文摘
The highly dispersed MgO-nanoflake modified diatomite (MgO–D) was synthesized by a two-step process and used for the adsorption of phosphate from wastewater. The adsorbents involved were characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and field-emission scanning electron microscopy (SEM). Different conditions such as solution pH, contact time, temperature, and coexisting anions were investigated. MgO–D exhibited an excellent phosphate adsorption capacity within the pH range of 3–10 and approached its maximum of 104.94 mg g–1 at optimal conditions. The adsorption kinetics followed the pseudo-second-order kinetic model. The adsorption isotherms had a good fit with the Langmuir model, while the maximum adsorption capacity reached 137.93 mg g–1 at 298 K. The thermodynamics parameters indicated that the sorption process was spontaneous and exothermic. A mechanism that involved (i) hydroxylation of MgO nanoflakes, (ii) electrostatic attraction of negatively charged phosphate ions with hydroxylated adsorbent, and (iii) in situ chemical conversion, was proposed. Results presented here indicated the potential use of MgO–D for phosphate recovery in water.
