Study On Electrochemical Sensor For Several Organic Pollutants

With the process of the society industrialization, the problem of environmentalpollution is getting worse, seriously affecting people’s quality of life and health.Especially, organic pollutants are really toxic to human body, which can accumulate inhuman body through the food chain. The organic pollutants will not only affect thehuman body itself, resulting in endocrine disorder, weakened immune system,metabolic disruption, necrosis of internal organs, cause cancer, etc., but also affect thenormal development and growth of their offspring, who may be deformity or slowmental development. Therefore, the analysis and treatment of organic pollutants is animportant aspect for promoting social development and improving people’s livingstandard. Electrochemical analysis techniques have several special advantages such aslow cost, easy operation, good selectivity, high sensitivity and wide range ofapplications. Besides, the electrical signals will be obtained during the process ofelectrochemical analysis, so it is easy to realize automated and continuous analysis. Itis well known that the sensitivity and lower detection limit of electroanalysis can beimproved by using nano-materials modified electrode. In this paper, the trace detectionof pentachlorophenol, nitrobenzene and carboxylated polycyclic aromatic hydrocarbonhas been carried out combing with electroanalysis, nano-materials and environmentalscience, providing a simple, fast and sensitive method for the analysis ofenvironmental contaminants. The main points in this thesis are summarized as follows:(1) The acid oxidation carbon nanotubes (AO-CNTs) were obtained by mixed acidtreatment and characterized by scanning electron microscopy (SEM). Cyclicvoltammetry (CV) and differential pulse voltammetry (DPV) were used to study theelectrochemical behavior of the AO-CNTs modified glassy carbon (GC) electrodeand its electrocatalytic property for the oxidation of pentachlorophenol (PCP). ThePCP electrochemical sensor based on the AO-CNTs modified glassy carbon (GC)electrode exhibits good selectivity and reproducibility, with a detection limit of16nM, a sensitivity of0.5367A M-1and a linear range from0.2μM to10M. Inaddition, this PCP electrochemical sensor was applied to detect the concentration ofPCP in tap water.(2) The hollow porous carbon materials (HPCMs) was synthesized by using SiO2microspheres as the template and an ionic liquid named1-Alyl-3-ethylimidazolium tetrafluoroborate ([AEIm]BF4) as the source of carbon. HPCMs were characterizedby scanning electron microscope (SEM), transmission electron microscopy (TEM)and nitrogen adsorption/desorption measurements. Linear sweep voltammetry (LSV)was used to study the electrocatalytic reduction of nitrobenzene at the HPCMsmodified glassy carbon (GC) electrode. The nitrobenzene sensor based on theHPCMs modified electrode has excellent characteristics, such as low detectionlimit (8nM), high sensitivity (2.3637A M-1), wide linear range (0.2μM to40M), good selectivity, stability and reproducibility. Beside, this sensor wassuccessfully used to detect nitrobenzene in tap water and lake water.(3) An electrochemical sensor for carboxylated polycyclic aromatic hydrocarbon(anthracene-9-carboxylic acid) was developed by the π-π electron donor-electronacceptor interaction between molecules of organic compounds. Theelectron-deficient nitrobenzene was firstly self-assembled onto the surface ofglassy carbon (GC) electrode, then the modified electrode was used to analysisanthracene-9-carboxylic acid in solution by square wave voltammetry (SWV).Compared with the bare GC electrode, the nitrobenzene modified electrode showedbetter electrocatalytic oxidation toward anthracene-9-carboxylic acid with a highersensitivity. This electrochemical sensor has a linear range of0.05-1M, and asensitivity of2.8724A M-1with a low detection limit (7nM).