Effects of the pyrolysis process on the oil sorption capacity of rice husk

Fixed bed slow pyrolysis experiments on rice husks were carried out in order to determine the effect of pyrolysis temperature upon: porous structure; surface morphology; phase composition; total amount, nature and distribution of the volatile compounds finely dispersed on the solid pyrolysis residues. The pyrolysis experiments were performed within the temperature range 250–700 °C. The sorption capacity of pyrolyzed rice husks for crude oil was determined. The results indicate that the increase in oil sorption capacity of rice husks after pyrolysis is the result of mutual influence of the above mentioned parameters. It was established that the oil sorption capacity was more strongly influenced by the porous structure of the adsorbents than by their phase composition and by the nature and amount of finely dispersed fluids. For achieving the purpose that was set in advance, the capabilities of: scanning electron microscopy, mercury porosimetry, Brunauer–Emmett–Teller method, Fourier transform infrared spectroscopy, gas-chromatography/mass spectrometric analysis, extraction and gravimetric analysis were used.

► The pyrolysis of rice husk results in a solid pyrolysis residue with: advanced macroporous structure, high specific surface area, deposited on it different types of oleophilic compounds.
► Amount and type of finely dispersed fluids on the solid pyrolysis residue and structural characteristics are a function of the pyrolysis temperature.
► The solid pyrolysis residues are natural composite C/SiO2 containing materials. Their physical–chemical characteristics make them suitable for purification of waste waters from different pollutants.
► The solid pyrolysis residues possess high adsorption capacity with respect to adsorption of crude oil from aqueous media.