Green Synthetic Procedure Of ?-cyclodextrin Polymer And Its Treatment Of Dyeing Wastewater

The pollution of dyeing wastewater has attracted widely attention in the word,and particularly the coexistence of endocrine-disrupting chemicals(EDCs),heavy metals and dyes in dyeing wastewater has highlighted a great necessity to develop new and effective approaches for their simultaneous removal.In this study,two(3-cyclodextrin polymer has been successfully prepared through environmental friendly procedures,and the application of two adsorbents was evaluated in the treatment of dyeing wastewater.Using ?-cyclodextrin as substrate,citric acid as crosslinking agent,a cationic adsorbent(CD/CA)was successfully prepared by esterification crosslinking reaction in this paper.And this adsorbent was applied for the adsorption of EDCs(bisphenol A,BPA),cationic dyes(methylene blue,MB)and heavy metals(Cu2+).In a monocomponent system,the adsorption behaviors exhibited a maximum adsorption capacity(qmax)of 76.8,288.8 and 45.9 mg/g for BPA,MB and Cu2+,respectively,at pH 6.0.Meanwhile,the multicomponent experiment indicated that BPA and MB adsorptions onto CD/CA were independent from each other,whereas MB and Cu2+ competed over the same sites,this is because that cyclodextrin cavities contributed to entrapment of non-polar BPA,and the surface carboxyl groups provided binding sites for polar MB and Cu2+ through electrostatic attractions.2-dimethylamino ethyl methacrylate monomer(PDMAEMA)was grafted on the surface of synthesized CD/CA polymer,a novel amphoteric adsorbent(CD/CA-g-PDMAEMA)was prepared successfully.And applied for the adsorption toward BPA,cationic dye MB and anionic dye(methyl orange,MO).In a monocomponent system,the adsorbent showed a qmax of 79.0 mg/g for BPA at pH 6.5,165.8 mg/g for MO at pH 4.0 and 335.5 mg/g for MB at pH 11.0,respectively.The results of multicomponent experiment indicated that,this adsorbent could simultaneously adsorb dyes and BPA from dyes/BPA binary system,and selectively remove MO at acid condition and MB at alkaline condition from MB/MO binary system.Meanwhile,BPA adsorption was largely unaffected by pH in the range of 2.0-10.0.Finally,the adsorption mechanisms were proposed that BPA could form inclusion complex with ?-cyclodextrin cavities,while MB and MO molecules could interact with the carboxyl and tertiary amino groups on CD/CA-g-PDMAEMA through electrostatic attractions.Practically,both of the two polymers exhibited excellent stability and reusability.