Preparation Of Iron-manganese-loaded Activated Carbon And Its Adsorption Efficiency Of Sb(Ⅴ)

In recent years,with the mining and smelting of antimony ore and the wide use of antimony products,excessive antimony-containing pollutants are discharged into natural water bodies,causing environmental pollution and serious threat to human health.Activated carbon is a large specific surface area,economical,green and widely used adsorbent.In order to enhance its adsorption capacity for Sb（Ⅴ）,activated carbon needs to be modified.In this study,granular activated carbon was used as a carrier to prepare iron-manganese-loaded activated carbon adsorbent,the preparation process parameters were optimized and characterized,The influence of various environmental factors on the adsorption process was investigated,the reaction conditions for the adsorption of Sb（Ⅴ）on iron-manganese-loaded activated carbon were optimized by response surface methodology.Exploring the regeneration performance of iron-manganese-loaded activated carbon.The adsorption mechanism of iron-manganese-loaded activated carbon was studied.Preparation of iron-manganese-loaded activated carbon adsorbent by coprecipitation-calcination method.The order of the influence of each parameter in the preparation process of the iron-manganese-loaded activated carbon adsorbent is as follows:Impregnation concentration>calcination temperature>impregnation time>calcination time.The optimal preparation parameters are:impregnation concentration 0.15 mol/L,calcination temperature 300℃,impregnation time 4.0 h,calcination time 1.0 h.The specific surface area and total pore volume of the iron-manganese-loaded activated carbon are 74.0 m²/g and 0.06cm³/g,respectively,and the iron and manganese oxides on the surface exist in an amorphous state.Compared with activated carbon,iron-loaded activated carbon,and manganese-loaded activated carbon,the surface of iron-manganese-loaded activated carbon is more abundant in hydroxyl groups and metal oxides,which is beneficial to the adsorption of Sb（Ⅴ）.The single factor test was used to investigate the effect of various environmental factors on the adsorption efficiency of iron and manganese-loaded activated carbon for Sb（Ⅴ）.The adsorption capacity of iron-manganese-loaded activated carbon decreased with the increase of dosage,and the adsorption equilibrium was basically reached when the reaction was 1230 min,Under acidic conditions,the adsorption performance of iron-manganese-loaded activated carbon is better,and the alkaline environment is not conducive to the adsorption process.The adsorption capacity tends to be stable when the initial concentration is 120 mg/L.Within a certain concentration range,Cl^-has little effect on the adsorption of Sb（Ⅴ）on iron-manganese-loaded activated carbon,while SO₄^2-,Mn²⁺,nigrosine and DOM have obvious inhibitory effects on it.The reaction conditions for the adsorption of Sb（Ⅴ）on iron-manganese-loaded activated carbon were optimized by response surface methodology,and the optimal reaction conditions were obtained as follows:initial concentration 120 mg/L,adsorption time 1230 min,p H 3.06.The regeneration test results of iron-manganese-loaded activated carbon show that the regeneration effect of Ca Cl₂solution is the best,and the regeneration rate of iron-manganese-loaded activated carbon is as high as 90.0%,The adsorption-saturated iron-manganese-loaded activated carbon was subjected to five desorption-adsorption cycles with 1.0 mol/L Ca Cl₂solution,and its adsorption capacity could still reach more than 80.0%of the original equilibrium capacity.The adsorption kinetic model and isotherm adsorption model were used to fit the adsorption process,and the characterization results of the Fe-Mn-loaded activated carbon before and after adsorption were analyzed.The pseudo-second-order kinetic model and the Langmuir model can well fit the adsorption process of Sb（Ⅴ）on the iron-manganese-loaded activated carbon,the adsorption process is mainly monolayer chemisorption and is affected by boundary effects and mass transfer processes.The thermodynamic parameters show that the adsorption process is a spontaneous endothermic process,and the temperature rise is conducive to the reaction.A large number of hydroxyl groups on the surface of iron-manganese-loaded activated carbon are involved in the adsorption process,Among them,the metal-coordinated hydroxyl groups are replaced by Sb（Ⅴ）after the adsorption reaction to form S-O-Sb complexes,which constitute the inner-layer surface complex structure,and there is also an outer-layer complexation effect.