Efficient removal of lipophilic compounds from eucalyptus wood by sewage sludge-based adsorbents

Abstract

Sewage sludge is a byproduct of wastewater treatment. When processed, this residue can also be used as adsorbent. The aim of this study was to produce adsorbents from the sewage sludge, characterize its structure and evaluate the efficiency in adsorption of lipophilic wood compounds. The sewage sludge was calcinated at seven temperatures (400-1000°C) for five hours. The morphology and texture properties of the materials were evaluated by scanning electron microscopy and nitrogen isotherms. The presence of chemical functional groups at their surface was analyzed by Fourier transformed infrared spectroscopy. Lipophilic compound adsorption rate was evaluated by gas chromatography-mass spectrometry. The results were compared with talc, an adsorbent traditionally used by the industry. The increase in temperature directly contributed to a decrease in the specific surface area. The adsorbents obtained between 600 and 700°C removed more than 60% of the lipophilic wood compounds, corresponding to 94.1% of the total amount of lipophilic compounds. These values are much higher than those presented by talc, being 2 and 11.8%, respectively. Therefore, the produced adsorbents can be studied as a new material in the removal of lipophilic wood compounds.