The authors gratefully acknowledge the financial support for this work provided by CONCYTEC (Project 371-2012-CONCYTEC-OAJ)

371-2012-CONCYTEC-OAJ

The authors gratefully acknowledge the financial support for this work provided by CONCYTEC (Project 371-2012-CONCYTEC-OAJ),

A series of CeαMn1-αO2 catalysts supported on g-alumina with various molar concentrations of Ce (α, from 0 to 0.90) was synthesized by coprecipitation, applying two different precipitating agents, namely, sodium hydroxide (method 1) and sodium carbonate (method 2), with the use of sodium permanganate as a redox agent for precipitation. XRD profiles of the supported samples revealed the predominant abundance of a typical fluorite crystalline structure. TPR thermograms of supported samples were displaced towards lower temperatures with increasing Mn concentration, in contrast with the bulk samples. The supported Ce-Mn samples exhibited a greater performance in n-hexane elimination than did the corresponding simple oxides. The sample Ce0.33Mn0.67O2 obtained by method 2 presented the best activity, probably due to the enrichment of Ce4+, Mn3+ and Mn4+ surface species, an excess of superfi...

An electrochemical sensor (CPE-IIHP) was developed for Cd(II) using a carbon paste electrode (CPE) impregnated with an ion-imprinted hybrid polymer (IIHP). A CPE-NIHP was also prepared for comparison. DPASV was used to optimize the sensor response and quantify Cd(II). The sensor presented a wide linear range from low concentrations of Cd(II): 1 to 100 ?g L?1 and high concentrations of Cd(II): 2.75 to 5.0 mg L?1. Ions such as Co(II), Pb(II), Ni(II), Zn(II), Fe(II), Fe(III), Sn(II) and Cu(II), showed no variation in the Cd(II) signal. The CPE-IIHP was successfully applied in river and drinking water analysis, revealing the great potential for its application.

The present work shows the synergistic application of reflectance spectroscopy and core-shell molecularly imprinted polymer (MIP) for rapid quantification of tartrazine in soft drinks. Studies evaluated the performance of the MIPs synthesized in the presence of silica nanoparticles unfunctionalized and functionalized with [3-(methacryloyloxy)propyl]trimethoxysilane. Although the use of functionalized silica nanoparticles promoted the highest adsorption capability of tartrazine, the material was found to be less selective when it was applied in real samples. Interestingly, the most accurate results were obtained via the application of the MIP synthesized in the presence of unfunctionalized silica nanoparticles (SiO2@MIP). The optimized core-shell MIP was also characterized by Raman spectroscopy and scanning electron microscopy. The use of direct reflectance spectroscopy in the analyte det...

Catalysts based on Ni-Fe-a with a catalyst ratio of a = Ni/(Ni + Fe) (a = 0.8 and 0.9) supported on γ-Al2O3 were prepared by coprecipitation-deposition and tested for the oxidative dehydrogenation (ODH) of ethane. The bulk mixed samples exhibited 30% greater selectivity toward ethylene than did the corresponding simple oxide NiO. Meanwhile, the most selective sample, NiFe-0.9/γ-Al2O3, achieved a maximum of 94% at 400 °C. The remarkable selectivity of NiFe-0.9/γ-Al2O3 was attributed to the partial substitution effect of Ni2+ by Fe3+, thus allowing those catalysts to form oxygen sites that are specific for the partial oxidation of ethane to ethylene. Some additional factors that could have contributed to ethylene selectivity were the formation of low-reducibility species with controlled particle size, a better dispersion of the active phase over the support and the synergy of Fe3+ with...

Two new ionic imprinted hybrid polymers (IIHP) and their corresponding non imprinted hybrid polymers (NIHP) were synthesized. The prepared IIHP was highly selective to Cd2+. To prepare the IIHP, 1-vinylimidazole (VIN) was used as the functional monomer, (3-mercaptopropyl) trimethoxysilane (MP) or (3-aminopropyl) trimethoxysilane (AMP) was used as the functional organosilane, trimethylolpropane (TRIM) was used as the crosslinking agent, AIBN was used as a radical initiator and TEOS was used as a functional precursor. The functional monomer was selected considering calculations based on the density functional theory (DFT). The fabricated materials were characterized via field emission gun scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX) and thermogravimetric analysis (TGA). The maximum adsorption capacity of ...

The present work reports the successful synthesis of a novel Pb2+ ion-imprinted polymer (Pb-IIP) based on a rhodizonate-like selective ligand by precipitation. Three functional monomers, namely acid acrylic (ACRY), 2-acrylamido-2-methylpropane sulfonic acid (AMPSA) and allylamine (ALLY), were chosen by computer simulation using density functional theory (DFT). The materials obtained were applied for the selective removal of Pb2+ from aqueous solutions and were characterized by Fourier transform Infra-red (FTIR), scanning electronic microscopy (SEM) and flame atomic absorption spectrometry (FAAS). The results obtained from the adsorption experiments performed under optimal conditions were in good agreement with the computational design and showed that IIP-AMPSA exhibited a relatively higher adsorption capacity for Pb2+ (51.84 mg g?1) than IIP–ACRY (31.02 mg g?1) and IIP-ALLY (12.90 mg g...

Methylmercury (MeHg+) is a mercury species that is very toxic for humans, and its monitoring and sorption from environmental samples of water are a public health concern. In this work, a combination of theory and experiment was used to rationally synthesize an ion-imprinted polymer (IIP) with the aim of the extraction of MeHg+ from samples of water. Interactions among MeHg+ and possible reaction components in the pre-polymerization stage were studied by computational simulation using density functional theory. Accordingly, 2-mercaptobenzimidazole (MBI) and 2-mercaptobenzothiazole (MBT), acrylic acid (AA) and ethanol were predicted as excellent sulfhydryl ligands, a functional monomer and porogenic solvent, respectively. Characterization studies by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) revealed the obtention of porous materials with specific surface areas...