Study On The Preparation Of Hydrophobic Mesoporous Molecular Sieves And Their Adsorption Properties For Endocrine Disruptors

Endocrine disruptors （EDCs） have attracted much attention because of its effect on theinterference with the usual functioning of the endocrine system in human and animals.Mesoporous molecular sieve MCM-41has high surface area, tunable pore size and longrange of ordered pore structure, thus widely used as adsorbent in the adsorption studies ofall kinds of organic pollutants. It was observed that the MCM-41with n-cetyl trimethylammonium bromide （CTAB） showed stronger adsorption on hydrophobic organic pollutant.In addition, many researchers focus on the organic functionlization of MCM-41（calcined）and its adsorption studies for the specific goal pollutants.Surfactant structure-directing agent was used to synthesize hydrophobic mesoporousmolecular sieve （MCM-41-dry） at room temperature and hydrophilic mesoporous material（MCM-41-cal） was prepared by removing the template with calcination. These twomaterials were characterized by XRD、FTIR、N₂adsorption-desorption isotherms and TG. Itwas found that these two materials were kept good mesoporous structure. The adsorptionproperties of these two materials towards bisphenol A from water were studied. It was foundthat the adsorption capacity of MCM-41-dry was much higher than that of MCM-41-cal,which was due to the higher hydrophobicity of MCM-41-dry and more adsorption sites. Itwas observed that pH play an important role on the adsorption of BPA on MCM-41-dry.When the pH>10, the adsorption capacity decreases, while at3<pH<10the adsorptioncapacity of bisphenol A remains nearly constant. The kinetic data could be fitted well bysecond-order kinetic model. The adsorption of BPA on MCM-41-dry is in good agreementwith Langmuir adsorption model, and the maximum adsorption capacity is as high as418mg.g-1at25℃. And with the increase of temperature, the maximum adsorption capacitydecreases. The value of the maximum adsorption capacity has a competitive advantage,which suggests that MCM-41-dry can serve as an efficient adsorbent to remove bisphenol Afrom water.MCM-41was functionalized with phenyltrimethoxysilane andhexadecyltrimethoxysilane by a post-synthesis grafting approach. The adsorbents preparedin this study include the monofunctionalized adsorbents phenyl-MCM-41and cetyl-MCM-41, and bi-functionalized adsorbents phenyl/cetyl-MCM-41（1/6），phenyl/cetyl-MCM-41（1/2） and phenyl/cetyl-MCM-41（1/1）. These materials werecharacterized by XRD, FTIR, N₂adsorption-desorption isotherms and TEM measurements.The adsorption properties of these materials towards dimethyl phthalate （DMP）, diethylphthalate （DEP）, dibutyl phthalate （DBP） which were three kinds of dialkyl phthalate esters（DPEs） were studied. All the functionalized adsorbents had higher adsorption capacity ofDMP, DEP and DBP than MCM-41. Meanwhile, the adsorption capacity ofphenyl/cetyl-MCM-41was much higher than that of phenyl-MCM-41and cetyl-MCM-41,which was due to the cooperative effect of hydrophobic interactions and π-π stackinginteractions. For a given functionalized adsorbents, the adsorptive affinity correlated wellwith hydrophobicity of DPEs with an order of DBP>DEP>DMP. But for MCM-41, theorder was DMP DEP>DBP. For a given DPEs, the adsorption capacity ofbi-functionalized adsorbents which have different mole ratio of phenyl/cetyl with an orderof phenyl/cetyl-MCM-41（1/6）> phenyl/cetyl-MCM-41（1/2）> phenyl/cetyl-MCM-41（1/1）.It implies that cetyl groups play more important role than phenyl groups.