Comparison of Leaching Characteristics of Lead in Waste CRTs
This study investigates four extraction methods (water extraction, toxicity characteristics leaching procedure (TCLP), modified TCLP with pH control and sequential chemical extraction (SCE)), each representing different liquid-to-solid (L/S) ratios, pH controls, and types of leachant and their effects on the leaching concentration of Pb in cathode ray tubes (CRTs).The results indicated that for extraction with distilled water,the lead leaching concentration (mg/L) decreased with L/S ratio in the range of 2-100. The results also showed that the leaching concentration was strongly pH-dependent in the TCLP and modified TCLP tests. In modified TCLP tests,in the case of pHs lower than 6.3,the leaching concentrations of Pb decreased with an increase in pH. Due to the nature of amphoteric elements, in the case of pHs higher than 7, the Pb leaching concentration increased with increasing pH. In SCE tests, the Pb speciation approached the extractable carbonate bound fraction. Both amounts of Pb leached from the SCE and modified TCLP tests were much higher than those for the regular TCLP and water extraction tests. The initial particle size of samples have great effect on the leachability of Pb from waste CRTs.
Yiwang Bao, Li Tian and Jianghong Gong
J. H. Cheng et al., "Comparison of Leaching Characteristics of Lead in Waste CRTs", Advanced Materials Research, Vol. 177, pp. 470-474, 2011