Electrochemical Detection Of Phenolic Pollutants Based On Carbon-based Nanocomposites

With the continuous development of the chemical industry,a large amount of organic pollutants are discharged into the environment,of which phenolic pollutants are a typical representative.Most of these phenolic pollutants are highly toxic and carcinogenic,and they are not easily degraded naturally in the environment.Efficient detection of phenolic pollutants has important practical significance for ecological environment protection and protection of human health.The current detection methods for phenols are mainly based on traditional instrumental analysis methods such as chromatography and mass spectrometry.But these methods all have high cost,complicated operation and cannot be detected in real time.Unable to adapt to current environmental monitoring needs.In contrast,electrochemical methods show greater potential.Electrochemical sensors usually use different composite materials to prepare chemically modified electrodes for different substrates to improve the sensor's selectivity and sensitivity to the substrate.Based on the excellent electrochemical properties of carbon-based nanomaterials,this paper constructs two different modified electrodes based on carbon-based nanocomposites for the electrochemical detection of different phenols.The main contents are as follows:?1?Preparation of electrochemical sensor of bisphenol A based on n-doped carbon quantum dot@carbon nanotubesIn this section,N-doped carbon quantum dots were hydrothermally synthesized using citric acid as a carbon source.At the same time,N-CQDs@CNTs were prepared by electrostatically self-assembling the acidified CNTs by PDDA treatment.An electrochemical sensor for the detection of bisphenol A was constructed by modifying it with the surface of glassy carbon electrode.The N-CQDs@CNTs nanocomposites were characterized by transmission electron microscope?TEM?,scanning electron microscope?SEM?,and X-ray powder diffraction?XRD?.Cyclic voltammetry?CV?and differential pulse voltammetry?DPV?were used to test its electrochemical performance.Experimental results show that the linear range of the sensor is 0.4-40?M,and the detection limit is 65nM?S/N=3?.At the same time,the sensor has good stability and anti-interference ability.?2?Preparation of electrochemical sensor based Ce-MOF composite carbon nanotubes and simultaneous detection of p-hydroquinone and catecholIn this part of the solvent method,Ce-MOF/CNTs was synthesized in one step,and then Ce-MOF/CNTs was treated with a mixed solution of hydrogen peroxide and sodium hydroxide to convert part of Ce³⁺to Ce⁴⁺.Ce-MOF?MV?/CNTs with mixed valence was obtained.Transmission electron microscopy?TEM?and scanning electron microscopy?SEM?were used to characterize the morphology.X-ray powder diffraction?XRD?and X-ray photoelectron spectroscopy?XPS?were used to study the valence states and crystal structure of the compounds on the surface.Based on MOF?MV?/CNTs,an electrochemical sensor for simultaneous determination of hydroquinone and catechol was constructed,and its electrochemical performance was studied by cyclic voltammetry?CV?and differential pulse voltammetry?DPV?.The results show that the Ce-MOF?MV?/CNTs/GCE electrode has obvious electrocatalytic effect on HQ and CC.DPV results showed that the oxidation peak current of HQ and CC was linearly correlated with the concentration between 10-90?M,and the detection limits were 5.3?M and 3.5?M,respectively.The sensor also has good selectivity,reproducibility and stability.