Research Progress and Development Trend of Antimony Contaminated Soil Remediation Technology

Antimony is a toxic metallic element and an important strategic resource,that is widely used with flame retardants and lead battery industries. The main large-scale antimony in the world is distributed in the Pacific Rim continental shell,and China ranks first in both antimony deposit reserves and antimony deposit output. Antimony mining and antimony smelting are the main sources of antimony pollution. During high temperature combustion of antimony-containing fuels,antimony is released into the air in the form of soluble and exchangeable state in particulate matter. Mining and smelting activities discharge a large amount of antimony-containing wastewater into the river. At the same time,the soil around the antimony mining area is seriously polluted. In China,antimony ore deposit is mainly distributed in Hunan,Guizhou,Yunnan,Guangxi and other provinces,and the degree of antimony contamination in soil decreases gradually from southwest to northeast. Antimony mainly exists in the soil in the form of inorganic substances of antimony trivalent and antimony pentavalent. The oxidation state of antimony in soil depends on pH and redox potential. Under oxidation conditions,the antimony usually exists in the form of Sb(OH)6- at pH ranging from 2.7 to 12. In reducing conditions,the antimony usually exists in the form of Sb(OH)3at pH ranging from 2 to 10.7. The redox process of antimony is related to the oxides,hydroxides,organic matter and microorganisms in soil. Fe(III)and Mn(III/IV)in soil can effectively oxidize Sb(III)to Sb(V). Natural organic matter as electron donor can directly oxidize Sb(III)to Sb(V)by producing reactive oxygen species and semiquinone radical. Adsorption/desorption and dissolution/precipitation are the main controlling processes of antimony migration in soil. Clay minerals in soil can reduce the migration of antimony by adsorption. In addition,stibnite(Sb2S3),senarmontite(Sb2O3),and antimony oxide(Sb2O4)in the environmental are released under the influence of light,pH,dissolved oxygen,and soil organic matter. In this paper,the research progress of antimony contaminated soil remediation technology was reviewed and the advantages and disadvantages of different remediation technologies and their application range were compared. The results showed that the soil pollutants were not treated by the methods of turning soil and covered with soil from other places,which was easy to cause secondary pollution. Soil leaching technology had high remediation efficiency and could completely remove heavy metals. However,the high efficiency leaching agent was expensive and the soil nutrient elements would be lost after leaching. It was suitable for heavily polluted sites with large area and high permeability coefficient. The fixed/stabilized technique had a short remediation period,but did not reduce the total amount of heavy metals in soil,so there was a risk of heavy metals being reactivated. Phytoremediation techniques were simple to operate and free of secondary contamination. However,it was dependent on hyperaccumulator,and there were few hyperaccumulator of antimony at present. Microbial remediation technology could improve soil fertility while removing heavy metals in soil,and could be widely used in collaboration with other remediation technologies. But there was a risk of invasion by exogenous microorganisms. Due to the complexity of contaminated sites, the remediation technology of antimony contaminated soil would be developed in the direction of synergistic interaction between materials and technology,and between technology and technology. © 2024 Editorial Office of Chinese Journal of Rare Metals. All rights reserved.