EFFECT OF REPEATED LEACHING ON THE RELEASE OF LEAD AND OTHER CATIONS FROM LEAD CRYSTAL GLASS (24-PERCENT PBO) BY ACID-SOLUTIONS AND WATER

The effect of repeat ed leaching of a commercially available lead crys tal glass (24% PbO), for regular periods of time at 22 and 95 degrees C by water; HCl, H2SO4, HNO3, acetic and citric acids on the release o f K, Na, Pb and Si was studied After each leaching the glass was washe d with water in order to simulate the conditions of consumer use of cr ystal glass hollow ware. In contrast to the method of continuous conta ct which leads to the accumulation of leached products in the attackin g solution the results revealed that, in general, the extracted quanti ties of K, Na, Pb and Si increased with increasing contact time and gr adually decreased with increasing number of leaching times. In particu lar leaching repeated 2-3 times for 1 h periods at 95 degrees C or 3 t imes for 10 day periods at room temperature was sufficient to leach mo st of the lead ions from the glass surface and to impart to it a great resistance to further corrosion by acid solutions. Accordingly, the p ractical conditions of use of lead crystal glass containers for prepar ing, storing or serving foods and drinks should provide a considerable improvement of the glass resistance to further attack and should decr ease lead leaching to negligible levels.