Synthesis Of4A Zeolite With Kaolin

As natural silicoaluminate mineral, Kaolin is very rich in China. In this paper,4Amolecular sieve is prepared by adding the aluminum source in the process ofhydrothermal synthesis process with Metakaolin which is made with raw materials. Theprocess is simple and the possibility of enlarging the scale of production becomesaccessible. This paper has great value in industry such as in green，deep process ofKaolin，cutting the costs of the synthesis of molecular sieve, broadening the applicationsof molecular sieve，and so on。By adopting single-factor experiment, the most appropriate temperature and time forcalcining can be respectively measured as800℃and2h during the calcining process. Byanalyzing the phase, structure and appearance of kaolin through different measures, suchas DSC, XRD, FT-IR, SEM, the results showe that, after calcining, the kaolin is finallytransformed into Metakaolin which features high whiteness, low impurity content, smallparticles and high reactivity.By adopting Single-factor experiment during the hydrothermal synthesis process, theoptimum process conditions are determined: n(SiO2)/n(Al2O3) is1.9; n(Na2O)/n(Al2O3) is2.4; n(H2O)/n(Na2O) is50；alkalization temperature is50℃; alkalization time is3h;crystallization temperature is90℃and crystallization time is6h.Through testing the properties and characterizing the structure of the sample whichis made in the optimized conditions. The results show that all the prosperities of4Amolecular sieve that is composted in this experiment are in line with national standards:pH is10.6, ignition loss is22%, static saturated water absorption is21%, and the contentof calcium ion adsorption is up to335mg/g (CaCO3). After analyzing the sample in themethods of DSC, XRD, FT-IR, SEM etc, the results show that the4A molecular sievecontains zeolite water structure which owns good thermal stability, its heat resistancetemperature can be reached to800℃, the sample is in cube crystal shape with intactgrowth; Its crystal are small particles with uniform distribution; and with high purity andcrystallinity.In the last part, we discuss the influences of various conditions on the calcium ionadsorption of4A molecular sieve. The results show that the best adsorption condition is:pH is10, temperature is40℃，time is60min in100ml solution with0.15mol/L initial solution concentration of Ca2+, when the usage of4A molecular sieve is1g, theadsorption of calcium ion can be reached to172mg/g.With the fixed pH, the calcium ionadsorption of4A molecular sieve is in accordance with the Langmuir molecularabsorption Isothermal model.