Effect of anodic alumina pore diameter variation on template-initiated synthesis of carbon nanotube catalyst supports

Catalytic efficiency of the eggshell calcined and enriched with glycerin in the synthesis of biodiesel from frying residual oil

Currently, there are several studies using calcium oxide, calcium alkoxide, and calcium hydroxide for biodiesel production. However, there is still a lack of studies highlighting the use of calcium diglyceroxide (calcium oxide enriched with glycerin in the presence of methanol) as a catalyst in the transesterification process. Therefore, the present work aimed to investigate the catalytic efficiency and reutilization of the eggshell calcined and enriched with glycerin and methanol (ECEG), in the synthesis of methylic esters from frying residual oil. As a result, thermochemically modified eggshells showed catalytic efficiency during methylic transesterification of residual oils in mass concentrations of 15%, 5%, 3%, and 1% due to the presence of a high level of esters (97.39, 96.97, 97.75, and 92.96%, respectively). The initial concentration of the enriched eggshell used in methanolysis had a direct effect on the final ester mixture. A 15% increase in the water content of the frying oil contributed to an increase in the ester content. The ECEG was reactive and efficient for four reaction cycles (without reactivation of the catalytic sites) due to the evidence of a high ester content (97.85%, 98.67%, 98.89%, 98.46%), reaching the standard quality of worldwide biodiesel regulations. Graphical abstract.

Fabrication of biocompatible high aspect ratio Au–Ni coaxial nanorod arrays using the electroless galvanic displacement reaction method

Biocompatible Au–Ni coaxial nanorod arrays, which enable a precise control of its stiffness (softness) by adjusting the array height, have been demonstrated to be able to manipulate the differentiation of endothelial cells (ECs) on the array surface.

Selective growth of palladium and titanium dioxide nanostructures inside carbon nanotube membranes

Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors.

A 3D monolithic CNT block structure as a reductant, support and scavenger for nanoscopic gold, platinum and zinc oxide

ZnO (8-10 nm), gold (10-50 nm), and platinum (2-5 nm) nanoparticles were deposited on monoliths of regularly arranged three-dimensional (3D) carbon nanotubes of 40 nm diameter and length up to 30 microm. The single-source precursor complex di-aqua-bis[2-(methoxyimino)propanato](2)Zn(ii) in dimethylformamide was used for the deposition of nanoparticulate ZnO on an ordered 3D CNT scaffold by solution-phase deposition at temperatures as low as 150 degrees C. Au and Pt nanoparticles were deposited by the spontaneous reduction of aqueous solutions of HAuCl(4) and K(2)PtCl(4) on the surface of the macroscopic 3D CNT scaffolds. X-Ray diffraction (XRD) and transmission electron microscopy (TEM) indicate the crystalline nature and nanosize structure of the deposited ZnO, Au and Pt nanoparticles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations revealed a dense and homogeneous decoration of the individual CNTs throughout the 3D CNT scaffold structure. Thus the nanovoids of the carbon scaffold structure are therefore completely accessible leading to a homogenous particle deposition on the complete CNT outer surface. The kinetics of the spontaneous reduction of gold(iii) and platinum(ii) ions on the CNTs of the scaffold was followed by UV-vis spectroscopy and indicate (i) first-order reaction kinetics with respect to Au(3+) and Pt(2+) concentration and (ii) that the rate of reduction of Au(3+) is one order of magnitude slower than that of Pt(2+).