The Research On Solubilization Of Polychlorinated Biphenyls By Hydroxypropyl-β-cyclodextrin

Polychlorinated biphenyls (PCBs) are wildly distributed environmental contaminants. Remediating soils contaminated by PCBs to protect human health and fulfill the sustainable development of the society is one of the subjects which are full of theoretical and practical significance in the environmental research field. Brief introduction of the physical and chemical properties, environmental toxicity, environmental adsorption behavior, environmental transport and transfer, and the pollution status of PCBs was presented in the thesis. Mechanism of solubilization of surfactants and cyclodextrins were discussed. Environmental research progress of solubilization of hydrophobic organic pollutants was reviewed.Solubilization of 2,2'CB, 2,2',4,4'CB, 2,2',5,5'CB, 2,2',4,4',6,6'CB and Aroclor1242 by hydroxypropyl-β-cyclodextrin (HPCD) was investigated in the thesis. The equilibrium of solubilization of 2,2',5,5'CB and 2,2',4,4',6,6'CB by HPCD at the concentration of 10 gram per liter was achieved after 7 days. The apparent solubility of 2,2'CB, 2,2',4,4'CB, 2,2',5,5'CB, 2,2',4,4',6,6'CB and Aroclorl242 increased by 128 times, 173 times, 235 times, 2114 times and 170 times respectively when the concentration of HPCD was 10 gram per liter. The apparent solubility of the 4 PCB congeners and Aroclor1242 increased linearly with the increasing of HPCD concentration. Inclusion compounds of HPCD and the 4 PCB congeners with the stoichiomitry of 1:1 were formed. Hydrophobic interaction between HPCD cavity and PCB molecules is the basis of solubilization of PCBs by HPCD, as a result, the solubilization effect is better if the PCB congener is more hydrophobic. The spacial matching degree between HPCD cavity and PCB molecules is a important factor influencing the solubilization effect of PCBs by HPCD. The spacial matching degree between HPCD cavity and 2,2'CB molecule is higher than that between HPCD cavity and 2,2',4,4'CB molecule, 2,2',5,5'CB molecule and 2,2',4,4',6,6' CB molecule, so the practical solubilization effect of 2,2'CB by HPCD is better than that determined only by its hydrophobicity.The MSR value of the 4 PCB congeners in 4-solutes system accounts for 62 percent of that in single-solute system averagely, and the MSR value of the 4 PCB congeners in Aroclor1242 system accounts for only 8.5 percent of that in single-solute system averagely, so co-solutes decrease the solubilization effect of PCBs by HPCD.The solubilization ability of HPCD to 2,2'CB is close to that of polyoxyethylene 10 lauryl ether (POL(10)), and the solubilization ability of HPCD to 2,2',4,4'CB, 2,2',5,5'CB and Aroclor 1242 is less than that of POL(10).