Adsorption characteristics of the phosphate on the hydrous ceric oxide
以综合利用稀土矿物资源和开发新型高效除磷吸附材料为目的,对稀土材料水合氧化铈(HCO)进行了吸附除磷的性能评价。实验结果表明,水合氧化铈具有优异的除磷特性,在较宽pH值范围内对磷酸根有较强的吸附能力,酸性条件更有利于吸附反应的进行。其吸附等温线能很好地用Langmuir方程进行描述。对于低浓度(1mg/L)的含磷溶液,水合氧化铈在所选pH值条件下能很快对磷酸根达到完全吸附。水合氧化铈对磷酸根的吸附属于吸热反应,其标准吸附热为6.24kJ.mol-1。但温度对吸附反应的影响较小。从实验结果推测,水合氧化铈对磷酸根的主要反应机理趋向于化学专性吸附。The present paper aims to give a report on our research of the adsorption characteristics of the phosphate on the hydrous ceric oxide. Seeking the utilization of rare earth resources and the development of novel efficient adsorbents for phosphate from wastewater, we have chosen the hydrous ceric oxide (HCO), CeO2·xH2O, as adsorbent material and made experimental measurements to test their adsorption features, including the adsorption isotherms, the influence of pH and initial phosphorus concentration, the adsorption rate and adsorption thermodynamics, etc. From our testing we have found that the HCO adsorbent is effective for removing phosphate from water. First of all, it was found that the adsorption isotherms are well-fit for the Langmuir model of adsorption at different pH and at different temperatures. Then, the adsorption capacity can keep comparatively high in a wide range of pH, though its acidic condition was quite suitable. At lower initial concentrations (1 mg/L),the phosphate removing rate could be easily made as high as 100 % nearly instantly at the selected pH values. Our investigation on its adsorption thermodynamics demonstrates that the adsorption is an endothermic reaction, with its thermodynamic adsorption parameters being: ΔH =-6.24 kJ·mol-1, which indicates that the effect of temperature on the phosphate adsorption is of no importance. Therefore, it can be presumed that the principal adsorption mechanism is that phosphate is a specific adsorbent onto HCO surfaces.