| A new cationic polymer epicholorohydrin-dimethylamine(EPI-DMA)as intercalary reagent was used to prepare a series of EPI-DMA cationic polymer/bentonite complex adsorbent.The technical condition of the intercalation reaction besides the thermodynamics and kinetics were studied.The change in specific surface area,zeta potential,granularity distribution,interlayer spaces,structure characteristic, hydrophilic/hydrophobic property,deposition and stabilization of bentonite after intercalated by EPI-DMA were investigated by varies physical chemistry methods and modem instruments analysis.The performance character of EPI-DMA/bentonite was defined.Based on the study of the adsorption property and adsorption thermodynamics and kinetics of EPI-DMA/bentonite for four species dyes,the adsorption mechanism was discussed.In addition,the application of EPI-DMA/bentonite for actual wastewater treatment was also studied.Furthermore,the technologies of regeneration and granulation for EPI-DMA/bentonite were exploringly studied.The main contents and results are following:1.The bentonite was modified with the new cationic polymer EPI-DMA as intercalary reagent by organic polymer direct intercalation method.The influences of EPI-DMA performance index,the EPI-DMA concentration and different experimental conditions on the formation of EPI-DMA/bentonite were investigated.The optimum conditions for synthesis were also concluded.The results indicated that the synthetic effect was impacted by the polymer viscousness,polymer initial concentration,reaction temperature,reaction time,pH values of the system and the salt concentration,in which the influence of EPI-DMA initial concentration was prominent.The optimum technical condition was 7.0 g·L-1of initial polymer concentration,55 0C of reaction temperature, 2.0 h of reaction time and system pH 7.0.2.Combined with the influence of different experimental condition on the intercalation,the thermodynamics and kinetics were studied and the reaction mechanism was also concluded.The process of EPI-DMA modifying bentonite included two parts which were the adsorption of EPI-DMA cation into bentonite interlayer by ion exchange and the adsorption of EPI-DMA cation onto bentonite surface by charge neutrality.The whole adsorption process could be simulated by Fruendlich adorption model and the kinetics followed the the two-steps kinetic rate equation well.Increasing temprature favored for the adsorption proceeding.Both the Van der Waals forces,hydrogen bond forces and hydrophobic bond forces exiting between the EPI-DMA cation and bentonite interlayers and the increase of entropy of unadsorbed EPI-DMA molecular in solution, were the driving force for the adsorption process.3.The configuration and performancewere of EPI-DMA/bentonite investigated by varies physical chemistry methods and modem instruments analysis.The specific surface area of EPI-DMA/bentonite increasecd with the increase of polymer content.The zeta potential of bentonite increased from-40.15 mV of raw clay to+15.21mV after the intercalation of EPI-DMA.The granularity distribution of EPI-DMA/bentonite spreaded to larger particle size and the average particle size could increase to 30μm,which belonged to the suitable applied range.XRD analysis proved that EPI-DMA polymer had intercalated into the bentonite interlayer indeed and the interlamellar spacing had been expanded effectively and increased with the polymer content increase.TEM analysis indicated that EPI-DMA made the montmorillonite lamina into prismatical layer association structure and the polymer adsorbed on the bentonite surface presented flocculent structure.SEM analysis showed that the surface of EPI-DMA/bentonite presented lamina separation,which favored for organic pollutant adsorption.TG-DSC analysis proved that the adsorbed water on bentonite interlayer and surface decreased, constitution water disappeared and the clay hydrophobic nature strengthen heavily. Further more,the FTIR analysis also verified the results.Compared with raw bentonite, EPI-DMA/bentonite possessed stronger hydrophobic property,better deposition and stabilization,all which favored for its application in wastewater treatment as adsorbent.4.Take four typical dyes for object of study,which were reactive dye,disperse dye, acid dye and reduced dye,the adsorption property of EPI-DMA/bentonite for dyes and the influence factors on the adsorption were studied.The results indicated that the adsorption capacity for dyes of EPI-DMA/bentonite was better than that of raw bentonite obviously.The decolorization property of EPI-DMA/bentonite was better or equivalent to active carbon,which made it have the potential to substitute for active carbon partly in dye wastewater treatment.The for four dyes increased with the EPI-DMA/bentonite addition and the percent for water-soluble reactive and acid dye were higher than that for water-insoluble disperse and reduced dye.The effect of solution pH on decolorization was remarkable and the percent of decolorization decreased with the increase of pH.The existing of salts in solution could strengthen the reciprocity between dye and EPI-DMA/bentonite,which made the decolorization property increase.On the contrary, the existing of dyeing and finishing auxiliaries could obstruct the reaction of dye and EPI-DMA/bentonite,and then weakened the adsorption capacity.5.Based on the study of thermodynamics and kinetics of dye adsorption onto EPI-DMA/bentonite,the adsorption mechanism was revealed.In the EPI-DMA/bentonite -dye adsorption system,besides the mechanism of organic matter distribution,the adsorption mechanism of EPI-DMA/bentonite for reactive and acid dyes included charge neutrality and ion exchange,by which-SO3H in dye structure exchanged with Cl- in EPI-DMA/bentonite to form -NH2+SO3- or=NH+SO3-.But for disperse and reduced dyes,besides organic matter distribution and charge neutrality mechanisms,the adsorption took place by the flocculation of EPI-DMA.The results of adsorption thermodynamics indicated that the adsorption could be described well by Freundlich model and the adsorption process was favourable.ΔHads0＞0 indicated the endothermic process and the value was in the range of 0～63 kJ·mol-1accounted for the physical adsorption.ΔSads0＞0 showed that the decrease of entropy caused by the adsorption of dyes could not counteract the increase of entropy caused by the desorption of water molecular.ΔGads0＜0 indicated that the adsorption process was spontaneous.The kinetics study indicated that the pseudo-second-order equation was more suitable in describing the whole process of EPI-DMA/bentonite for dyes adsorption.In addition,intraparticle diffussion existed in the whole adsorption process but was not rate control stage.With the increasing of temperature,the pseudo-second-order decreased but the intraparticle diffussion rate constant kp increased,which indicated the change of adsorption mechanism.The energies of adsorption activation values also confirmed the physical adsorption process.6.The effects of different agent for wastewater were compared by the treatment experiment for actual dyeing wastewater and oily wastewater.The results indicated that EPI-DMA/bentonite possessed good capacity for colour removal,oil removal and COD removal,and was much better than that of either raw bentonite,EPI-DMA polymer, active carbon or adding EPI-DMA and bentonite respectively.The sluge after water treatment deposited quickly and the volum was small.For different wastewater,all the agent amount,reaction time and solution pH were different.When EPI-DMA/bentonite used in actual dyeing wastewater and oily wastewater treatment,the removal effect for colour and oil were better than that for COD.7.The study of granulation technology for EPI-DMA/bentonite indicated that bentonite granules could be prepared by coal as pore-causing agent and amylum as crossing-linking agent.The raw material was mixed according to the ratio of 20:4:0.4 and then was high-temperature roasted under 600℃for 6.0 hours,after which the water-fast and fine granulating bentonite granules were obtained.The EPI-DMA/bentonite granules,which had excellent adsorption capability,could be obtained by modifying raw bentonite granules with 5.0%EPI-DMA polymer under 40℃for 4.0 hours.The study of colour removal showed that all the adsorption of EPI-DMA/bentonite granules for reactive blue,reactive brilliant red,disperse yellow brown and disperse blue fitted to Langmuir model well and belonged to monolayer adsorption.The adsorption kinetics agreed with pseudo-second-order equation and there did not exist intraparticle diffusion.
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