Evaluation of phosphorus adsorption capacity of sesame straw biochar on aqueous solution: influence of activation methods and pyrolysis temperatures

J. H. Park, Y. S. Ok, S. H. Kim, J. S. Cho, J. S. Heo, R. D. Delaune, D. C. Seo

Research output: Contribution to journalArticlepeer-review

126 Citations (Scopus)


The phosphorus (P) adsorption characteristic of sesame straw biochar prepared with different activation agents and pyrolysis temperatures was evaluated. Between 0.109 and 0.300 mg L−1 in the form of inorganic phosphate was released from raw sesame straw biochar in the first 1 h. The release of phosphate was significantly enhanced from 62.6 to 168.2 mg g−1 as the pyrolysis temperature increased. Therefore, sesame straw biochar cannot be used as an adsorbent for P removal without change in the physicochemical characteristics. To increase the P adsorption of biochar in aqueous solution, various activation agents and pyrolysis temperatures were applied. The amount of P adsorbed from aqueous solution by biochar activated using different activation agents appeared in the order ZnCl2 (9.675 mg g−1) > MgO (8.669 mg g−1) ⋙ 0.1N-HCl > 0.1N-H2SO4 > K2SO4 ≥ KOH ≥ 0.1N-H3PO4, showing ZnCl2 to be the optimum activation agent. Higher P was adsorbed by the biochar activated using ZnCl2 under different pyrolysis temperatures in the order 600 °C > 500 °C > 400 °C > 300 °C. Finally, the amount of adsorbed P by activated biochar at different ratios of biochar to ZnCl2 appeared in the order 1:3 ≒ 1:1 > 3:1. As a result, the optimum ratio of biochar to ZnCl2 and pyrolysis temperature were found to be 1:1 and 600 °C for P adsorption, respectively. The maximum P adsorption capacity by activated biochar using ZnCl2 (15,460 mg kg−1) was higher than that of typical biochar, as determined by the Langmuir adsorption isotherm. Therefore, the ZnCl2 activation of sesame straw biochar was suitable for the preparation of activated biochar for P adsorption.

Original languageEnglish
Pages (from-to)969-983
Number of pages15
JournalEnvironmental geochemistry and health
Issue number6
Publication statusPublished - 2015 Dec 1
Externally publishedYes

Bibliographical note

Funding Information:
This research was supported by the National Research Foundation of Korea grant funded by the Korea Government (Ministry of Education, Science and Technology), [2012R1A2A2A01015706, 2014R1A1A2007515].

Publisher Copyright:
© 2015, Springer Science+Business Media Dordrecht.


  • Activated biochar
  • Freundlich model
  • Langmuir model
  • Phosphorus adsorption
  • Pyrolysis temperature
  • Sesame straw biochar

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Water Science and Technology
  • General Environmental Science
  • Geochemistry and Petrology


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