Preparation Of Functionalized Carbon Nanocomposites And Study On Electrochemical Detection Of Dihydroxybenzene Isomers

Dihydroxybenzene Isomers(DHB)include hydroquinone(HQ),catechol(CC)and resorcinol(RS).They have the same molecular structure and very similar properties.And using as synthetic intermediates or raw materials for many industrial productions,they are often present in industrial wastewater and are discharged into the environment,seriously threatening human health or even survival.Therefore,the detection of hydroquinone isomers has very important practical significance in environmental monitoring and maintenance of human health.In this paper,an electrochemical sensor based on functionalized carbon nanocomposites is constructed,which provides new ideas and methods for the separation and detection of hydroquinone isomers.The specific research content is as follows:(1)An electrochemical sensor based on MWCNT@r GONR was constructed for the detection of dihydroxybenzene isomers.The multi-walled carbon nanotubes@reduced graphene oxide nanoribbons(MWCNT@r GONR)with core-shell heterostructures were synthesized by solution stripping method.Then it was characterized by scanning electron microscope(SEM),transmission electron microscope(TEM),Fourier infrared spectrometer(FT-IR)and X-ray diffractometer(XRD)and studied the performance of the sensor based on MWCNT@r GONR.The results showed that MWCNT@r GONR was modified the glassy carbon electrode,which increased the effective area of the electrode and the electrochemical active site,improved the electron transfer efficiency and the electrocatalytic activity of the material,and realized the independent detection and simultaneous detection of HQ,CC and RS.The linear concentration range of simultaneous detection was 15?921 ?M,15?1101 ?M and 15?1301 ?M,the detection limits were 3.89 ?M,1.73 ?M and 5.77 ?M respectively.Moreover,the sensor had good reproducibility and selection performance and relative stability.Through the spiked recovery experiments in actual samples,and compared with standard methods of high performance liquid chromatography(HPLC),the results showed that MWCNT@r GONR was feasible for the actual detection of DHB.(2)An electrochemical sensor based on ZIF-8/CNF was constructed for the detection of dihydroxybenzene isomers.A zeolite-like imidazole framework material(ZIF-8)based on metallic zinc was prepared,and then conductive carbon nanofibers(CNF)were introduced by ultrasonic mixing to obtain a ZIF-8/CNF composite material.The morphology and structural characterization of the material was shown by XRD and SEM,then did the performance research of the sensor based on ZIF-8/CNF.The results showed that,compared with the single material ZIF-8 or CNF,the ZIF-8/CNF composite material increaseed the effective area of the glassy carbon electrode,made more conductive sites of CNF available,and improved the overall electron transfer efficiency.At the same time,ZIF-8 exhibited good electrocatalytic activity and the synergistic effect of the two improves the electrochemical response to HQ,CC and RS.The linear concentration range of DHB detection was 2?400 ?M,and the detection limits were 0.06 ?M,0.08 ?M and 0.32 ?M respectively.The recovery results of the spiked samples in the lake and the Yangtze River water samples were good,and there was no significant difference from the HPLC test results,and it has applications potential in DHB detection.(3)An electrochemical sensor based on PCN-224/?-CD/PPGE was constructed for the detection of dihydroxybenzene isomers.We chose a cheap and easy-get pencil graphite electrode(PGE)as a conductive substrate,and then used electrochemical cyclic voltammetry(CV)to redox the electrode surface to obtain a pretreated pencil graphite electrode(PPGE).Then,a pore-channel framework material(PCN-224)based on metal zirconium(Zr)was prepared and modified on the surface of PPGE,and then the host molecules ?-cyclodextrin(?-CD)and PCN-224 were electrically charged by CV polymerization,and a PCN-224/?-CD/PPGE electrochemical sensor was constructed.After pretreatment,the surface structure of PPGE had been deformed,and the densely packed bulk graphite became more fine and loose,increasing the specific surface area of the conductive carbon material,and enhancing the conductive effect.PCN-224 was interspersed in the compact block of ?-CD,so that the sensing interface of the composite material increased to a certain extent,and the function of host-and-guest selective inclusion between the material and DHB was better played.Realizing separation and simultaneous detection of HQ,CC and RS,the linear concentration range of simultaneous detection was 1?750 ?M,the detection limits were0.07 ?M,0.12 ?M and 0.41 ?M.In addition,the actual recovery results were basically consistent with the HPLC detection,and the accuracy is good.This construction method of electrode is simple and cheap,which provides an effective method for the detection of DHB,and also provides a development idea for the construction of electrochemical sensing equipment for detecting other electroactive inorganic and organic environmental pollutants.