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(NO₃)₃ (HT-Fe(NO₃)₃) 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 As₂S₃ dissolution, formation of amorphous ferric arsenate and then crystallization within the amorphous precursor. In this process, sulfur originated from As₂S₃ 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）通常是从含砷废水处理过程中产生的副产品。在这项工作中，一种新的借助Fe（NO ₃）₃（HT-Fe（NO ₃）₃）被开发为通过将砷转化为臭葱石并一步提取硫来解毒ASS。经水热处理后，ASS中的As（III）被氧化并固定在稳定的臭葱石中，As固定效率高（〜99％），含砷固体废物的毒性浸出能力从634.2大大降低至2.5 mg / L，远低于固体废物的排放标准。进一步的研究表明，Avrami-Erofeev模型与成核和生长过程非常吻合，并遵循Ostwald步骤法则，其中涉及As ₂ S ₃溶解，无定形砷酸铁的形成，然后在无定形前体中结晶。在此过程中，硫源自As ₂ S ₃通过充当异质核来减少形成非晶态砷酸铁的障碍，并促进形成的臭葱石从纳米片状聚集体转变为块状和致密的球形多晶型物，从而发挥了重要作用，进一步提高了其稳定性。含砷的固体产物。这项研究将为开发用于处理工业固体废物和回收有用资源的新技术提供启示。