Preparation Of Industrial Adsorbent For Removal Of Chromium(Ⅲ) Ions And Optimization Of Its Adsorption Process

With the development of modern industry,the pollution of Cr（Ⅲ）in water becomes more and more serious.A large number of Cr（Ⅲ）do harm to the ecological environment and threaten human health.More attention has been paid to remove Cr（Ⅲ）from water.Among various methods,adsorption is an effective and common method to deal with Cr（Ⅲ）pollution in water.SBA-15 material has large specific surface area,highly ordered pores,good hydrothermal and chemical stability,and the pore size is adjustable.Therefore,SBA-15material is an ideal adsorbent for removal of heavy metal ions from solution.However,SBA-15 is lack of active group and has low adsorption capacity of Cr（Ⅲ）.To improve adsorption properties of SBA-15 materials,modification of SBA-15 was carried out.Firstly,SBA-15 was synthesized by hydrothermal method,and then was modified with APTMS to obtain NH₂-SBA-15,and on this basis,functionalized with 2-acetylthiophene to prepared A-SBA-15.The as-prepared samples were characterized by SEM,FT-IR,TEM,TGA,N₂ adsorption desorption and XRD.The adsorption performance of the adsorbent for Cr（Ⅲ）was studied under different initial concentrations,adsorption temperatures,adsorption time and pH values,and the optimal adsorption conditions were determined.The thermodynamics and kinetics of the adsorption process were analyzed,and the corresponding adsorption mathematical model was established.The adsorption mechanism of Cr（Ⅲ）by adsorbent was determined.A-SBA-15 was used as packing in the continuous adsorption experiment of fixed bed column,the breakthrough curves under different bed heights,velocities and initial concentrations were studied,and the relevant models were fitted.The results showed that:（1）the crystal structure of SBA-15 modified by APTMS and2-acetylthiophene not change significantly,but the specific surface area and pore size of the modified SBA-15 decreased.The adsorption experiments show that A-SBA-15 has good adsorption capacity for Cr（Ⅲ）.The maximum adsorption capacity of SBA-15,NH₂-SBA-15and A-SBA-15 for Cr（Ⅲ）is 9.8mg/g,18.10mg/g and 114.2mg/g,respectively.（2）Langmuir model well describe the adsorption characteristics of NH₂-SBA-15 and A-SBA-15 for Cr（Ⅲ）.According to the adsorption kinetic analysis,the adsorption process is consistent with the pseudo second-order kinetic model for Cr（Ⅲ）is monolayer adsorption,mainly chemical adsorption.The adsorption of Cr（Ⅲ）on NH₂-SBA-15 and A-SBA-15 is a feasible spontaneous process.And the prepared adsorbents have good regeneration performance.（3）The kinetic parameters of different bed heights,velocities and initial concentrations were calculated by Thomas and Yan model,and the breakthrough curves of different bed heights,velocities and initial concentrations were predicted.The results show that A-SBA-15 has potential industrial application value in removing Cr（Ⅲ）from water.