Development Of Chitosan/β-cyclodextrin Dased Adsorbent And Degradation Of PNP

Water pollution is an urgent problem to be solved in China’s sustainable development.Due to the rapid development of industry,a large number of p-nitrophenol（PNP）wastewater is directly discharged into the water body,which seriously threatens human health.Therefore,the treatment of PNP is of great significance.Among the many methods of treatment PNP,adsorption method with high efficiency,economy,simple operation and wide range of applicable,has been widely concerned.At the same time,the electrochemical method is also concerned,due to high efficiency,simple operation and no secondary pollution.Therefore,the key to treatment PNP is to study the cheap,efficient and widely available green adsorbents and stable electrodes.Chitosan（CS）contains a large number of amino and hydroxyl groups,which provide a large number of active sites for adsorption.The cavity structure ofβ-cyclodextrin（β-CD）can envelop organic molecules,and Ti substrate has good conductivity and low price.Using the properties ofβ-CD,CS and Ti substrates,adsorbents and electrodes were prepared by using CS,β-CD and Ti substrates as substrates for the treatment of PNP.The specific research work and results are as follows:（1）β-cyclodextrin polymer microsphere（β-CDPM）were prepared by reverse phase emulsion method withβ-CD as substrate.The preparation process ofβ-CDPM and the adsorption behavior of PNP were studied.The adsorbents were characterized by SEM and FTIR,and the characterization results showed thatβ-CDPM fully retained the cavity structure ofβ-CD,which provided the conditions for the adsorption of PNP.Adsorption experiments show that acidity and low temperature are favorable forβ-CDPM adsorption of PNP.Under pH=2.0 and 25℃,the adsorption equilibrium of PNP onβ-CDPM was reached within 420min,the adsorption isotherm was well fitted by the Langmuir model,and the maximum adsorption capacity is54.17mg.g^-1.Adsorption kinetics followed the pseudo-second-order kinetics.The adsorption thermodynamics indicate that the adsorption process is a spontaneous and orderly increasing adsorption process.（2）Aβ-cyclodextrin modified chitosan polymer（β-CD-CSP）was prepared with CS as the substrate and modified byβ-CD.The preparation process ofβ-CD-CSP and the adsorption behavior of PNP were studied.The adsorbents were characterized by SEM,FTIR and elemental analysis.Characterization results showed that there were more folds on the surface of theβ-CD-CSP,which was beneficial to the adsorption of PNP,and theβ-CD was successfully modified onto CS.Adsorption experiments show that acidity and low temperature are favorable forβ-CD-CSP adsorption of PNP.Under pH=6.0 and 25℃,the adsorption equilibrium of PNP onβ-CDPM was reached within 180min,the adsorption isotherm was well fitted by the Langmuir model,and the maximum adsorption capacity is 124.22mg.g^-1.Adsorption kinetics followed the pseudo-second-order kinetics.The adsorption thermodynamics indicate that the adsorption process is a spontaneous and orderly increasing chemical adsorption process.（3）Bi³⁺and polyethylene glycol（PEG）doped PEG-Bi-PbO₂ electrode was prepared by electrodeposition on a titanium substrate.The preparation process of PEG-Bi-PbO₂ electrode and the degradation behavior of PNP were studied.The electrode was characterized by morphology analysis and XRD.The characterization results show that the distribution of the active layer on the surface of the PEG-Bi-PbO₂ electrode is the best uniform among PbO₂ electrode、Bi-PbO₂ electrode and PEG-Bi-PbO₂ electrode.The degradation experiments showed that the degradation rate of PEG-Bi-PbO₂ reached 92.3%under the condition of 20mA/cm²,C_Na2SO4=0.08mol/L,pH=5.0 and 60℃,and the degradation process accorded with pseudo-first-order kinetics.