Biogenic iron oxides have been collected from
a water stream and subsequently magnetically modified
using water-based magnetic fluid. Both natural and magnetically
modified materials have been characterized in
detail using wavelength dispersive X-ray fluorescence
spectrometry, X-ray powder diffraction, Mo¨ssbauer spectroscopy,
electron microscopy and BET surface area
measurements. The natural material is composed of 2-line
ferrihydrite, forming hollow microtubules—sheaths of
Leptothrix ochracea
, and detrital components. As a result
of the ferrofluid modification, maghemite nanoparticles
were identified on the surface of the treated material. The
active surface area of the bulk, magnetically-modified
sample was 148 m
2 g
-1. The magnetically modified
material was tested as inexpensive magnetically responsive
adsorbent for the removal of selected organic xenobiotics,
namely organic dyes, from aqueous solutions. The
observed maximum adsorption capacities ranged between
34.3 and 97.8 mg of dye per 1 g of adsorbent.