Figure 1. Schematic of capillary electrophoresis system.

Inconsistency in leaching results using the Toxicity Characteristic Leaching Procedure (TCLP) indicates that the procedure should contain specific guidance with respect to the following parameters: (1) minimum particle size, (2) contact time limit between leachant and waste. Experimental data show that there is approximately a 50% decrease in the amount of waste leached when a minimum particle size of 8 mm is applied. Results indicate that as the contact time between leachant and waste increases, the amount of waste leached increases drastically. The results suggest that restrictions should be set on these two parameters for TCLP results to be reliable and comparable for solidified/ stabilized waste.

Curing temperature was found to dramatically affect the amount of waste leached from a solidified waste/cement matrix between 2 and 40°C. Using lead nitrate as a model waste, samples cured for 7, 14, and 28 days at a cure temperature of 40°C leached very little lead (1-3 mg/liter), while at a cure temperature of 2°C samples leached approximately 25 times more lead (20 -90 mg/liter). The results indicate that curing temperature is a very crucial variable to consider when solidifying waste with cement if maximum stabilization is to be achieved.