Treatment of Biogenic Iron-Containing Materials

Abstract

Abstract. Biogenic iron oxides could find application in catalysis but their structure and composition should be well characterized. The content of organic rests due to their origin should also be controlled. Samples of natural biomass and biomass obtained after cultivation in Adler's medium of the SphaerotilusLeptothrix group of bacteria were treated by different techniques to reduce or totally remove the organic residues. The aim of the study was to find procedures, which prevent changes in the oxidation state of the iron and of the type of iron-containing compound(s) during treatment. Mössbauer spectroscopy, IRS, DTA, and SEM were used in the study. Chemical treatment with H 2 O 2 or NaOH at room temperature did not significantly change the samples. Thermal treatment in oxidative flow mixture conducted up to 250 °C resulted in a transformation of the iron-containing phases only. The organic matter, which is included in the structure of the particles, cannot easily be affected. DTA revealed that removal of organic rests occurred in the interval of 250-600 °C. However, the transformation of the initial compounds could not be prevented using such a treatment.

Synthesis and characterization of iron and iron nitride microtubes obtained from biogenic iron oxide

“…However, the calcined powder shows low carbon content and is magnetic, in agreement with the calcined biogenic iron oxide reported by Tadashi et al [9]. Furthermore, calcination at 600 o C in a flow air was effective for the removal of organic matter, in agreement with the work published by Shopska et al [11]. The formation of the iron oxide during calcination was accomplished with a slight change in the red colour compared to the raw dried powder.…”