Synthesis of highly effective adsorbents from natural raw materials (zeolites)

Natural raw materials bentonite, silica tuff and diatomaceous earth from Macedonia were used in synthesis of zeolites type A, ZSM-5 and multilayer silicate magadiite-adsorbents. The bentonite was subject to pretreatment with acids (HCl and H2SO4 - 5, 10, 15 and W%) or NaOH, and used in synthesis of zeolite type A having molar ratio of: 2Na2O : Al2O3 : 2SiO2 : 100H2O. Silicate tuff was applied (without any pretreatment, in a two stage reaction) in a high temperature synthesis, using butylamine as an organic 'template' component in order to get high silica zeolite type ZSM-5 having molar ratio of: 59.37SiO2 : Al2O3 : 3.84Na2O : 1.90R2O : 2025.10H2O. Multilayer silicate magadiite MS-H was synthesized from natural raw material diatomaceous earth. The product with a molar ratio of: 8SiO2 : Na2O : 75H2O showed the best characteristics. The proposed method of alkaline pretreatment is a new one and it is acceptable from the economy point of view due to low energy consumption. The conclusion shows that the final result of the synthesis was not perfect, i.e. it has 70% of zeolite ZSM-5 and the rest were some amorphous phases. This product is suitable for industrial application in catalytic processes due to the fact that commercial catalyst contain typically 20 to 50% of zeolite type ZSM-5. On the other hand, the magadiite being multilayer silicate with no aluminium inside, is well suited as a carrier due to its ability of intercalation. The experimental results indicate that natural raw materials from Macedonia could be used for synthesis of synthetical silicates with high qualities and acceptable overall costs, specially when alkaline pretreatment is used. 14 refs., 4 tabs., 11 figs