含砷电子废物热解过程中砷的迁移转化行为及硫化脱除回收

With the excellent semiconducting properties, materials such as GaAs, GaInAs have been intensively applied in many electronic products such as intelligent mobile phones, computers, light emitting diodes, etc. With the increasingly upgrading speed, amounts of electronic wastes (e-wastes) containing arsenic are generating. Pyrolysis is regarded as a promising method for the resource utilization of wastes. However, when the e-wastes containing arsenic are treated by pyrolysis, there may be problems about environment contaminations and human health risks due to the uncontrolled release of kinds of arsenide speciation with high toxicity. This project will carry out an intensive study about the transfer-transportation and remove-recovery of arsenic during the pyrolysis. The arsenic speciation and distribution during the pyrolysis will be studied. The effect of sulfur on the arsenic in the pyrolysis system containing a variety of ingredients will be discussed. The forming condition of arsenic sulfide, which is an arsenide with low toxicity will be explored. On this basis, the dynamics of arsenic sulfide evaporating separation and condensing recovery will be studied, and the controlled removing can be expected. Then the uncontrolled releasing of arsenide during the pyrolysis process could be prevented. This study will contribute to the pyrolysis theory of foundations, and provide the scientific basis for the resource utilization and harmless recycling of e-wastes.

砷化镓、砷化铟镓等半导体材料具有优越的半导体性能，广泛应用于智能手机、计算机、发光二极管等电子产品中，更新换代的不断加速导致大量含砷电子废物的产生。热解技术被认为是一项有发展前景的废弃物资源化技术，但是，在处理含砷电子废物时，存在多形态、高毒性砷化物的无序释放而污染环境、危害人类健康的隐患。本项目针对含砷电子废物热解过程中砷的迁移转化与脱除回收开展深入研究。分析砷在热解过程中的形态转化与分布特征，研究多组分热解体系中硫对砷的作用方式，探索低毒性砷硫化物的生成条件，在此基础上，研究砷硫化物的蒸发分离-冷凝回收动力学，最终实现砷的可控脱除回收，从而避免热解资源化过程中各形态砷化物的无序释放。本研究有助于热解资源化基础理论的进一步完善，为电子废物的资源化、无害化回收提供科学依据。

电子废物中的LED、集成电路芯片等复杂电子元器件，同时具有砷等毒害元素以及镓、铟等稀散战略金属。在热解资源化处理过程中，封装材料中有机成分产生的-OH、Br-、Cl-等自由基会与As等发生反应，促进金属的挥发，以多种形态挥发进入热解气，不利于后续资源化利用。研究As等重金属在资源化过程中的迁移转化规律，进而对其进行有效调控，对电子废物中砷的污染防范具有重要理论意义和实际意义。本项目以LED和集成电路芯片为研究对象，阐明了“三步氧化”机理，揭示了热解过程对砷冷凝形态的影响作用；硫的引入可抑制热解过程中氧化砷的生成，在冷凝物中收集到多种砷硫化物的混合物；综合分析冷凝物的XRD检测结果和残渣的XPS检测，探明砷化镓硫化反应的生成物种类及形态；结合热力学软件，得出砷化镓基电子废弃物硫化热解调控机理的化学方程式为：2GaAs+(2x+3)S→2AsSx+Ga2S3 。本研究建立并完善了硫化调控-脱除回收机理机制，为含砷电子废物的环境友好回收提供新思路和理论依据。围绕该项目，发表标注该项目号的SCI论文共10篇，其中9篇一区论文，获国家授权发明专利4项。