Core-shell structured catalysts for thermocatalytic, photocatalytic, and electrocatalytic conversion of CO2.

Catalytic conversion of CO2 to produce fuels and chemicals is attractive in prospect because it provides an alternative to fossil feedstocks and the benefit of converting and cycling the greenhouse gas CO2 on a large scale. In today's technology, CO2 is converted into hydrocarbon fuels in Fischer-Tropsch synthesis via the water gas shift reaction, but processes for direct conversion of CO2 to fuels and chemicals such as methane, methanol, and C2+ hydrocarbons or syngas are still far from large-scale applications because of processing challenges that may be best addressed by the discovery of improved catalysts-those with enhanced activity, selectivity, and stability. Core-shell structured catalysts are a relatively new class of nanomaterials that allow a controlled integration of the functions of complementary materials with optimised compositions and morphologies. For CO2 conversion, core-shell catalysts can provide distinctive advantages by addressing challenges such as catalyst sintering and activity loss in CO2 reforming processes, insufficient product selectivity in thermocatalytic CO2 hydrogenation, and low efficiency and selectivity in photocatalytic and electrocatalytic CO2 hydrogenation. In the preceding decade, substantial progress has been made in the synthesis, characterization, and evaluation of core-shell catalysts for such potential applications. Nonetheless, challenges remain in the discovery of inexpensive, robust, regenerable catalysts in this class. This review provides an in-depth assessment of these materials for the thermocatalytic, photocatalytic, and electrocatalytic conversion of CO2 into synthesis gas and valuable hydrocarbons.

Highly dispersed nickel catalysts via a facile pyrolysis generated protective carbon layer.

Highly dispersed nickel catalysts were synthesized by simple Ni(acac)2 impregnation followed by pyrolysis of organic ligands, which produces a protective carbon coating on the Ni nanoparticles, reducing the metal mobility and sintering. The synthesized catalyst shows high thermal stability and enhanced CO methanation activity compared to the catalyst prepared by the traditional impregnation/calcination method.

Determination of competitive adsorption isotherm parameters of pindolol enantiomers on alpha1-acid glycoprotein chiral stationary phase.

In this paper, inverse method (IM) was used to determine the binary competitive adsorption isotherm of pindolol enantiomers by a least-square fitting of the proposed model to the experimentally measured elution curves of racemic pindolol. The isotherm parameters were determined by minimizing the least-square error using an adaptation of genetic algorithm, non-dominated sorting genetic algorithm with jumping genes (NSGA-II-JG). An equilibrium dispersive (ED) model combined with bi-Langmuir isotherm was used in predicting the elution profiles. The determined parameters show good agreement with the experimental profiles at various experimental conditions such as sample volume, concentration and flow rates of the racemic mixture. Robustness and validity of the isotherm parameters were also verified by frontal analyses at various step inputs. Results from both the pulse tests and the frontal analysis indicate that adsorption isotherm derived from the inverse method is quite reliable. This method requires relatively less number of experiments to be performed and therefore, lower experimental costs confirming that inverse method is an attractive alternative approach of experimental technique in determining the competitive adsorption isotherm for binary systems.

Fe3O4/cyclodextrin polymer nanocomposites for selective heavy metals removal from industrial wastewater.

In this work, carboxymethyl-ß-cyclodextrin (CM-ß-CD) polymer modified Fe(3)O(4) nanoparticles (CDpoly-MNPs) was synthesized for selective removal of Pb(2+), Cd(2+), Ni(2+) ions from water. This magnetic adsorbent was characterized by TEM, FTIR, XPS and VSM. The adsorption of all studied metal ions onto CDpoly-MNPs was found to be dependent on pH, ionic strength, and temperature. Batch adsorption equilibrium was reached in 45 min and maximum uptakes for Pb(2+), Cd(2+) and Ni(2+) in non-competitive adsorption mode were 64.5, 27.7 and 13.2 mg g(-1), respectively at 25 °C. Adsorption data were fitted well to Langmuir isotherm and pseudo-second-order models for kinetic study. The polymer grafted on MNPs enhanced the adsorption capacity because of the complexing abilities of the multiple hydroxyl and carboxyl groups in polymer backbone with metal ions. In competitive adsorption experiments, CDpoly-MNPs could preferentially adsorb Pb(2+) ions with an affinity order of Pb(2+)>>Cd(2+)>Ni(2+) which can be explained by hard and soft acids and bases (HASB) theory. Furthermore, we explored the recyclability of CDpoly-MNPs.

ß-Cyclodextrin conjugated magnetic, fluorescent silica core-shell nanoparticles for biomedical applications.

We present synthesis of highly uniform magnetic nanocomposite material possessing an assortment of important functionalities: magnetism, luminescence, cell-targeting, and hydrophobic drug delivery. Magnetic particle Fe3O4 is encapsulated within a shell of SiO2 that ensures biocompatibility of the nanocomposite as well as act as a host for fluorescent dye (FITC), cancer-targeting ligand (folic acid), and a hydrophobic drug storage-delivering vehicle (ß-cyclodextrin). Our preliminary results suggest that such core-shell nanocomposite can be a smart theranostic candidate for simultaneous fluorescence imaging, magnetic manipulation, cancer cell-targeting and hydrophobic drug delivery.