Study On Removal Of Dyes And Endocrine Disruptors In Water By Cyclodextrins Polymeric Materials

With the rapid development of society and the improvement of living quality,the demand for printing and dyeing products has increased year by year,which indirectly leads to an increase of dye wastewater emitted into nature.Dye wastewaters are complex and difficult to be naturally degraded,causing serious damage to natural water bodies.Therefore,a safe and effective wastewater treatment has become the primary goal of environmental workers.In this paper,a simple and pollution-free green synthesis process based on?-Cyclodextrins(?-CD),and hexafluorotetracarboxylic acid(PDA)was studied.The cross-linking agent successfully prepared a water-insoluble ?-Cyclodextrins polymer,PDA/CD,by the principle of carboxyhydroxyesterification crosslinking.The morphological and structural characteristics of PDA/CD were analyzed by SEM,BET and FT-IR,in order to further study PDA/CD.The properties of the polymer was measured by adsorption of typical pollutants,such as cationic dye methylene blue(MB),neutral red(NR)and endocrine disruptor bisphenol A(BPA)as target pollutants.With the study of adsorption kinetics,adsorption isotherms,influencing factors experiment(solution initial pH,adsorbent dosage,inorganic salt ion,fulvic acid and regeneration experiments),the adsorption performance and stability of PDA/CD polymer were proved.Also the regeneration waste liquid generated during regeneration was deeply treated,which avoide a secondary pollution causing by recycled waste liquid.The results show that the surface of PDA/CD material not only retains the hydrophobic cavity of ?-Cyclodextrins,but also contains the carboxyl group of hexafluorotetracarboxylic acid.The adsorption kinetics of MB,NR and BPA by PDA/CD accorded to the pseudo second-order kinetics model.Under the condition of solution pH=6,the isothermal adsorption process of MB and NR by PDA/CD accords to the Sips isotherm adsorption model.The maximum adsorption amount qm,cal of the model were 113.1 mg/g and 106.8 mg/g,respectively.The adsorption of BPA was in accordance with the Langmuir isotherm adsorption model,and the maximum adsorption capacity qm,cal of the model was 55.6 mg/g.The adsorption sites of MB and NR on PDA/CD are mainly carboxyl groups(-COOH),while the adsorption sites of BPA on PDA/CD are mainly Cyclodextrins hydrophobic cavities.Inorganic salt ions and fulvic acid have little effect on the adsorption process.The PDA/CD adsorbent was regenerated with 0.5M hydrochloric acid solution and absolute ethanol,respectively.The adsorption capacity of the adsorbent for MB,NR and BPA after the first regeneration retained 90.2%and 87.1%and 72.4%of the adsorption capacity of the adsorbent before regeneration,respectively.The results of the treatment of the regeneration waste liquid showed that after 60 min of UV/H2O2 treatment,the concentration of MB,NR and BPA in the regeneration solution could be removed by 95.3%,93.3%and 91.2%,under the condition of 10W UV lamp and H2O2 concentration of 100 mg/L.The treatment of the recycled waste liquid by UV/H2O2 greatly reduces the risk of secondary pollution of the recycled waste liquid to the environment.This study fully demonstrates the potential of Cyclodextrins polymers in practical wastewater treatment.