Partially pyrolyzed-non-activated olive stones: Characterization and utilization of olive stones partially-pyrolyzed at various temperatures for 2-chlorophenol removal from water

Abstract

This paper reports the development of the chemical and structural properties of partially pyrolyzed olive stones (OS) (at 250, 400, 500, 600, 700 and 850 °C) intended for use as a less expensive and more environmental-friendly adsorbent within water treatment applications. The following properties were followed: mass loss, surface chemistry (acid/base titrations and IR analysis), crystalline matter and elemental analysis, SEM, BET and TGA analysis. The major mass loss (68%) occurred between 250 and 400 °C. Acidic oxides disappeared after 500 °C, while surface basicity increased with increasing pyrolysis temperature. The partially pyrolyzed-non-activated OS sorbents were used for 2-chlorohenol (2-CP) removal from water, where 2-CP uptake increased with increasing pyrolysis temperature. The maximum adsorption was recorded at pH 7 using the pyrolyzed OS at 850 °C, which was only 13% more than that of OS pyrolyzed at 600 °C (sorbent carb600). So that carb600 (adsorption capacity: 34.1 mg g−1) was recommended as a cost-effective-environmental-friendly adsorbent. The re-usability of carb600 for removing 2-chlorophenol from real water sample was evident, where ∼70% of its adsorption efficiency was reserved even in the presence of competing ions.

Keywords

• Olive stones
• Controlled pyrolysis
• Water treatment
• Adsorption of phenols