Porous β-Cyclodextrin Copolymer For Separating Phenol From Wastewater Via Concentrated Emulsion Copolymerization

Phenolic wastewater is a kind of industrial wastewater with large-area pollution and greatly harm to environment. The emissions and accumulation of phenol and its derivatives to the soil and water led to the deterioration of the ecological environment. Currently, research is focused on the treatment of this kind of wastewater. The molecular structure ofβ-cyclodextrins(β-CD) seems like hollow, truncated cone, and the special molecular structure makesβ-CD gain unique property to form host-guest complexes with various organic compounds and inorganic ions, thus (3-CD could be used for removing phenol organic compounds in wastewater.Per(2,6-di-O-ally1)-β-cyclodextrin was prepared by the modification of β-cyclodextrin with ally1bromide using sodium hydroxide as catalyst. Effect of the amount of allyl bromide and catalyst, reaction time and temperature to the yield of preparation was discussed. The result of the synthesis experiment showed the best reaction condition was n((3-CD): n(C3H5Br)=1:76.0, n(NaOH):n(C3H5Br)=1.34:1.After the chemical modification of β-cyclodextrin, per(2,6-di-O-ally1)-β-cyclodextrin copolymerized with styrene via solution polymerization. Effect of β-cyclodextrin to the hydrophilic performance of polystyrene was discussed, and the contact angle dropped to79.3°from96.1°. Per(2,6-di-O-allyl)-(3-cyclodextrin copolymerized with styrene via concentrated emulsion to prepare P-cyclodextrin grafted porous materials, and the materials were used for separating phenol from wastewater.The movements of per(2,6-di-O-allyl)-β-cyclodextrin towards the water/oil interface in the concentrated emulsion and its influence to the the adsorption capacity of movements was also dicussed by changing the standing time and polymerization temperature of concentrated emulsion. The gathering of β-CD rose first and then decreased with the increasing of the standing time and polymerization temperature of concentrated emulsion, and the phenol adsorption capacity of porous β-cyclodextrin copolymer showed the same variation tendency as well as the gathering of β-CD. The phenol adsorption capacity was5.74mg/g at room temperature when the standing time was8h and polymerization temperature was60℃.Phenol adsorption kinetics and thermodynamics was studied. Phenol adsorption of porous β-cyclodextrin copolymer was a kind of liquid-solid adsorption process, firstly the adsorption happened on the surface of the materials, and then diffused at the inner side after adsorption equilibrium on the surface. Phenol adsorption thermodynamics conforms to the Langmuir equation and Freundlich equation,△G1<0suggested that it was a spontaneous adsorption.△H1=-25.22kJ/mol suggested that the adsorption was exothermic and it was physical adsorption coupled with hydrogen bonding adsorption.Effect of pH to the phenol adsorption performance was discussed, when the pH=5-8, the porous β-cyclodextrin copolymer showed better adsorption capacity. Adsorption and desorption of porous β-cyclodextrin copolymer were studied, and the experiment showed the excellent regenerative adsorption of the porous β-cyclodextrin copolymer, this property made up for the low adsorption capacity to some extent.