Ultrasensitive determination of selenium in food samples and its speciation in water and beverages using thiosemicarbazide-incorporated graphene and total-reflection X-ray fluorescence spectrometry.

The paper presents a new analytical procedure for the determination and speciation of trace and ultratrace selenium in water, beverages, seafood, milk, and vegetables. The developed method is based on the dispersive micro-solid phase extraction with the use of new thiosemicarbazide-incorporated graphene as a solid sorbent, in combination of the total-reflection X-ray fluorescence spectrometry (TXRF). As a result, we have created an auspicious analytical tool for fast and sensitive analysis of samples with a complex matrix.

Spatially Formed Tenacious Nickel-Supported Bimetallic Catalysts for CO Methanation under Conventional and Induction Heating.

The paper introduces spatially stable Ni-supported bimetallic catalysts for CO methanation. The catalysts are a combination of sintered nickel mesh or wool fibers and nanometal particles, such as Au, Pd, Re, or Ru. The preparation involves the nickel wool or mesh forming and sintering into a stable shape and then impregnating them with metal nanoparticles generated by a silica matrix digestion method.

Long-Term Isothermal Phase Transformation in Lead Zirconate.

Lead zirconate PbZrO has been the subject of research interest for several dozen years. Recently, even its antiferroelectric properties have started to be questioned, and many researchers still deal with the so-called intermediate phase below Curie temperature (T), whose existence is not fully understood. It turns out that PbZrO doped with Nb exhibits below T phases with complex domain structures.

Ultrasensitive and selective determination of mercury in water, beverages and food samples by EDXRF and TXRF using graphene oxide modified with thiosemicarbazide.

The paper presents novel analytical methods for sensitive mercury determination in various samples, i.e., waters, beverages, seafood, plants, and biological samples.

Sensitive determination of uranium using β-cyclodextrin modified graphene oxide and X-ray fluorescence techniques: EDXRF and TXRF.

β-cyclodextrin/graphene oxide (GO-β-CD) was applied for dispersive micro-solid phase extraction (DMSPE) of uranyl ions (UO) from water samples and their determination by energy-dispersive (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The structure of GO-β-CD was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The results of batch adsorption experiment indicate that the maximum recoveries for UO ions are observed at pH 4.

Determination of ultra-trace gold in cosmetics using aluminum-magnesium layered double hydroxide/graphene oxide nanocomposite.

A new solid-phase microextraction method for preconcentration and determination of ultra-trace Au(III) and AuNPs was developed. For this purpose, a nanosized aluminum-magnesium layered double hydroxide (AlMg-LDH)/graphene oxide (GO) nanocomposite was synthesized. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy confirmed the successful synthesis of the nanocomposite AlMg-LDH/GO with a well-crystallized hexagonal structure.

Cellulose mini-membranes modified with TiO for separation, determination, and speciation of arsenates and selenites.

Sorptive and selective mini-membranes based on TiO directly synthesized onto cellulose filters (TiO@cellulose) have been developed. The in situ synthesis of TiO@cellulose applied is simple and economically advantageous. The obtained membranes can be useful for (1) separating arsenic(V) and selenium(IV) from other ions and organic matter, (2) speciation of arsenic and selenium, and (3) determining ulratraces of these ions in water samples.

Graphene Oxide/Carbon Nanotube Membranes for Highly Efficient Removal of Metal Ions from Water.

Graphene oxide (GO) has an excellent adsorption capacity toward metal ions. Therefore, it is widely recognized as an auspicious material for fabrication of membranes applied in metal ion separation. However, GO membranes are not stable in aqueous solution because of electrostatic repulsion between GO nanosheets which are negatively charged.

A Study of Catalytic Oxidation of a Library of C₂ to C₄ Alcohols in the Presence of Nanogold.

The classical stoichiometric oxidation of alcohols is an important tool in contemporary organic chemistry. However, it still requires huge modifications in order to comply with the principles of green chemistry. The use of toxic chemicals, hazardous organic solvents, and the large amounts of toxic wastes that result from the reactions are a few examples of the problems that must be solved.

