Water sorption characteristics of MCM-41 with post modification by Al grafting and cations doping

摘要

Post modification method was used to synthesize MCM-41 with different pore size, Al grafted MCM-41 and cation doped MCM-41. Water sorption isotherms were measured by dynamic water vapor sorption and a detailed analysis was performed with PCMMS model. The results show that Al grafting and cation doping modification of MCM-41 promote an increase of the water sorption capacity in the low RH. Pore size and surface property have a restraining effect on the water cluster formation process. Doped cations have strengthened the water sorption capacity in the low RH in an order of Al-C12-C-Mg>Al-C12-C-Li>Al-C12-C-Na. The isotherm type transition with post modification indicates an effective way to modify and alter the water sorption characteristic of porous materials.