Preparation Of Modified Silicon-based Mesoporous Adsorbent And Its Synergistic Removal Of Phenanthrene And Copper In Water

With the rapid development of urbanization,industrialization and agricultural activities,polycyclic aromatic hydrocarbons(PAHs)and heavy metals as two kinds of persistent pollutants have been continuously detected in various water environment,which has attracted wide attention.Although the concentrations of PAHs and heavy metals are very low(ug/L to ng/L),the cumulative long-term toxicity effects of PAHs,heavy metals and their combined pollutants could not be ignored.Therefore,there is an urgent need to find effective ways to remove low-dose and high-toxic PAHs and heavy metals synergistically from water environment.In this paper,phenanthrene and copper were used as pollutants of the typical polycyclic aromatic hydrocarbons and heavy metals,and their physical and chemical characteristics were analyzed.Silicon-based mesoporous materials were selected as adsorbents.The amino-functionalized and organic-inorganic double-modified silica-based mesoporous adsorbents were prepared successively.The adsorption behavior and mechanism of the prepared adsorbents for phenanthrene and copper in water were studied.Finally,the organic-inorganic double modified silica-based mesoporous were used to remove polycyclic aromatic hydrocarbons and heavy metals in water.The main conclusions are as follows:(1)Silicon-based mesoporous materials SBA15 and MCM-41 were successfully synthesized by hydrothermal reaction and direct synthesis.The organic functional groups of SBA15 and MCM-41 were modified.N,N-SBA15 and N,N-MCM-41 were successfully synthesized.The adsorption behavior of N,N-SBA15 and N,N-MCM-41 on phenanthrene and copper were studied.The results showed that N,N-SBA15 and N,N-MCM-41 could adsorb phenanthrene and copper rapidly,and their kinetics accorded with pseudo-second-order kinetic model.The isotherms were also conformed to Langmuir model.In addition,the pH value and ionic strength of the solution had great influence on the adsorption of phenanthrene and copper onto N,N-SBA15 and N,N-MCM-41.In binary pollutant system,N,N-SBA15 inhibited the removal of phenanthrene and copper,while N,N-MCM-41 promoted the removal of phenanthrene and copper.(2)A new silicon-based mesoporous adsorbent was successfully prepared by doping the active group Fe on the basis of amino modification and named as Fe-N,N-MCM-41.The adsorption behavior of Fe-N,N-MCM-41 for phenanthrene and copper in water was studied by batch experiments.The results showed that the adsorption rate of Fe-N,N-MCM-41 for phenanthrene and copper were fast,and the adsorption kinetics accorded with pseudo-second-order kinetics model,and the isotherm accorded with Langmuir model,which indicated that the adsorption process of phenanthrene and copper onto Fe-N,N-MCM-41 was a single-layer chemical complexation reaction.With the increase of pH and ionic strength,the adsorption capacity of phenanthrene onto Fe-N,N-MCM-41 decreased and increased respectively,the adsorption capacity of copper onto Fe-N,N-MCM-41 increased and decreased,respectively.The maximum adsorption capacities of Fe-N,N-MCM-41 for phenanthrene and copper were: 29ug/g and 6.34mg/g,respectively.In addition,Fe-N,N-MCM-41 also promoted the removal of phenanthrene and copper.(3)By comparing the adsorption capacity and adsorption rate of N,N-MCM-41 and Fe-N,N-MCM-41 for phenanthrene and copper,the Fe-N,N-MCM-41 adsorbents were selected to study their removal of polycyclic aromatic hydrocarbons and heavy metals in water.Phenanthrene,pyrene,phenanthrene and pyrene mixtures,lead,copper,lead and copper mixtures were selected as the research objects.The adsorption isotherms and kinetics of Fe-N,N-MCM-41 for these pollutants were studied respectively.The results showed that the adsorption capacity of Fe-N,N-MCM-41 for pyrene was higher than that phenanthrene,and for lead was higher than that copper.These indicated that the adsorption of pollutants onto Fe-N,N-MCM-41 were related to the characteristics of pollutants themselves.In addition,the adsorption capacity of Fe-N,N-MCM-41 to phenanthrene and pyrene were reduced when phenanthrene and pyrene coexist.Similarly,the adsorption capacity of Fe-N,N-MCM-41 for lead and copper decreased under the coexistence of lead and copper,which may be the result of competitive adsorption between pollutants.