| Since the reform and opening up,the development of dye industry has been riding the wind and waves,and the solution of wastewater discharge is urgent.Adsorption method is the main way to treat dye wastewater at home and abroad.Therefore,it is urgent to prepare a suitable adsorbent to solve the problem of wastewater.The raw material selected in this study is polyester fiber,and a modified new polyester composite material is prepared after alkali solution pretreatment and surface modification of silane coupling agent.A set of gravity compression filtration and adsorption device is designed according to the composite material,and after single factor experiment,The optimal preparation conditions,morphology and structure,adsorption kinetics,dye removal mechanism and regeneration properties of polyester fiber composites were revealed.The main conclusions are as follows:（1）In this study,polyester fiber and β-cyclodextrin were used as the main raw materials,and silane coupling agent was used as the coupling agent to prepare polyester fiber composites.The effects of different alkali treatment concentration,alkali treatment temperature,β-cyclodextrin treatment concentration,β-cyclodextrin treatment temperature and silane coupling agent concentration on the adsorption performance of Congo red were investigated,it is concluded that the optimal synthesis conditions for polyester fiber composites: alkali treatment temperature of 30 ℃,alkali treatment mass fraction is 10%,beta cyclodextrin processing temperature of 40 ℃,the concentration of β-cyclodextrin treatment is48g/L,silane coupling agent additive amount is 0.1%.（2）Through scanning electron microscopy characterization,it was found that the surface morphology of the polyester fiber was not changed by weak alkali treatment,but only the roughness of the polyester fiber was increased.In the process of adsorption,the azo dye was adsorbed by adsorbent,and after regeneration treatment,it was eluted again.According to the FTIR characterization results,the positions and shapes of the spectral bands before and after alkali treatment,modification and adsorption are basically the same,which further proves that the internal polymer structure of polyester fiber has not been damaged during the modification process.The results of XPS characterization showed that the decolorization was due to the fact that the color-producing macromolecules in the Congo red group were decomposed into colorless small molecules after chemical oxidation.The comparison of different types of regenerated liquids showed that different types of regenerated liquids had a great influence on the adsorption regeneration rate.When the concentration of sodium hypochlorite was0.1mol/L,the regeneration rate was the highest,and after five regeneration experiments,the regeneration rate was always maintained at more than 80%.（3）Through the single factor method,the adsorption application of the fiber ball to azo dyes was studied,and it was found that:In the range of p H 5-9,the removal rate of Congo red is always maintained between 96% and 100%,and the adsorption capacity is between 9.48 mg/g and 11.65 mg/g.Finally,p H 8is selected as the optimal p H condition for the application of composite materials.The adsorption time has a significant effect on the adsorption.The results show that the adsorption can be roughly divided into three stages: one is the rapid reaction stage,which occurs in the first 6 hours;The second is the slow adsorption stage within 6-8 hours;Thirdly,the adsorption tends to be stable at 8h.Therefore,8 hours was selected as the best adsorption time for Congo red.The dosage of fiber ball has an influence on the adsorption performance of Congo red.Too low or too high dosage of adsorbent will not enhance the adsorption performance.The optimal dosage chosen in this study is 48 g/L.The adsorption performance is also affected by the initial concentration of the dye: the initial concentration is negatively correlated with the removal rate,while the removal rate is positively correlated with the time,reaching equilibrium after a period of time.（4）The kinetic fitting study of adsorption experimental data showed that the adsorption process of Congo red molecules was more consistent with the first-order kinetic model under the condition of p H5-9,which was mainly physical adsorption.The theoretical adsorption capacity is 11.07mg/g,which is close to the actual adsorption capacity of 11.2mg/g.（5）The treatment effects of azo dyes under three operating conditions of circulating,non-circulating and non-aeration were compared and analyzed.It was found that the chroma of Congo red wastewater could be greatly reduced under three conditions,and the removal rate increased gradually with time.The adsorption effect of Congo red is the best under aeration and continuous condition.The adsorption effect of Congo red is the worst under aerated but discontinuous parts. |
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