Preparation Of Aromatic Hydrocarbon Modifiedβ-Cyclodextrin Gel And Its Adsorption Performance For Polybenzene Pollutants

With the advancement of science and technology and the development of industry,the benzene ring-containing pollutants discharged into the water seriously endanger the natural environment and human health.Cyclodextrin has become a hot material for researchers due to its special macrocyclic hollow structure,low cost,stable chemical properties,internal hydrophobic and external hydrophilic properties.However,with the in-depth research on cyclodextrin,the performance and structure of cyclodextrin alone can no longer meet the demand for increasingly complex sewage environmental treatment,so the controllable modification and cross-linking of cyclodextrin.The research on function enhancement and effect enhancement needs to be further explored and discussed.In this paper,β-cyclodextrin was selected as the core unit,and the primary hydroxyl group at position 6 of the cyclodextrin was mono-substituted and modified,and the structural units containing different numbers of benzene rings were modified on the cyclodextrin to construct a cyclodextrin cavity,construct a cooperative adsorption system of cyclodextrin cavity andπ-πinteraction of benzene ring,and then by selecting the appropriate crosslinking agent,crosslinking the modified cyclodextrin derivatives,several water-insoluble cyclodextrin-based hydrogel adsorbents were prepared.The prepared cyclodextrin hydrogel adsorbent was effectively used to adsorb benzene ring pollutants(bisphenol A,bisphenol AF,rhodamine B)in water,and its adsorption kinetics,adsorption equilibrium,and adsorbent were studied.The regeneration performance of this kind of cyclodextrin-based gel material has laid the foundation for the practical application of this type of cyclodextrin-based gel material.The main research contents are as follows:(1)Three kinds ofβ-cyclodextrins modified by aromatic hydrocarbons(benzene,naphthalene,anthraquinone)were prepared,and three kinds of benzene ring-containing cross-linked compounds including decafluorobiphenyl,terephthaloyl chloride and tetrafluoroterephthalonitrile were selected.The linking agent cross-linked the cyclodextrin derivatives synthesized above,and successfully prepared 10 kinds ofβ-cyclodextrin gel adsorbents,using ~1H NMR,SEM,BET,FT-IR,etc.The basic properties were characterized,and the possibility of its adsorption performance for benzene ring-containing pollutants was analyzed.The test found that the synthesized gel material has cross-linking efficiency,cross-linking density,porosity.The specific surface area will change greatly.According to the BET results,the cross-linked gel materials are all“non-porous materials”,that is,the adsorption process is less dependent on the specific surface area and porosity.(2)The adsorption performance of the synthesized 10 kinds of crosslinks on different gradients of benzene ring pollutants was studied,and the same cyclodextrin derivative gel material and different groups of the same adsorbent after crosslinking with different adsorbents were found.The modified cyclodextrin hydrogels materials exhibited large differences in the adsorption performance of pollutants.Among them,the equilibrium adsorption capacity of TFN-B-CD for bisphenol A and bisphenol AF reached 613.29 mg/g and 581.77 mg/g,respectively,while DFB-N-CD has an equilibrium adsorption capacity of 505.78 mg/g for rhodamine B.In addition,the adsorption process of all adsorbent materials for pollutants containing benzene rings conforms to the Langmuir isotherm model,indicating that the adsorption process is mainly homogeneous adsorption.The adsorption performance of the adsorbent material for bisphenol A and bisphenol AF is greatly affected by the p H value,so the adsorbent can be regenerated by using hydrochloric acid.The cyclodextrin gel cross-linked by decafluorobiphenyl and tetrafluoroterephthalonitrile can maintain high adsorption performance for rhodamine B under acidic conditions due to the presence of fluorine.When multiple pollutants containing benzene ring pollutants coexist,the adsorption performance of the adsorbent for pollutants,especially Rhodamine B,is greatly improved,indicating that the benzene ring pollutants themselves also have aπ-πattraction effect,which makes the adsorbate on the adsorbent becomes a new adsorption site,which greatly improves the overall adsorption effect.