| Environmental security is a main challenge for a long time.With the rapid development of industrialization and urbanization,heavy metals are used more widely.Unlike waste gas and waste residue,heavy metals are difficult to degrade in the environment.It can only change their physical and chemical forms,and are gradually enriched in animals and plants through the food chain.Finally it would enter the body and cause harm to human through diet and skin contact.Therefore,based on the present situation of environmental safety and the key problems,it is of great significance to establish a new technology for rapid quantitative detection of trace heavy metals from water environment,which can effectively control and prevent food-borne diseases caused by heavy metal pollution.In this paper,electrochemical sensors based on chitosan/graphene nanocomposites were constructed via one-step electrodepositing for the determination of heavy metal ions such as Cr?VI??Cd?II?and Pb?II?.The structure,morphology and properties of electrochemical sensors were characterized by SEM,TEM,XRD,EDS,FT-IR,CV,EIS,and DPV.The effects of pH,monomer-template ratio,temperature,incubation time to the sensor electrochemical performance were studied.The specific contents and results of the study are as follows.1.The graphene?GR?,chitosan?CS?and Cr?VI?were co-deposited onto the gold electrode?Au?surface by one-step deposition method with glutaraldehyde as cross-linker.EDTA was used to remove Cr?VI?from polymer matrix to construct a Cr?VI?ion imprinted sensor?CS/GR/Au-IIP?.The linear detection range for Cr?VI?was1.0×10<sup><sup>-9 1.0×10-5 mol/L,and the detection limit was 6.4×10-10 mol/L?S/N=3?.A series of studies have proved that the CS/GR/Au-IIP sensor has excellent selectivity,stability and repeatability for detecting Cr?VI?.The sensor has been successfully applied to the determination of Cr?VI?in tap water and river water with the recovery rate of 96.5%-104%.2.Gold nanoparticle?AuNP?is one of the metal nanomaterials with high chemical stability,high electronic conductivity,large specific area and good biocompatibility.The CS-AuNPs/GR sensor was fabricated on the surface of glassy carbon electrode?GCE?by electrodeposition and imprinting based on the metal chelation of chitosan and the electron synergistic enhancement effect between AuNPs and GR.The results showed that CS-AuNPs/GR/GCE has the two linear detection range for Cd?II?of 1×10-89×10-7 mol/L and 3×10-54×10-4 mol/L with the detection limit of 1.62×10-10mol/L.In addition,AuNPs improves the sensitivity of the sensor to Cd?II?,and enhances the anti-interference ability,stability and repeatability of the sensor.And CS-AuNPs/GR/GCE has a good recovery rate for the detection of Cd?II?in real water samples.3.In order to enhance the sensitivity and stability of the sensor for the detection of heavy metal micropollutants,MWCNT,which has high conductivity and chemical stability,was introduced into CS-AuNPs/GR matrix.The glassy carbon electrode modified by CS-AuNPs/GR@MWCNT bilayer film was firstly prepared.The sensor has five wide detection range for Pb?II?of 1.0×10-92.0×10-8 mol/L,2.0×10-89.0×10-8 mol/L,9.0×10-81.0×10-6 mol/L,1.0×10-65.0×10-5 mol/L with a detection limit of2.83×10-10 mol/L.Compared with monolayer modified electrode,CS-AuNPs/GR@MWCNT/GCE exhibits more excellent anti-interference,repeatability,stability and actual sample detection ability. |
PDF Full Text Request