含锰复合氧化物同步吸附砷、磷的界面调控机制与强化除砷原理

Adsorption technology is one of the most effective methods for removing arsenic (As) from groundwater. However, the poor performance for removing As (especially arsenite [As(III)]) under the combined pollution conditions of As and phosphate (P) is a difficult problem in the application of adsorption technology. In this study, we will prepare several kinds of Mn-oxide-containing binary oxides (MOCBOs) through an oxidation-coprecipitation process, and used them as adsorbents for removing As(III)/As(V) and P simultaneously. This research will be concentrated on the various micro-interface reaction processes, including the oxidation-adsorption process of As(III) and the competitive adsorption process of As and P. We will make efforts to analyze the functions and the transformation of the active sites on the surfaces of MOCBOs during these reaction processes, and then modify the chemical constitutions of these adsorbents for better As/P removal performances. Afterwards, we will try to reveal the dynamic processes for removing As(III)/As(V) and P at the composite interfaces, which could exhibit the capacities for both oxidation and adsorption. Several surface characterization methods, such as in-situ Fourier Transform Infrared Spectrometer (FTIR), in-situ Raman spectra, X-ray photoelectron spectroscopy (XPS) etc., will be performed to elucidate the changes in the surface properties of these adsorbents before and after the reactions with As(III)/As(V) and P. Additionally, we will explain the competitive adsorption mechanisms for As(III)/As(V) and P, together with the effects of As transformation involved in the competitive adsorption processes. Finally, the technological principle for the simultaneous removal of As and P could be proposed according to the aforementioned results, which will provide scientific evidences and a theoretical basis for the effective control of multifunctional materials to enhance the As removal under the combined pollution of As and P.

吸附法是治理地下水砷(As)污染的有效方法之一，在砷、磷（P）复合污染条件下如何提高吸附材料对As特别是三价砷[As(III)]的专性吸附效能是除砷技术面临的重要难题。本研究将以含锰复合氧化物与As、P的形态作用关系为基础，围绕As(III)氧化/吸附和As、P竞争吸附的不同微界面反应过程，采用"氧化-共沉淀"法制备不同的含锰复合氧化物并对其表面位点进行功能表达和修饰，探明"氧化/吸附"界面同步去除As(V)/As(III)和P的动态过程和水质作用要素；利用原位傅里叶变换红外光谱、原位拉曼光谱、X射线电子能谱等多种表征手段，阐明吸附材料在吸附As、P前后的结构性质变化特征，揭示As形态转化对As、P在"氧化/吸附"界面的竞争吸附机制的作用效应，提出采用含锰复合氧化物共去除As、P的技术原理，为实现As、P复合污染条件下对复合功能材料强化除As的有效调控提供科学依据和理论基础。

本项目以开发高性能的复合功能吸附剂为目标，制备出了对砷、磷均具有良好吸附性能的新型吸附材料——铝锰复合氧化物；采用多种表征手段研究了该吸附材料的表面特性，明确了该材料的最佳制备方法，通过静态吸附实验系统考察了铝锰复合氧化物对砷、磷的吸附特性和影响要素，并通过红外光谱和XPS表征等手段探明了该材料单独去除砷、磷的吸附机制。. 在上述研究基础上，我们探索了锰氧化物的掺入对铝氧化物和铁氧化物同步吸附砷&磷特性的作用效应，系统比较了铁锰复合氧化物和铝锰复合氧化物对砷、磷的吸附动力学特征和水质因子作用规律。研究发现，为获得最佳除砷效果，含锰复合氧化物的种类及成分组成需要根据砷磷比和砷形态来进行优选，在此基础上初步提出了针对不同砷&磷污染条件的吸附材料功能调控方法。. 在研究复合污染条件下的砷&磷同步吸附规律的基础上，从固液微界面反应的角度揭示了锰氧化物对吸附剂功能位点组成的影响以及砷、磷在吸附剂表面的作用机制。研究发现，锰氧化物的介入可以在铝基吸附剂或铁基吸附剂上形成具有“氧化/吸附”复合功能的新型活性位点，不同功能的活性位点能分别起到氧化三价砷和捕获五价砷或磷的作用。磷的竞争作用对三价砷的氧化以及三价砷/五价砷的吸附过程都有显著的影响。此外，五价砷/三价砷和磷在对不同功能位点的争夺能力和结合强度方面存在着较明显的差异。这为有针对性地优化调控含锰复合氧化物的成分比例提供了充分的科学依据。