The Synthesis Of Mesoporous Fenton Composite Catalyst And Its Application In Organic Pollutants Degradation

Since its emergence, Fenton catalysis has drawn considerableattention in the field of environmental science because of its highefficiency in wastewater treatment. Presently, homogeneous Fentoncatalysis has been considered as a good alternative in wastewatertreatment, but it still had various shortages. Therefore, heterogeneousFenton catalysis became a focus area. In this paper, we chose MCM-41ascatalyst support, and hoped to grope a possible way to resolve two majorobstacles in heterogeneous Fenton catalysis: the catalyst itself wasinactive without external power supplies; the separation of pulverescentcatalyst particles from a complex heterogeneous system was difficult.Based on the problems mentioned above, the major research contents andresults are listed as follows.（1） A new heterogeneous Fenton catalyst, Fe-Cu bimetallic oxidessupported aluminum-containing MCM-41, was synthesized byco-precipitation method. The physicochemical characteristics of thesynthesized samples were evaluated by various techniques such as XRD,TEM, Nitrogen physisorption, Zeta potential and XPS. The incorporationof metal species did not alter the well-ordered hexagonal mesostructure ofMCM-41support. Compared with the monometallic or the Al absent catalysts, this new bimetallic oxides supported aluminum-containingMCM-41catalyst exhibited a higher activity and stability in phenolmineralization. The effects of temperature, pH and H₂O₂dosage wereinvestigated in terms of the TOC conversion. At pH4,60℃and0.049mol/L of H₂O₂dosage, a47%TOC reduction has been achieved. Withincorporating aluminum, the increase in surface oxygen-containinggroups was observed by zeta potential analysis, and thus, thedecomposition of adsorbed H₂O₂into H₂O and O₂has been greatlysuppressed. Moreove, the downshift binding energy of active metals wasfound by XPS measurement. As a result, the amount of adsorbed H₂O₂around the active sites increased and an enhancement of H₂O₂utilizationratio was achieved. On the basis of our findings, the beneficial role of Alhas been explained.（2） A novel magnetically separable core/shell type nanocompositewas synthesized in a facile way and characterized by XRD, UV–Vis,FT-IR, TEM, Nitrogen physisorption and Magnetite susceptibilitymeasurements. In the synthesis procedure, the magnetic particles weremodified firstly by trisodium citrate to prevent them from aggregation.The effect of trisodium citrate concentration on magnetic core dispersionwas also investigated. Then, the mesoporous silica shell was coating onthe surface of magnetic core directly via a nano-assembling method. Aftercalcination at high temperature （550℃） for template removal, the spinel phase of maghemite core was retained without any transformation.The resulting material possessed a regularly hexagonal mesoporousstructure with a high specific surface area （908.70m²/g）, which werefavorable to further functional modification. Once incorporated with ironspecies by in situ synthesis, the nanocomposite could serve as a Fentoncatalyst. At the end of the reaction, it was easily collected by an externalmagnetic field.（3） Fenton catalysis of phenol solution using magneticnanocomposite as catalyst was conducted. At the given conditions （40℃,pH=4）, the nanocomposite demonstrated an excellent catalytic activity.According to our findings in Fenton reaction, a thin SiO₂shell wascoating on magnetic core to stabilize it in catalytic reaction. Moreover,the effect of CTAB and ammonia dosage in synthesis precursor onmagnetic nanocomposite synthesis was studied. At last, the application ofmagnetic nanocomposite on photochemical catalysis was also proposed.