| Antibiotics as a new type of environmental pollutants,possessed persistent input and potential toxicity,thus it is significant to remove antibiotics from water.Adsorption was a fast,efficient and economical method that has been extensively used to remove antibiotics.The exploitation of efficient adsorbent was important for adsorption technology.Metal-organic frameworks(MOFs),an important class of inorganic-organic hybrid material with porous structures,could be used as versatile precursors or sacrificial templates for preparation of nanomaterials.MOFs derived porous materials displayed hierarchical pore structures with high ultramicroporosity,specific surface area and high total pore volume,which were beneficial to adsorption antibiotics.In this paper,three metal-organic frameworks frameworks derived nanoporous materials were synthesized and theirs adsorption performance for norfloxacin,ciprofloxacin and tetracycline were evaluated.The main research content:(1)ZIF-67 derived Co,N co-doped porous carbon as an adsorbent for removal of norfloxacin antibiotics from water;(2)ZIF-67 derived hollow cobalt sulfide as superior adsorbent for effective adsorption removal of ciprofloxacin antibiotics;(3)ZIF-8 derived nitrogen-doped hollow porous carbons as highly efficient adsorbents for removal of TC from wastewater.The paper could be classified as follow:Chapter 1: The literature on the adsorption of antibiotics were investigated.The development of adsorption antibiotics were introduced from three parts including the disadvantage of antibiotics,the type of adsorbents and the influencing factors.Chapter 2: The Co,N co-doped porous carbon(Co-NPC)was synthesized by one-step carbonization of zeolitic imidazolate framework-67(ZIF-67)and used for norfloxacin(NOR)removal from water.The resultant products were characterized by SEM,TEM,FT-IR,Raman,N2 adsorption-desorption analysis,XRD,TGA and Zeta potential.Pyrolysis temperature show a significant effect on the property of MOF-derived porous carbons,Co-NPC-800(carbonized at 800 oC for 3 h)was found to be the best candidate for NOR.The effects of contact time,initial NOR concentration,adsorbent dosage,p H,ionic strength and humic acid concentration on NOR adsorption process were investigated.Kinetics of NOR removal was found to follow pseudo-second-order rate equation.The equilibrium adsorption data were well fitted by Langmuir model.The relatively high correlation coefficient of Tempkin model(r2=0.962)indicated a stronger electrostatic interaction between NOR and Co-NPC-800,which was consistent with the observation from the effects of p H and ionic strength.The maximum adsorption capacity for NOR based on Langmuir model was 414.8 mg g-1,which was higher than other adsorbents.The Co-NPC-800 material showed little apparent loss in NOR adsorption after five cycles.These features reveal that the ZIF-67 derived NPC may be a promising adsorbent for NOR removal from water.Chapter 3: The hollow nanostructures receive increasing attention in recent years.In particular,the confined cavity in the hollow nanostructures can function as a carrier for loading target molecules,whereas the porous walls are beneficial for shortening the transport distance of target molecules from solution to surface of adsorbent,making it possible to achieve high adsorption capacity with short adsorption time.Here,the hollow Co3S4 was synthesized by using ZIF-67 as template and thioacetamide as sulfide reagent through a simple solvothermal method,and characterized by SEM,TEM,HRTEM,XRD,FT-IR,Zeta potential measurement,TGA,N2 adsorption-desorption and XPS analys is.The adsorption performance of hollow Co3S4 for ciprofloxacin(CIP)antibiotics was evaluated in neutral aqueous solution.The equilibrium adsorption data were well fitted by Langmuir model and a high maximum CIP adsorption capacity of 471.7 mg g-1 was obtained.The relatively high correlation coefficient of Tempkin model(r2=0.960)indicated a stronger electrostatic interaction between CIP and hollow Co3S4,which was consistent with the observation from the effects of p H and ionic strength.Result of adsorption kinetic investigation indicated fast CIP adsorption by hollow Co3S4.The adsorption kinetics follows the pseudo-second-order kinetic model and liquid-film diffusion model.CIP adsorption by hollow Co3S4 was hardly affected by humic acid.Further,the hollow Co3S4 exhibited no obvious loss in CIP removal after recycling for five times.The result displays an important environmental significance of hollow Co3S4 for CIP sequestration,in particular in wastewater,where CIP antibiotics are only slightly transformed or even unchanged.Chapter 3: Herein,three carbon-based materials(named as NPC,NHPC-1 and NHPC-2)were synthesized using ZIF-8 and its composites as precursors through high-temperature pyrolysis method The SEM,TEM,FT-IR,Raman,N2 adsorption-desorption analysis,XRD and XPS were used to confirm the morphology and structure of synthesized materials.The adsorption performance of three carbon materials for tetracycline(TC)antibiotics were identified in neutral aqueous solution.The adsorption equilibr ium time of NPC with non-hollow structure was 16 h,which was longer than the equilibrium time of NHPC-1 and NHP C-2(10 h)with hollow structure.This result indicating that the hollow structure were beneficial for shortening equilibr ium time.The adsorption kinetics of TC removal on three carbon samples were found to follow pseudo-second order model and intra-particles diffusion model.The Langmuir model fitted well with the adsorption data.The maximum adsorption capacities of TC on the NPC,NHPC-1 and NHPC-2 were 180.2,284.9 and 518.1 mg g-1 at 25 oC,respectively.The excellent performance of NHPC-2 for TC removal is mainly attributed to the suitable pore size distribution and pore volume,high nitrogen contents and large amounts of defects.TC adsorption by NHPC-2 was slightly affected by p H and humic acid.The adsorption on NHPC-2 was spontaneous and endothermic reactions.Also,the NHPC-2 showed excellent TC adsorption capacity after eight cycles.The obtained results indicated that the MOF-derived nitrogen-doping hollow porous carbon have promising potential for the removal of TC from wastewater. |
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