Study On Electrochemical Sensor For Detection Of Persistent Organic Pollutants Pentachlorophenol

Pentachlorophenol （PCP） is one kind of persistent organic pollutants （POPs）.Because of its environmental persistent, high toxicity, bioaccumulation and longdistance migration, the determination of PCP in water has been attracting wideattention. At present, the chromatographic technique is one of most common methodsapplied in the detection of PCP. Due to its has some disadvantages such as theexpensive equipment of chromatographic, the strict demand for operator and the needof pre-treatment, the chromatographic technique is limited for rapid detection andpopular application. However, the electrochemical methods have attracted wideapplication for the advantage characters such as simple instrumentation, rapidresponse, portability, low production, high sensitive and good stability. In this paper,several electrochemical sensors based on different electrode materials for the PCPdetection were investigated and the main results are shown as follows:（1） Multi-walled carbon nanotubes （MWCNTs） were functionalized by a developeddiazonium approach. Because of the electrostatic adsorption effect between the aminogroups in the surface of MCNTs and hydroxyl of PCP, the amino functionalizedMWCNTs （NH₂-MWCNTs） exhibit better catalytic performance towards theelectrochemical oxidation of PCP comparaed to that of the pristine MWCNTs. Thesensor based on NH₂-MWCNTs/GC electrode, while applied in the determination ofPCP, possessed some advantages such as the wide linear range （0.2-20μM）, goodreproducibility, excellent anti-interference, high sensitivity （1.05μA/μM） and lowerlimit of detection （0.01μM，S/N=3）.（2） Nano needle-like CdS microsphere was prepared by hydrothermal synthesismethod with cadmium acetate as the cadmium source, L-cysteine as the sulfur source.The behaviors of electrochemical detection for PCP were investigated on the surface ofCdS microsphere modified GC electrode. The results showed that the CdS microsphere,with the special surface morphology and high surface area, possessed excellentperformance for the electrochemical oxidation of PCP than that of GC electrode. Thesensor based on CdS modified GC electrode possessed wide linear range （0.2-2.0μM,4.0-17μM）, good reproducibility and excellent anti-interference.（3） The pure titanium dioxide （TiO₂）, TiO₂-CNTs composites and W-TiO₂-CNTscomposites were prepared by a modified sol-gel. The morphology, crystal structure and elements of the catalytic materials were characterized by scanning electronmicroscopy （SEM）、X-ray diffraction （XRD） and energy scattering X-ray spectrograph（EDS）. The behaviors of electrochemical detection for PCP were investigated on thesurface of different catalytic materials modified GC electrode. The results showed thatW-TiO₂-CNTs/GC electrode possessed higher response current to PCP than the pureTiO₂/GC electrode and TiO₂-CNTs/GC electrode. Based on the W-TiO₂-CNTs/GCelectrode, a high performance electrochemical sensor for PCP detection was developed.The linear range is from0.2μM to3.0μM, the limit detection is0.011μM, and thesensitivity （1.853μA/μM） is higher than that of pure TiO₂/GC electrode （0.106μA/μM）and TiO₂-CNTs/GC electrode （0.903μA/μM）.（4） Poly glutamic acid （PGA） had successful modified on the GC electrode bycyclic voltammetry （CV） method with glutamic acid as monomer. The branches-likeand particles morphology of PGA was observed on the surface of electrode by SEM.Based on the PGA modified GC electrode, the electrochemical sensor for PCPdetermination have wide linear range （0.2-5.0μM）, high sensitivity, excellentreproducibility and good anti-interference. Besides, due to the biocompatibility andbiodegradability, the PGA would be promising for the development of a green andenvironmental electrochemical sensor for PCP detection.