Copper and Lead in Food and Water by Flame Atomic Absorption Spectrometry

The presented study investigates the application of MnO₂/3MgO nanocomposite, as a new sorbent for solid phase extraction and determination of trace amounts of Pb²⁺ and Cu²⁺ from various samples using flame atomic absorption spectrometry. After extraction, the analytes were desorbed using 0.01 M ethylenediaminetetraacetic acid. The effects of various parameters were studied and optimized. Under optimized experimental conditions the linear dynamic ranges for Cu²⁺ and Pb²⁺ were 10?900 and 30?900 μg/L, respectively, with a preconcentration factor of 20. The detection limits of Cu²⁺ and Pb²⁺ were 4 and 11 μg/L, respectively, and relative standard deviations for eight determinations of 100 μg/L were 3.6 and 3.8% for Cu²⁺ and Pb²⁺, respectively. The method was successfully applied for determination of copper and lead in mushrooms, rice, tap water and refinery wastewater with good spike recoveries ranging between 95?106%.     

A PVC-membrane bulk optode for gallium(III) ion determination

An optical probe responsive to gallium(III) ion has been developed. The gallium sensing system was prepared by incorporating 4-(p-nitrophenyl azo)-pyrocatechol (NAP) as ionophore in a plasticized PVC membrane containing tributylphosphate (TBP) as plasticizer. The sensing membrane in contact with gallium ion at pH 3.5, changes color from yellow-brown to pink-brown. Under optimum conditions, the proposed membrane displayed a linear range of 5-83 μM with a limit of detection of 4 μM. The response time of the membrane was within 10-15 min depending on the concentration of Ga³⁺ ions. The selectivity of the probe towards gallium determination was found to be very good. Experimental results showed that the probe could be used as an effective tool in analyzing the gallium content of water samples.     

Modified Magnetite Nanoparticles for Hexavalent Chromium Removal from Water

Water treatment is an important concern of human societies. Using magnetic nanoparticles as adsorbents for metal removal has been greatly considered due to their particular characteristics such as small sizes, high surface area to volume ratios, and good magnetic properties. In the present study, a modification was implemented in magnetite particles by functionalized carbon nanotubes and carboxylic groups to enhance the performance of magnetite particles in removing hexavalent chromium from water using the adsorption method. The applicability of the nanoadsorbent and magnetic nanoparticles was compared based on adsorption factors affecting the chromium removal including pH, contact time, pollutant concentration, and the adsorbent amount. Properties of the nanocomposites were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the highest percentage of Cr (VI) removal for both adsorbents was under acidic ambient conditions and lasted less than 45 minutes. The study of Langmuir, Freundlich, and Temkin isotherms in the prediction of adsorption behavior revealed that the Langmuir model better fitted the adsorption equilibrium data. The kinetic analysis of pseudo-first and second-order equations showed that the pseudo-second-order equation was more suitable for describing the kinetic behavior of data. Moreover, the obtained nanocomposite had a better performance in Cr (VI) removal from water in comparison to magnetite nanoparticles.     

Copper(II)–diaminosarcophagine‐functionalized SBA‐15: a heterogeneous nanocatalyst for the synthesis of benzimidazole,benzoxazole and benzothiazole derivatives under solvent‐free conditions

Solvent‐free organic reactions were studied over periodic mesoporous silica (SBA‐15) containing a Cu(II) organometallic complex. This heterogeneous catalyst was achieved by coordination of Cu(II) ions with the diaminosarcophagine ligand and then its grafting onto the surface of SBA‐15. This catalyst displayed ordered mesoporous channels, which implies an extremely high dispersion of the Cu(II) complex and the convenient diffusion of reactant molecules into the pore channels. Therefore, this catalyst can offer high activity and also facile separation or recycling when compared with its homogeneous counterparts. Copyright © 2015 John Wiley & Sons, Ltd.     

A Novel Electrochemical Sensor for Simultaneous Determination of Hydroquinone,Catechol, and Resorcinol Using a Carbon Paste Electrode Modified by Zn-MOF,Nitrogen-doped Graphite,and AuNPs

In this work, the carbon paste electrode was modified with a composite of a metal-organic framework, nitrogen-doped graphite, and gold nanoparticles and used as an electrochemical sensor for dihydroxybenzene isomers. The morphology and characteristics of the modifiers were found by SEM and FT-IR. Electrochemical techniques showed the specific surface of the electrode to be significantly enhanced. The outcome achieved shows that this novel sensor displays an excellent electro-catalytic activity towards the oxidation of these isomers. The sensor was applied to the simultaneous determination of each three isomers using DPV with a linear response in the concentration range of 5–10⁵ nM.