| Adsorption technology shows great application potential for removal of the rare toxic and refractory pollutants from water.Special ordered pore gives the inorganic meso-silica particular advantage on removal of rare contaminates after functionalization.However,the commonly used organical functionalization has limitations such as complicated organic modification path,strict reaction condition.In this study four kinds of toxic and refractory pollutants,including antibiotic,heavy metal,cationic dyes and aniline,were selected as targeted pollutants.After analysis of the character of these pollutants,the selective adsorption characters were developed and utilizationed during the different stages of meso-silica synthesis process from the aspect of the preparation route and inorganic modification.The selective removal of the targeted pollutants and the reutilization of meso-silica were realized,and the mechanism was discussed.Based on the analysis of the structure and characters of the targeted pollutants,four types of the modified MCM-41 were synthesized and characterized,the removal efficiencies were evaluated.According to the hydrophobicity/hydrophilicity of enrofloxacin and norfloxacin,the template retained MCM-41 and the pure MCM-41 were synthesized and characterized.Removal efficiency of the hydrophilic enrofloxacin by C16-MCM-41 and pure MCM-41 were 91.3% and 61.0%,and those for the hydrophobic norfloxacin were 27.9% and 51.9%.Based on the complexation properties and hydrolysis properties of Cu2+ and Cd2+,the template retained MCM-41 was synthesized and characterized.Removal efficiency of Cu2+ and Cd2+ were increased from 5% and 2% to 92% and 35%.Based on the dissociation property of the cationic dye crystal violet and methylene blue,the Cu O loaded MCM-41 was synthesized and chartered,removal efficiency of crystal violet and methylene blue were increased from 67% and 80% to 78% and 93%.Based on the de-electron property of the amido functional group in aniline,the electron-attracting iron oxides loaded MCM-41 were synthesized,and removal efficiency of aniline was increased from 8% to 93%.Based on the evaluated removal efficiencies of the targated pollutants by the functionalized MCM-41,effects of the factors were investigated.pH was proved to be the key factor for the adsorption of enrofloxacin and norfloxacin by the C16-MCM-41 and MCM-4,and maximum removal was 84% and 63% at pH 6.4 and 7.2.pH and ion strength were the important factors for the removal of Cu2+ and Cd2+ by C16-MCM-41,the removal of crystal violet and methylene blue by CuO/MCM-41,and the removal of aniline by Femodified MCM-41.With pH range 5.6-7.5 and 52.-8.9,adsorption efficiencies of Cu2+ by C16-MCM-41 increased from 32.7% to 96.1%,and those for Cd2+ increased from 10.7% to 60.6%,and high ion strength enhanced the removal of Cu2+ and Cd2+.At pH range 4.3-9.3 and 4.1-9.3,removal efficiencies of crystal violet increased from 59.3% and 85.9%,and those of methylene blue increased from 79.4% to 96.4%,and high ion strength(<0.02 M NaCl)enhanced the removal of crystal violet and methylene blue.At pH range 4.4-9.1,removal efficiency of aniline by Fe-modified MCM-41 decrease was decreased from 89.% to 25.7%,and high ion strength(>0.05 M NaCl)enhanced the removal of aniline.pH is a key factor for the selective adsorption of the targeted pollutants,and the targeted pollutants showed effective removal in the optimal pH range(6.5-8.5).To reveal the adsorption mechanism,the selected adsorption characters were studied scientifically.The adsorption processes of enrofloxacin and norfloxacin in C16-MCM-41 and MCM-41 were fitted the pseudo-first order model well and the equilibrium time was 90 min,and the adsorption isotherm were fitted the Langmuir model well and the Qmax were 5.02 mg/g and 1.74 mg/g and increased with the temperature;C16-MCM-41 showed well selected adsorption towards the hydrophobic quinolone antibiotics;the hydrophobic enrofloxacin was adsorbed by the hydrophobic bond in C16-MCM-41,but the hydrophilic norfloxacin was adsorbed by the hydrogen bond.The adsorption processes and the adsorption isotherm of Cu2+ and Cd2+ in C16-MCM-41 were fitted the pseudo-first order model and the Langmuir model well.The equilibrium time was 20 min,and the Qmax were 32.2 mg/g and 8.0 mg/g,which increased with the temperature.The C16-MCM-41 showed well selected adsorption towards the heavy metals with complexibility.With the help from the anions(Cl-and OH-)electronically adsorbed on the interface of the template micelles,adsorption of Cu2+ and Cd2+ in C16-MCM-41 was related to the complexation between the metal ions and the cationic heads.The adsorption processes and the adsorption isotherm of crystal violet and methylene blue in CuO-loaded MCM-41 were fitted the pseudo-second order model and the Langmuir model well.The equilibrium time was 60 min,and the Qmax 52.9 mg/g and 87.8 mg/g,which were increased with the temperature.The CuO/MCM-41 showed well selected adsorption towards cationic dyes.Due to the surface charge of CuO and the protonation of the dye molecules,the electrostatic forces between the loaded CuO and the organic cationic dyes contributed to the enhanced adsorption of crystal violet and methylene blue by CuO/MCM-41.The adsorption processes and the adsorption isotherm of aniline in Fe-modified MCM-41 were fitted the pseudo-second order model and the Langmuir model well.The equilibrium time was 30 min and the Qmax was 17.94 mg/g,which increased with the temperature.The Fe-modified MCM-41 showed well selected adsorption towards aniline.The attracting electron ability of oxygen atom and the electron donating ability of amido group in aniline were contributed to the enhanced adsorption.Based on the properties of the selected targeted pollutants,the functionalized mesosilica adsorbents were synthesized in this work,and the targate pollutants were selected removed.The results of this study were meaningful for extending the application of mesosilica to the rare pollutants control,and gave a new way for aquatic pollution control and water purification. |
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