Study On The Removal Of Antimony And Molybdenum By Using Activated Carbon Loaded Iron Composite Adsorbent

With the widely using of antimony molybdenum and their compounds in production and life,the demand for antimony and molybdenum is constantly increasing,leading to more antimony minerals and molybdenum minerals were exploited.However,the high emissions and high pollutions mining method,which caused serious water environmental pollution.Therefore,how to effectively remove the pollution of antimony and molybdenum in water has caused the extensive attention.In this paper,activated carbon loaded iron composite adsorbent was prepared by using activated carbon and ferric salts as raw materials,and the composite adsorbent was used for removing antimony and molybdenum in aqueous solution.The following experimental results were obtained:?1?Activated carbon particle size,the type of iron salts,the number of loading has great impacts on the removal of antimony in aqueous solution.Under the conditions of Sb???concentration of 5mg/L,iron salt concentration of 0.25mol/L and temperature of 298.15K,activated carbon with particle size of 0.425-1mm was used,iron sulfate was used as iron salt and the equilibrium adsorption capacity was22.93mg/g,the removal rate reached 89.12%.?2?The effects of initial pH of solution,competing anions(Cl^-,SO₄^2-,NO₃^-,PO₄^3-)on the adsorptions of Sb???,Sb???,Mo???were investigated.The results showed that under the conditions of Sb???concentration of 5mg/L and dosage of1g/L,the removal efficiency of Sb???was the best when the pH was 5.88 and the removal rate reached 91.28%;Under the conditions of Sb???concentration of 5mg/L and dosage of 1g/L,The best removal efficiency of Sb???was at pH 2.97 with the removal rate of 72.78%;Under the conditions of Mo???concentration of 5mg/L and dosage of 1g/L,the best removal efficiency of Mo???was at the pH 3.24,the removal rate was 80.9%.In the experimental concentrations range,the adsorption of Sb???on activated carbon loaded iron is not affected by the competing anions(Cl^-,SO₄^2-,NO₃^-,PO₄^3-);Sb???was affected by the competing anions of SO₄^2-and PO₄^3-;Mo???was affected by the competing anions of PO₄^3-.?3?Kinetic studies showed that the adsorption data of Sb???,Sb???and Mo???could be well described by pseudo-second order kinetic model.The adsorption reaction activation energies of Sb???,Sb???and Mo???calculated is7.38,7.62 and 9.01 kJ/mol,respectively.It shows that the reaction rate of Sb???on activated carbon loaded iron composite adsorbent is faster and the reaction is easier.The activation enthalpies of adsorption reaction were all positive values,which were calculated by the experimental data,indicating that the adsorptions of Sb???,Sb???and Mo???on the activated carbon composite adsorbent were endothermic reaction.?4?The adsorption isotherms of Sb???,Sb???and Mo???were fitted by the Langmuir and Freundlich models.The results showed that the Langmuir model can better describe the adsorption of Sb???,Sb???,Mo???.The maximum adsorption capacity were calculated by Langmuir isotherm model,and the results were 24.47,13.95 and 18.35 mg/g,respectively.In the same temperature conditions,q_m?Sb????>q_m?Mo????>q_m?Sb????;For Sb???,Sb???,Mo???,within the experimental temperature range,the higher the adsorption temperature,the higher the adsorption capacity.