The synthetic ferrihydrite, FerrorMox (FM), was used as adsorbent for removing phosphorus from wastewater. SEM, EDS, XRD, FTIR and Raman were used to characterize FM, and the results indicated that FM was amorphous 2 L ferrihydrite and was composed of Fe, O, Ca and Si, etc. Afterwards, FM was applied to adsorb phosphorus from wastewater, and the adsorption performance, influence factors and adsorption mechanism were investigated. The phosphorus removal rate reached 99.14% under the condition of adsorption time of 60 min, initial pH phosphate solution of 2, relative dosing quantity of 7 g·L-1, reaction temperature of 25℃, initial concentration of 10 mg·L-1, and solution volume of 50 mL. Adsorption isotherms were well fitted with the Langmuir isothermal adsorption model at different temperature with the correlation coefficient reaching above 0.95. The thermodynamic parameters showed that the phosphorus adsorption by FM was a spontaneous endothermic reaction. The phosphate removal kinetics well followed both pseudo-first-order model and pseudo-second-order model. About 99% of phosphate adsorbed on FM could be desorbed in 0.1 mol·L-1 NaOH solution. Therefore, FM was a promising absorbent material for the removal of phosphate from waste water.
Keywords: characterization of morphology; desorption; dynamics; ferrihydrite; isothermal adsorption; thermodynamics.