新型镧铁复合吸附除磷剂的合成及其除磷机理

Phosphrous removal from wastewater is the important approach for the prevention of eutrophication and the control of water sollution. The study of the highly effective adsorbent with low cost for phosphate removal is in urgent demand..Activated lanthanum have attracted more attention due to their high phosphate adsorption capacity. Activated iron has the advantage of cheap price and affinity to phosphate. Activated carbon fibers (ACF) have demonstrated many properties, including cheap and easily availability, high adsorption capacity, well intensity, stable chemical property, convenient regeneration and simple operation. Considering their dephosphorization effects together, the novel complex phosphorus adsorbent from lanthanum, iron and ACF (denoted as La-Fe-ACF), is prepared and employed for phosphate removal. Response surface methodology (RSM) is employed to assess the individual and collective effects of the main independent parameters on the phosphate removal; Static, dynamic and wastewater experiments of adsorption and desorption are carried out to investigate the phosphrous removal capability and regeneration ability of La-Fe-ACF; In addition, the relationship between the structure and the phosphate adsorption capacity of La-Fe-ACF is investigated by multiplicate instrumental analysis means, original observation method, the adsorption thermodynamics and kinetics, and the studies of pH value and ionic strength on phosphate adsorption. The phosphrous removal mechanism is discussed. Then, based on the relationship of structure with effect and the phosphrous removal mechanism, the synthesis of novel high-performance and economical La-Fe-ACF and the efficient phosphrous removal process is directed. .The project has the great reference value and theoretical basis for the preparation and developing of dephosphorization adsorbent with high-performance and low cost. It also enriches the application of the rare earth in water control.

有效降低废水中磷的含量是防治水体富营养化、治理水体污染的重要途径，高效、经济除磷剂的研发是环保领域十分迫切的任务。.活性镧具有磷吸附容量高的突出优点，活性铁具有价廉、除磷的特点，活性炭纤维具有易得、吸附强、强度好、性质稳定、易于再生、操作简便等优良性能。考虑到三者之间的协同除磷作用，本项目拟合成镧铁活性炭纤维复合吸附除磷剂La-Fe-ACF，应用响应曲面法分析各单因素及交互作用对除磷性能的影响；通过静态、动态和废水吸脱附实验，考察La-Fe-ACF除磷性能和再生能力；通过多种仪器分析手段、原位观测方法、吸附热动力学研究、吸附过程pH值及共存离子研究等，揭示La-Fe-ACF组成结构与除磷性能间的关系，探讨吸附除磷作用；进而以构效关系及除磷作用为基础，有目的地指导设计合成及有效除磷。.本项目对于高效、经济除磷剂的研制具有重要的参考价值和理论依据，并丰富和拓展了稀土材料在水处理领域的应用。

过量磷导致水环境生态平衡的破坏、引起水体富营养化现象日趋严重。对水体中的过量磷进行去除是治理水体富营养化、防治水体污染的重要途径。近年来，吸附法由于占地面积小、工艺简单、操作方便、无二次污染等优点而倍受关注，寻找新的吸附剂是其关键所在。.稀土镧具有优异的除磷吸附容量,较现有其它合成吸附材料成数倍地提高,是一种可能的高效废水除磷吸附材料；而金属铁则具有价廉、易得的优点，在废水除磷方面已被广泛应用，是一种理想的廉价吸附材料。本文选用具有高比表面积、大孔容、价格低廉和容易回收等优点的活性炭纤维吸附材料作为载体，分别将金属镧、铁及其复合氢氧化物颗粒负载在活性炭纤维上制备了一系列吸附剂：ACF-La、ACF-Fe和ACF-LaFe，利用单因素和响应曲面法(RSM)优化了吸附剂的制备参数；研究了吸附条件(初始磷浓度、投加量、吸附时间、pH、温度、干扰离子)对吸附材料的除磷性能的控制作用并考察了其再生性能；并通过研究吸附剂在不同pH下对磷吸附特性和借助X射线衍射光谱仪(XRD)、红外光谱(FT-IR) 、扫描电子显微镜(SEM) 及比表面积（BET）的表征方法，探讨了吸附材料的除磷作用机制。主要结论如下：.1. 成功制备了具有良好除磷效果的负载了镧、铁及镧铁复合活性颗粒的活性炭纤维复合吸附材料ACF-La、ACF-Fe、ACF-LaFe，材料在吸附过程中具有较好的稳定性。.2．吸附性能研究表明：吸附剂ACF-La，ACF-Fe，ACF-LaFe的吸附容量分别为15.3mg/g，12.86mg/g，29.44mg/g；吸附主要以单分子层化学吸附为主；高温不利于吸附过程；吸附剂的吸附容量随pH值变化显著, 同时水体中共存阴离子的对磷的吸附有负面的干扰影响；.3. 再生性能表明：吸附剂ACF-La，ACF-Fe，ACF-LaFe对磷的吸附主要以化学结合为主，结合比较紧密，NaOH脱附液对材料吸附活性位点的恢复效果有限。.4．除磷的作用机制：三种吸附剂具有类似的吸附机理，吸附性能主要由活性炭纤维表面负载的金属活性组分提供，吸附机理包括静电吸引作用、离子交换作用和Lewis酸碱作用。pH值对吸附机理有重要影响，随着吸附液pH增大，静电吸附作用和离子交换机理对吸附剂除磷的贡献逐渐变弱，而路易斯酸碱作用逐渐占到主导地位。