Uptake of nitroaromatic compounds from aqueous solution by methylated MCM-41
甲基化MCM-41吸附水中硝基苯类化合物的研究

Surface silylation of MCM-41 with trimethylchlorosilane was carried out to adsorb nitroaromatic compounds (NACs) from aqueous solution based on batch adsorption tests. The methylated MCM-41 was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that the adsorption rate of NACs was very fast and the adsorption process was exothermic. The linear model could fit the adsorption isotherm of NACs over the methylated MCM-41 well. Substituents with electron donating groups on the aromatic rings decreased the methylated MCM-41 adsorption, whereas substituents with electron withdrawing groups on the aromatic rings strengthened the methylated MCM-41 adsorption. The increase of pH had no noticeable effect on non-ionized NACs adsorption. However, for ionized NACs, the amount of adsorption decreased with the increase of pH. Evidenced from the results given above, the formation of an electron donor-acceptor complex between electron donor functions at the siloxane surface and the aromatic ring system of the NACs may be postulated as a plausible mechanism of the methylated MCM-41 adsorption. The regeneration results showed the suitability of methylated MCM-41 as a reusable adsorbent.