The Study On Trsnsforming Geopolymers Into NaA Zeolite And The Synthesis Of GMS-CdS Photo-Catalyst Material

"Geopolymers"was first named and identified by Joseph Davidovits in 1978 at the Macromolecular meeting of IU PAC. Joseph Davidovits synthesized a new type of inorganic polymer materials-geopolymer with homogeneous mixing material of kaolin and quartz (mass ratio 1:1), Solid sodium hydroxide and some water through condensation polymerization.This work prepared Al2O3-SiO2 powder with the method of sol-gel at first and produced Na2O-Al2O3-SiO2-nH2O geopolymer slurry with sodium silicate (SiO2/Na2O=0.9) according to the theory ratio of NaA zeolite and explore the effect of the transformation from geopolymer to NaA zeolite.We found that water play a vital part in the process of the transformation,then this work studied the effect of water in the transformation.Geopolymer spheres were prepared through the method of suspension solidifi-cation with fast solid mechanism and the Cd2+ ions can easily combine with GMS via Van de Waals Force and ion exchange. The geopolymers with CdS was prepared through photochemical growth method. CdS-GMS exhibited excellent performances in the decolourisation of MO.The main results as follows:(1) This work produced a NaA zeolite via the geopolymer-gel-thermal con-version (GGTC) method, which does not require a hydrothermal process. The 1.11 Na2O-Al2O3-2SiO2 geopolymer transformed into NaA zeolite crystals with good crystallin i ty after curing above 60 ℃. Thus, the conditions necessary for the geopolymer-gel-thermal-conversion method (GGTC) are as follows:1) high aluminate and silicate dissolution,2) low-modulus sodium silicate solutions,3) an appropriate Si/Al/Na molar ratio.(2) If the geopolymers with different content of water was sealed with paraffin, the transformation conditions will become lower when the water in geopolymers required the content in the transformation process. If put this geopolymers in the non-sealed environment, the crystalline phase will not produce. Because of the water molecule become active and the movement of hydrated sodium become more active and transport more nutritional ingredient, so the transformation conditions reduc-ed.While because of the losing water in the non-sealed geopolymers during curing time, the nutritional ingredient can not reach to the crystal location and affected the crystallization process.(3) This work evidence that Cd2+ ions can easily combine with GMS via Van de Waals Force and ion exchange. CdS particles can readily growth on the surface of GMS by photochemical growth method and formed yellow CdS-GMS. Bcause of the synergetic performance in degradation process, CdS-GMS exhibited excellent perfor- mances in the decolourisation of MO and the degradation efficiency reached 90.568%. The analysis of the CdS-GMS degradation kinetics of MO indicates that it is corresponding to the pseudo-second-order rate equation.