Síntese e caracterização de zeólita tipo A obtida a partir de caulim natural da Amazônia

Abstract

The synthesis of zeolite A has been an alternative for the production of ceramics for the purpose of water treatment. The structure of the zeolite is formed by a labyrinth of nanometric scales of molecular size pores with irregular arrangements of channels and cavities that can be filled by water or other molecules, which gives a special feature called “molecular sieve”, justifying its application as a filter medium, as this allows the total removal of heavy metals dissolved in the fluid. This research studied the ceramic processing of type A zeolite synthesized in the laboratory from Amazonian kaolin for possible application as water filtering ceramics. The synthesis was carried out using the hydrothermal method with calcination in a muffle furnace at 800 ºC for 2 h, followed by cationic exchange (Na +) in the presence of a 2.25 mol / L NaOH solution, heated next to the activated kaolin conditioned in a reactor at temperature 110 ºC for 4 h. The samples were characterized by X-ray diffraction and thermo analytical analysis (TG / DTG / DSC / DTA), formed into pellets and calcined at 500, 600 and 700 ºC for 4 h. After the heat treatment, the parts were physically evaluated for density, porosity and mechanical resistance to the passage of water, the density results were subjected to DBC statistical treatment with ANOVA and Tukey's test. The statistical conclusion was that: at 600 ºC only zeo_01 presented satisfactory results, at 700 ºC the three types of zeolites presented acceptable results and at 500 ºC no samples obtained acceptable density according to the criterion of 5% significance in the F-statistic (Fisher-Snedecor). The research concluded that the zeolite A synthesis process is efficient for all studied samples, the ceramic processing showed a better result for the sample identified as zeo_04 at a temperature of 700 ºC, as it reached mechanical resistance, apparent porosity and absorption index of satisfactory water levels maintaining the crystallographic phase.