Kinetics and thermodynamic study of phosphate adsorption on the porous biomorph-genetic composite of α-Fe2O3/Fe3O4/C with eucalyptus wood microstructure

A novel porous biomorph-genetic composite of α-Fe2O3/Fe3O4/C (PBGC-Fe/C) was prepared with eucalyptus wood template to removal phosphate from water and wastewater. Adsorption of phosphorus from aqueous solution onto the PBGC-Fe/C adsorbent has been investigated to evaluate the effects of solution pH, adsorbent grain size, contact time, initial P concentration, and temperature on the removal systematically. At the initial P concentrations of 2, 5, and 10 mg/L, the adsorption capacities for the unpulverized PBGC-Fe/C (0.841-2 mm) were determined to be 0.18, 0.34, and 0.69 mg/g, respectively, which exhibited a similar average value to those of fine particles or nanoparticles of iron oxides reported in the literatures. With increasing initial P concentration from 2 to 50 mg/L, the amounts of P sorbed on the pulverized PBGC-Fe/C adsorbent (0.074-0.149 mm) increased from 0.20 to 1.56 mg/g at 25 °C, and the corresponding removal efficiencies decreased from 98.0% to 31.3%. The adsorption could well be described by the pseudo-second-order kinetic equation and the Freundlich isotherm equation.