Preparation Of Nano-Zerovalent Iron Modified Ultrafiltration Membrane And Its Application In The Treatment Of Chlorophenol Wastewater

Chlorophenols（CPs）are raw materials or intermediates for dyes,pesticides and organic synthesis,and are widely used in chemical,pharmaceutical,pesticide and other fields.Because of its strong toxicity,difficult to degrade,bioaccumulative,and"three effects"on organisms,it is listed as a priority pollutant.Nano zero valent iron（nZVI）has great advantages in pollutant removal due to its extremely small particle size,high specific surface area,and strong reducing power of iron,but its poor dispersibility and easy agglomeration limit its development and application.In this dissertation,polyvinylidene fluoride（PVDF）membrane is used as the research object,and nZVI is used as a modifier of organic membranes to prepare hydrophilic and functional modified membranes,and the in-depth exploration of the addition of nZVI to the filtration performance and resistance of modified membranes is explored.Pollution performance and the effect of CPs retention and removal.A set of filter-degradation integrated CPs removal process was developed,and the membrane fouling mechanism of nZVI modified membrane was analyzed in combination with the membrane attenuation total reflection infrared spectrum imaging platform.The research results will be membrane filtration It provides a theoretical basis for the integration of degradation and integrated treatment of refractory wastewater.The research contents and main conclusions of this article are as follows:（1）Preparing nZVI/PVDF membranes by surface coating,and applying modified membranes in an ultrafiltration process to treating 2-chlorophenol（2-CP）wastewater,and explore effect of different nZVI loadings,p H values,the types and concentrations of DOM and competitive ions in wastewater on the 2-CPs removal.The experimental results indicated that addition of nZVI effectively improved the membrane flux.The 2-CP degradation efficiency of the modified membrane was the highest when the nZVI loading was 2 mg/cm²,and the removal efficiency reached 92%at 280 minutes.The 2-CP removal efficiency was highest at neutral p H.When humic acid（HA）,sodium alginate（SA）,and different competing ions was co-existed with 2-CP respectively,2-CP removal by the modified membrane was slightly decreased,but it still maintained a good 2-CP degradation efficiency.（2）A membrane fouling characterization platform was built to study membrane fouling caused by HA,SA,and xanthan gum（XG）during nZVI/PVDF membrane filtration.In the HA-XG system,when HA:XG=1:1,the membrane flux attenuation was the highest,J/J₀=42%,and the TEP content of the solution was 30.29 Xeq/L;when SA:XG=1:2,the membrane flux was minimized with J/J₀ value of 24%,and the TEP content was also the highest.These results indicated that the membrane flux reduction was a certain extent positively correlated with the TEP content of the solution,but also with the characteristic of contaminants.The spatial distribution of pollutants shown that in the HA-XG mixed system,the spatial distribution of HA on the membrane surface was more uniform,while XG was distributed on the Part of the membrane surface,but the relative concentration was high,which demonstrated that XG was the major pollutants for nZVI/PVDF membrane fouling.In the SA-XG system,the spatial distribution of SA and XG was basically the same,but the relative concentration of XG was higher.And the pollutants concentration on the membrane surface increased with the increase of filtration time.