Supported l-tryptophan on Fe3O4@SiO2 as an efficient and magnetically separable catalyst for one-pot construction of spiro[indene-2,2′-naphthalene]-4′-carbonitrile derivatives

l-Tryptophan functionalized silica-coated magnetic nanoparticles were prepared and evaluated as a magnetic nanocatalyst for the synthesis of spiro[indene-2,2′-naphthalene]-4′-carbonitrile derivatives through the one-pot four-component reaction.

Synthesis and Characterization of SiO2@CNTs Microparticles: Evaluation of Microwave-Induced Heat Production

This study was focused on the growth of multi-walled carbon nanotubes (MWCNTs) on iron chloride-functionalized silica microspheres. In addition, the microwave absorption potential and the subsequent heat production of the resulting structures were monitored by means of infrared thermometry and compared with pristine commercially available MWCNTs. The functionalized silica microparticle substrates produced MWCNTs without any amorphous carbon but with increased structural defects, whereas their heat production performance as microwave absorbents was comparable to that of the pristine MWCNTs. Two-minute microwave irradiation of the SiO2@CNTs structures resulted in an increase in the material’s temperature from ambient temperature up to 173 °C. This research puts forward a new idea of charge modulation of MWCNTs and sheds light on an investigation for the development of bifunctional materials with improved properties with respect to efficient microwave absorbance.

Adsorption Separation of Arsenic(III) and Arsenic(V) using Functionalized Silica Gels

A method for the adsorption separation of inorganic arsenic species (As(III)/As(V)) using sequentially connected preconcentrating columns filled with functionalized silica gels and their determination by inductively coupled plasma optical emission spectrometry was proposed. As(V) was effectively retained at pH 3.5–6.5 by an adsorbent containing groups of quaternary phosphonium bases on the surface and exhibiting the properties of an anion exchanger. In this pH range, As(III) was not extracted, which made it possible to separate As(V) from As(III). As(III) was retained in a wide pH range of 1–6 by a complexing adsorbent containing mercapto groups on the surface. Adsorbed As(V) was quantitatively eluted from the surface with 1M HNO3, and As(III) – with 5 % unithiol solution in 2M HCl. The use of «non-aggressive» eluents allows us to reuse adsorbents for preconcentration of As(III) and As(V) at least 5 times. The separation efficiency was confirmed by the analysis of model solutions