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Abstract: The Mg2+ and Ca2+ exchange properties in the meso-zeolite LTA were investigated. These meso-zeolite materials with intracrystalline mesopores ca. 3nm were prepared using organic functioned fumed silica as silica source. The Dual-site Langmuir (D-L) expression appropriately describes the equilibrium data for the Ca2+ and Mg2+ exchange. The fitting results with D-L model suggest that two kinds of ion-exchange sites in the meso-zeolites exist, one in the part of intrinsic micropore structure (internal surface area) and the other one in the part of established mesopore structure (external surface area). The latter site has lower enthalpy values of Ca2+ or Mg2+ exchanges than the former one. Ca2+ or Mg2+ exchange kinetics is conducted at 273K, 288K and 308K. The results show the emergence of mesopores lowering the activation energy of ion exchange and accelerating Mg2+ exchange extremely in the materials. The diffusion rate of hydrated Mg2+ in the meso-zeolite LTA increases by 17.5 times, higher than that of conventional LTA at 273K. And the meso-zeolite LTA possesses large Mg2+ competitive ability in a solution containing Ca2+ and Mg2+. These properties make the meso-zeolite LTA a suitable material which could be used effectively in hard water softening and detergent building for Mg2+ removing. [Copyright &y& Elsevier]

Abstract: A series of nanosized ZSM-5 zeolite samples with intracrystalline mesopores has been synthesized using organosilane functioned fumed silica as silica source and tetrapropylammonium hydroxide as microporous structure directing agent. The organic moiety linked on the surface of fumed silica blocks the growth of zeolite crystal, forming the nanosized zeolite crystal and intracrystalline defects inside the nano-crystal. The formation of the mesopores is by bond-blocking function in crystallization. The XRD results indicate that the samples are high crystalline ZSM-5 and the TEM images show that the samples are nanosized with the size ca. 20nm and the intracrystalline mesopores about 3nm exist inside the nanosized crystal. [Copyright &y& Elsevier]