Development of Purified and Zeolite-coated Filter Aids

A developmental work was conducted in view of full utilization of the diatomaceous-earth resources including low-grade diatomite containing some content of iron as an impurity. We first purified parent diatomite by eliminating the inherent iron with help of some organic acids. Oxalic acid was evaluated to be best under the experimental conditions selected. Furthermore, we tried forming a sort of zeolites on the acid-modified surface of diatomite. NaA zeolite was successfully produced at 65°C for more than several hours in suspension with sodium aluminate, sodium hydroxide, and water. The purified and zeolite-coated filter-aids are possible candidates for advanced utilization as earth-friendly ecomaterials.