Study On The Preparation Of Yttrium-Doped Cerium Oxide Composites And The Treatment Of Cr(Ⅵ) Wastewater By Sol-Gel Method

Since chromium-containing wastewater generated by industries such as coal chemical,coal and fuel oil has endangered human health,the problem of treating chromium-containing wastewater is urgent.The adsorption method is considered to be one of the effective methods for treating chromium-containing wastewater,but the traditional adsorbent has the disadvantages of low saturation capacity and poor regeneration effect.In this thesis,a high adsorption capacity,renewable yttrium-doped cerium oxide composite was prepared and characterized by sol-gel method.The optimal preparation conditions of yttrium doped cerium oxide were obtained by orthogonal experiment,and the adsorption of chromium-containing wastewater by Ce_0.9Y_0.1O₂composites was carried out,and the chromium removal mechanism was discussed.The results are as follows:（1）The results of orthogonal test and univariate test show that the main influencing factors of composite preparation are reactant ratio,roasting temperature,yttrium addition and drying temperature.The optimal preparation conditions were yttrium addition 10%,reactant ratio 1:1,drying temperature 100℃,roasting temperature 350℃.（2）The material characterization results showed that by X-ray diffraction characterization,yttrium was successfully doped on cerium oxide to form a solid solution.Scanning electron microscopy characterization analysis shows that the composite is a sheet structure with a rough surface and abundant porous structure inside.By analyzing the EDS energy spectrum,it can be seen that chromium is adsorbed to the surface of Ce_0.9Y_0.1O₂composite.The specific surface area of Ce_0.9Y_0.1O₂composites is 93.1765 m²/g,the pore volume is 0.0871cm³/g,and the pore size is 4.1368nm.（3）The results of static adsorption test showed that the removal rate of chromium-containing wastewater with a concentration of 20 mg/L of 50 m L could reach 97.44%when the chromium-containing wastewater with a concentration of 20mg/L was treated at p H=3,Ce_0.9Y_0.1O₂composites were added to 0.04 g.0.04g Ce_0.9Y_0.1O₂composites were treated with different concentrations of Cr（VI）solutions（10,20,30,40,50,60mg/L）,and the static saturated adsorption capacity of Ce_0.9Y_0.1O₂composites was 28.785mg/g.（4）The adsorption kinetic test showed that the Ce_0.9Y_0.1O₂composite adsorbed hexavalent chromium composite secondary kinetic model.The equilibrium adsorption capacity was 24.333mg/g at 20mg/L at 20mg/L and 298K at 298K,and the equilibrium adsorption capacity at 308K and 318K was 25mg/g.The reaction activation energy is 20.8237,and the adsorption of Ce_0.9Y_0.1O₂composite Cr（VI）is mainly physical adsorption.（5）The adsorption thermodynamic test shows that the Langmuir model is in good agreement with the test results,and the adsorption process is spontaneous and endothermic.ΔH is 20.192KJ/mol,and the adsorption force is hydrogen bonding force.（6）The results of orthogonal test and univariate test show that the main influencing factors of composite preparation are reactant ratio,roasting temperature,yttrium addition and drying temperature.The optimal preparation conditions were yttrium addition 10%,reactant ratio 1:1,drying temperature 100℃,roasting temperature 350℃.