| A palygorskite-modified carbon paste electrode (CPE) was constructedusing graphite powder mixed with palygorskite particles. The palygorskiteexhibits catalytic activity to catechol and significantly improves thedetermining sensitivity. The sensor shows a linear response range between5and100M catechol with a correlation coefficient of0.998. The detectionlimit was calculated as0.57μM (S/N=3).A palygorskite expanded graphite (EG) electrode was developed fordetermination of phenol. The novel electrode appeared to induce catalyticelectro-oxidation of phenol. The dependence of signals on operatingconditions was studied. The modified electrode exhibited a linear responseover a wide range of phenol concentrations from50to500μM, with adetection limit of4.5μM (S/N=3).A simple and reliable voltammetric sensor for simultaneousdetermination of catechol and hydroquinone was developed at anelectrochemically activated glassy carbon electrode. The cyclicvoltammograms in a mixed solution of catechol and hydroquinone haveshown that the oxidation peaks became well resolved and are separated by108mV, which makes it suitable for simultaneous determination of theseisomersThe electrochemical polymerization of hydroquinone on EG substratehas been carried out using repeated potential cycling between-0.5and1.5V(versus SCE). Hydroquinone has different polymerization mechanisms atdifferent pH values, and the electrochemical activity decreases as the pH ofthe solution increases from2.0to12.0.The electrochemical polymerization of hydroquinone on glassy carbonelectrode using potentiostatic at1.8V (versus SCE), and then was followedby over-oxidized in NaOH solution. The impedence of over-oxidizedpoly(hydroquinone) film which had absorbed hydroquinone was more smaller than that absorbed catechol. The square wave voltammograms shows that theoxidation peak current of catechol has a little impact on that of hydroquinone,the over-oxidized poly(hydroquinone) film has good recognition abitlity tohydroquinone. |
PDF Full Text Request