Multifunctional Magnetic-graphene Nanocomposites For The Treatment Of Micro-pollutants In Water

Find, design and synthesis of novel materials for the detection and depth purification ofthe micro-pollutants in water has important scientific significance and practical value. Hereinthe bifunctional Fe3O4-graphene composites were successfully synthesized, whichsimultaneously possesses the magnetic property of Fe3O4nanoparticles, the high adsorptionperformance of graphene, and the catalytic property of Au and Ag noble metal nanoparticles,TiO2or Ag@AgCl and other three functional components. Then we preliminarily research thecatalytic performance of the composite systems.The results are summarized as follows:1.Fe3O4-reduced graphene oixde(rGO)-M(M=Au and Ag) were successfully prepared byin situ growth method and their structure were characterized by TEM, FESEM, XRD, FTIR,XPS, VSM, TG-DTG and UV-Vis. With NaBH4reduction of p-nitrophenol response as model,we discusses the effect of Fe3O4-rGO-M composite enrichment, raman detection, magneticseparation, in-situ catalytic reduction of p-nitrophenol and collect the useful product of aminophenol. The results showed that with Fe3O4-rGO-Au and Fe3O4-rGO-Ag as the catalysts, thefull reduction of4-NP by NaBH4was completed within10min and15min; the amount of4-NP absorbed to the catalysts can be reached170mg/g and148mg/g, respectively; theamount of4-AP absorbed to the catalysts can be approached447mg/g and440mg/g; thereaction followed pseudo first-order reaction with the apparent rate constant of0.4964min-1and0.2310min-1. In addition, the synthesized nanomaterials exbihited good magneticresponse and the reusability study suggested that the prepared nanocomposites were stableenough and still maintained high catalytic rate after eight cycles.2.A quaternary nanocomposite of Fe3O4@SiO2@TiO2/graphene oxide (GO) was firstsuccessfully synthesized in this work for adsorption and photocatalytic degradation ofrhodamine B (RhB). The resultant sample was characterized by TEM, XRD, XPS, VSM,FTIR and TG-DTG. Its photocatalytic activity was evaluated in the photocatalytic RhB underthe high-pressure mercury lamp irradiation. The results showed that about63%of RhB was absorbed to the prepared Fe3O4@SiO2@TiO2/GO nanocomposites for just30minutes mixing,and after120min high-pressure mercury lamp irradiation, about92.03%of RhB wasconverted. The photocatalytic degradation followed pseudo first-order reaction with theapparent rate constant of0.00882min1. In addition, the synthesized nanomaterial exbihitedgood magnetic response and the reusability study suggested that the prepared nanocompositeswas stable enough and still maintained high degradation rate and catalyst recovery after fivecycles, verifying its potential application in water purification.3.rGO/Fe3O4/Ag@AgCl composite is fabricated by photoreducing AgCl/rGO/Fe3O4hybrids prepared by deposition-precipitation method. The resultant sample was characterizedby TEM, SEM, EDS, XRD and UV-Vis. Its photocatalytic activity was studied using RhB asdegradation substrate. The results showed that about47%of RhB was absorbed to theprepared rGO/Fe3O4/Ag@AgCl nanocomposite for just30minutes mixing, and after50minhigh-pressure mercury lamp irradiation, about98%of RhB was converted. By using the realtime SERS measurements, the mechanism of the catalytic reduction of RhB was proposed.4.GO-COOH and Au nanorod were self-assembled on a silicon substrate simultaneously.The results revealed that at532nm excitation wavelength, the GO/Au nanorod compositeexhibited high catalytic activities, and Raman effect was enhanced with the increasing numberof the assembled layers. This phenomenon can be widely used in medicine, biology, waterpurification and other fields. At the same time for the further preparation of the GO/Aunanorod/Fe3O4composites and their application in the micro water pollutant treatment effectprovides the theoretical and experimental basis.