Structure Regulation Of Organobentonites And Their Sorption Characteristics

The sorption capacity of organobentonite towards organic contaminants was excellent, and it has been found wide applications as effective sorbents for the removal of organic contaminants in wastewater treament. Optimizing the sorption capacities of organobentonites and designing high efficient organobentonites towards special contaminant for certain treament demands are the key problems for its wide use. In this dissertation, series of surfanctant with different structure were chosen as model molecules to synthesized organobentonites with certain structure. Then structural characteristics of the organobentonites were characterized. Sorption capacities of organobentonites towards organic contaminants were exmined and related with the organobentonites' structure in order to reveal the sorption mechanisms. The influence of co-exist surfactant on the sorption of organic contaminants in one-step process. The main original conclusions of this work are as follows:1. The influence of surfactant loading form on the sorption capacities of organobentonites was clarified. At high loading region (>0.8CEC), long-alkyl surfactant salt molecules appeared in the clay interlayer via hydrophobic interaction between alkyl chains, the strong hydration of surfactant ammonium heads and the counterions in aqueous system interfered the hydrophobic interaction of the alkyl clusters and destroyed the close packing. So, the sorption capacity towards HOCs was sharply reduced. The sorption capacities of organobentonites synthesized with double-chain surfactant (DODMA) towards naphthalene and nitrobenzene were higher than that of the organobentonites synthesized with mono-chain surfactant (OTMA).2. It was found that in the sorption of short-alkyl organobentonite towards organic contaminants, the alkyl chaind of organic cations could not form effective adsorption sites, while they contributed to enhancing hydrophobic environment and the affinity for organic contaminants. As results, the saturated adsorption amount was reduced, and the sorption ability towards low conceration contaminant was enhanced, e.g., K_d of 30HM-Bent towards phenol when concerntration below 100 mg/L was 1.5 times than that of 60TMA-Bent.3. It was found that the co-exist nonionic surfactant loaded on the bentonite and form partition phase together with cation surfactant in one-step process, and enhanced the sorption ablity towards organic contaminants such as naphthalene. While the resudial surfactants concentration was higher than their CMC, the sorption ability of organobentonie was reduced.