| With rapid development of non-ferrous metal industry and mining in our country,a large amount of industrial antimony-containing wastewater and antimony ore residues have entered the water environment,increasing the content of heavy antimony in the water environment,causing heavy metal antimony pollution in the surface water and the mining area,which seriously harms human health.The use of new modified low-cost adsorbents to treat antimony in wastewater has received widespread attention.In recent years,making full use of the adsorption capacity of iron oxides on antimony,and developing sepiolite-loaded composite supported modified adsorbents is a hot spot in today’s research.In this paper,acid-base composite modification and ferric chloride modified sepiolite were used to load iron oxyhydroxide（Fe OOH）on sepiolite to prepare an iron-modified acid-base composite modified sepiolite composite adsorbent（HI/ABsep）,and compare the adsorption performance of other modified sepiolite with other modified sepiolite.Through a series of static adsorption experiments,the effects of the dosage of different adsorbents,p H value of the solution,contact time and strength of the competitive coexisting ions in the solution on the adsorption effect were studied.At the same time,the reusability of the materials was tested.Through specific surface area and aperture analysis（BET）,X-ray diffractometer（XRD）,scanning electron microscope（SEM）,infrared spectroscopy（FTIR）,etc,the physical and chemical state of sepiolite before and after modification was characterized and analyzed.And through the kinetic equation,thermodynamic equation and other related theoretical knowledge,the mechanism of Sb（Ⅲ）adsorption by the HI/ABsep composite adsorbent prepared with sepiolite as the raw material was studied.The research results show that the modified sepiolite composite adsorbent HI/ABsep has uneven surface and well-developed pore structure.The iron oxide on its surface is proved to be hydroxy iron Fe OOH by characterization.The adsorption of Sb（Ⅲ）by HI/ABsep basically reached equilibrium at 180 min,and it has a certain buffering capacity for p H.For the Sb（Ⅲ）solution with an initial concentration of 10 mg/L,when the dosage is 100 mg（2 g/L）,the p H value of the solution is 6.0,and the contact time is 180 min,the HI/ABsep composite material has a positive effect on Sb（Ⅲ）The removal rate can reach 95.47%.The eight competitive cations and anions studied in this paper have almost no effect on the Sb（Ⅲ）removal performance of the modified sepiolite composites at low strength.After five adsorptiondesorption experiments,the Sb（Ⅲ）removal rate of the prepared HI/ABsep composite material dropped by about 25%,but remained above 72%.In the kinetic study,the quasi-second-order kinetic model can well describe the effect of the prepared HI/ABsep composite on Sb（Ⅲ）,and it is speculated that the adsorption process is dominated by chemical adsorption.In the study of adsorption isotherms,it is found that both the Langmuir isotherm adsorption model and the Freundlich adsorption isotherm model can describe the process of HI/ABsep composites adsorbing Sb（Ⅲ）at different temperatures,and the Freundlich model shows a higher correlation The coefficient indicates that the adsorption process may show as uneven multi-layer adsorption.The values of the parameter KL in the Langmuir isotherm adsorption model and the parameter 1/n in the Freundlich adsorption isotherm model are between 0-1,which indicates that the prepared HI/ABsep has a higher affinity for Sb（Ⅲ）.The Langmuir model is fitted under the conditions of p H=6 and temperature of 298.15 K,and the maximum adsorption capacity of the material is 25.73 mg/g.The study of thermodynamic parameters found that the adsorption reaction is a spontaneous endothermic reaction,and increasing the temperature is more conducive to the material’s full performance of adsorption.The characteristic peaks of Fe-O bond shifted after HI/ABsep composite material adsorbed Sb（Ⅲ）by FTIR and XPS analysis.The antimony removal mechanism of the adsorbent includes physical adsorption such as pore effect and electrostatic effect on the one hand,and chemical adsorption dominated by the hydroxyl iron structure on the other hand.In a word,the HI/ABsep composite prepared in this research has the advantages of good adsorption,wide p H adaptability,broad source of raw materials and easy preparation.It is of great practical significance to apply it to the treatment of heavy metal wastewater. |
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