电沉积砷锑合金及控制剧毒气体AsH3和SbH3析出的研究

The disposal and recylcle of arsenic-containing wastewater has been an important issue in both of industrial and academic communities around the world. Fabrication of nontoxic elementary arsenic from high concentration arsenic-containing wastewater by electrochemical method is one of the development directions in this field. However, the electrodeposited elementary arsenic is nonconductive and toxic AsH3 will be produced during the electrodeposition process, which restricts the application of this method. To solve these problems, we propose co-deposition of AsSb alloy by adding Sb3+ and additives into the wastewater containing arsenic and HCl acid. The influence of acidity, concentrations of As(III) and Sb(III), charge state of arsenic ion, additives, cathode and anode materials, current, potential, temperature, etc on the removal efficiency of arsenic and AsSb electrodeposition will be systemically investigate, Futhermore, both cathodic process and anodic process,as well as the nucleation and growth characteristics on electrode surface, will be investigated intensively. Associating the electrolyte compositions and electrolytic process parameters with the corresponding composition, structure and surface properties of cathode deposits, it is expected to obtain conductive AsSb layer and have a good understanding about the crystal nuleation and growth on the cathode surface, from which a relative model can be proposed. In addition, the mechanism on the evolution of AsH3, SbH3 and the main control step will be discussed, and then an effective measure to control the produce of AsH3, SbH3 is established based on the deep understanding of the effects of surface features on AsH3, SbH3 evolution. Based on these results, the methodology of AsSb alloy electrodeposition can be established. Therefore, this project has some scientific values and can provide theoretical guide for the treatment of arsenic-containing wastewater and the preparation of functional As alloy materials.

含砷废水的治理及综合回收一直是国内外关注的焦点。从高浓度含砷废水中直接电沉积制备无毒的单质砷，是处理含砷废水的发展方向之一。针对电沉积砷的不导电性及阴极有毒气体AsH3析出的问题，提出在含砷盐酸溶液中加入锑离子以及添加剂从而实现砷锑合金的电沉积以及有毒气体的抑制。本项目将系统研究溶液酸度、砷锑离子浓度及价态、添加剂，以及阴阳极材料、电流电压、温度等对砷的去除效率及电沉积砷锑合金的影响规律，进而研究盐酸体系中砷锑合金电沉积的阴阳极过程，探讨阴极表面晶核形成及晶体生长规律，建立电解液组成、电沉积工艺参数等与沉积物组成、结构及表面性质的关联模型，同时研究阴极AsH3、SbH3气体析出机理及主要控制步骤，建立阴极表面特性与阴极气体析出之间的关联，提出有效措施实现对有毒气体的控制，获得导电性良好的砷锑合金电沉积技术，为含砷废水的治理及功能性砷系合金的制备提供理论指导，实现砷资源综合回收及循环利用.

本项目针对电沉积砷的不导电性及阴极有剧毒气体砷化氢析出的问题，提出在含砷盐酸溶液中加入锑离子以及添加剂从而实现砷锑合金的电沉积以及有毒气体的抑制。系统研究了溶液酸度、砷锑离子浓度及价态、添加剂浓度以及阴阳极材料、电流密度、温度等工艺条件对电沉积砷锑合金的影响规律，同时详细研究了阴极AsH3、SbH3气体析出机理及主要控制步骤。. 研究结果表明：优化工艺条件下，As3+浓度为10 g/L，Sb3+浓度为2 g/L，盐酸浓度为4 mol/L，电流密度为4 m A/cm2，温度为20°C，电流效率达到94.74%，沉积层含70.26%As和29.74%Sb（质量分数），所制备的As-Sb合金沉积层为非晶结构。. 砷化氢的产生是一个多步骤的还原过程：(a) As3+ + 3e =As；(b) H+ + e = H*；(c) As + 3H* = AsH3。抑制H原子的产生以及降低电沉积所得单质砷的活性是抑制AsH3气体析出的有效途径。研究发现在As（III）溶液中添加柠檬酸铵、Sb3+以及增加HCl浓度，砷化氢的析出量显著下降。. 在盐酸体系中采用铜粉作为置换剂去除体系中的三价锑和三价砷，并回收盐酸。在合适条件下锑、砷的去除效率均高达99%。实现了污染物去除和回收再利用的目的。. 采用泡沫铁酸铜对含砷物料处理过程中所产生的含砷废水进行吸附处理，不仅具有良好的除砷能力，而且块体结构的泡沫金属易于回收，具有良好的循环使用性能，可实现含砷废水达标排放。. 上述研究结果将为含砷溶液的处理以及功能性砷系合金的制备提供理论指导，可实现砷资源综合回收及循环利用，具有广泛的应用前景。