Alumina/nano-graphite composite as a new nanosorbent for the selective adsorption, preconcentration, and determination of chromium in water samples by EDXRF.

Obtaining new nanocomposites with sorption properties towards chromium is highly important not only from the environmental point of view but also for developing eco-friendly methods of chromium determination. The potential use of aluminum oxide-coated nano-graphite (AlO/nano-G) as a new nanosorbent in ultrasound-assisted dispersive micro-solid-phase extraction (DMSPE) for rapid speciation of trace chromium(III) and chromium(VI) ions in natural water was evaluated. In the developed method, the crucial issue is the new nanocomposite synthesized by coating alumina on a nano-graphite surface with sorption properties.

Determination and speciation of ultratrace arsenic and chromium species using aluminium oxide supported on graphene oxide.

Alumina supported on graphene oxide (AlO/GO) nanocomposite as new nanosorbent in dispersive micro-solid phase extraction (DMSPE) for As(V) and Cr(III) preconcentration is described. The crucial issue of the study is synthesis of novel nanocomposite suitable for sorption of selected species of arsenic and chromium. AlO/GO demonstrates selectivity toward arsenates in the presence of arsenites at pH 5 and chromium(III) ions in the presence of chromate anions at pH 6.

Ceria nanoparticles deposited on graphene nanosheets for adsorption of copper(II) and lead(II) ions and of anionic species of arsenic and selenium.

A nanocomposite prepared from graphene nanosheets and cerium nanoparticles (G/CeO) was applied to the extraction of Se(IV), As(V), As(III), Cu(II) and Pb(II). The structure of G/CeO was investigated by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The optimal pH values for extraction are 4.

Electrolytic copper as cheap and effective catalyst for one-pot triazole synthesis.

Electrolytic copper is a well-known form of pure, oxygen free copper that is used for industrial applications. In this work, the catalytic potential of this relatively cheap material was studied. The addition of less than 0.

Graphene Oxide Decorated with Cerium(IV) Oxide in Determination of Ultratrace Metal Ions and Speciation of Selenium.

Graphene oxide decorated with cerium(IV) oxide (GO/CeO) was synthesized and applied in adsorption of several metal ions such as As(III), As(V), Se(IV), Cu(II), and Pb(II) from aqueous samples. The important feature of GO/CeO nanocomposite is also its selectivity toward selenite in the presence of selenate. The structure of GO/CeO has been proven by microscopic and spectroscopic techniques.

Highly selective determination of ultratrace inorganic arsenic species using novel functionalized miniaturized membranes.

A simple method for highly selective determination of trace and ultratrace arsenic ions, i.e. arsenite and arsenate, was developed.

Method for the determination of Pb, Cd, Zn, Mn and Fe in rice samples using carbon nanotubes and cationic complexes of batophenanthroline.

Among cereals, rice is the second most cultivated staple crop in the world. It may be contaminated by toxic heavy metals present in water or soil. Therefore, monitoring the presence of heavy metals in rice and its products is a matter of a great importance from the nutritional and toxicological view.

Selective adsorption and determination of hexavalent chromium ions using graphene oxide modified with amino silanes.

Novel adsorbents are described for the preconcentration of chromium(VI). Graphene oxide (GO) was modified with various amino silanes containing one, two, or three nitrogen atoms in the molecule. These include 3-aminopropyltriethoxysilane (APTES), N-(3-trimethoxysilylpropyl)ethylenediamine (TMSPEDA), and N-(3-trimethoxysilylpropyl)diethylenetriamine (TMSPDETA).

Preconcentration of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Pb(II) with ethylenediamine-modified graphene oxide.

We describe a novel solid phase sorbent that was synthesized by coupling graphene oxide (GO) to ethylenediamine (EDA). This nanomaterial (referred to as GO-EDA) is capable of adsorbing the ions of iron, cobalt, nickel, copper, zinc and lead. The ethylenediamine-modified graphene oxide was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy and Fourier transform infrared spectroscopy.

