EFFECT OF CRYSTALLINITY OF NANOMAGNETITEAS ACARBONPASTEELECTRODE MODIFIER ITS PERFORMANCE IN DETERMINATION OF IODIDE IN CYCLIC VOLTAMMETRY

• Main Author: Saprudin, Deden
• Format: Dissertations
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/34553
• Institution: Institut Teknologi Bandung

Iodine is one of the biologically important element, adults need 100-150 µg / day. To meet this need, it is often added to the potassium iodide or potassium iodate in table salt. Methods of detection of trace amounts of iodine such as UV-Vis spectrophotometry methods, catalysis, chromatography, ion selective electrode, cyclic voltammetry, and ICP-AES, but the methods are plagued by the presence of chloride. Anodic stripping voltammetry method using colloidal shaped nanoparticles of silver sulphate are impregnated on graphite has been successfully developed to determine iodide in table salt. The use of this nanoparticle is less friendly to the environment. The use of platinum-coated electrodes PAMDAN (Poly 8-( 3-acetylimino-6-methyl-2 ,4-dioxopyran)-1-aminonaphthalene) in the analysis of iodide has affected by perchlorate. Nanomagnetite (Fe3O4) are environmentally friendly and has been widely used as an electrode modifier in sensors and biosensors. The use magnetite to detect heavy metals (Pb 2 +) has been successfully carried out. In this method, a suspension of magnetite placed on the surface of glassy carbon. In order to increase adsorbtion of Pb2+ ion on the electrode surface, it is necessary to add iodide to form complex compounds, PbIn(n-2) - are easily adsorbed by magnetite that sensitivity increased by 10 times when compared to not using magnetite. Meanwhile, the use of nanomagnetite for analysis of ascorbic acid has elektrocatalysis effect, so as to shift the peak of the oxidation of ascorbic acid to a more easily oxidized (low potential). It was also reported that magnetite made by hydrothermal processes (high temperature and pressure) provides a significant improvement compared to the current magnetite made at normal temperature and pressure. Magnetite by hydrothermal synthesis by varying the synthesis time giving different degrees of crystallinity. In synthesis, usefour types of chemicals ie, FeCl3, urea, sodium citrate, and polyacrylamide. Among the four materials, polyacrylamide is a material that is expensive and relatively difficult to obtain. To increase the use of nanomagnetit in agriculture and address the problem of environmental pollution required nanomagnetit creation of simple, easy, and inexpensive, with good quality. Synthesis without polyacrylamide be a challenge for researchers. The difference in the degree of crystallinity of magnetite will affect the adsorption of a molecule or ion on the surface of magnetite. A large number of ions that move to the surface of the electrode will affect the resulting current, so it will affect the performance of the electrode in response to an ion. These responses can be seen from the resulting cyclic voltammograms. Because nanomagnetit has a good electrocatalysis and electrochemical capacitors, then the material has potential use as a carbon paste electrode modifier for the analysis of iodide, as well as initial assessment for use as a replacement anode for solar cells using platinum. This study consists of three main stages, namely synthesis nanomagnetite, electrode manufacture, and testing of magnetite as carbon paste electrode modifier for iodide analysis by voltammetry technique. Synthesis of magnetite nanoparticles carried by hydrothermal technique. To determine the success of the synthesis, the results obtained were characterized by XRD, SEM-EDS. Furthermore, the three types of electrodes made, ie electrode Ag / AgCl, carbon paste electrode (EPK), and EPK modified magnetite. After that, testing of magnetite as a modifier EPK for iodide analysis done by observing the effects of magnetite, magnetite crystallinity effects, scan rate, electrolyte concentration, the concentration of iodide ions are bullies to the signal generated in the cyclic voltammetry technique. Nanomagnetit is synthesed by hydrothermal for 3, 6, and 12 hours with three ingredients, namely FeCl3, urea, and sodium citrate produce the degree of crystallinity, respectively 47.81%, 77.15%, and 84.67%. These three ingredients can increase the oxidation peak current iodide in medium KCl respectively, 1.25 times, 1.50 times and 3,00 times when compared to carbon paste electrodes only. With increasing content of nanomagnetit (5, 10, 15%) in the carbon paste electrode, the oxidation peak currents rise linearly iodide concentration. Data from the slope of the curve between the current peak and root-scan rate, with increased crystallinity will increase the slope of the curve, which is proportional to the increase in effective surface area of electrode. Nanomagnetit with high crystallinity (about 85%), has linierity for iodide concentration and anodic peak current (R2 = 0,994), limit of detection 1,4 µM, limit of quantization 4,2 µM, high selectivity towards NaCl, and KBr.