Preparation And Adsorption Properties Of Novel Adsorbent Materials Based On Cyclodextrin

The shortage of fresh water resources is one of the most important challenges that human society faces in the 21st century.The conversion of seawater into fresh water is an effective way to solve the current situation of water scarcity,but in the process of industrial desalination,boron exit in neutral state in seawater which is difficult to remove.Excessive boron could cause toxicological reactions in organisms,resulting in the consequences of crop yield reduction,which seriously affects industrial and agricultural production and daily life.Whether drinking water purification or treatment of boron-containing wastewater,boron removal is an urgent problem to be solved.With the development of industrialization,more and more organic pollutants enter natural water and further enrich in the biosphere,which greatly threatens human health and ecosystems.The rapid adsorption and regeneration technology for organic pollutants in water have received much attention in recent years.Boric acid can reversibly chelate with cis-dihydroxyl with high affinity,and cyclodextrin polymer is an excellent adsorbent material.This paper was based on the chelation of boric acid and sugar,combined with the superior envelope adsorption capacity of cyclodextrin for organic pollutants in water,designed and prepared a kind of multifunctional adsorption material with adsorption of micro-organic pollutants and boric acid sequestration ability.It exploreed the structure-activity relationship between the structural composition of the material and the adsorption performance.First,the surface of cyclodextrin polymer with azide-containing functional group was prepared by modifyingβ-cyclodextrin（β-CD）to obtain azide cyclodextrin,and then using terephthaloyl chloride as a crosslinking agent.The acetylenical sugar monomer was immobilized on the cyclodextrin polymer by"click chemistry",the obtained glycopolymer nanosponge which have cross-linked cyclodextrin polymer as a skeleton.The amount of immobilized monosaccharide was controlled by controlling the content of azide cyclodextrin in the cyclodextrin polymer,using Fourier transform infrared（FTIR）,thermogravimetric analysis（TGA）,elemental analysis（EA）,and pore structure analysis,（N₂adsorption/desorption）,scanning electron microscopy（SEM）and other characterization tools to characterize the chemical composition and surface morphology of the polymer before and after immobilized monosaccharide,which would prove the successful immobilization of monosaccharides.In the adsorption experiments,the adsorption capacity and rate of boric acid and organic dye（methylene blue）supported by glycopolymer nanosponge with different monosaccharides were systematically tested.It was found that the presence of monosaccharides could give polymer ability to adsorb boric acid.The secondary bond between glycosyl and methylene blue molecules could significantly increase the adsorption capacity rate.Dye desorption experiments have shown that nanosponge materials have excellent recyclability.Secondly,based on the above work,we further optimized the synthetic route and developed a synthetic route that did not utilize metal catalysts,then prepared glycopolymer nanosponge with a cyclodextrin as a skeleton which has a porous structure and boron chelation ability.The cross-linked cyclodextrin polymer was prepared by using two different crosslinking agents,tetrafluoroterephthalonitrile（TFN）and terephthalic chloride（TCL）,and then the azide functional group was reduced to an amino group which was used to undergo a ring opening reaction with gluconolactone.The reaction finally producted two types of glycopolymer nanosponges that had different surface properties and structures.By comparing the adsorption of boric acid and bisphenol A（BPA）by two series of glycopolymers,it was found that the glycopolymer with TFN as cross-linked agent had better performance in adsorption rate and adsorption capacity than that of TCL.Both types of glycopolymers have an ultra-fast adsorption rate for BPA,and the time that took to equilibrium adsorption state was not exceed 30s,which was only 1/12 of the equilibrium adsorption time of market-based commercial resin Amberlite IRA743.