Synthesis, performance, and modeling of immobilized nano-sized magnetite layer for phosphate removal

Adva Zach-Maor, Raphael Semiat, Hilla Shemer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


A homogeneous layer of nano-sized magnetite particles (<4nm) was synthesized by impregnation of modified granular activated carbon (GAC) with ferric chloride, for effective removal of phosphate. A proposed mechanism for the modification and formation of magnetite onto the GAC is specified. BET results showed a significant increase in the surface area of the matrix following iron loading, implying that a porous nanomagnetite layer was formed. Batch adsorption experiments revealed high efficiency of phosphate removal, by the newly developed adsorbent, attaining maximum adsorption capacity of 435mg PO4/g Fe (corresponding to 1.1mol PO4/mol Fe3O4). It was concluded that initially phosphate was adsorbed by the active sites on the magnetite surface, and then it diffused into the interior pores of the nanomagnetite layer. It was demonstrated that the latter is the rate-determining step for the process. Innovative correlation of the diffusion mechanism with the unique adsorption properties of the synthesized adsorbent is presented.

Original languageEnglish
Pages (from-to)440-446
Number of pages7
JournalJournal of Colloid and Interface Science
Issue number2
StatePublished - 15 May 2011
Externally publishedYes


  • Adsorption
  • Granular activated carbon
  • Iron oxide
  • Isotherm
  • Mössbauer spectroscopy

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