The Preparation, Modification And Application Of Layered Silicates

In recent years, research and development of magadiite and kenyaite related materials arebecoming more and more attention by people. Magadiite and kenyaite are two-dimensionallayered structure of silicate material, its laminates is composed by negativelycharged[SiO4]tetrahedron, the Interlaminar have the hydrated sodium ions can be exchanged,and the laminates has good expansibility which can be intercalated by various protons andeven organic molecules. The composites consist by different guest molecules and inorganiclayered host material has important applications in the field of catalysis, adsorption andnano-composite materials.The pure and well-crystallized magadiite and kenyaite were successfully prepared byhydrothermal synthesis method in SiO2-NaOH—Na2CO3-H2O system. The influence of keyreaction parameters, including reaction time, temperature and the content of H2O and SiO2, onthe formation of magadiite and kenyaite were investigated and the structure of magadiite andkenyaite were also characterized. The results showed that The higher content of H2O and SiO2,crystallization time and crystallization temperature tends to make magadiite converted tokenyaite. The as-synthesized magadiite and kenyaite has a rosette like morphology and hashigh stability under the temperature of250℃.The tetradecyl tributyltetradecylphosphonium bromide, hexadecyl triphenylphosphoniumbromide and hexadecyl trimethyl ammonium Bromide as the organic modifier to prepareorganic magadiite and organic kenyaite by ion-exchange method, The influence of keyreaction parameters, including reaction time, temperature and the modification agent content,on the formation of modification were investigated and the structure of organic magadiite andorganic kenyaite were also characterized. The results showed that the three kinds of organicmodifier were intercalated into the magadiite and kenyaite interlayer, the rosette morphologyof magadiite and kenyaite were damaged, the distance of laminates was increased; The highercontent of modifier, the better intercalation effect, while the reaction temperature has littleeffect on the intercalation, the balance of the intercalated reaction time is2h.The magadiite modified by hexadecyl triphenylphosphonium bromide and pure magadiite as the filler to prepare magadiite/PP composite materials by melt blending method,and the structure and properties of the magadiite/PP composite materials have beencharacterized. The results showed that the molecular chains of PP had intercalated into theorganic magadiite interlayer and the laminates of magadiite was exfoliated, forming thenanocomposite material, while PP macromolecular unable to form nanocomposites with puremagadiite; the joining of magadiite has a little effect on the thermal stability and melting pointof PP, but the crystallization temperature of PP was improved obviously. The mechanicalproperties of the composite material were improved.The magadiite adsorption on Zn2+in the aqueous solution was studied. Effect of theadsorbent dosage, adsorption time, pH value and the beginning concentration of heavy metalson the adsorption capability was discussed, the kinetics and thermodynamics of adsorptionand adsorption mechanism were also studied. The results showed that the removal rate of Zn2+is improved with increase in quantity of magadiite, adsorption time and pH value, but itdecreased with t the initial concentration of the heavy metal ions. The pseudo second orderkinetics model and the Langmuir model are more suitable to describe the adsorption processof magadiite adsorption Zn2+. Ion-exchange, surface complexation reaction and physicaladsorption exist in magadiite adsorption process for the adsorption of Zn2+. Ion-exchange andsurface complexation reaction plays a major role, physical adsorption play a supporting role.