Adsorption Of Tylosin And Trimethoprim On Functionalized Materials Mesoporous Carbons And Mesoporous Silica

In this paper,mesoporous carbons(marked as CMK-3,C-LTA)and mesoporous silicon(marked as SBA-15)were prepared by template method.Mesoporous carbons and mesoporous silica were modified by nitric acid and boric acid.The adsorbents were characterized by Fourier transform infrared spectrometer,X-ray photoelectron spectroscopy(XPS),nitrogen adsorption-desorption isotherms and Bonn titration.The activated carbon F-300 and polyethylene were used as reference adsorbents of mesoprous carbons to study the adsorption behaviors on tylosin,trimethoprim and sulfamethoxazole.The FT-IR spectra of F-300,CMK-3 and C-LTA before and after nitric acid modification showed that both the surface of the material and the channels of the pores were loaded with carboxyl groups and phenolic hydroxyl groups.The XPS and Bonn titrations showed that the surface oxygen content of F-300,CMK-3 and C-LTA was improved by nitric acid modification,and the functional group loading of CMK-3 and C-LTA was higher than that of F-300.Nitrogen adsorption and desorption experiments showed that the specific surface area and pore volume of F-300,CMK-3,and C-LTA decreased,indicating that the oxygen-containing functional groups were successfully loaded on the surfaces of the F-300,CMK-3,and C-LTA.The adsorption isotherm experiment at pH=5 showed that the adsorption capacity of tylosin and trimethoprim in the F-300,CMK-3,and C-LTA modified by nitric acid was higher than that before the modification,and the adsorption of CMK-3and C-LTA is higher than that of F-300.The effect of pH on the adsorption experiments shows that with the change of pH,the adsorption of CMK-3 and C-LTA is greatly affected by pH,which is due to the strength of the Lewis acid-base interaction between the functional group and the adsorbed material.The adsorption kinetics experiments investigated the adsorption rates of tylosin and trimethoprim showed that the adsorption rates of tylosin and trimethoprim in the adsorbents modified with nitric acid were improved.And the adsorption rate is related to the content of acidic functional groups.In summary,the acidic functional groups loaded on the mesoporous carbons CMK-3 and C-LTA by nitric acid modification can increase the adsorption and adsorption rates of tylosin and trimethoprim,and the adsorption effect of modified materials is affected by the effect of pH is more obvious.The FT-IR spectra of boric acid modified mesoporous silica indicate the formation of boron-oxygen bonds on the surface of the boric acid-modified mesoporous silica.Nitrogen adsorption results indicate that the specific surface area and pore volume of the boron-containing mesoporous are all higher than the raw materials and the materials with silicon-to-boron ratio 1:15 has better pore structure parameters.This shows that the introduction of boric acid can support acidic functional groups on the surface of mesoporous silicon,and that the excessive content of boric acid can affect the mesoporous structure of mesoporous silicon materials.The results of pH=5 adsorption isotherm indicated that the boric acid modified mesoporous silicon material had good adsorption performance to trimethoprim,which was due to the fact that trimethoprim in the form of a cation of pH=5 could be loaded on the surface of the material.The acidic functional group undergoes Lewis acid-base action,and when sulfamethoxazole,which has a neutral molecule at pH=5,is difficult to react with the acidic functional group with low adsorption amount.In the co-adsorption experiment of trimethoprim and sulfamethoxazole,the electron-withdrawing and electron donating groups on the molecular structure of sulfamethoxazole and trimethoprim were attracted to each other,which increased the adsorption of sulfamethoxazole.The effect of pH onalso indicated that with the change of pH value,the ion form of the adsorbate largely determines the adsorption of trimethoprim and sulfamethoxazole the amount of the reaction with the acidic functional group supported on the mesoporous silica.Thus affecting the adsorbent's adsorption of trimethoprim and sulfamethoxazole.The results of adsorption kinetics show that the boric acid-modified mesoporous silica is superior to the pre-modified material in the adsorption rate.In summary,the increase in the adsorption and adsorption rate of trimethoprim in boric acid-modified mesoporous silica,and the difference in the adsorption amounts of trimethoprim and sulfamethoxazole all indicate that the boric acid modified oxygen functional groups are largely Affects the adsorption behavior of mesoporous silica on trimethoprim and sulfamethoxazole.The adsorption amount of trimethoprim in mesoporous silica before and after modification was much higher than that of sulfamethoxazole,while the adsorption amount of sulfamethoxazole was greatly improved in co-adsorption experiments.