Production and characterization of porous magnetic biochar : before and after phosphate adsorption insights

Oleksii Tomin*, Maryam Roza Yazdani

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)
69 Downloads (Pure)


The modification process of biochars enables different advantages including enhanced adsorption properties for different pollutants. Herein, porous magnetic biochars (PMB) were successfully produced from softwood biomass through a two-step pyrolysis process together with FeCl3 modification. The effect of production temperature on adsorption was studied at 200 or 300 °C, followed by iron salt modification and subsequent pyrolysis at 600 or 800 °C. Biochars were characterized before and after phosphate adsorption via various characterization methods to acquire structural, elemental, and morphological properties of the adsorbent. The effects of phosphate concentration, contact time, and temperature on the adsorption process were examined in the batch mode. The characterization showed embedded iron oxide crystals of 23 nm within the biochar structure with a magnetic strength of 38.9 emu/g, which can assist the separation process of the powdered adsorbent from the aqueous medium. The surface area of the PMB was measured as 93 m2/g and 0.002 cm3/g pore volume. PMB showed complete removal (100%) of phosphate at the lower concentration (5 mg/l P). At higher concentration (25 mg/l P), the biochar prepared under 200/800 °C showed the highest removal (30%). The adsorption was enhanced with time (optimal 3 h) and temperature, which shows endothermic chemisorption following Langmuir isotherm and Pseudo-second order kinetic models. The desorption study suggested the slow release of phosphate from the spent adsorbent and potential reuse for soil enhancement. These results point towards the sustainable use of PMB as an effective and magnetically recyclable adsorbent for phosphate removal and reclaim.

Original languageEnglish
Pages (from-to)849-859
Number of pages11
JournalJournal of Porous Materials
Issue number3
Early online date1 Mar 2022
Publication statusPublished - Jun 2022
MoE publication typeA1 Journal article-refereed


  • Adsorption
  • Characterization
  • Chemical activation
  • Phosphate removal
  • Porous magnetic biochar
  • Water treatment


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