Influence of reaction conditions on the properties of sodium alumino silicate synthesized by simultaneous addition of precursors

In this study we have examined the properties of sodium alumino silicate (SAS) synthesized by simultaneous addition of sodium silicate and aluminate under controlled reaction conditions. The varied conditions include the concentration of the reactants and the pH (low, neutral, and high); while the stirring speed, precipitating temperatures, and the drying conditions were kept constant. XRD, SEM, and EDS results indicate that the materials developed were amorphous and have irregularly-textured particles. They were rich in Si, Al, O, and Na; and had Na/Al molar ratios of about 0.4 to 1. The SiO2:Al2O3 molar ratio in the final product ranges from 2.2 to 5.8 as determined by EDS. FTIR studies confirmed the formation of Si–O–Al bond. Nitrogen physisorption studies were done to examine the surface area and porosity of the final product. The SAS samples examined have bulk density greater than 2.5 g/cm3, pore volume up to 0.85 cm3/g, and the pore diameters between 13 to 20 nm. The BET surface area ranges from 80 to 318 m2/g, and oil absorption from 75 to 200 ml/100 g. The products obtained have desirable properties and are expected to be a potential low-cost alternative as functional fillers for paper and paint industries.