On the textural and crystalline properties of Fe-carbon xerogels. Application as Fenton-like catalysts in the oxidation of paracetamol by H2O2

Abstract

A series of five Fe-carbon xerogels has been prepared by a sol-gel modified method of polymerization of resorcinol and formaldehyde, iron being incorporated in the form of ferrous acetate. Some modifications, such as the monomer used, the use of a surfactant and the step of addition of the ferrous acetate have been done in order to study their influence on the textural and crystalline properties of the final solids obtained. Fe-carbon xerogels have been characterized by N2 adsorption, mercury porosimetry, thermal analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS). All samples contain micropores, with the exception of that prepared in the presence of an anionic surfactant. However, they are mainly meso- and/or macropores samples, the ratio of mesopore to macropore volume depending on the synthesis conditions. The amounts of iron in the samples, as well as the crystalline phases formed are also different. Fe-carbon xerogels were tested as catalysts in the removal of paracetamol from aqueous solution by a combined process of adsorption and Fenton-like oxidation under mild conditions, 25 °C and pH nearly neutral. Values of oxidations of paracetamol between 78 and 95% were achieved after 5 h of reaction, and the 90% of paracetamol was removed after only 37 min with two of the catalysts. The activity seems to be correlated with the high dispersion of small nanoparticles of iron, mainly present as zero-valent iron.