Multistage optimizations of slow pyrolysis synthesis of biochar from palm oil sludge for adsorption of lead

Xin Jiat Lee, Lai Yee Lee*, Billie Yan Zhang Hiew, Suyin Gan, Suchithra Thangalazhy-Gopakumar, Hoon Kiat Ng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


This research investigated the removal of lead (Pb2+) by a novel biochar derived from palm oil sludge (POS-char) by slow pyrolysis. Multistage optimizations with central composite design were carried out to firstly optimize pyrolysis parameters to produce the best POS-char for Pb2+ removal and secondly to optimize adsorption conditions for the highest removal of Pb2+. The optimum pyrolysis parameters were nitrogen flowrate of 30 mL min−1, heating rate of 10 °C min−1, temperature of 500 °C and time of 30 min. The optimum Pb2+ adsorption conditions were concentration of 200 mg L−1, time of 60 min, dosage of 0.3 g and pH of 3.02. The various functional groups within POS-char played a vital role in Pb2+ uptake. Regeneration was demonstrated to be feasible using hydrochloric acid. Adsorption equilibrium was best described by Freundlich model. At low concentration range, adsorption kinetic obeyed pseudo-first-order model, but at high concentration range, it followed pseudo-second-order model. Overall, the results highlighted that POS-char is an effective adsorbent for Pb2+ removal.

Original languageEnglish
Pages (from-to)944-953
Number of pages10
JournalBioresource Technology
Issue numberPart A
Early online date1 Sept 2017
Publication statusPublished - Dec 2017


  • Adsorption
  • Biochar
  • Palm oil waste
  • Pb
  • Process optimization

ASJC Scopus subject areas

  • Bioengineering
  • Environmental Engineering
  • Renewable Energy, Sustainability and the Environment
  • Waste Management and Disposal


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