Carbon/Silica Based Nanocomposites Construction For Application And Mechanism Study In Selective Separation And Analysis

Nanocomposite materials have play a more and more important role in modern industry,due to their better functionality and wider application field than many traditional materials.One of the research point focuses on constructing novel nanocomposite with specific properties.Carbon/Silica nanomaterials possess higher surface area,outstanding mechanical stability and temperature stability,making them favorable to be used to construct novel nanocomposite,having promising application prospect in separation and detection field.It is essential to design carbon/silica-based novel nanocomposite for selective separation and analysis.Herein,several technologies,such as surface imprinting technology,revisable addition-fragmentation chain transfer?RAFT?polymerization,microemulsion polymerization,temperature responsive separation and elution,and selective fluorescent detection,were used for novel carbon/silica-based novel nanocomposite construction,which can be used for selective separation and detection.The main research content and results are as follows:?1?A dual temperature responsive Cd???imprinted polymer?DT-IIP?was newly synthesized by taking merits of surface imprinted technology and photo-initiated controlled/living RAFT polymerization.DT-IIP was a nanocomposite base on SBA-15,which was prepared from two kinds of temperature responsive monomer.It was found that DT-IIP possess imprinted layer of 60 nm on SBA-15.DT-IIP was used for Cd???adsorption,finding the optimal pH was 6.0 and adsorption time was 60 min.The adsorption of DT-IIP towards Cd???was chemical adsorption with higher selectivity.DT-IIP possesses dual temperature sensitive shells which account for thermo-responsive behaviors.Moreover,the temperature switching controlled absorption,separation and regeneration of DT-IIP was simply performed,so that the distinguished thermo-responsive behaviors can be effectively controlled by single temperature factor.The structure changes of temperature sensitive shells in DT-IIP are responsible for the temperature controlled behaviors.The reusability of DT-IIP was also appraised after temperature controlled adsorption,separation and regeneration sections,proved to be with splendid competence.It is of great value for sorbent recycling.?2?A novel graphene oxide?GO?-based cadmium imprinted polymer?Cd???-IIP?was prepared via surface ion imprinted technology and RAFT polymerization in microemulsion system.In the polymerization methodology,the RAFT technology was applied to controlling the morphology and functionality of the imprinted polymer.The polymerization was conducted in the microemulsion system to keep stable polymerization process.It was found that the Cd???-IIP possessed uniform polymer structure and morphology with uniform microsphere of 30 nm grafted on GO,the saturated adsorption capacity of 83.76 mg/g and remarkable selectivity and recognition.The optimized adsorption condition were found to be in pH of 6.0 and contact time of30 min.The ratio of RAFT agent and inhibitor,and the reaction time were further controlled to investigate the controlling polymerization process,find that the ratio of[BDAAT]/[AIBN]=3/1 and 3.5 h can contribute to the Cd???-IIP with the most uniform structure.The thermal adsorption of Cd???onto Cd???-IIP was better fitted by the Langmuir model.The kinetic data of Cd???-IIP towards Cd???was better fitted by the pseudo-second-order model.The adsorption process was demonstrated to be endothermic and spontaneous process accompanying with randomness increased.?3?In this work,fluorescent graphene quantum dots?GQDs?,hydroxylated graphene quantum dots?HGQDs?and amino-functionalized graphene quantum dots?AGQDs?were prepared and combined with BSA to construct different kinds of BSA stabilized GQDs nanocomposite probes Properties of three types of GQDs and their BSA stabilized composite probes were compared through FT-IR,TEM,zeta potential and fluorescent spectra.The optimized conditions to prepare nanocomposite probes and optimal detection circumstances were further investigated.BSA stabilized nanocomposite probe was used as a novel selective label-free fluorescent biosensor for trypsin,proving to be with remarkable fluorescence enhancement effect,high selectivity and sensitivity.The most suitable composite probe was selected out by comparison.It was demonstrated that the BSA stabilized amino-functionalized GQDs can be viewed as the best sensor for trypsin with a lower limit of detection of 0.004?g/mL when compared to the other two composite probes.The detection liner range was 0.1-20.0?g/mL.The selective detection mechanism for trypsin was also further studied,suggesting that chemical reduction of GQDs and AGQDs result from lysine and arginine residues of degraded BSA and electronics transfer were responsible for enhanced fluorescence.?4?The carbon quantum dots?CDs?was prepared by microwave assisted method.Then polypyrrole?PPy?was prepared to construct CDs/PPy nanocomposite by using the passivation effect of PPy towards CDs.The structure and properties of CDs and CDs/PPy were characterized by several methods such as SEM,TEM,XPS,zeta potential detection and fluorescent detection.Afterwards,CDs/PPy nanocomposite was used for Cr?VI?and SO₃^2-detection.It was found that the liner range and limitation of detection towards Cr?VI?were 0.1-250.0?mol/L and 2.4 nmol/L respectively.The liner range and limitation of detection towards SO₃^2-were 0.5-500.0?mol/L,121.0 nmol/L.The detection mechanism was further studied,finding that the fluorescent inner filter effect and redox reaction are responsible for Cr?VI?and SO₃^2-specific detection respectively.The CDs/PPy nanocomposite was also used for real water and beverages sample detection,finding satisfied recovery,proving that CDs/PPy nanocomposite is a promising fluorescent probe.