纳米磷酸铈的制备及其对酸性废水中氟的吸附性能

采用液相沉淀法制备了磷酸铈纳米吸附剂(CeP)，并研究了CeP对酸性废水中氟化物的去除特性。结果表明，与纳米水合氧化铈(HCO)相比，CeP在酸性条件下具有更强的稳定性。溶液pH对CeP的除氟性能有较大影响，酸性条件更有利于CeP对氟的吸附，在pH=2~3时其除氟吸附量达到最大值。
基于CeP与氟之间的静电吸引、配体交换和内配位络合等作用，CeP对氟表现出优异的吸附选择性。CeP对氟的吸附符合伪二阶吸附动力学模型，Langmuir模型能较好地描述等温吸附过程，298 K条件下由Langmuir模型拟合所得最大吸附量为49.72 mg·g⁻¹，热力学计算结果表明CeP对氟的吸附属于自发放热过程。吸附饱和的CeP可采用NaOH溶液进行高效再生，再生后CeP的除氟性能没有明显下降，可长期重复使用，在酸性含氟废水处理领域具有良好的应有潜力。

Preparation of nano-cerium phosphate and its adsorption properties for fluoride in acidic wastewater

In this study, the cerium phosphate (CeP) nano adsorbent was synthesized by liquid-phase precipitation method for efficient fluoride removal from acidic wastewater. The results showed that CeP exhibited better chemical stability under acidic conditions compared with nano hydrated cerium oxides (HCO). Fluoride uptake onto CeP was a pH-dependent process and acidic conditions were more conducive to its adsorption towards fluoride, which could reach the maximum capacity at pH 2~3. Based on the effects of electrostatic attraction, ligand exchange and inner-sphere complexation, CeP showed a conspicuous adsorption affinity towards fluoride. The adsorption of fluoride onto CeP followed pseudo-second-order kinetic model, and the Langmuir model could better describe the adsorption isotherm process than other thermodynamic models.
The maximum adsorption capacity of CeP towards fluoride calculated by the Langmuir model was 49.72 mg·g−1, and the thermodynamic calculation results demonstrated the adsorption of fluoride was a spontaneous exothermic process. The exhausted CeP could be readily regenerated using NaOH solution, the fluoride removal performance of the regenerated CeP decreased slightly, and could be adapted for a long-term reutilization. The above results verified that CeP is an efficient adsorbent for fluoride removal from acid wastewater.