Immobilization of phenol in cement-based solidified/stabilized hazardous wastes using regenerated activated carbon: leaching studies

In this research, we investigated the use of an inexpensive thermally regen erated activated carbon as a pre-adsorbent in the solidification/stabilizat ion of phenol-contaminated sand. Our results show that even the addition of very low amounts of regenerated activated carbon (1%-2% w / w sand) result ed in the rapid adsorption of phenol in the Chemical solidification / stabi lization (S / S) matrix, with phenol leaching reduced by as much as 600%. A dsorption studies indicated that the adsorption of phenol on the reactivate d carbon was found to be partially irreversible over time in the S / S wast e form, indicating possible chemical adsorption. Pore-fluid analyses of the cement paste containing phenol suggested the formation of a calcium-phenol complex, which further reduced the amount of free phenol present in the po res. Studies using several micro-structural techniques, including field emi ssion scanning electron microscopy. X-ray diffraction, fourier transform in frared spectroscopy and energy dispersive X-ray spectroscopy, indicated sig nificant morphological changes in the cement matrix upon the addition of ph enol and reactivated carbon. The hydration of cement in the presence of phe nol was retarded concomitant with formation of amorphous portlandite. (C) 1 999 Elsevier Science B.V. All rights reserved.