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Characterization of KOH modified biochars from different pyrolysis temperatures and enhanced adsorption of antibiotics

Lookup NU author(s): Professor David WernerORCiD

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Abstract

Poplar biochars from pyrolysis at temperatures of 300, 500 and 700 °C were modified with KOH and characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and nitrogen adsorption–desorption isotherm studies. Adsorption experiments were carried out on the modified biochars to remove tetracycline (TC) from aqueous solution. The results showed that KOH modification could increase or decrease TC adsorption onto biochars depending on the different pyrolysis temperatures. Maximum adsorption capacities (q_e,m) of TC in modified biochar from a low pyrolysis temperature of 300 °C increased up to 21.17 mg g⁻¹ relative to 4.30 mg g⁻¹ in unmodified biochar of 300 °C (final TC concentrations were 8.83 and 25.70 mg L⁻¹, respectively). In contrast, q_e,m decreased from 7.37 and 11.63 mg L⁻¹ to 4.97 and 7.13 mg L⁻¹ in biochars from higher pyrolysis temperatures of 500 and 700 °C with and without modification, respectively, even with an increase in S_BET. The adsorption ability of biochar can remain over a wider range of pH in modified biochar relative to unmodified biochar. Further analysis indicated that there was a strong linear regression relationship between q_e,m and total functional oxygen groups using Bohem titration (n = 6, R² = 0.84), whereas no significant relationship was observed between q_e,m and S_BET in this experiment. The result suggested that KOH modification of biochar from a low pyrolysis temperature can enhance TC adsorption and can be used over a wide range of pH, which may be a good choice for disposal of organic pollutants in aqueous solution.

Publication metadata

Author(s): Huang H, Tang J, Gao K, He R, Zhao H, Werner D

Publication type: Article

Publication status: Published

Journal: RSC Advances

Year: 2017

Volume: 7

Issue: 24

Pages: 14640-14648

Online publication date: 06/03/2017

Acceptance date: 24/02/2017

Date deposited: 06/03/2017

ISSN (electronic): 2046-2069

Publisher: Royal Society of Chemistry

URL: http://dx.doi.org/10.1039/C6RA27881G

DOI: 10.1039/C6RA27881G

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