| The preparation of bentonite modified by organic cationic polymer is one of the new hot spot in the research of organic bentonite in recent years. Utilizing the easy expansion in water and good ion-exchange properties of bentonite, this paper uses a new cationic polymer epicholorohydrin-dimethylamine (EPI-DMA) as intercalary reagent, and select a liquid-phase intercalation method to preparate a series of EPI-DMA /bentonite. The adsorption performance of EPI-DMA / bentonite on pollutants has been studied. In order to improve its adsorption capacity furtherly, a new modifying method has been explored. The comparison of different modifying methods is also carried out. This paper includes four parts as follows:1. EPI-DMA/bentonite, as a new type of sorbent, was synthesized by using cationic polymer epicholorohydrin-dimethylamine (EPI-DMA) and Na-bentonite. The surface function groups and morphology were characterized with the help of SEM photos, TEM photos and XRD. The experiment also showed the equilibrium amount of cationic polymer was 100 mg/g, while the specific surface area is 20.5 m~2/g, and the Zeta is more than 10 mV.2. The adsorption characteristics for phenol and p-chlorophenol in water by EPI-DMA/bentonite were studied. By using the bottle-point technique, the effective factors such as the amounts of EPI-DMA/bentonite, adsorption time, solution pH, time of reaction had been studied.The adsorption kinetics and adsorption thermodynamics of phenol and p-chlorophenol on EPI-DMA/bentonite were investigated. And the thermodynamic parameter was calculated.The results showed that the adsorption ability of the bentonite adsorbing phenol and p-chlorophenol was improved after modifying. The order of removal efficiency were: phenol > p-chlorophenol. The adsorption of phenols onto bentonite was markedly pH-dependent. The uptake of phenols on EPI-DMA/bentonite was better at pH<7. Adsorption increased rapidly at initially 10 minutes and then attained equilibrium at about 30 minutes. The pseudo-second kinetic model, the Freundlich and D-R isotherm model provided a better correlation for the adsorption of phenol and p- chlorophenol onto EPI-DMA/bentonite. The adsorption of phenol also could be described by isotherm equation. For phenol and p-chlorophenol,ΔH<0, their adsorption was exothermic reaction. |ΔH|<30 KJ/mol, their reaction was phisical adsorption.ΔG>0, their adsorptions was non-spontaneous.3. The adsorption of Cr (VI) on EPI-DMA/bentonite were studied. The results shows that the sorption capacity of Cr (VI) was increased more than five times compared with the original one. The load of cationic polymers in bentonites, the dosing quantity of EPI-DMA/Bt and PDMDAAC/Bt, the solution pH, temperature (T), time of reaction (t) affected the adsorption. When T=20℃, pH=4.0, t=120 min, EPI-DMA/Bt (the load of cationic polymer was 99.6 mg/g) and PDMDAAC/Bt (the load of cationic polymer was 55.1 mg/g) adsorbed 0.71 mg/g and 0.56 mg/g Cr (VI), respectively. The adsorption kinetics were fitted well by pseudo second-order equation. The adsorption isotherms of EPI-DMA/bentonites to Cr (VI) were fitted well by the Langmuir equation. Its thermodynamic parametersΔH<0 andΔG>0, showed that the adsorption was exothermic and non-spontaneous reaction.4. Some new research of modifying methods was carried out. Dimethylamine, epichlorohydrin, ethylenediamine were used as inter-layer reagents to preparate a series of EPI-DMA/bentonite with monomer- insert interlayer-polymerization method. The influence of the amount of dimethylamine, epichlorohydrin, ethylenediamine, reaction temperature and reaction time on the performance of EPI-DMA/Bt were investigated. The results showed that, when the amount of dimethylamine was 3 mmol/g bentonite, n ( epichlorohydrin / dimethylamine ) = 1:1 and m ( ethylenediamine / epichlorohydrin + dimethylamine ) =2 %, reacting at 65℃for 3 h, the amount of cationic polymer of the EPI-DMA/Bt prodution was 100 mg/g and the adsorption efficiency to the activated jade blue (K-GL) was above 90 %. Compared with the Organic polymer solution straight insertion method,the monomer- inserted interlayer-polymerization method was moreeffective.
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