水介质中氢键吸附与疏水吸附协同作用的研究

研究了丙烯酸型树脂(D152)在水、乙醇和正己烷中对苯胺、N-甲基苯胺和N,N-二甲基苯胺的吸附行为.在水中D152树脂对3种吸附质的吸附亲合性随N上甲基数的增加而增大,说明疏水作用是主要的吸附机理,但其吸附焓己超出范德华力的范围而在氢键的键能范围内,故氢键吸附也同时在起作用.在正己烷中,D152树脂对3种吸附质的吸附亲合性随N上甲基数的增加而减小,与水中呈相反的趋势,说明氢键作用是主要的吸附机理.在乙醇中,D152树脂对3种吸附质均无吸附,因为疏水作用和氢键作用均受到的乙醇抑制.在水中,吸附质与树脂间的氢键作用同样受到水的抑制,但氢键吸附却依然存在,说明水介质中氢键吸附和疏水吸附可能存在一种协同作用.在热力学上对水介质中氢键吸附和疏水吸附的协同作用给于合理的解释.

ADSORPTION FROM AQUEOUS SOLUTION BASED ON THE SYNERGISM BETWEEN HYDROGEN BONDING AND HYDROPHOBIC INTERACTIONS

The adsorption of aniline, N-methyl aniline and N,N-dimethyl aniline on carboxyl resin (D152) in different media, water, ethanol and hexane have been studied. In water the adsorption affinity of three sorbates on D152 increased with the enhancing number of methyl group on N atoms, which indicated that the adsorption of three sorbates on D152 was driven by the hydrophobic interaction. But the adsorption enthalpy of three sorbates exceeded van der Waals force and was in the range of hydrogen bonding interactions, which indicated that the hydrogen bonding also played an important role. In hexane the adsorption affinity decreased with the increasing number of methyl group on N atom, presenting the reverse order to that in water. This fact revealed that the hydrogen bonding played a predominant role for the adsorption in hexane. In ethanol, there were no adsorptions of three sorbates on D152 resin, because both the van der Waals force and hydrogen bonding interaction between the resin and sorbate were depressed. The hydrogen bonding between resin and sorbates in water was also depressed but the hydrogen bonding adsorption was remained. This result suggested that there might be synergetic effect between the Van der Waals and hydrogen bonding interactions in the adsorption of sorbate on D152 resin in water. The synergetic effect was explained thermodynamically.