Research On Electrochemical Sensors For The Detection Of Phenolic Pollutants

In recent decades,my country’s rapid economic development has brought serious environmental pollution problems.Now,as people’s awareness of environmental protection is getting stronger and stronger,environmental protection action has become urgent.At present,environmental pollution is a serious problem of water pollution,and it will seriously endanger our lives.Phenolic pollutants are one of the important water pollutants,which not only cause the death of animals and plants in water bodies,but also endanger human health.Its toxic effect on the human body mainly depends on the level of their concentration.When the concentration is low,the cells will be degenerated and the normal function of the organs will be affected.At high concentrations,the protein can coagulate,resulting in organ failure and death.Although the local damage of phenolic pollutants to the human body is not particularly serious at low concentrations,its penetration is strong and it has an enrichment effect in the human body.It can penetrate deep into the internal tissues and organs of the human body,violate the nerve center of the brain,and eventually lead to a systemic poisoning reaction.Therefore,we need an effective analytical method to detect the water environment around us.Electrochemical sensors have the advantages of high sensitivity,easy portability,simple operation,low cost,and short detection time,which just meet our requirements for efficient detection of phenolic pollutants.Therefore,we constructed three simple electrochemical sensors for the quantitative detection of hydrocatechol and hydroquinone,phenol,and p-nitrophenol,respectively.The experimental contents are as follows.（1）Simultaneous analysis of catechol and hydroquinone by polymelamine/carbon nanotube dual-template molecular imprinting techniqueIn this part,melamine（Mel）was used as functional monomer,catechol（HQ）and hydroquinone（CC）as templates,and a layer of HQ and CC bimolecularly imprinted films were prepared by electropolymerization.Dual-template molecularly imprinted polymer/carbon nanotube/glassy carbon electrode（MIP/CNTs/GCE）.The morphology,structure and electrochemical properties of MIP/CNTs/GCE were characterized by scanning electron microscopy（SEM）,Fourier transform infrared spectroscopy（FIRT）and electrochemical techniques,respectively.The experimental parameters for the sensor construction were optimized in detail,including the molar ratio of reagents,the number of electropolymerization cycles,elution time,and p H of the electrolyte.Under optimal conditions,the simultaneous detection of HQ and CC was achieved by cyclic voltammetry（CV）and differential pulse voltammetry（DPV）.Compared with CNTs/GCE,the molecularly imprinted membrane can significantly improve its response current to HQ and CC.Meanwhile,the linear ranges of HQ and CC measured by DPV were both 10–100μM,with detection limits of 3.1μM and 3.5μM,respectively.The experiments also demonstrated the good reproducibility and stability of MIP/CNTs/GCE.Finally,MIP/CNTs/GCE was successfully used for the detection of HQ and CC in river water with good recovery.（2）In-situ synthesis of Ce O₂ nanoparticles-modified carbon nanotube composites for the detection of phenolIn this section,in situ grown Ce O₂/CNTs nanocomposites were synthesized in one step by a simple hydrothermal method.The morphology and structure of Ce O₂/CNTs were characterized by transmission electron microscopy（TEM）and X-ray diffraction（XRD）.The results show that Ce O₂ nanoparticles grow uniformly on the surface of carbon nanotubes.The composite material was used to construct a novel modified electrode for phenol（ph）detection.We used differential pulse voltammetry（DPV）for the determination of phenol with a linear range of 1-500μM with a detection limit of 0.3μM.At the same time,it was found that the Ce O₂/CNTs/GCE also had good reproducibility and stability.Finally,we used Ce O₂/CNTs/GCE to detect phenol in river water and found that it has good detection ability.（3）Electrochemical sensor based on Cr-MOF for the detection of p-nitrophenolIn this part,a simple hydrothermal method was used to synthesize Cr-MOF material,and the morphology and structure of the material were characterized by XRD,SEM,and TEM techniques.And the Cr-MOF material was used to construct the modified electrode,and the prepared Cr-MOF/GCE was used for a series of electrochemical detection.It is proved that the Cr-MOF material has a good electrocatalytic effect on p-NPs.At the same time,the electrochemical sensor constructed by Cr-MOF material was analyzed by DPV with a good detection limit of 0.6μM for p-NP,and a wide detection range（2-500）μM,and in the presence of various interfering substances Cr-MOF/GCE still has excellent detection effect.At the same time,it also shows good performance in river water and has the potential for practical application.