Catalytic Gas-Phase Glycerol Processing over SiO2-, Cu-, Ni- and Fe- Supported Au Nanoparticles.

In this study, we investigated different metal pairings of Au nanoparticles (NPs) as potential catalysts for glycerol dehydration for the first time. All of the systems preferred the formation of hydroxyacetone (HYNE). Although the bimetallics that were tested, i.

Ni-Supported Pd Nanoparticles with Ca Promoter: A New Catalyst for Low-Temperature Ammonia Cracking.

In this paper we report a new nanometallic, self-activating catalyst, namely, Ni-supported Pd nanoparticles (PdNPs/Ni) for low temperature ammonia cracking, which was prepared using a novel approach involving the transfer of nanoparticles from the intermediate carrier, i.e. nano-spherical SiO2, to the target carrier technical grade Ni (t-Ni) or high purity Ni (p-Ni) grains.

Green approach for ultratrace determination of divalent metal ions and arsenic species using total-reflection X-ray fluorescence spectrometry and mercapto-modified graphene oxide nanosheets as a novel adsorbent.

A new method based on dispersive microsolid phase extraction (DMSPE) and total-reflection X-ray fluorescence spectrometry (TXRF) is proposed for multielemental ultratrace determination of heavy metal ions and arsenic species. In the developed methodology, the crucial issue is a novel adsorbent synthesized by grafting 3-mercaptopropyl trimethoxysilane on a graphene oxide (GO) surface. Mercapto-modified graphene oxide (GO-SH) can be applied in quantitative adsorption of cobalt, nickel, copper, cadmium, and lead ions.

Determination and speciation of trace and ultratrace selenium ions by energy-dispersive X-ray fluorescence spectrometry using graphene as solid adsorbent in dispersive micro-solid phase extraction.

A dispersive micro-solid phase extraction (DMSPE) with graphene as a solid adsorbent and ammonium pyrrolidinedithiocarbamate (APDC) as a chelating agent was proposed for speciation and detemination of inorganic selenium by the energy-dispersive X-ray fluorescence spectrometry (EDXRF). In developed DMSPE, graphene particles are dispersed throughout the analyzed solution, therefore reaction between Se(IV)-APDC complexes and graphene nanoparticles occurs immediately. The concentration of Se(VI) is calculated as the difference between the concentration of selenite after and before prereduction of selenate.

Suspended aminosilanized graphene oxide nanosheets for selective preconcentration of lead ions and ultrasensitive determination by electrothermal atomic absorption spectrometry.

The aminosilanized graphene oxide (GO-NH2) was prepared for selective adsorption of Pb(II) ions. Graphene oxide (GO) and GO-NH2 prepared through the amino-silanization of GO with 3-aminopropyltriethoxysilane were characterized by scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The batch experiments show that GO-NH2 is characterized by high selectivity toward Pb(II) ions.

Indirect determination of dissolved silicate in surface water using energy-dispersive X-ray fluorescence spectrometry.

An ultrasound-assisted methodology for the determination of dissolved silicate in water has been developed by combining the miniaturized ion-associated based preconcentration method with energy dispersive X-ray fluorescence spectrometry (EDXRF). The method has been devised for the determination of silicate through molybdenum in the ion-associated complex between 12-molybdosilicate and crystal violet. Because silicate is determined indirectly via molybdenum fluorescent radiation the difficulties resulting from low fluorescence yield and low energy of silicon radiation were successfully overcome.

Spherical silica particles decorated with graphene oxide nanosheets as a new sorbent in inorganic trace analysis.

Graphene oxide (GO) is a novel material with excellent adsorptive properties. However, the very small particles of GO can cause serious problems is solid-phase extraction (SPE) such as the high pressure in SPE system and the adsorbent loss through pores of frit. These problems can be overcome by covalently binding GO nanosheets to a support.