Sensitive Electrochemical Sensors For The Deterction Of The Phenolic Compounds Based On Nanomaterials Modified Glassy Electrode

The phenolic compounds which caused pollution to the soil and water environment have been widely used in the industrial field with the development of economy.Even worse,it is very difficult to degrade the phenolic pollutants for the environment.Additionally,the phenolic compounds can enter the human body through the food chain.Because of the greater toxicity of phenols,even a little concentration of the phenolic compounds can cause the disorder of human body.Therefore,a rapid and accurate method for the determination of phenolic pollutants is neccesary.Due to the advantages of fast response,low cost,high sensitivity,electrochemical method has been widely applied in the environmental monitoring.In the electrochemical analysis,it is possible to increase the electrochemical response and improve the sensitivity by adding the excellent electrode materials to the electrode surface.In this paper,four kinds of nanomaterials modified electrodes were prepared for determining phenolic compounds.The research contents were as follows: 1.Electrochemical sensor for bisphenol A based on ionic liquid functionalized Zn-Al layered double hydroxide modified electrodeThe Zn-Al layered double hydroxide modified with 1-aminopropyl-3-methylimid-zaolium tetrafluoroborate?named as ILs-LDH?was synthesized by coprecipitation method.A novel electrochemical sensor based on ILs-LDH modified glass carbon electrode?GCE?was developed for bisphenol A?BPA?determination.ILs-LDH/GCE performed the excellent electro-oxidation ability towards BPA with the more negative oxidation overpotential and larger peak current than bare GCE or LDH/GCE.Differential pulse voltammetry determination of BPA afforded a wider linear range from 0.02 to 3 ?M with the detection limit of 4.6 nM?S/N = 3?.The fabricated sensor demonstrated an acceptable reproducibility,good stability and high sensitivity.The proposed method was successfully used to detect BPA in real water samples with satisfactory recovery ranging from 94.9% to 102.0%.2.Electrochemical bisphenol A sensor based on exfoliated Ni₂Al-layered double hydroxide nanosheets modified electrodeThe ultrathin exfoliated Ni₂ Al layered double hydroxide?ELDH?nanosheets were prepared by using L-asparagine as pre-intercalator in aqueous medium.The transmission electron microscopy and atomic force microscopy images displayed that ELDH nanosheets had lost the original hexagon of hydrotalcite with about 200 nm lateral size and less than 3 nm thickness.Then a sensitive electrochemical sensor was fabricated for bisphenol A?BPA?detection based on ELDH modified glassy carbon electrode with aid of film-forming agent chitosan.The proposed sensor showed an efficient electrocatalytic performance on the oxidation of BPA with the enhanced oxidation response and the lowered oxidation overpotential?0.489 V?.Differential pulse voltammetry?DPV?was employed for the determination of BPA with a wide linear range from 0.02 to 1.51 ?M.The detection limit was calculated as 6.8 nM?S/N =3?.The resultant sensor exhibited good reproducibility,selectivity and acceptable stability due to the contribution of the more active sites and the large surface area from ELDH nanosheets.Additionally,the concentrations of BPA in milk samples were analyzed by this developed method with an acceptable result.3.A sensitive electrochemical sensor for 2,4-dichlorophenol based on the ionic liquid structured C3N4 nanosheetsThe ionic liquid structured C3N4 nanosheets?IL-eC3N4?was synthesized with bromine and protonated C3N4.The IL-eC3N4 was modified on the bare GCE electrode surface to prepare the IL-eC3N4/GCE.The modified electrode showed good catalytic activity for the electrochemical oxidation of 2,4-dichlorophenol with the oxidation peak potential of 2,4-dichlorophenol was significantly negative.The current-time curve showed that the peak current was proportional to the concentration of 2,4-dichlorophenol ranging from 0.02 to 160 ?M with the detection limit 6.67 nM?S/N=3?.The proposed sensor was successfully applied to determine 2,4-DCP in lake water and pond water and the recovery was in the range from 97% to 106%.4.A electrochemical sensor based on carbon quantum dots-silver nanocomposite for the quantitative detection of catecholA high sensitive electrochemical sensor based on N-S doped carbon quantum dots-silver nanocomposite?N-S-CQDs-Ag?modified glassy carbon electrode?GCE?was fabricated for the detection of catechol?CC?.The as-modified electrode material was synthesized in instu with AgNO3 and carbon quantum dots which was synthesized in one step.The analysis results showed that the separation of anodic and cathodic peak was significantly decreased and the peak current was linear with the catechol concentration ranging from 0.2 to 180 ?M with the detection limit 0.013 ?M?S/N=3?,revealing excellent performance and good reversibility towards catechol.Futhermore,the proposed sensor was successfully applied to determine CC in lake water and tap water with the recovery ranging from 97% to 107%.