Study On Adsorption And Release Behavior Of Sb In Soil Of Antimony Ore Smelting Mine

China has the word's largest of antimony.Sb mining and smelting processes,large of Sb have been released resulting in serious Sb contamination of the local environments and threat to human health.In order to deepen the understanding of the fixation,migration and transformation of Sb in the antimony smelting area,and provide a theoretical basis for the prevention and control of soil pollution,We investigated Basic physical and chemical properties of soils,the isothermal adsorption process and adsorption kinetics of Sb?V?in wasteland and forest land of the smelting area and the effect of soil organic matter on the adsorption process by batch experiment,Combined with the actual situation of the study area,at solution pH?4.5,6,7.5?conditions was simulated to study the release behavior of Sb in the smelting area,At the same time,the effect of removing organic matter on the release of Sb was discussed.Results showed that:?1?The minerals in the soil of the study area are mainly quartz,containing a small amount of illite,hornblende,calcite,dolomite,kaolinite,iron minerals and montmorillonite.The content of soil organic matter in the study area ranges from 11.77g/kg to 50.15 g/kg,and the average organic matter in forest land is higher than the cultivated land and wasteland.The content of calcium carbonate is 1.12-15.73g/kg,and the average content of calcium carbonate shows that the wasteland soil is higher than the cultivated land than the forest.The pH ranged from 4.9 to 7.8with an average of 6.7.The cation exchange capacity in the study area ranges from 13 to 38 cmol/k.The soil near the mining area was contaminated by Sb,Pb and As from the chimney.the average content of Sb in the contaminated area is 232.8 mg/kg,and the average content of Pb is 303.8mg/kg.The average content of As is 250.6 mg/kg.The speciation of antimony in soil has following distribution order:residual phase>Fe/Mn hydrous oxides>organic/sulphidic phase>cation exchangeable and water-soluble fraction>carbonate fraction.?2?The adsorption isotherms of wasteland and woodland soils fitted with both the Langmuir and Freundlich equations very well?R²?0.988?.The wasteland soils had the larger adsorption capacity to Sb?V?than the woodland soils,and its adsorption amount is 2.9 times that of woodland soils.Wasteland soils showed a strong ability to adsorb Sb?V?,especially in conditions with higher concentrations of Sb.Combined with the basic physicochemical properties and mineralogical characteristics of the soils,this study suggested that clay,iron minerals and calcium carbonate are the main factors impacting soil adsorption of Sb?V?.The effect of organic matter?OM?on soil adsorption of Sb?V?was only observed under the condition of low initial concentration of Sb?V?.However,under the condition of high initial concentration of Sb?V?,the effect of OM on soil adsorption was not obvious..?3?Sb?V?adsorption kinetics for all the treatments were initially fast in the first 70 min,and then the adsorption continued at a slower rate for the observation period of the experiments.The adsorption kinetics of Sb?V?on the both of wasteland and woodland soils followed the Elovich equation under the condition of low initial concentration?C₀=0.01mM?;in the condition of medium initial concentration?C₀=0.2mM?,while double constant equation fitted the best for the wasteland soils,and Elovich equation fitted the best for the woodland soils,and in the condition of high initial concentration?C₀=2mM?,double constant equation fitted the best for the wasteland soils,and the pseudo-first-order and pseudo-second-order models were suitable for fitting the process of Sb?V?adsorption on woodland soils.?4?The release of Sb in the soil increases with time,and the release of Sb is a slow process.After 7 days,the release does not reach equilibrium.The maximum release of Sb from organic matter removal is 3.3 times that of the original soil.It shows that soil organic matter can effectively inhibit the activity of Sb.?5?The release of Sb is strongly influenced by the pH,Since the Sb in the watery environment mainly is[Sb?OH?₆^-],The release amount of soil Sb has a positive correlation with the pH value of the system.This feature is especially obvious under the condition of pH?7,indicating that the alkaline environment is more conducive to the release of Sb.The study area is a typical acid rain area,and its acid deposition can induce the release of Sb to a certain extent.The wide distribution of carbonate rocks in the study area makes the pH value of the system gradually weaken from weak acid to weakly alkaline under the action of carbonate rock.Thus exacerbates the release of Sb,thereby increasing the endangering and risk of the release of Sb in the soil mites.