Electroanalysis Determination of Nitrite Ions Using Nano Zeolite ModifiedCarbon Paste Electrode

The determination of nitrite concentration, especially for drinking water quality, wastewatertreatment, for the food industry , dyes, bleaches, fertilizers as well as for medicinal purposes andfor the control of remediation procedures, is of rapidly increasing interest[1-2]. Nitrite ions arecritical precursors in the formation of nitrosamines, many of which have been shown to becarcinogens and harmful on our environment [3]. Nitrite ions are used as food preservativesagainst food poisoning microorganisms such as clostridium botulinum[4]. The nitrite salts areknown to occur in high quantity in soil and ground waters. Then, determination of nitrite hasreceived substantial attention. several methods have been developed to determination nitrite,which are laborious to perform or require chemical reagents , the electrochemical approaches arefavorable due to the rapid response, low costs and simple operation in compare of other methods[5]. In this research nano zeolite-modified electrodes have been developed for the determinationof nitrite ions. Zeolite-supported electrocatalysts can be subjected to improve the performance ofthe electrocatalytic responses with reduced overpotentials and increased electroanalysis signalsallowing low detection limits and high sensitivities. The used nano ZSM-5 zeolite wassynthesized as literature [6]. Graphite powder and ferrous chloride ,phosphoric acid, and sodiumnitrite used in this work were also purchased from Merck. Electrochemical experiments werecarried out using a potentiostat/galvanostat (Auto Lab PG 302 N). An Ag|AgCl|KCl (3M)electrode as reference electrode, a platinum wire as the auxiliary electrode and carbon pasteelectrode modified with nano zeolite as the working electrode were used. Appropariatedammount of synthesized nano zeolite was lightly ground and immersed to 10 ml 1 M FeCl2 solution for 3 h. Then the solid was dried. The 30% (W/W) Fe2+-zeolite to graphite powder pastewas made by mixing the given quantity of Fe2+-zeolite and graphite powder in diethyl ether andthe solvent was evaporated by stirring a mixture. Then paraffin was blended by hand mixing andthe resulting paste was inserted in the bottom of a glass tube. The electrical connection wasimplemented by a copper wire fitted into the opposite opening of the glass tube. For thecomparission the unmodified carbon paste was prepared. Obtained results show that proposedmodified carbon paste electrode can used for couantitative determination of nitrite inos withdetection limit 1.45*10-6 M and the catalytic rate constant for this process was calculated as2.75*103 M-1 s-1 (Fig 1).

Keywords:

Nitrite ion , Electrocatalytic determination , Nano-zeolite , Voltammetry