Influnces Of DOM And PH On Adsorption And Migrations Of Carbamazepine

In order to research the influence of p H and organic matters on migration and transportation of carbamazepine(CBZ) and its migration mechanism in water environment, a series of batch experiments were carried out with several different initial concentration of CBZ. In the experiments, humic acid and kaolin were used for preparation of organic-mineral complexes with different contents of organic matter and p H, the adsorption characteristic of CBZ on which was explored. Furthermore, CBZ column experiments were completed with various dissolved organic matters(DOM) concentrations and components to study the influence of DOM on the migration characteristic of CBZ. The results show that:1) The influence of p H on complexes mainly comes from its influence on Humic acid(organic matter), and Kd increases with the increase of organic matter concentration. In addition, it is found that p H also affects the increase scope of Kd, when p H=7, Kd increases significantly, while moderately at p H=4 and slightly at p H=10. This is because that when p H varies from 4 to 10, condensed humic acid would convert to dispersed state so that more adsorption sites could be created. Besides, the deprotonation of active groups on humic acid and kaolin is strengthened with p H increase, this also results in decrease of CBZ adsorption.2) Humic acid superposes three layers on kaolin surface with the increase of organic matter concentration. In different p H level, the content of the three layer humic acid on the kaolin are different which lead to a influence on adsorption capacity of the soil organo-mineral complexes.3) The results of column experiments showed that silica sand had a certain adsorption effect on carbamazepine, adding DOM could enhance the retention time of carbamazepine in silica sand column, and with the increase of DOM concentration, the blocking effect enhanced. The retardative effect of the hydrophilic components was weaker than DOM when they had the same concentration. It is because that the addition of DOM could provide a middle medium for adsorption, siloxane pressad(Si-OH) on the surface of silica sand could form adsorption sites with DOM as the main active component, which increased the adsorption quantity of carbamazepine. The DOM hydrophilic components have a strong adsorption effect with silica sand and occupies a large amount of adsorption sites which led to a weaker adsorption of carbamazepine in the early stage of the experiment, which wasmanifested as the retardation factor smaller than that with the exist of original DOM.4) In the desorption experiments, the desorption rates of each columns were 54.09%, 50.96%, 26.42% and 37.54%, the results showed that the higher the concentration of DOM, the more difficult of desorption process, and when with the same concentrations of DOM, the silica sand columns with hydrophilic components had the higher desorption rate comparing to that with the original DOM solution. The result showed that the desorption of carbamazepine had a certain hysteresis. For the reason of CBZ entering into the microvoid of silica sand and of DOM so that the CBZ could not be desorbed.