Study on sodium functionalized ultrasonic-diatomite and its performance for phosphorus removal

The sodium functionalized ultrasonic-diatomite (U-D-Na) was used as an adsorbent to remove phosphorus from an aqueous solution. After simple ultrasonic purification, diatomite was functionalized by the cheap NaCl reagent to prepare U-D-Na. The microstructure and properties of U-D-Na were achieved by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller, Fourier-transform infrared spectroscopy and thermogravimetry/differential scanning calorimetry. The effect on the contact time, the temperature, the dosage of adsorbent, pH and the initial concentration of phosphorus were investigated during the adsorption kinetics and equilibrium studies. The U-D-Na exhibited that the adsorption efficiency reached more than 90% at optimal conditions. Multiple cycles of adsorption and desorption tests showed that the adsorbent performed good renewability. The experimental values were coincidence with the pseudo-second-order kinetic model and the Langmuir isotherm model. Also, thermodynamic parameters such as the Delta G degrees, Delta H degrees and Delta S degrees illustrated that the adsorption process is essentially exothermic and spontaneous. The results indicated that a promising application prospect for water pollution management by U-D-Na.