Freundlich adsorption isotherms and isosteric enthalpy of adsorption indicate that the process of adsorption of caffeine from aqueous solutions by JDW-2 and Duolite S-761 is an exothermic process.

• Freundlich吸附等温线和等量吸附焓表明: JDW-2和Duolite S-761对咖啡因吸附是放热过程。