A novel class of gemini pyridinium surfactants with a four-methylene spacer group was synthesized, and their surface-active properties and interactions with polyacrylamide (PAM) were evaluated by surface tension, fluorescence, and viscosity measurements. A comparison between the gemini pyridinium surfactants and their corresponding monomers was also made. The cmc's of gemini pyridinium surfactants are much lower than those of the corresponding monomeric surfactants. The C20 value is about one order of magnitude lower than that of corresponding monomers, and the longer the hydrophobic chains of the surfactants, the lower the cmc value. Surface tension measurements of the surfactant-PAM mixed systems show that the critical aggregation concentration (cac) value is much lower than the cmc value of the surfactant system alone. Viscosity measurements of the surfactant-PAM mixed systems show that the relative viscosity of the surfactant-PAM system decreased with increasing concentration of surfactant. Additionally, fluorescence measurements of the surfactant-PAM mixed system suggest the formation of surfactant-polymer aggregates, and the gemini pyridinium surfactant with longer hydrophobic chains have a stronger interaction with PAM, owing to the stronger hydrophobic interaction.

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A new type of composite adsorbent, MOF-5/Cu(I), was prepared by MOF-5 doped with different amount of CuCl using a spontaneous monolayer dispersion technique. These new composite adsorbents were characterized by X-ray diffraction, thermogravimetric analysis, electrondispersion X-ray scope, and N2 adsorption, respectively. The desulfurizaion performance of the prepared adsorbents was evaluated by the selective adsorption of dibenzothiophene from the simulated oils in a fixed-bed breakthrough column at room temperature. From the obtained breakthrough curves, both the breakthrough capacity and the saturation capacity of the adsorbents for sulfur element were determined. The results show that MOF-5/Cu(I) exhibited high desulfurization capacities, which are superior to those reported previously in the literature. In addition, these novel composite adsorbents possessed good durability and affinities for the adsorption of dibenzothiophene in the presence of aromatic components and moisture. The saturated composite adsorbent MOF-5/Cu(I) can be regenerated with nitrogen atmosphere sweeping at 623 K for 4 h. About 97% of the desulfurization capacity was recovered after regeneration.