| Antibiotics are routinely used in human and veterinary medicine for the therapeutic treatment of infectious diseases,as well as for animal growth promoters.However,antibiotic abuse contributes to poor gut absorption or incomplete metabolism resulting in potential hazards to human health and environment.Therefore,it is urgent to solve the environmental toxicity of antibiotics.Advanced oxidation and adsorption are two mature,effective and economical methods in which degradation catalysts and adsorbents are the most critical factors that affect the practical application of the two processes.The transition metal-nitrogen codoped carbon based hybrids synthesizes by a facile physically mix metal salts and carbon source?glucose,graphene or carbon nano-tubes?and a nitrogen agent?NH4Cl,organic ligands or NH3?procedure,followed by high temperature carbonization to obtain a porous carbon composite material.Metal-organic Frameworks?MOFs?are an important class of inorganic-organic hybrid materials with porous structures.They are often used as general precursors to prepare various forms of nanomaterials and new multifunctional metal oxide carbon composites.The porous metal or metal oxide nano-carbon hybrids prepared by high temperature carbonization of the mixture of metal salt,carbon source and nitrogen source or MOFs has the potential to be highly effective antibiotics adsorbents or catalysts due to their unique properties such as high active metal/metal oxide sites,high graphitization,magnitism and large specific surface area etc.To this end,sulfadiazine and tetracycline were used to study the performance of three different nanoporous magnetic nano-carbon composites as novel adsorbents or catalysts in this thesis,mainly:?1?Magnetic porous Fe-N/C-x to assist the degradation of tetracycline under ultrasound irradiation;?2?Porous ZnxCo1.5-xO@Cs derived from bimetallic MOFs for the effective removal of tetracycline in water;?3?MIL-100?Fe?@ZIF-8 derived porous magnetic nano-carbon hybrid adsorptive removal of sulfadiazine in water.The full text consists of four chapters,and the main contents are as follows:Chapter 1:Investigating the literatures on the removal of antibiotics,the current development status is introduced from three aspects:the type of antibiotics,the use of antibiotic and threaten to environment,main treatment methods.Chapter 2:The degradation of tetracycline?TC?in water by the integrated ultrasound?US?-Fenton process was investigated.For this,a new composite Fe/N-C-x?x is the molar ratio of iron salt Fe?NO3?3·9H2O?catalyst was synthesized through simple carbonization of the mixture of glucose and iron salt Fe?NO3?3·9H2O in the presence of ammonium chloride as the nitrogen source.The resultant catalysts were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,Vibrating sample magnetometer,and N2 adsorption-desorption,showing a typical graphite porous structure and good magnetic properties.The results indicated that the optimizedFe/N-C-2catalystpreparedwithamoleratioof glucose/Fe?NO3?3·9H2O/NH4Cl of 5:2:16.8 exhibited the highest TC removal in the Fe/N-C-2/H2O2/US system at a wide pH range from 3.0 to 11.0.At an initial pH of 7.0,TC removal in the Fe/N-C-2/H2O2/TC/US system was 1.83,18.69 and 28.75 times of that in Fe/N-C-2/TC/H2O2,H2O2/TC/US,and TC/H2O2 systems,showing a positive synergistic action between US and Fe/N-C-2.The effects of catalyst dosage,H2O2concentration,ultrasonic power,humic acid,and coexisting anions on TC removal were investigated.The preliminary analysis suggested that the Fe-N species and the graphite N dispersed in the carbon matrix are responsible for the efficient catalytic activity.By a simple magnetic separation and de-ion water wash process,the Fe/N-C-2 catalyst was easily recovered and used for the next degradation experiment.Above 88%catalytic ability of Fe/N-C-2 was retained even after six successive runs,suggesting its good reusability.The simple preparation strategy,good magnetic property and good catalytic ability of the Fe/N-C-2 materials make it promising alternative Fenton-like cataly.Chapter 3:Bimetallic metal-organic frameworks?bimetallic MOFs?have become a research hotspot since they had explored as convenient precursors of various functional materials.In this work,we synthesized a series of Zn-Co-BTCs with different morphology through a one-pot reaction,and they were converted into binary metal oxides@carbon composites(ZnxCo1.5-xO@Cs,x means the mole ratio of Znic,x=0,0.25,0.5,0.75 and 1.5)by pyrolysis strategy.The obtained ZnxCo1.5-xO@Cs were characterized by SEM,TEM,XRD,FT-IR,Zeta potential measurement,TG,N2adsorption-desorption and XPS analysis,presenting great potential for pollutants adsorption applications.When evaluating the adsorption performance on tetracycline?TC?,the Zn0.5CoO@C exhibited the highest adsorption efficiency.The effects of reaction parameters such as pH,Zn0.5CoO@C dosage,HA concentration and coexisting ion were investigated.Under optimal conditions,the adsorption performance of Zn0.5CoO@C material showed little loss in TC adsorption after ten cycles.Moreover,the kinetic process following the pseudo-second-order model and isotherm equilibrium adsorption data were well fitted by the Langmuir model.The mechanism for very favorable adsorption of TC over Zn0.5CoO@C could be explained by the hydrophobic effect,?-?interaction and H-bonding on the basis of the contents of organic functional groups in the graphite carbon structure.The result displays that Zn0.5CoO@C has an important environmental significance for pollution remediation.Chapter 4:A novel dual-MOF derived magnetic microporous nano-carbon material was successfully fabricated by using MIL-100?Fe?@ZIF-8 composite as a precursor,combining with a facile pyrolysis process.TEM,XRD,XPS and FT-IR characterization strategies confirm that nano-Fe3O4 was highly loaded and uniformly dispersed in the carbon matrix.N2 adsorption-desorption analysis of as-synthesized material shows micro-porous structure with Brunauer-Emmett-Teller surface area of 370.4 m2/g and pore volume of 2.20 cm3/g.To take good use of this material,we put it into adsorption application for sulfadiazine?SDZ?removal.Freudlich isotherm model and the second-pseudo-order adsorption module adsorption kinetic were well agreed of SDZ based on the carbonized MIL-100?Fe?@ZIF-8?CMZ?.The CMZ shows excellent removal ability on SDZ with capability of 408.16 mg/g,which was competitive than other adsorbents.In addition,magnetic characteristic shortened separation process and maintained up to 81%removal efficiency after forth cycle.These features reveal that the dual-MOFs derived CMZ may be a promising adsorbent for water contaminant SDZ removal. |
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