Effect of Fe(III)-modified montmorillonite on arsenic oxidation and anthracene transformation in soil

Review of Fe/Mn-based chemical stabilizers for remediating arsenic and antimony co-contaminated soil

Arsenic (As) and antimony (Sb) frequently co-occur in soil contaminated by mining, smelting and traffic emissions, creating an urgent need for effectively simultaneous remediation strategies. Although chemical stabilization has garnered significant attention for its high remediation efficiency, a systematic comparison of stabilization effects and mechanisms for As and Sb in co-contaminated soil remained unexplored. Iron-based materials are widely recognized as the most effective stabilizers for As and Sb in soil. Meanwhile, manganese-based materials, owing to their superior oxidizing capacity that maintains As and Sb in the less toxic pentavalent species, have also attracted considerable interest. Iron-manganese-based materials provide an efficient solution for stabilizing As and Sb in soil by synergistically combining the advantages of both iron and manganese components. This review therefore elaborated on the core stabilizers, including iron-, manganese-, and iron-manganese-based materials. The stabilization efficiencies and underlying mechanisms of As and Sb in soil were comprehensively examined, with key environmental factors also discussed in relation to their stabilization performance. As widely used soil amendments, raw biochar and clay materials demonstrate limited efficacy in stabilizing As and Sb in soil. However, they can be employed as functional modifiers to enhance the dispersion of iron or manganese particles, thereby improving stabilization performance. While current progress is systematically evaluated, the development of stabilizers enabling simultaneous immobilization of As and Sb remains a critical research priority for future research.

Arsenic(III) sequestration by terrestrial-derived soil protein: Roles of redox-active moieties and Fe(III)

Glomalin-related soil protein (GRSP) has demonstrated significant potential for water purification and remediation of heavy metals in soils; however, its redox reactivity for As(III) sequestration and the corresponding redox-active component are still poorly understood. This study investigated the photochemical properties of GRSP and its mechanism of oxidation/adsorption of As(III). The results showed that UV irradiation triggered electron transfer and the production of reactive oxygen species (ROS) in GRSP, thereby facilitating As(III) oxidation with promotion rates ranging from 43.34 % to 111.1 %. The oxidation of As(III) occurred both on the GRSP photoforming holes and in the ROS reaction from the oxygen reduction products of the photoforming electrons. OH• and H2O2 played an important role in the oxidation of As(III) by GRSP, especially under alkaline conditions. Moreover, the presence of Fe(III) in GRSP facilitated the formation of OH• and its the oxidation capacity towards As(III). The binding of As(III) to the -COOH, -OH, and -FeO groups on the GRSP surface occurred through surface complexation. Overall, these findings provided new insights into the roles of the redox-active moieties and Fe(III) on GRSP in the promoted oxidation of As(III), which would help to deepen our understanding of the migration and transformation of As(III) in soils.

Recent advances in soil remediation technology for heavy metal contaminated sites: A critical review

With the increasing development of industry and urbanization, heavy metal contaminated sites have become progressively conspicuous, particularly by unreasonable emissions from electroplating, nonferrous metals smelting, mine tailing, etc. In recent years, soil remediation technologies for heavy metal contaminated sites have developed rapidly. New and effective remediation technologies have emerged successively, and more successful practical applications have appeared. Therefore, systematical summarization of the current progress is essential. As a result, in this paper, some mainstream soil remediation technologies for heavy metal contaminated sites, including physical remediation (soil thermal desorption and soil replacement), bioremediation (phytoremediation and microbial remediation), chemical remediation (chemical leaching, chemical stabilization, electrokinetic remediation-permeable reactive barrier, and chemical oxidation/reduction), as well as various combined remediation are comprehensively reviewed. The influencing factors, advantages, disadvantages, remediation mechanism, and practical applications are also deeply discussed. Besides, the corresponding remediation strategies are put forward for the remediation of heavily polluted sites such as the chemical industry, smelting, and tailing areas. Overall, this review will be beneficial for the in-depth understanding and provide references for the reasonable selection and development of soil remediation technology for heavy metal contaminated sites.