Preparation And Application Of Conducting Polymer/Nanocellulose Modified Electrode

Nanocellulose?NCC?has become a research hot topic in materials field due to high surface area,thermal stability,renewable and biodegradable properties.Carboxylated nanocrystalline cellulose?CNCC?is generated by the removal of amorphous regions of microcrystalline cellulose?MCC?using ammonium persulfate.CNCC possesses better dispersibility and stability compared with NCC for high density of carboxyl groups on its surface which could be used as a substrate for loading nanoparticles.Conductive polymers have unique electrical conductivity and redox properties,which could be synthesized on the surface of the electrode by electrochemical deposition.In this paper,conductive polymer sand CNCC were used as basic materials for the modified electrodes.Modified electrodes were prepared to detect of food additives?nitrite?and small molecules of drugs?paracetamol and chloramphenicol?.The main content of this thesis are summarized as follow:?1?CNCC was prepared by oxidation degradation of MCC using ammonium peroxydisulfate and modified with Fe₃O₄ nanoparticles to form Fe₃O₄-CNCC nanocomposite via a simple refluxing process.The Fe₃O₄-CNCC nanocomposite doped poly?3,4-ethylenedioxythiophene??PEDOT?was successfully decorated on the glassy carbon electrode?GCE?by electrochemical deposition.The PEDOT/Fe₃O₄-CNCC modified GCE with enlarged real electrochemical surface area was used to determine nitrite.Using amperometric current-time?i-t?curve,the proposed sensor provided a wider linear range?0.5-2450?M?and a lower detection limit?0.1?M?towards nitrite compared with the method of differential pulse voltammetry?DPV?.This modified GCE was highly stable and unresponsive to potentially interfering substance and can easily distinguish DA,AA,UA and nitrite.?2?A two-step electrochemical deposition method was developed to synthesize nanocomposite of CNCC doped conducting polymer PEDOT decorated with MoS₂nanoparticles.CNCC doped PEDOT composite was firstly electropolymerized onto the GCE through cyclic voltammetry,followed by cyclic voltammetry scan in a solution containing?NH₄?₂MoS₄ at the potential of-1.2⁰.5 V.The MoS₂/PEDOT/CNCC composite modified GCE showed outstanding electrocatalytic activity towards the oxidation of paracetamol?PCT?.Under optimum experimental conditions,the linear range was 0.1-170?M and the detection limit was 43 nM.?3?Hydrothermal synthesis method was used to synthesize cerium molybdate?CeM?nanoparticles.CeM/CNCC composite was synthesized via simple sonication process.CeM/CNCC composite modified electrode was prepared by drop coating method.The CeM/CNCC composite modified electrode exhibited excellent electrochemical performance in catalytic reduction of antibiotic drug chloramphenicol?CAP?.CeM/CNCC composite showed a good analytical performance toward the determination of CAP including wide linear range?0.97-270.09?M?,low detection limit?37 nM?.The practical ability of CAP toward the real sample analysis was assessed in honey and milk samples with good recoveries.