Synthesis Of New Cyclodextrin Polymers And Adsorption Of Pollutants In Water

Because of increasingly environmental pollution in recent years,the environmental situation has become so worse that focus of attention of the countries all over the world is developed.Chlorophenol compound is common organic pollutants in environment,it is greatly hazardous to human health.It has been a preferent control pollutants in many countries,our country considers it as the major pollutants.In water treatment,it is difficult to treat in the conventional process.Dyes and heavy metals pollution are thought to be an important environmental problems.This topic prepares a kind of new and nonselective adsorption materials,which was used to deal with 2,4,6-trichlorophenol(TCP),ponceau 4R,Zn2+ and other pollutants,and good results are achieved,providing a new route and method for other pollutants in wastewater treatment.This article adopted beta-cyclodextrins(CD)and self-made polyamide-amine(PAMAM)as raw material,initially CD is modified with 4-toluene sudonyl chloride,subsequently cross-linked polymerization with PAMAM,generates a new cyclodextrins cross-link polymer(PAMAM-CD),which insolubled in water.The structures were characterized by IR,elemental analysis,XPS,TGA-DSC,XRD,SEM and other methods,to determine the nature of the polymer.After purification,drying,grinding,sieving,polymer are used to treat TCP,P4R、Zn2+ and other pollutants,respectively the content of the phenol is determined by UV-visible spectrophotometer and flame atomic absorption spectrometer.The results show that:(1)PAMAM-CD has both the C-O-C and-OH of CD,the N-H,C-N and N-C=O structure of PAMAM;CD and PAMAM mole ratio was 2.0:1 in PAMAM-CD;its an average of aperture is 7.4490nm,specific surface area was 1.1899 m2/g,is amorphous collective state polymer,the swelling ratio to 323%in the water,which insoluble in common acid、alkali and organic solvent,which was stable below 200℃,and started slow decomposition above 200 ℃;PAMAM-CD has smooth surface and ist interior has a porous network structure on basis of SEM.This structure was beneficial to the adsorbates into quickly entermy the internal of the adsorbent through pore,and full contact with the active site of polymer,so as to facilitate the adsorption.(2)The equilibrium time was 120min,the adsorption capacity of TCP was up to 112.42、110.40、107.36 mg/g when the initial concentration of TCP solution was120mg/L at 288、298、308K and the pH value is 5,PAMAM-CD and TCP formed three kinds of hydrogen bonding in acid conditions were mentioned;The equilibrium time was 120min,the adsorption capacity of P4R up to 241.93、240.81、237.07mg/g when the initial concentration of P4R solution was 280 mg/L at 288、298、308K and the pH value is 5,PAMAM-CD and ponceau 4R formed ionpair in acid conditions were mentioned;The equilibrium time was 600min,the adsorption capacity of Zn2 + up to 52.63,52.51、46.67、44.46 mg/g when the initial concentration of Zn2+ solution was 160 mg/L at 288、298、308K and the pH value is 6,PAMAM-CD and Zn2 + possible 5 kinds of coordination way were mentioned.(3)The equilibrium adsorption capacities of TCP onto PAMAM-CD were slightly lower,but the P4R and Zn2 + increased when NaCl were added into the solution.Adsorption kinetics followed the pseudo 2nd order model of the three substances,the rate determining step in the process of adsorption of TCP and Zn2 +were particle introa diffusion,but the P4R was membrane diffusion.(4)Equilibrium isotherm data of TCP and Zn2 + adsorption onto PAMAM-CD were satisfactorily fitted by the Freundlich equation,but the P4R fitted by the Langmuir model,the △G value is negative,thus the adsorption process was spontaneous.(5)After adsorbed TCP、P4R and Zn2 +,the PAMAM-CD were easily desorbed using ethanol、hydrochloric acid and nitric acid as washing solvent.It was observed that the sorption capacity did not decrease after this treatment,it was show that the PAMAM-CD could be used many recycling.