基于基团配位的重金属冶炼烟气洗涤废水中砷的净化研究

Different from general arsenic containing wastewater, flue gas washing wastewater from heavy metal smelting process (commonly known as "acidic wastewater") has the characteristic of high acidity, high concentrations of arsenic in various forms. Traditional lime and sulfide precipitation method is difficult to realize advanced purification of arsenic and reach the emission standard. Nonferrous metals industry is facing a major challenge of high-concentration arsenic advanced purification from flue gas washing wastewater. The key bottleneck is that arsenic usually exists in the known anionic form of H2AsO4-、HAsO42-、AsO43- and other unknown forms, whose transformation are difficult to control. Based on the earlier research of cations (Cu2+, Pb2+, Cd2+) advanced purification by various groups complex, the new idea of controlling the arsenic pollution in acidic wastewater by group complex was developed. This study includes the following three aspects: ①arsenic distribution, transformation and controlling behavior in flue gas washing wastewater from heavy metal smelting process, ②group-complex design for various arsenic speciation, ③arsenic advanced purification mechanisms based on the group complex. Therefore, the rules of arsenic transformation and the method of group-complex design and arsenic purification during the treatment of smelting gas washing wastewater were explored. The obtained results will enrich the fundamental theory system for the advanced purification of wastewater containing heavy metals.

区别于一般含砷废水，重金属冶炼烟气洗涤废水（俗称"污酸"）具有酸度高、砷浓度高及其形态复杂多变等特征，传统石灰、硫化沉淀法难以实现砷的深度净化与达标排放，污酸中砷的处理已成为有色金属行业面临的重大环保难题。其关键瓶颈在于污酸中砷常以H2AsO4-、HAsO42-、AsO43-等已知阴离子形态和其它可能未知形态赋存，而且其形态转化难以控制。基于前期铜、铅、镉等重金属阳离子多基团配位实现深度净化研究的启示，率先提出基团配位深度净化污酸中砷阴离子的新思路，拟研究：①重金属冶炼烟气洗涤废水中砷的形态分布、转化及调控行为，②不同阴离子形态砷的基团配位设计，③废水中砷的基团配位深度净化机制。旨在揭示砷在污酸处理过程中的形态转变规律，建立不同形态砷的基团配位与净化方法，丰富重金属废水深度净化的基础理论体系。

针对有色重金属冶炼烟气洗涤废水中高浓度砷存在形态复杂多变、难以深度净化的难题，系统开展砷形态分布与转化、基团配位、净化机制研究，绘制了多元组分-As-H2O系离子分率图及Eh-pH图，发明了一种基于电化学体系辅助判定废水中未知砷形态的方法，阐明了砷在典型有色冶炼废水处理过程中的形态分布特征与转化规律；开展了酸性体系中砷酸铁配合物的形成研究，发现了FeH2AsO42+ 和FeHAsO4+两种配合物的形成机制，采用同步辐射结合量子化学计算对含砷配合物的结构进行解析及量子描述与表征；选取代表性砷净化剂——铜离子配位聚间苯二胺，开展废水中砷净化效果的影响因素研究、废水中砷深度净化的配位反应平衡研究以及及热、动力学研究，揭示深度净化含砷废水的机制，形成了复杂含砷废水深度净化技术原型。