Macroscopic aggregates of microcrystalline zeolites for static water softening applications

#The present invention is directed to novel aluminosilicate zeolite structures useful as water softening materials. The unique zeolite materials of this invention can be used to form both regenerable as well as disposable static water softening devices.

#Water softening is a process of water treatment by which undesirable cations, in particular, calcium and magnesium, are removed. Water, which contains such cations, is considered hard, wherein hardness is usually expressed as calcium carbonate equivalents in parts per million. The presence of these cations in water is undesirable for household purposes, such as for bathing, cleaning, and laundry, as well as for industrial purposes, such as boiler feed, food processing and chemical processing, because of reactions which form soap scum, boiler scale, and unwanted byproducts. Hard waters have been softened by precipitation processes which involved the use of hydrated lime or cation-exchange processes which involved the use of sodium-cation exchangers such as aluminosilicate zeolites or hydrogen cation-exchangers such as in the form of resins in bead form.

#Water softening with ion exchange material such as resin particles or the like is well-known in the art. During the softening process, or service cycle, the ion exchange resin particles acquire hardness inducing ions (Ca2+, Mg2+) from the water in exchange for soft ions, (H+, Na+, K+) which do not induce hardness. After prolonged contact of the resin particles with raw water, the ion exchange capacity of the resin is diminished considerably and periodic regeneration of the resin particles must be accomplished, conventionally by contacting the resin particles with a brine solution, i.e., an aqueous solution of sodium chloride or potassium chloride or the like.

#Microspheres of microcrystalline Zeolite A were prepared by combining 125 grams of Luminex®-derived 40 micron microsphere metakaolin with a solution containing 22 grams N-Brand sodium silicate and 390 grams 50% NaOH solution in 422 grams of water. This mixture was heated to 65° C., with stirring, and reacted for 3 hours. The resultant product was hot washed to remove residual traces of entrained silica. Particle size distribution indicated retention of approximately 40 micron average size. SEM indicated individual crystal size well below 0.5 micron, much smaller than typical commercial Zeolite A.

#A test was conducted to assess the relative performance of the microspheres for multivalent cation sequestration versus a commercial organic ion-exchange resin employed in contact water softening by Brita. The test was carried out in the following manner:

#1) Calcium/Magnesium solution was made following Brita's procedure for test water preparation (Temporary Hardness Reduction Protocol).