Preparation Of Carbon-based Modified Electrode And Its Detection Of Phenolic Pollutants In Water

Phenolic compounds are an important raw material in industrial production and are widely used in cosmetics,pharmaceuticals,coal tar,leather making,plastics,dyes and other fields.However,most phenolic compounds are highly toxic.They are mainly through the discharge of industrial waste into the environment,becoming one of the major pollutants in the environment.Phenolic compounds pose a serious threat to human health and ecosystems and are listed as very important indicators in environmental monitoring.At present,traditional analytical methods of phenolic compounds include gas chromatography,liquid chromatography,spectrophotometry and chemiluminescence.These methods have high sensitivity and selectivity,but there are some disadvantages in practical application,such as complex preparatory work,large-scale instruments and equipment,strict experimental conditions and high analytical cost.Therefore,it is necessary to develop a simple,rapid and accurate electrochemical sensor to determine phenolic contaminants.The main research contents of this paper include the following three parts:?1?The composite materials of acetylene black?AB?and chitosan?CS?were prepared by electrostatic self-assembly method and their morphology was characterized by scanning electron microscopy?SEM?.The glassy carbon electrode?GCE?was modified with AB/CS composite materials to construct an electrochemical sensor.The electrochemical performance of the modified electrode was characterized by cyclic voltammetry?CV?.Under optimized conditions,the constructed electrochemical sensor was used to detect acetaminophen by square wave voltammetry?SWV?.The results showed that there was a good linear relationship between peak current and concentration of acetaminophen in the concentration range of 0.5⁸.5?mol/L and 8.5²4?mol/L.The sensitivity is 5.7357?A/?M,and the limit of determination is 9.3 nmol/L?S/N=3?.In addition,AB/CS modified electrode has satisfactory selectivity and stability.?2?Co₃O₄ and N-rGO/Co₃O₄ nanocomposites were synthesized by hydrothermal method and microwave hydrothermal method,respectively.Their morphology and structure were characterized by SEM and X-ray diffractometer.The surface of the glassy carbon electrode was modified by Co₃O₄ and N-rGO/Co₃O₄ nanocomposites,respectively.Co₃O₄/GCE and N-rGO/Co₃O₄/GCE were constructed.The electrochemical properties of two electrochemical sensors were studied by CV.The results show that N-rGO/Co₃O₄/GCE has better catalytic performance than Co₃O₄/GCE,which is beneficial to the redox reaction of the analyte at the electrode surface.Under optimal conditions,the constructed N-rGO/Co₃O₄/GCE was used to detect p-nitrophenol by SWV.The detection sensitivity and limit of detection were 0.1277?A/?M and 0.2316?mol/L,respectively.In addition,N-rGO/Co₃O₄/GCE has excellent stability,selectivity and anti-interference.?3?Carboxylated graphene?CG?and L-asparagine?L-Asn?were sequentially modified on glassy carbon electrode by drop coating method and electrochemical polymerization method.TheelectrochemicalsensorCG/poly-L-Asn/GCEwasconstructed.The electrochemicalperformanceofthemodifiedelectrodewasstudiedbyCV.CG/poly-L-Asn/GCE can simultaneously detect hydroquinone?HQ?and catechol?CC?by differential pulse voltammetry.Under the optimum conditions,the peak current of HQ has a good linear relationship with the concentration in the range of 3.3²0?mol/L and 20⁴0?mol/L,and the peak current of CC has a good linear relationship with the concentration in the range of 3.3²0?mol/L and 20⁶6.7?mol/L.The sensitivity of HQ and CC were0.8327?A/?M and 1.2499?A/?M,respectively.The detection limits were 0.0750?mol/L and0.1362?mol/L,respectively.In addition,CG/poly-L-Asn/GCE has good selectivity and stability for HQ and CC mixtures,which provide a new research idea for the development of electrochemical sensors for phenolic isomers.