CARBON PASTE ELECTRODE MODIFIED BY ZNO NANOPARTICLE FOR CR(VI) ANALYSIS BY VOLTAMMETRY

• Main Author: Triaz Putra, Alvin
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/82982
• Institution: Institut Teknologi Bandung

Chromium is one of the elements that is quite abundant on earth and classified as a heavy metal. Chromium exists in various forms distributed in the natural environment of air, soil, and water. The form of chromium with high toxicity to the environment is Cr(VI), which has a higher solubility compared to Cr(III). The impact of heavy metal Cr(VI) when entering the body in excessive amounts includes being carcinogenic, disrupting the respiratory tract, and affecting secretory tissues such as the kidneys and liver. Therefore, a method for analyzing Cr(VI) that can serve as a preventive reference is needed. Voltammetry is a suitable method for measuring processes involving reduction and oxidation, has high sensitivity, and is easy to use. In this study, ZnO nanoparticles were used as a modifier for carbon paste electrodes (CPE) to enhance the sensitivity of the CPE used. The steps undertaken in this study included the fabrication and characterization of the Ag/AgCl reference electrode with a result of Ipc/Ipa = 1,023 dan ?E = 0,011 V. Next, the fabrication of CPE modified with ZnO nanoparticles was performed. In measuring Cr(VI) ion solutions, ZnO-CPE provided higher currents compared to unmodified CPE. ZnO-CPE 7% w/w and the SWV voltammetry technique were found to be the optimal composition and technique for the measurement. During measurement by ZnO-CPE, the Cr(VI) ion solution had an optimum pH of 1, with the process occurring on the ZnO-CPE surface being controlled by diffusion. ZnO-CPE had two linear measurement regions, namely 1 µM - 10 µM (R2 = 0.9954) and 10 µM - 100 µM (R2 = 0.9933), with a detection limit of 0.448 µM. The fabricated ZnO-CPE demonstrated repeatability of up to 40 measurements and could be reproduced with consistent results. ZnO-CPE also has good selectivity. When measuring river water samples, a comparison was made between the voltammetry method and the atomic absorption spectroscopy (AAS) method, showing that the data from both methods were homogeneous and not significantly different.