Pentachlorophenol Sorption in the Cetyltrimethylammonium Bromide/Bentonite One-Step Process in Single and Multiple Solute Systems

摘要

The selective sorption of pentachlorophenol (PCP) in a multiple solute system provides the possibility of using the cetyltrimethylammonium bromide (CTMAB)/bentonite one-step process as a promising technique for hydrophobic organics removal from wastewater. The PCP sorption mechanism, especially the effects of coexisting solutes, was studied. Compared to raw bentonite and conventional CTMAB modified organobentonite, the one-step process exhibited higher PCP removal efficiency. In a single solute system, the PCP sorption isotherm implied that the dominating sorption mechanism is a partition mechanism. The logarithms of sorption coefficients (K_d) for different organics are linearly related to the logarithm of their octanol—water partition coefficients (K_(ow)). In a multiple solutes system, phenol and 2,4-dichlorophenol (2,4-DCP) could effectively enhance PCP sorption. The PCP sorption coefficient increases in the order: PCP/phenol < PCP/2,4-DCP < PCP/phenol/2,4-DCP. The PCP sorption enhancement is likely resulted from the interlayer space expansion and the organic carbon content increase. On the basis of the comparison between the single and the multiple solute systems, phenol and 2,4-DCP sorption coefficients decrease in the order: K_d of a single solute system > K_d of a binary solute system > K_d of a ternary solute system, and no enhancement for phenol and 2,4-DCP sorption was observed.