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Durham University

Department of Earth Sciences

Postgraduate Students

Publication details for Prof. Chris Greenwell

Al Jaberi, Muayad, Mallet, Martine, Greenwell, H. Chris, Abdelmoula, Mustapha & Ruby, Christian (2019). Using Ca-Fe layered double hydroxide transformation to optimise phosphate removal from waste waters. Applied Clay Science 182: 105281.

Author(s) from Durham

Abstract

Single phase CaFe layered double hydroxide (LDH) minerals containing Cl− species in the interlayer was synthesized by coprecipitation with a CaII: FeIII ratio of 2: 1. In both phosphate (PO4) free water and at low aqueous PO4 concentration, the LDH was fully transformed into a mixture of a “ferrihydrite-like” material, calcite and soluble calcium species. Mössbauer spectroscopy and transmission electron microscopy showed that phosphate was removed by the “ferrihydrite like” phase that contained a significant quantity of Ca. At high phosphate concentration the Ca species released from the LDH precipitated to form hydroxyapatite leading to a maximal removal capacity of ~ 130 mg P-PO4 g−1. The CaFe LDH was deposited onto a pozzolana volcanic rock in order to perform a column experiment under hydrodynamic conditions for 70 days. A high removal capacity was observed, a qB of ~ 4 mg P-PO4 g−1 was measured at the breakthrough of the column, however the pH in the outflow was measured to be higher than 11. Such an increase was due to the very high solubility of the CaFe LDH.