College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, PR China; Key Laboratory of Resource Cycle and Pollution Control of Fujian Province, Fujian Normal University, Fuzhou 350007, PR China; Key Laboratory of Environmental Nano-technology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China; National Engineering Laboratory for VOCs Pollution Control Materials & Technology, University of Chinese Academy of Sciences, Beijing 101408, PR China.
Key Laboratory of Environmental Nano-technology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China; National Engineering Laboratory for VOCs Pollution Control Materials & Technology, University of Chinese Academy of Sciences, Beijing 101408, PR China.
J Hazard Mater. 2021 Mar 15;406:124735. doi: 10.1016/j.jhazmat.2020.124735. Epub 2020 Dec 1.
Arsenic sulfide slag (ASS) is typically by-produced from arsenic-containing wastewater treatment. In this work, a novel hydrothermal treatment method with the assistance of Fe(NO) (HT-Fe(NO)) was developed to detoxify ASS by transforming arsenic into scorodite and extracting sulfur in one step. After hydrothermal treatment, As(III) in ASS was oxidized and immobilized into the stable scorodite with a high As immobilization efficiency (~99%), and the toxicity leachability of arsenic-containing solid waste significantly reduced from 634.2 to 2.5 mg/L, well below the discharge standard of solid waste. Further study reveals that the nucleation and growth process was fit well by Avrami-Erofeev model and followed Ostwald step rule, which involved the AsS dissolution, formation of amorphous ferric arsenate and then crystallization within the amorphous precursor. In this process, sulfur originated from AsS played an important role by serving as the heterogeneous nuclei to decrease the barrier for the formation of amorphous ferric arsenate, and facilitated the transformation of as-formed scorodite from nano-sheet aggregates to the bulk and dense spherical polymorph, which further increased the stability of the arsenic contained solid product. This study will shed light on the development of new technologies for treatment of industrial solid waste and recycle of useful resources.
硫化砷渣（ASS）通常是含砷废水处理的副产物。在这项工作中，开发了一种新的水热处理方法，在 Fe(NO)（HT-Fe(NO)）的辅助下，通过一步将砷转化为硫砷铁矿并提取硫，来解毒 ASS。水热处理后，ASS 中的 As(III)被氧化并固定到稳定的硫砷铁矿中，砷的固定效率很高（~99%），含砷固体废物的毒性浸出率从 634.2 降低到 2.5mg/L，远低于固体废物的排放标准。进一步的研究表明，成核和生长过程符合 Avrami-Erofeev 模型，遵循奥斯特瓦尔德步骤规则，涉及 AsS 的溶解、无定形铁砷酸盐的形成，然后在无定形前体中结晶。在这个过程中，来自 AsS 的硫通过作为异质核发挥重要作用，降低了形成无定形铁砷酸盐的障碍，并促进了形成的硫砷铁矿从纳米片状聚集体向块状和致密的球形多晶型体的转变，进一步提高了含砷固体产物的稳定性。这项研究将为工业固体废物处理和有用资源回收的新技术开发提供启示。
