ANALYTICAL EVALUATION OF IMMOBILIZATION OF HEAVY-METALS IN CEMENT MATRICES

The method of Cd, Pb, Zn, and Cr immobilization in alkali-activated sl ag cement mortars and Portland cement mortars are evaluated. It has be en found that differential pulse anodic stripping voltammetry enables the determination of trace amounts (from 0.1 to 400 mu g/L) of Cd, Pb, and Zn in extract solutions obtained as a result of leaching the meta ls from cementitious materials. The heavy metals were determined by an odic stripping voltammetry after the UV mineralization of water extrac ts performed to destroy organic surfactants and sulfide present in the solutions. To determine the chromium amounts in the extracts (20 mu g / L-200 mg/L), several polarographic, adsorptive stripping voltammetri c, and spectrophotometric methods were tested. The spectrophotometric method with diphenylcarbazide has been selected as it possesses the re quired sensitivity and enables the speciation studies. Precision and a ccuracy data of the applied methods are presented along with comparati ve studies using AAS and ICP AES analysis of the extracts. It has been found that the proposed method enables the immobilization of 1% addit ion of Cd, Pb, Zn, and Cr(VI) to the cement matrices with the final ef ficiency of 99.9%, 99.9%, 99.9%, and 98.8-99.6%, respectively.